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178 Cards in this Set
- Front
- Back
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list 5 infection prevention measures
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Glove use
Hand hygiene Isolation and barrier precautions Antibiotic restriction Environmental disinfection |
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areas of the body colonized w/ varying numbers of aerobic colonizing flora
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Perineal & inguinal areas = 5 x 106 CFU/cm2
Scalp = 1 x 106 CFU/cm2 Axilla = 5 x 105 CFU/cm2 Abdomen = 4 x 104 CFU/cm2 Forearm = 1 x 104 CFU/cm2 |
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bacterial count on hands of medical personnel
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Bacterial counts on hands of medical personnel = 4 x 104 to 5 x 106
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charicteristics of resident flora on the skin
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Attached to deeper layers of skin
Less likely to be associated with health-care associated infections Resistant to removal |
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charicteristics of transient flora on the skin
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Colonize superficial layers of skin
Most frequently associated with healthcare-associated infections Often acquired by healthcare workers during direct patient contact or after contact with contaminated environmental surfaces More easily removed by routine handwashing |
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common organisms on intact skin and number range?
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Organisms present on intact skin can vary from 102 to 106 CFU/cm2
S. aureus, Enterococci, Proteus, Klebsiella, Acinetobacter |
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How much skin cells are shed each day containing viable bacteria? Can that shedding spread pathogens?
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Normal skin sheds approximately 1,000,000 squamous cells containing viable bacteria each day
Patient gowns, bed linens, bedside furniture, etc. easily contaminated Direct patient contact not required for transmission of potential pathogens to occur |
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which hand hygiene agent works the fastest and is broad spectrum (Gram+/-, mycobacteria, fungi, viruses)
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alcohols
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which hygeine agent is used tyupically for surgical scrubs because of intermediate action and spectrum mainly against bacteria and viruses?
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chlorhexidine
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what are the other types of hand hygeine agents besides alcohol and chlorhexidine that can be used?
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iodine, iodophores, phenols, triclosans, benzalkonium chloride
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selected indications for decontamination (wash using and alchohol based product)
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Before direct contact with patients
After contact with a patient’s intact skin After contact with fluids, mucous membranes, nonintact skin, dressings After contact with medical equipment, other inanimate objects in direct vicinity of patient (including patient charts, medications, IV pumps, etc.) After removing gloves |
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selected indications for handwashing
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Before eating
After using restroom If hands are visibly soiled or contaminated with blood or other body fluids, substances |
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proper methods for handwashing
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During handwashing, hands should be rubbed together vigorously for at least 15 seconds
Water first Soap second Rub & rinse well |
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when should gloves be worn?
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Gloves should be worn as part of routine universal precautions whenever contact with blood, body fluids, etc. are expected or possible
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Additional infection prevention for select patients
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Strictly obey posted instructions for patients with various other infection prevention considerations:
Contact precautions MRSA, VRE, C. difficile, MDR Acinetobacter, other Neutropenic precautions Respiratory isolation |
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Initial assessment for antibiotic use
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History:
***Including prior antibiotic exposure Physical exam Laboratory data Other risk factors, e.g.: Travel history Exposure to other infected patients Community- or hospital-acquired? |
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Indications for antibiotic(AB) therapy
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Localized infections
Presumed infections, moderately to severely ill Sepsis Febrile neutropenia patients Endocarditis Meningitis Cellulitis Is the clinical syndrome infectious in origin? What is the risk of not treating? |
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WBC evaluation for AB use
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absolute WBC elevation
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what is a left shift?
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“Left shift” based on number of immature neutrophils present (a.k.a. bands, segs)
higher than normal |
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types of WBCs (differential)
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Neutrophils (a.k.a. PMNs, polymorphonuclear leukocytes) = bacterial and fungal infections
Lymphocytes = viral infections Monocytes = certain bacteria such as Listeria monocytogenes or M. tuberculosis Eosinophils = allergic reaction, parasitic infections Basophils = allergic response |
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why is there a left shift in severe, acute infections?
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immature neutrophils are a signal of active immune response..
the body dumps all neutrophils from bone marrow to treat the infection, even before they are mature |
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example of a left shift...which white cell is important?
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Bands: 13% (normal 0-9%)
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A patient has a WBC of 15,000 and a differential as follows: neutrophils 76%, bands 3%, lymphocytes 19%, monocytes 2%. These results would be described as:
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Leukocytosis without left shift
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normal absolute WBC count
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5,000-10,000
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normal neutrophil predominance
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40-70%
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ways to obtain appropriate clinical specimens
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Obtain appropriate specimens before initiating or changing antibiotic therapy
Minimize contamination(clean urine sample, etc) Obtaining cultures should not cause unnecessary delays in initiating antibiotic therapy The sicker the patient & more severe the infection, the less time should be required to initiate antibiotics (ex. sepsis) |
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clinical realities to culture results
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Ideally, you’d like to have culture results (both identification and susceptibilities) before beginning antibiotic therapy
BUT Culture sensitivity is highly variable depending on timing, specimens, and actual pathogen(s) Specimens often contaminated Cultures often difficult or impractical Painful and/or invasive procedures High risk of complications from sample collection High rate of sample contamination at some sites |
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determining the most likely organism?
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Clinically relevant pathogens based on type/site of infection
Method of acquisition (e.g. travel history, exposure history) Hospital-acquired (nosocomial, healthcare-associated) Community-acquired Patient-specific factors Age Immune status Underlying illness Previous antimicrobial therapy |
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Goal of AB therapy?
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CURE of infection
Supportive care (adjunctive therapy) Pain management Primary care: fluids, antipyretics, decongestants, cough suppressants, expectorants Intensive care: hemodynamic support, respiratory support, nutrition Prevention of complications |
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determining the best antibiotic?
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Activity & efficacy against suspected or known pathogen
Clinical efficacy vs. in vitro activity Narrow vs. broad spectrum of activity Bactericidal vs. bacteriostatic Resistance issues --Local prevalence --Use best available information for empiric selection |
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Risks associated with use of broad specturm AB regimens include:
Potential for increased antibiotic resistance Potential for superinfections Increased toxicities All of the above None of the above |
Answer: All of the above
Potential for increased antibiotic resistance Potential for superinfections Increased toxicities |
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what is an antibiogram?
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table that tells which organism is susceptible to which drugs
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choosing the best AB based on host factors?
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Age
Allergies Prior antibiotic therapy Immunosuppression Prosthetic devices Concurrent disease states Renal and hepatic function Site and severity of infection Penetration of drugs to site of infection Desired routes of administration Potential adverse effects of drugs Compliance issues Cost--last thing to look at after taking into account all other factors |
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AB drugs of choice for pregnancy to lactation
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PCN, cephs, erythro base, aztreonam
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AB cautionary drugs in pregnancy/lactation
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Caution: AG, vancomycin, clindamycin, imipenem/cilastatin, TMP
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contraindicated AB drugs in pregnancy and lactation
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chloramphenicol, erythro estolate, tetracyclines, FQs, SMX, metronidazole
Breast milk: Chloramphenicol, tetracyclines, metronidazole, FQs |
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PK factors in choosing AB therapy?
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Tissue penetration
Route of elimination Oral versus parenteral therapy Duration of administration |
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side effect concerns for choosing AB therapy
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Avoid or reduce overlapping toxicities
Minimize adverse effects |
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alterations in organ/body systems in critically ill patients
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GI failure
hepatic dysfxn CNS dysfxn CV failure neuromuscular dysfxn immunologic failure respiratory failure renal failure endothelial failure endocrine dysfxn ***PK/dosing issues |
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compliance considerations in choosing AB therapy
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Dosing frequency and # of drugs
Adverse effects Taste |
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cost considerations when choosing AB therapy
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Antibiotic, IV vs. IM vs. PO, monitoring of toxicity, # of drugs, frequency of dosing, availability of generics
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determining need for combination AB thearpy
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Multiple organisms causing infection
Infection at single site may be "mixed" infection May have more than one site of infection Antimicrobial synergy against infecting organism(s) Pseudomonas aeruginosa Enterococcus spp. Staphylococci |
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Aims of combination AB thearpy
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Prevent emergence of drug resistance during therapy
Serratia marcescens Pseudomonas aeruginosa Acinetobacter spp. Citrobacter spp. Enterobacter cloacae Mycobacterium tuberculosis Reduce toxicities and cost through use of reduced doses Decreased duration of therapy by more rapid or more complete eradication |
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potential disadvantages of combination therapy
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Increased resistance
Increased risk of superinfection Increased toxicities Increased potential for drug interactions Increased costs |
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route of administration:
mild infections |
consider topical vs. oral therapy
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route of administration:
moderately sever infection |
consider oral vs. IV / IM therapy
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route of administration:
severe infection |
IV therapy
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IV to PO conversion?
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major consideration for many infections, change over whenever possible
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should all pts. with moderate-severe infections recieve IV antibiotics as initial thearpy?
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IV drugs should be used initially in many but not all cases, but should quickly be switched to PO drugs
*important to choose the right drug(can be oral) |
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choosing appropriate dose for AB therapy?
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The lowest dose of antibiotic that will provide the desired effect is used
Consider PK/PD principles and goals when deciding what the “lowest” dose might be Lowest effective dose lowest FDA-approved dose Lowest effective dose least expensive dose Aggressive dosing required in many clinical situations due to PK/PD variability |
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choosing duration of therapy for AB therapy?
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Poorly defined for many infectious diseases
Duration may depend on many factors Infecting organism Location of infection Host factors Response to therapy Antibiotic selected Comfort level of providers |
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monitoring parameters for AB therapy:
Efficacy? |
Efficacy parameters: resolution of signs/symptoms
Vital signs Fever may be masked by age, NSAIDs, steroids, immunosuppression Fever may also be caused by non-infectious sources: malignancies, drugs, inflammatory diseases Specific signs & symptoms of infection Local signs = erythema, swelling, discharge, pain Systemic signs = myalgia, arthralgia, heart and respiratory rates, blood pressure History of illness White blood cell (WBC) count with differential Absolute WBC elevation Type of white cells "Left shift" Culture and susceptibility results Gram stain Cultures Susceptibilities Biological fluid chemistry and/or cell count Antigen detection (e.g. Group A streptococci, Legionella spp.) Serological antibody testing (e.g. Chlamydophila, HIV) IgG, IgM titers Radiologic Tests Chest radiograph Computed tomography (CT) scans Magnetic resonance imaging (MRI) Acute phase reactants Erythrocyte sedimentation rate (ESR) C-reactive protein (CRP) Platelets |
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monitorying parameters for AB therapy:
safety? |
Safety of therapy - dependent on drug(s) being used
Subjective reports/complaints Physical exam Labs |
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monitoring parameters for AB therapy:
Patient counseling |
Resolution of signs and symptoms
Potential drug toxicities Potential drug interactions Compliance issues Need to take full course of therapy |
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De-escalation of therapy
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Defined as adjustment of antibiotic regimens based on culture & susceptibility data
Discontinuation of unnecessary antibiotics from multi-drug empiric regimens Changing broad-spectrum agents to narrower-spectrum drugs Also involves stopping antibiotics when possible Lack of proven infection Favorable clinical response & reasonable duration |
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Host factors influencing clinical outcomes
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genetic determinants
underlying illnesses altered PK/PD |
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drug factors influencing clinical outcomes
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MOA
in vitro MICs PK properties |
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Bug factors influencing clinical outcomes
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virulence factors
intrinsic susceptibility resistance mechanisms |
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iatrogenic reasons for clinical AB failure
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Incorrect diagnosis
Delay in initiating antibiotic therapy |
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drug factors for clinical AB failure
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Inappropriate drug
Suboptimal dose Poor drug absorption Lack of penetration to site of infection Unusual dug clearance Emergent resistance |
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host factors for clincal AB failure
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Severe underlying diseases/ “poor protoplasm”
Immunocompromised, elderly, critically ill, chronic underlying disease, malnutrition Non-compliance |
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microbial factors for clinical AB failure
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Resistant pathogens
Untreated pathogens (not covered by selected antimicrobials) Unusual pathogens not covered by selected antimicrobials |
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non-drug related reasons for apparent AB failure
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Noninfectious sources of fever, leukocytosis
Unfavorable conditions at site of infection New sites of infection Superinfection ***Normal variation in clinical course of the infection and/or underlying diseases |
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CAP occurence
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CAP occurs throughout the year
Great variability in relative incidence within certain populations or caused by certain pathogens Most common and severe in very young, elderly, and patients with chronic underlying diseases Mortality rates vary from <1% in outpatients to 30-40% in severely ill hospitalized patients |
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pathogenesis of CAP
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Pathogens gain entry to lower airways through:
Aspiration of oropharyngeal secretions Inhalation of aerosolized particles Hematogenous spread Infections involve alveolar spaces, inflammation and destruction of alveolar membranes and terminal bronchioles |
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most common way to aquire CAP
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microaspirations of oropharyngeal secretions
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complications of CAP
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abscess, empyema, sepsis, ARDS, metastatic spread to other organs
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alveolar spaces normal vs. CAP
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normal: spongy, spacey
CAP: spaces are packed with WBCs, fluids, etc...obliterates gas exchange |
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normal host defenses of the respiratory tract
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Gag reflex
Antimicrobial substances on mucosal surfaces Lysozyme Lactoferrin Secretory IgA Mucous production Ciliary “sweeping” actions Coughing & sneezing Alveolar macrophages Lung surfactant |
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risk factors for CAP
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Risk factors for infection are those that result in compromised host defense mechanisms of the respiratory tract and/or increased risk of aspiration:
advanced age chronic pulmonary disease neurologic disorders CHF chronic liver dx chronic renal dx neoplastic dx DM immunosuppression neutropenia cigarrete smoking alcoholism |
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pathologic etiology of CAP
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Causative pathogen identified in only 30-50% of CAP cases
Most bacterial CAP caused by single pathogen, although polymicrobial infection can occur Atypical pathogens cause approximately 20% of all cases of CAP, but greatly increased in outpatient infections Commonly referred to as “walking pneumonia” May occur concomitantly with “typical” infections |
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is most CAP mono or polymicrobial?
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mono
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most common microbial pathogens in CAP
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The "Big three"
Streptococcus pneumoniae 20-60% Haemophilus influenzae 3-10% Moraxella catarrhalis |
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mortality rates associated with CAP pathogens
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Pseudomonas 61%
Klebsiella 36% Staph. aureus 32% Not common, but significant mortality |
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CAP: aspiration pneumonia
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Occurs in patients who aspirate large volumes of oropharyngeal secretions
Alcoholism, seizure disorders, general surgery, CVA, drug intoxication, head injury, severe illness with obtundation, neurologic disorders, esophageal dysfunction, nasogastric feedings, tracheotomy, endotracheal tubes, periodontal disease Commonly associated with, and treated as, anaerobic infection Commonly involve mixed aerobic/anaerobic infections |
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what additional microbes do you need to treat with aspiration risk?
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anaerobes
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clincal presentaiton: CAP
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Typically includes fever, chills, dyspnea, productive cough, tachycardia, tachypnea, chest radiograph abnormalities
Signs and symptoms do NOT easily differentiate between specific causative pathogens Most “typical” bacterial pneumonias are unilateral and involve single lobe of lung |
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what pathogens cause "atypical" CAP
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legionella
chlamidophila pneumoniae mycoplastma peneumoniae |
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clinical presentation of typical CAP
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sudden onset
toxic, ill appearance high fever >39C elevated WBC with left shift, sometimes leukopenia possible chills, rigors productive, prululent cough bacteria, WBCs on gram stain cyanotic, increased RR, chest pain, pleural pain dense lobar infiltrates, consolidation on chest radiograph |
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clinical presentaiton of atypical CAP
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insidious onset
maliaise, fatigue, diarrhea, muscle aches low grade fever <39C normal, slight WBC elevation chills, rigors absent nonproductive cough, mucus mixed oral flora or no bacteria on gram stain unremarkable RR status patchy, diffuse infiltrates on chest radiograph |
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T.J. is a 23 y.o. female previously in good health. She begins a new semester of graduate school and three weeks later starts complaining of headache, fatigue, lethargy, a nagging cough productive of thin, clear sputum, and a fever of 100oF. Her clinical findings are most consistent with:
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acute atypical pneumonia
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Pathogens most likely associated with T.J.’s infection include:
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mycoplasma pneumonia, and chlamydia pneumoniae
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B.K. is a 68 y.o. male with a history of alcoholism. He is brought to the Emergency Department by his wife after “acting funny” and running a fever. Clinical findings in the ED include fever to 41oC, tachycardia, tachypnea, hypotension, cough productive of thick greenish sputum, and altered mental status. He smells of alcohol and his wife states that he has “been on a binge”. Organisms suspected to be involved in this infection include:
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Streptococcus pneumoniae and oral anaerobes
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outpatient sputum cultures?
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Sputum cultures not universally recommended in outpatients
Usefulness controversial (b/c typically atypicals that dont show up well on gram stain) |
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hospitalized patient sputum cultures/blood cultures?
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In most hospitalized patients: blood cultures x 2, sputum gram stain and culture
Specimens should include >25 PMNs and <10 epithelial cells on high-power microscopic field Gram stains and cultures should usually show a single predominant pathogen Remember that many patients will have no pathogen identified |
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A sputum culture from a woman with suspected pneumonia shows the following on a high-power field: 10-15 PMNs, 30-40 epithelial cells, and many Gram-positive cocci, Gram-negative bacilli, and Grm-negative cocci. This sputum specimen would be considered to be:
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contaminated specimen (mixed oganisms)
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goals of CAP tx therapy
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Goals of therapy
Complete eradication of causative pathogen Complete clinical cure of the infection |
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inpatient vs outpatient CAP tx decision
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Decision to treat patient as outpatient vs. inpatient often regarded as single most important treatment decision
Severity of infection Risk of complications and/or mortality Ability of patients to successfully complete therapy |
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what is PORT/PSI?
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pneumonia severity index
tool for clinician to help make thearpy decision put patients in a Risk Class I-V and mortality rate |
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PSI outpatient risk class
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I-II
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PSI hospital risk class
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IV-V
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PSI clinical judgement class?
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III, short hospital, finish at home?
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non pharm treatment of CAP
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Bed rest
Adequate hydration Humidifier or vaporizer Adequate nutrition Chest physiotherapy Supplemental oxygen Mechanical ventilation |
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pharmacologic treatment of CAP
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Antipyretics
Antitussives (dextromethorphan, codeine) Bronchodilators Antibiotics |
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what is empiric AB CAP tx based on?
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Severity of illness
Risk factors for more resistant pathogens Risk of complicated course, increased mortality |
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TRUST 10:
H. influenzae resistance |
very resistant to ampicillin and TMP-SMX
susceptible: azithromycin, cefuroxime, ceftriaxone, levofloxacin |
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TRUST 6-8:
M. Catarrhalis resistance |
nearly ALL produce beta-lactamase
very susceptible to other agents dont use amoxicillin, ampicillin |
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strep. pneumoniae PCN resistance
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many strains are PCN resistant, but PCN is drug of choice for PCN susceptible strains
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erythromycin non-susceptible strep. pneumoniae high vs low level resistance
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high level: ribosomal methylation
low level: efflux |
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risk factors for drug resistant S. pneumoniae (DRSP)q
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Risk factors for drug-resistant S. pneumoniae (DRSP)
***Recent antibiotic exposure Older patients (age >65 y) ***Multiple medical comorbidities (including COPD, diabetes, renal failure, CHF, or malignancy) Recent stay in hospital of long-term care facility Children in day care + parents, siblings & other close contacts Alcoholism Immunosuppressive illness, drugs |
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considerations for endocarditis prevention
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Cardiac conditions associated with endocarditis
Procedures causing bacteremia Likely pathogens Drugs PK, spectrum of activity, cost, adverse effects, ease of administration |
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high risk for endocarditis
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Prosthetic valves
Previous bacterial endocarditis Cyanotic congenital heart disease Systemic pulmonary shunts or conduits |
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moderate risk for endocarditis
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Valvular dysfunction (e.g. rheumatic heart disease)
Hypertrophic cardiomyopathy Mitral valve prolapse with regurgitation |
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low risk for endocarditis
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Low Risk (prophylaxis not recommended)
Atrial septal defect CABG Mitral valve prolapse without regurgitation Heart murmur Rheumatic fever without valve dysfunction Pacemaker Implanted defibrillator |
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dental procedures where AB prophylaxis is recommended
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Dental extractions
Periodontal procedures (root planting) Dental implant placement Root canal Orthodontic band placement Local anesthetic injections Teeth cleaning where bleeding is anticipated |
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dental procedures where AB prophylaxis is not recommended/necessary
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Restorative dentistry (filling cavities)
Local anesthetic injections (nonintraligamentary) Placement of rubber dams Suture removal Oral impressions Oral radiographs Shedding of teeth Fluoride treatments Placement or removable prosthodontic or orthodontic appliances |
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endocarditis prophylaxis for dental oral or URT procedures:
Standard Regimen KNOW |
amoxicillin 2 grams
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endocarditis prophylaxis for dental oral or URT procedures:
PCN Allergy KNOW |
Most common: Clindamycin 600 mg
or... Cephalexin or cefadroxil 2 g Azithromycin or clarithromcyin 500 mg |
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endocarditis prophylaxis for dental oral or URT procedures:
Unable to take PO meds KNOW |
Standard: Ampicillin 1 g IM/IV
PCN allergy: Clindamycin 600 mg(common) Cefazolin 1 g |
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endocarditis prophylaxis for GU/GI procedures:
High Risk KNOW |
Ampicillin 2 g + Gentamicin 1.5 mg/kg
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endocarditis prophylaxis for GU/GI procedures:
moderate Risk KNOW |
Amoxicillin 2g or Ampicillin 2g IM/IV
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endocarditis prophylaxis for GU/GI procedures:
PCN Allergic, high risk KNOW |
Vancomycin 1g + Gentamicin 1.5 mg/kg
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endocarditis prophylaxis for GU/GI procedures:
PCN Allergic, moderate risk KNOW |
Vancomycin 1g
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why is there a difference b/w dental vs. GI endocarditis prophylaxis?
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want more gram negative coverage for GI/GU procedures
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DF is a 45 yo male who is schedule for a routine teeth cleaning at his family dentist.
PMH: non-significant, except for mitral valve prolapse with regurgitation All: Sulfa Does DF need to receive a prophylactic antibiotic for this procedure? |
Yes,
Moderate risk |
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What Prophylactic antibiotic should DR receive?
(mod risk, dental procedure) |
amoxicillin 2 grams 1 hr prior to procedure
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defn surgical site infections (SSI)
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Infection occurring within 30 days after operation (or within 1 year if implant present)
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2 classifications of SSI
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incisional
organ/space |
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incisional SSI
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infection at incision site
Superficial – skin or subcutaneous tissue Deep incisional – fascia and muscle layers |
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organ/space SSI
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infection of anatomic area other than incision site
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incidence of post op wound infection
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Prevalence of postoperative wound infection
5% (800,000-2,000,000 cases/year) Accounts for 15% of nosocomial infections Primary cause (40%) of infection in surgical patients |
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impact of post op infection
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Increased length of stay (~ 1week)
Increased cost ($1.5 – $10 billion) |
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% post op infection that is preventable
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40-60%
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% of post op infections involved in inappropriate AB use?
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25-50%:
Overuse Underuse Improper timing Misuse |
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what % C. difficile infections are from prophylaxis?
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16%
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complications of SSI
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in order of increased severity:
Cellulitis at incision site Abscess formation Osteomyelitis Mediastinitis (sternum) Meningitis Sepsis Death |
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risk factors for infection
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Degree of bacterial contamination
(depends on location: ex intestine vs. heart) Virulence of infecting organism (staph. most common and most virulent) Host defenses |
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risk factors SSI: Bacterial contamination
exogenous sources |
Operative team
Instruments Airborne organisms |
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risk factors SSI: Bacterial contamination
endogenous sources |
Patient’s skin microflora
Respiratory Genitourinary Gastrointestinal tract |
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risk factor for bacterial contamination
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duration of surgical procedures and hospital stay
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pt. characteristics that influence risk of SSI
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Age(young/old)
Nutritional status Obesity Smoking Malnutrition Diabetes Altered immune response Length of preoperative hospitalization Coexisting infections at remote sites Colonization with Resistant organisms |
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operation characteristics that influence risk of SSI
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Duration of surgical scrub
Preoperative skin preparation Preoperative shaving Duration of operation OR ventilation Instrument sterilization Implantation of prosthetic material Surgical drains Surgical technique |
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SENIC risk factors
(study of efficacy of nosocomial infection control) |
score of 0-4
Abdominal surgery Operations > 2 hours ≥ 3 associated diagnoses Contaminated or dirty procedures |
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surgical wound classification:
Clean KNOW |
No acute inflammation or entry into GI, respiratory, GU, or biliary tracts
Aseptic technique maintained Closed wound |
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surgical wound classification:
Clean-Contaminated KNOW |
Controlled opening of GI, respiratory, biliary, or GU tract without significant leakage
Clean wounds with major break in aseptic technique |
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surgical wound classification:
Contaminated KNOW |
Penetrating trauma (<4 hours old)
Major break in aseptic technique or major leakage from GI tract |
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surgical wound classification:
Dirty KNOW |
Penetrating trauma (>4 hours old)
Preoperative perforation of viscera |
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SENIC wound infection rates findings:
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infection rate incrased as the classification of wound increases from clean-->dirty
pts. will need treatment, not just prophylaxis |
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microbiology of SSI common pathogens
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mostly skin microbes:
Staph. aureus 20% coag neg. staph 14% Enterococcus 12% E. coli 8% Pseudomonas 8% Enterobacter 8% Candida 3% Colon: anaerobes bowel/abdomen: gram negative |
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AB is a 60 year old white male admitted to UCH with chest pain. His past medical history is significant for 2 MIs. Cardiac catheterization reveals > 90% occlusion in the LAD and circumflex vessels. He is schedule for an emergent CABG.
PMH: Diabetes, CAD Allergies: NKDA Should AB receive prophylaxis for his CABG surgery? |
yes
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determining if prophylaxis is necesssary
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Ask: Is prophylaxis necessary
What agent is preferred Appropriate time of administration How many doses? Re-dosing during surgery Post-operative duration |
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Defn: prophylaxis
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Antibiotic given for the purpose of preventing infection when infection is not present, but the risk of post-operative infection is present
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Ideal Prophylactic agen
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Easy to administer
Covers most likely pathogens Low cost Single dose Minimal adverse effects Does not induce resistance |
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benefits to AB prophylaxis
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Prevent surgical site infections
Decrease morbidity and cost decrease LOS |
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risks of prophylaxis
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Drug toxicity
Selection of resistant organisms Superinfection Cost of therapy |
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methods for maximizing prophylaxis
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Use agent that has been shown in clinical trials to reduce SSI or in operations in which incisional or organ/space SSI would be catastrophic
Use safest agent, inexpensive and bactericidal with spectrum of activity that covers most probable pathogens Give antibiotic infusion so that bactericidal concentrations are present in tissues at time of incision Maintain therapeutic levels for duration of surgery and preferable for a few hours after closure |
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when should timing of pre op prophylaxis dose occur?
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30 minutes or less prior to incision bc want peak conc. to occur 30 mins or less before operation
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when is it ok to give prophylaxis immediately after incision
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C-section, to avoid exposure of drug to the baby
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prophylaxis timing and rates of SSI: when its best to give AB
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0-2 hrs before procedure is lowest risk <1% b/c highest peak conc. of AB at that time compared to >2 hrs before and 0-3+ hrs after procedure
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Intraoperative doses of AB prophylaxis?
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Maintain therapeutic tissue concentrations at time of surgical site closure
Dosing frequency Dependent on half-life Dose every two half-lives Typically one dosing interval shorter than normal e.g. Cefazolin (t1/2 = 2hrs) q4 hrs rather than q6 hrs Agents with long half-lives may not require re-dosing (e.g. vancomycin in a renal failure patient) |
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how often are intraoperative doses given for prophylaxis?
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every 2 T1/2s
ex: Cefazolin T1/2=2 hrs, so it is dosed intraoperatively every 4 hrs |
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KNOW how to dose intraoperative prophylaxis
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T1/2 given on exam
dose every 2 T1/2s |
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Recommendations for No prophylaxis in surgery?
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Clean surgery
Exceptions: Implantation of prosthetic material Significant morbidity associated with infection (CABG, Neurosurgery, Vascular) |
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Exceptions for prophylaxis for clean surgery?
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Implantation of prosthetic material
Significant morbidity associated with infection (CABG, Neurosurgery, Vascular) b/c high risk of complication if an infection occurs |
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recommendations for prophylaxis in surgery?
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Clean-Contaminated
Contaminated wounds |
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recommendations for treatment, not just prophylaxis in surgery?
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Dirty surgeries
b/c the pt. is likely already infected |
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Typical drug choices for AB prophylaxis
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Cefazolin (gram +)
Cefotetan/Cefoxitin (gram+/-anaerobe) Vancomycin (MRSAS, beta lactam allergy) Others (PCN allergy) |
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when to use Cefazolin
KNOW |
Excellent Gram (+) activity
S. aureus Preferred agent unless allergy or need for anaerobic coverage Limit duration to ≤ 24 hours Typically only need 1 dose Inexpensive |
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when to use cefotetan or cefoxitin
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Added coverage against anaerobes
Bacteroides fragilis Use in intraabdominal surgeries Appendectomy Colorectal Hysterectomy |
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when to use vancomycin for prophylaxis?
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High suspicion of resistant organism
MRSA Severe allergy to beta-lactams Half-life dependent on renal function Possible re-dosing advantage Administer pre-op dose over 60 minutes Limit use due to possible resistance development VRE, VISA, VRSA |
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how to admin pre op dose of vancomycin?
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over 60 mins to avoid red man syndrome
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other drugs used for prophylaxis:
options for PCN allergic pts. |
Gentamicin ± Clindamycin or Metronidazole
**Levofloxacin + metronidazole or moxifloxacin Limited data on fluoroquinolones Not generally recommended due to resistance concerns GU procedure: ciprofloxacin or other fluoroquinolone |
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45 year old male with Crohn’s Disease scheduled for an elective colon resection
Allergy: Penicillin What are the most likely pathogens? |
pathogens: anerobes
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normal flora intra-abdominal surgeries
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High content of facultative and anaerobic bacteria
E. coli and other gram (-) Enterococcus B. fragilis Role of Enterococcus is controversial |
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use of nonabsorbable agents?
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Sterilization of gut flora
Use agent with in vitro activity against gut flora Reduce complications from leakage or translocation of bacteria from gut Reduction of post-op infection rates 40% to <10% |
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non and semi-absorbable agents for colorectal procedures
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Neomycin Sulfate
Gram (-) coverage 1 gm orally for 3 doses prior to surgery Erythromycin 1 gm orally for 3 doses *give one or both also: Mechanical cleaning (definite) Mannitol electrolyte solution Polyethylene glycol Fleet’s phospho-soda |
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45 year old male with Crohn’s Disease scheduled for an elective colon resection
Allergy: Penicillin What is the most appropriate prophylactic regimen for this patient? |
IV agent to cover skin flora, gram -/+, and anaerobic during procedure
mechanical cleaning Neomycin+/- erythromycin |
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Duration of prophylaxis?
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Pre-operative dose only when appropriate
Some procedures may warrant 24 - 48 hour administration CABG, Orthopedic joint replacement Typically no need for prophylaxis > 24 hours If patient is thought to be infected then start antibiotic treatment |
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Topical decontamination:
Nasal colonization |
Nasal Colonization
S. aureus colonizes the nares Risk factor for SSI 2 small prospective trials Cardiac and Gastrointestinal surgery Used Mupirocin 2% to eradicate S. aureus in nares Reduced SSI incidence compared to historical controls *esp. heart surgery |
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Topical decontamination:
S. aureas/others colonize in oral mucosa/skin |
Chlorhexidine
Oral swab – oral solution Baths – Chlorhexidine impregnated washcloth |
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Adverse effects of prophylaxis
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Drug related toxicities
Clostridium Difficile Vancomycin Resistant Enterococcus Development of bacterial resistance Emergence of superinfections Fungal, etc. |
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SSI prophylaxis monitoring
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Monitor incision site
Clinically apparent within 30 days Abscess or deep seeded infection may occur weeks to months after procedure Prosthetic implants may become infected up to a year after surgery Look for purulent drainage |
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BC is a 26 year old female scheduled for an appendectomy at 8am. The procedure is expected to take 2 hours. They expect a clean-contaminated procedure.
What is your recommendation for prophylaxis? |
cefotetan 1gram IV x1
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Drug(s) of choice Clean Procedure Prophylaxis:
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Cardiac
Sternotomy, cardiopulmonary bypass Pathogens – S. aureus, S. epidermidis Cefazolin or Vancomycin Vascular Aortic resection, groin incision, prosthesis Pathogens – S. aureus, S. epidermidis, gram negative enterics Cefazolin or Vancomycin Orthopedic Total joint replacement, internal fractures Pathogens – S. aureus, S. epidermidis Cefazolin or Vancomycin Neurosurgery Pathogens – S. aureus, S. epidermidis Cefazolin or Vancomycin ***Cefazolin drug of choice, VAN only if allergic or MRSA risk |
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Drug(s) of choice Clean contaminated prophylaxis:
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Head and Neck
S. aureus, oral anaerobes, streptococci Cefazolin (Clindamycin ± gentamicin) Gastoduodenal Gram-negative enterics, S. aureus, mouth flora Cefazolin(b/c not below duodenum) Colorectal Gram-negative enterics, anaerobes (B. fragilis) Cefoxitin, cefotetan, neomycin, erythromycin Appendectomy Gram-negative enterics, anaerobes (B.fragilis) Cefotetan or Cefoxitin |
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Drug(s) of choice clean contaminated prophylaxis:
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Biliary tract (High risk only)
Gram-negative enterics, E. faecalis, Clostridia Cefazolin Cesarean section Group B strep, enterococci, anaerobes, gram-negative enterics Cefazolin Hysterectomy Group B strep, enterococci, anaerobes, gram-negative enterics Vaginal – Cefazolin; Abdominal - cefoxitin, or cefotetan Genitourinary (High risk only) Gram-negative enterics, enterococci Ciprofloxacin |
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JL is a 52 year old male scheduled for a appendectomy at UCH tomorrow.
This is a clean-contaminated procedure PMH: Noncontributory All: PCN (rash), Cephalosporins (hives) What is the most appropriate antibiotic prophylaxis regimen to use in JL? |
Rash: no cefotetan
Give: levofloxacin + metronidazole |
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Summary of AB prophylaxis
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Surgical site infections (SSI) have significant morbidity and associated cost
Risk factors Common pathogens Antimicrobial prophylaxis significantly reduces SSI in patients at risk Timing and duration of prophylaxis is important to effectiveness and safety of regimen Risks and benefits of antibiotic prophylaxis Risk stratify endocarditis Optimal regimen for colon procedures |
