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161 Cards in this Set

  • Front
  • Back
What are Nosocomial Infections?
Infections which are a result of treatment in a hospital or a healthcare service unit, but secondary to the patient’s original condition.
What is the easiest/best way to prevent Nosocomial Infections?
Hand Washing.
What are some of the reasons why nosocomial infections are so common?
Patients are sicker when admitted, Medical staff move from patient to patient providing a way for pathogens to spread, Many medical procedures bypass the body’s natural protective barriers, Crowded hospitals, ER overflow, Patients are very mobile within the hospital, New microorganisms, Increasing bacterial resistance to antibiotics, Comorbidities,and Sanitation protocols are not followed properly or fail.
Name some of the most common nosocomial bacteria.
-Ventilator associated pneumonia
-Staph. aureus
-Methicillin Resistant Staph aureus
-Pseudomonas aerugenosa
-Clostridium difficile
-Tuberculosis (there is a resurgence)
What do you are the most common nosocomial infections?
-Urinary tract infections (#1)
-Pneumonia (resp. inf.)
-Diarrhea
-Wound infections (Infections following surgery)
-Gastroenteritis
Name the easiest, most obvious thing we can do to help prevent nosocomial infections?
Hand Washing.
What is a Host?
Any organism capable of supporting the nutritional and physical growth requirements of another organism.
What is an Infection?
The presence and multiplication of a living organism on or within the host.
Infection is used interchangeably with what term?
Colonization
What is Mutualism?
An infection in which the microbe AND the host derive benefit.
What is a Parasitic relationship?
One in which ONLY the infecting organism derives benefit.
If the host sustains injury or pathologic damage in response to a parasitic infection, the process is called what?
Infectious Disease
What is Virulence?
Disease-producing potential.
What is commensalism?
Microogranisms acquire nutritional needs and shelter, but host is not adversely affected.
What are the colonizing microbes called that acquire nutritional needs and shelter, but host is not adversely affected?
Commensal flora.
Microorganisms capable of producing an infectious disease when the health and immunity of the host have been severely weakened by illness, famine, and medical therapy are called what?
Opportunistic pathogens
What are protein particles that lack any kind of demonstrable genome, however they are infectious and capable of causing disease?
Prions
Normal proteins to prion proteins .
PrPc to PrPsc.
What are are the smallest obligate intracellular pathogens?
Viruses.
What is the Protein coat around a virus called?
Capsid.
T/F
Viruses have possess both RNA and DNA within their capsids.
False.
How do Retroviruses work?
1) Viral RNA genome is first translated into DNA by reverse transcriptase.
2) Viral (translated) DNA integrated into host chromosome where it remains latent.
What are Oncogenic viruses?
Viruses that have the ability to transform host cells into malignant cells.
How are Viruses Classified?
-Type of viral genome
-Mechanism of replication
-Mode of transmission
-Type of disease produced
What are autonomously replicating unicellular organisms (known as prokaryotes)?
Bacteria.
What are the following shaped also known as: Spherical, Helical, Elongated?
Spherical = Cocci
Helical = Spirilla
Elongated = Bacilli
What are whiplike appendages on some bacteria which make them motile?
Flagella
What are hair-like structures projecting from the surface which aids adherence to mucosa or other bacteria?
Pili or Fimbriae
What determines the microscopic shape of the bacterium?
Structure and synthesis of the cell wall .
What are:
Cocci reproducing in chains called?
Cocci reproducing in pairs called?
Cocci reproducing in clusters called?
Cocci reproducing in chains = streptococci
Cocci reproducing in pairs = diplococci
Cocci reproducing in clusters = staphylococci
Each individual species has a well-defined growth parameters: nutrition, temperature, light, heat, and atmosphere. Provide the proper nomenclature for the following definitions:
1) Extremely strict growth parameters
2) Requires oxygen
3) Cannot survive in oxygen environment
4) Can adapt metabolism to aerobic or anerobic environment
1) Fastidous = extremely strict growth parameters
2) Aerobes = require oxygen
3) Anerobes = cannot survive in oxygen environment
4) Facultative anerobes = can adapt metabolism to aerobic or anerobic environment
What are the general Spirochete characteristics?
-Technically gram-negative rods
-Cell’s shape is helical and length is many times its width
-Series of filaments are wound around the cell wall and propel the organism liked a corkscrew
-Anaerobic or facultative anaerobic
What are the three Spirochete genus?
Leptospira, Borellia, and Treponema.
What are the three Mycoplasma genus that infect humans?
Mycoplasma, Ureaplasma, and Acholeplasma.
What are the major characteristics of Rickettsiae, Chlamydiae, Ehrlichieae, Coxiella?
-Obligate intracellular pathogen like viruses
-Produce a rigid peptidoglycan wall like bacteria
-Reproduce asexually by cellular division
-Contain both DNA and RNA
What is the defined life cycle of Chlamydiae?
Elementary body -->
reticulate body inside host cell --> active replication into multiple elementary bodies -->
shed into extracellular area to start new cycle
Molds produce long, hollow, branching filaments called what?
Hyphae
What are Fungi incapable of growing at body core temp and therefore only grow on the skin?
Dermatophytes
What are fungi that can grow at core body temperature (and potentially cause infections)?
Systemic mycoses
What is Incidence?
The number of new cases of an infectious disease that occur within a defined population over time.
What is Disease prevalence?
The number of active cases at any given time.
What is Endemic?
Disease numbers in a geographical area if the incidence and prevalence are expected and relatively stable.
What is Epidemic?
An abrupt and unexpected increase in the incidence over endemic rates
What is Pandemic?
The spread of disease beyond continental boundaries.
What is Portal of entry?
Process by which pathogen enters the body, gains access to susceptible tissues, and causes disease
What are the major potential modes for portal of entry?
Penetration, direct contact, ingestion, inhalation.
What is the most common vertically spread infection in US?
CMV
What is the collection of signs and symptoms expressed by the host during the disease process?
Symptomatology (also known as “clinical picture” or “disease presentation”).
What is the outward expression of the struggle between invading organisms and the retaliatory inflammatory and immune responses of the host.
Symptoms.
Infectious diseases are divided into what several distinguishable stages from the point of entry?
Incubation period; Prodromal stage; Acute stage; Convalescent stage; Resolution stage.
What stage does the pathogen replicates without any recognizable symptoms?
Incubation Period
What stage do the symptoms initially appear in the host?
Prodromal stage
What stage does the host experience maximum impact due to rapid proliferation and dissemination of pathogen?
Acute stage
What stage does the body do the following?:
Containment of infection, progressive elimination of pathogen, repair of damaged tissue, and resolution of associated symptoms
Convalescent period
What stage is there total elimination of pathogen from the body without residual signs or symptoms of disease?
Resolution
What is it called when an illness progresses from infection to resolution without symptoms?
Subclinical or Subacute
What is it called when the prodromal period is lengthy?
Insidious
What is it called when the abrupt onset of symptoms with little or no prodrome?
Fulminant
Site of infection is determined by what?
(1)Type of pathogen
(2)Portal of entry
(3)Competence of Host’s immune system
What are Virulence factors?
Substances or products generated by infectious agents that enhance their ability to cause disease.
What are the 4 categories of Virulence factors?
Toxins, adhesion factors, evasive factors, and invasive factors.
What are substances that alter or destroy the normal function of the host or host’s cells?
Toxins
What material are Exotoxins composed of?
Proteins
Where are Endotoxins usually found?
Gram-Negative Bacteria
What is it called when a small amount of endotoxin enters the circulatory system can cause clotting, bleeding, inflammation, fever, hypotension, and death?
Gram-Negative Shock or Endotoxic Shock.
What is it called whan many viral agents (flu, mumps, measles, adenoviruses) produce filmentous appendages or spikes which recognize carb receptors on the surface of cells in upper respiratory tract?
Hemagglutins
What are the virulence factors called that are produced by microbes the enhance virulence by evading/destroying components of the immune system?
Evasive Factors
Products produced by infectious agents that facilitate the penetration of anatomic barriers and hoist tissue are characteristic of which virulence factors?
Invasive Factors
What is SIRS?
Systemic Inflammatory Response Syndrome. Usually have 2 of the following:Tachypnea,Tachycardia, Leukocytosis, leukopenia, neutrophilic bands (>10%), Fever (> 38C), or hypothermia (<36C).
Sepsis is usually caused by what type of bacteria?
Gram negative
What are some common Dermatologic lesions seen in sepsis?
Secondary seeding of skin and soft tissue producing cellulitis, pustules, bullae, erythema gangrenosum lesions, petechiae/purpura, hemorrhagic lesions, etc.
What are some of the Non-septic causes of Systemic Inflammatory Response Syndrome (SIRS)?
-Pancreatitis
-Burns
-Trauma
-Adrenal insufficiency
-Pulmonary embolism
-Dissecting or ruptured aortic aneurysm
-Myocardial infarct
-Occult hemorrhage
-Cardiac tamponade
-Post-cardiopulmonary bypass surgery
-Drug overdose
-Anaphylaxis
Severe sepsis is defined by what?
(1) Sepsis with one or more signs of organ dysfunction, such as:
-Metabolic acidosis
-Acute encephalopathy
-Oliguria
-Hypoxemia
-Disseminated intravascular coagulation (DIC)

OR

(2) Hypotension (that is unresponsive to fluid resuscitation)
What is the Staphylococcus bacterium?
-Gram Positive
-Cocci
-In clusters
-Have the ability to produce coagulase (Coagulase Negative species vs. Coagulase Positive species)
What is Toxic Epidermal Necrolysis?
A life-threatening skin disorder characterized by a blistering and peeling of the top layer of skin. This disorder can be caused by a drug reaction (most often penicillin) or another disease (i.e. Staph.)
What is Staph. Scalded Skin Syndrome?
An acute skin disorder that is characterized by widespread erythema, peeling, and necrosis of the skin, that is caused by a toxin produced by a bacterium of the genus Staphylococcus.
What is Nikolsky's sign?
Nikolsky's sign is a skin condition in which the top layers of the skin slip away from the lower layers when slightly rubbed.
>90% of Staph. are resistant to ___ due to ____________ production?
>90% of Staph. are resistant to PCN due to penicillinase production.
What are the drugs of choice for tx of MRSA?
1) BACTRIM (Trimethoprim-sulfamethoxazole)
2) Clindamyicin (for sulfa allergic)
3) Vancomycin
If your pt has MRSA and a sulfa allergy, what is the best drug for tx?
Clindamyicin
What is Haemophilus influenzae?
-Pleomorphic Gram Negative Rod
-Exclusive Human Pathogen
-Classified by polysaccharide coating
What is most effective tx for Haemophilus influenzae?
Third generation cephalosporins (i.e. Cefotaxime, Ceftriaxone).
Fastidous characteristics?
Extremely strict growth parameters
Aerobic characteristics?
Requires oxygen
Anerobic characteristics?
Cannot survive in oxygen environment
Facultative anerobic characteristics?
Can adapt metabolism to aerobic or anerobic environment
Beta hemolysis (in Strep.)
complete lysis
Alpha hemolysis (in Strep.)
partial lysis
Gamma hemolysis (in Strep.)
no hemolysis
What the most common cause of CAP (community acquired pneumonia)?
Streptococcus pneumoniae
What is the most common cause for UTI in women?
Escherichia coli
Endotoxin LPS ( lipopolysaccharide) plays major role in development of fulminent disease in relation to which bacteria?
Neisseria meningitidis
What is used as prophylaxis for Neisseria meningitidis for close personal contacts (household contacts, daycare etc.)?
Rifampin
What is the most common manifestation of Gonococcal Infections and the most common site it affects?
Arthritis in the knee
What are the 3 most common organisms in Otitis Media?
1) Streptococcus pneumoniae
2) Non-typable Hemophilus influenzae
3) Moraxella catarrhalis
What are common tx for Pseudomonas aeruginosa?
-Aminoglycosides (Gentamycin, Tobramycin)
-3rd generation cephalosporins
-Antipsuedomonal penicillin
What are the common treatments for Chlamydiae?
1) Tetracyclines!!!
2) Macrolides
3) Floxacins
What are the antibiotics that do/don't work on Mycoplasma?
-Sensitive to macrolides/tetracyclines
-Resistant to PCN
What is Empirical treatment?
Medical treatment (usually antibiotics) started before a diagnosis is confirmed. The most common reason is because investigations needed to confirm the diagnosis will take a long time or are delayed, and because delay in treatment will harm the patient.
What is BACTRIM (Trimethoprim-sulfamethoxazole) and how does it work?
Trimethoprim selectively inhibits bacterial purine and ultimately DNA synthesis in bacteria. Sulfamethoxazole works synergistically with Trimethoprim, blocks sequential steps in folate synthesis, and results in a combo bactericidal reaction.
What is Clindamyicin and how does it work?
It inhibits protein synthesis by binding to the 50S subunit of the bacterial ribosome. It targets strep., staph, and pneumococci (along w/ others). Gram- bact. are usually resistant because of poor membrane permeability.
What is Vancomycin and how does it work?
It is only active against Gram- bact. (esp. staph.). It inhibits cell wall synthesis and weakens the peptidoglycan cell wall (and cell membrane) promoting lysis.
What is Rifampin and how does it work?
It binds to the beta subunit of bacterial DNA dep. RNA polymerase and inhibits RNA synthesis. It is active against Gram +/- cocci, mycobacteria, and chlamydia.
What are Aminoglycosides and how do they work?
Includes Streptomycin, Neomycin, Gentomycin, etc. They are irreversible inhibitors of protein synthesis (but the precise mech. for bactericidal activity is not known). They are used mainly against Gram- enteric bact. (esp. in bacteremia/sepsis) or w/ other drugs for tx of tuberculosis.
What are 3rd generation cephalosporins and how do they work?
Are active against more Gram- bact. than 2nd gen. Beta-lactam antibiotic that inhibits bact. growth by interfering with the transpeptidation rxn of bacterial cell wall synthesis.
What is Antipsuedomonal penicillin and how does it work?
A.k.a Extended-spectrum penicillins. Have better activity against Gram- bact. than other penicillins but are relatively susceptible to hydrolysis by Beta-lactamases.
What are Tetracyclines and how do they work?
Broad spectrum drugs that inhibit protein synthesis and act against many Gram -/+ bact.
What are Macrolides and how do they work?
Have the characteristic macrocyclic lactone ring. Bind to ribosomes and block protein synthesis (bacteriostatic).
What are Floxacins and how do they work?
A.k.a. Fluoroquinolones. They block DNA synthesis by inhibiting bact. topoisomerase II/IV, needed for normal transcription/replication.
T/F
It is usually a good idea to start antibiotics before obtaining a culture to get your patient on the road to recovery.
False. You need to obtain your specimen before starting antibiotics.
T/F
It is a good idea to get a blood specimen when the patient is febrile.
True
What are some indications for Sputum collection?
For all pts w/ hospital-acquired pneumonia. Pts w/ ICU admission, Failure of outpt antibiotic therapy, Cavitary lesion, Active alcohol use, Severe obstructive of structural lung disease, Pos urine antigen test for pneumococcus, Pos urine antigen test for legionella, and Pleural. effusion
Nucleic acid amplification is a method used on urethral samples and urine to detect ________ because it is more sensitive than culturing.
Chlamydia.
What are “clue cells” found on a saline wet mount of vaginal of discharge and what do they indicate?
Coccobaccili, vaginal bacteriosis.
KOH (potassium hydroxide) wet mount can reveal _________.
Candida organisms.
What are some of the normal skin flora bacteria?
Staph epidermidis, *S. aureus, Microcci, few gram neg bacilli moist skin, Corynebacterium, and Propionibacterium acnes.
T/F
The Lower Respiratory tract will have a handful of normal bacterial to maintain a healthy flora.
False. The Lower Respiratory tract is supposed to be sterile in a healthy patient.
What is first-line treatment for strep throat?
PCN (specific, narrow spectrum antibiotic)
What is Chemotherapy?
Term was first defined as the use of chemicals against invading microorganisms (e.g., bacteria, viruses, fungi).
What is Antibiotic?
Means “destructive to life,” and strictly speaking, an antibiotic is a chemical that is produced by one microorganism and has the ability to harm other microbes.
What is Antimicrobial?
Defined as any agent, natural or synthetic, that has the ability to kill or suppress microorganisms.
What is Selective Toxicity?
Defined as the ability of a drug to harm a target cell or target organism without injuring cells or organisms with which the target is in intimate contact.
How do Beta-lactam drugs work?
Disruption of the Bacterial Cell Wall.
What is Bactericidal?
Drug that is directly lethal to bacteria at clinically achievable concentrations.
What is Bacteriostatic?
Drugs that can slow microbial growth but do not cause cell death.
What is the main advantage of using a bacteriostatic drug?
When a bacteriostatic drug is used, elimination of bacteria must ultimately be accomplished by host defenses
What is the most expensive antibiotic?
The one that doesn't work.
What are some characteristics of a good antibiotic?
-Greater efficacy
-Lower toxicity
-Narrow spectrum
-Lower cost
What are some risk factors for antimicrobial resistance?
Age >65 years, ABX therapy within the past 3-6 months, alcoholism, immunosuppression, exposure to a child in a day care center.
What is Additive?
Antimicrobial effect of combination is equal to the sum of the effects of the two drugs alone.
What is Synergistic?
One in which the effect of the combination is greater than the sum of the effects of the individual agents.
What is Antagonistic?
A combination of two antibiotics may be less effective than one of the agents.
What are some reasons for Antibiotic Combinations?
-Initial Therapy of Severe Infection
-Mixed Infections
-Prevention of Resistance
-Decreased Toxicity
-Enhanced Antibacterial Action
What are some Disadvantages of Combination Therapy?
-Increased risk of toxic and allergic reactions
-Possible antagonism of antimicrobial effects
-Increased risk of superinfection
-Selection of drug-resistant bacteria
-Increased cost
What are some major indications for Prophylactic Use of Antibiotics?
-Surgery (Prophylactic use of antibiotics can decrease the incidence of infection in certain kinds of surgery. Prophylactic antibiotics should be administered before the surgery begins.)
-Bacterial Endocarditis (Individuals with congenital or valvular heart disease and those with prosthetic heart valves are unusually susceptible to bacterial endocarditis)
-Other Indications (Young women or pregnant women with recurrent UTIs. Amantadine [antiviral]--influenza. Individuals who have had severe rheumatic carditis.)
Name some common Gram-positive aerobes.
-Staph aureus
-Staph epidermidis
-Streptococcus
-Enterococcus
-Pneumococcus
-Listeria monocytogenes (rods)
-Nocardia
-Lactobacillus (rods)
Name some common Gram-negative Bacteria.
-Enteric bacteri (E. coli and other Enterobacteriaceae)
-Pseudomonas
-Acinobacter
-Serratia
-Bacteroides and other anerobes
-Bordetella pertussis (facultative G-neg rod)
-Gram-neg coccobaccilli (Haemophilu influenza, Moraxella)
What are the main Beta lactam drugs?
-Penicillins
-First-generation Cephalosporins
-Second-generation Cephalosporins
-Third-& Fourth-generation Cephalosporins
-Carbopenems
-Beta-Lactamase Inhibitors
How do Beta lactam drugs work?
Interferes with transpeptidation of cell wall synthesis. Beta-lactams bind to a family of related enzymes that are called—penicillin binding proteins (PBPs)‏. Beta-lactam antibiotics bind to the PBPs and inhibit transpeptidation which stops the cross-link-ing of polysaccharides, the cell wall is destroyed and the bacteria is lysed.
What is the most common mechanism of resistance to Beta-lactam drugs?
Inactivation by beta-lactamase (most common), chromosomal & plasmid mediated.
Describe the structure of the Penicillins.
Thiazolidine ring, beta-lactam ring, a secondary amino group on the beta-lactam ring where substituents can attach to form different compounds.
What are some major beta-lactamase inhibitors?
Potassium clavulanate/clavulanic acid (Augmentin or Timectin), tazobactam sodium (Zosyn), and sulbactam (Unasyn).
All ___________ can cause Clostridium difficile colitis.
Antibiotics
What are some PCN pitfalls?
1. Can cause bleeding problems
2 Can cause interstitial nephritis (autoimmune reaction to a penicillin-protein complex)
3. Pts w/ renal failure PCN high doses can cause seizures
4. Common to see secondary infections such as vaginal candidiasis or C. Diff.
What are four mechanisms of Beta-lactamase resistance by bacteria?
1. Inactivation by beta-lactamase (plasmid/chromosomal)
2. Modification of target PBPs (PCN binding Proteins)
3. Impaired penetration of drug to PBPs
4. Efflux
Giving PCNs with __________increases blood levels of all PCNs
probenecid
T/F
All PCNs should be taken on an empty stomach.
False. With the exception oral amoxacillin, all PCNs should be given on an empty stomach.
How do Tetracyclines work?
Binds to 30S subunit of the bacterial ribosome and inhibit bacterial protein synthesis.
How do Macrolides work?
Bind irreversibly to a site on the 50S subunit of the bacterial ribosome, thus inhibiting the translocation steps of protein syntthesis.
Macrolides are first line alternative treatment for group A streptococcal pharyngitis (strep throat)
make into questions
What's up with Chloramphenicol?
Even though it is active against a wide range of gram-positive and gram negative organisms, because of its high toxicity, its use is restricted to life-threatening infections in which there are no alternatives.
How does Chloramphenicol work?
Binds to the bacterial 50S ribosomal subunit and inhibits protein synthesis at the peptidyl transferase reaction.
What are some major Chloramphenicol adverse rxns?
Hemolytic Anemia
-Aplastic Anemia (which is usually idiosyncratic and usually fatal, this occurs independent of dose and may occur after therapy has ceased!)
-Gray Baby Syndrome (because of interference with human mitochondrial ribosomes, can lead to poor feeding, depressed breathing, cardiovascular collapse, cyanosis, and death)
-Can interfere with a number of other drugs
Clostridium difficile is ALWAYS resistant to what Lincosamide?
Clindamycin!!!!
What is the only Macrolide that is NOT a P450 drug?
Azithromycin
it also has the fewest drug interactions
Are Macrolides stable in the presence of beta lactamase?
Yes
What is the MOA of Macrolides?
Bind irreversibly to a site on the 50S subunit of the bacterial ribosome
What is the MOA of Tetracyclines?
Binds to the 30S subunit of bacteria
Which drug class can cause staining in the teeth, especially in young children?
Tetracyclines
T/F GI distress and diarrhea are major adverse effects in all Macrolides.
False it is only a problem with Erythromycin. The other two are well tolerated
What drug increase PCN levels in the blood?
Probenecid