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156 Cards in this Set
- Front
- Back
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what is the gram classification of staphylococci?
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gram positive
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are staphylococci aerobic or anaerobic?
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facultatively anaerobic
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how do you tell staph from strep?
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staph is positive for hydrogen peroxide going to oxygen and water via catalse
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what are important staphylococci examples that most commonly cause disease in humans?
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staph aureus
staph epidermidis staph lugdunesis staph saprophyticus staph haemolyticus |
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what is the only species that is coagulase positive?
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staph aureus
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what structural components contribute to teh virulence of S. aureus?
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capsule, slime layer, peptidoglycan, teichoic acid, protein A
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what toxins contribute to the virulence of S. aureus?
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cytotoxins, exfoliative toxins, enterotoxins, toxic shock syndrome-1
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what enzymes contribute to teh virulence of S. aureus?
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coagulase, hyaluronidase, fibrinolysin, lipase, nucleases
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what enzymes cause virulence in S. aureus
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coagulase, hyaluronidase, fibrinolysin, lipase, nucleases
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what purpose does the peptidoglycan layer in staphylococci serve?
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endotoxin-like activity that starts a process that leads to release of necrotic enzymes
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what makes up the cell wall of staphylococci?
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N-acetyl glucosamine linked by oligosaccharides (alanine, lysine)
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how is the peptidoglycan layer in G+ bacteria catalyzed?
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by PBP enzyme (penicillin binding protein)
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how do staph aureus become resistant to penicillin?
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by acquiring the gene mecA
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what enzyme does mecA target?
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changes PBP to PBP2A, making staph aureus resistant to penicillin (beta lactam antibiotics)
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what is the mechanism of action of mecA?
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alters the shape of PBP-2 (which binds methicillin) to PBP-2A, resulting in a loss of target affinity
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where is teichoic acid found?
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gram positive ONLY
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what is the purpose of teichoic acid?
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makes cell walls more rigid, used by bacteria to attach to mucosal membranes.
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what is the purpose of protein A?
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aids survival and virulence of S. aureus. has sites that bind the Fc portion of IgG, protects organism from opsonization and phagocytosis
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what are the toxin-mediated diseases caused by superantigens?
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staphylococcal scalded skin syndrome (SSSS)
staphylococcal enterocolitis toxic shock syndrome |
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what are other names for staphylococcal scalded skin syndrome?
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pemphigus neonatorum or Ritter's disease
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what does SSSS look like?
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red blistering skin that looks like a burn or scaled, LOCALIZED
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what causes SSSS?
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release of 2 exotoxines (epidermolytic toxins A and B)
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wha causes staphylococcal enterocolitis?
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s. aureus that produce enterotoxin A and leukotoxin Luke/LukD
secondary to suppressed normal colonic flora |
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what is a particularly virulent form of TSS?
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purpura fulminans
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what cytokines are associated with TSS?
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IL-1 and TNF-a
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what are examples of staph pyogenic infections?
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furuncles, folliculitis, carbuncles, impetigo,
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what systemic diseases does staphylococcus cause?
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osteomyelitis, pneumonia, empyema, endocarditis, bacteremia
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what are examples of coagulase negative staphylococcus?
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staphylococcus epidermidis
staphylococcus saprophyticus |
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where are staph epidermidis found?
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it is a normal skin inhabitant
prosthetic and natural heart valves catheters and shunts prosthetic joints |
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where is staph saprophyticus found?
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UTI, in young women.
may be painful or asymptomatic |
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what is the treatment of staph infections?
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vancomycin (iv) for hospitalized patients
outpatient infections: clindamycin, trimethoprin-sulfamethoxazole or doxycycline |
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what is another name for PBP?
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transpeptidase
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what toxins cause disease?
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exfoliatin- causes SSSS (skin sloughs off)
enterotoxin (heat stable)- cause food poisoning toxic shock syndrom toxin-1 |
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what are the Runyon classifications of mycobacterium?
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slow, photochromogen
slow, scotochromogen slow, nonpigmented rapid |
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which mycobacterium are slow growing and photochromogens?
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M kansasii, M marinum
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which mycobacterium are slow growing and scotochromogens?
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m gordonae
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which mycobacterium are slow and nonpigmented?
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m avium, m intracellularae
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which mycobacterium are rapid growing ?
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m chelonae
m fortuitum m abscessus |
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which bacteria is also known as the "white plague"
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mycobacterium
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what is the prevalence of mycobacterium tuberculosis?
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1/3 of the world's population is infected with Tb
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how is Tb diagnosed by x-ray?
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hilar lymphadenopathy
calcification of primary focus/LN |
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what is the most rapid way to confirm the infection of Tb?
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microscopy
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what does PPD stand for?
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purified protein derivative
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what is a BCG reaction to a PPD test?
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false positive due to person exposed to Tb antigen during vaccination
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what is a sensitive, more specific alternative to PPD test?
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IFN-g release assays like ESAT-6 and CFP-10.
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which gene is the target in PCR diagnosis of Tb?
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SecA gene
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what are some anti-tuberculosis drugs?
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INAH, Rifampicin, ethambutol, pyrazinamide
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what is M kansasii
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presents like pulmonary tuberculosis but resistant to anti-Tb drugs
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M scrofulaceum
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infection of cervical lymph nodes- treated with surgery
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what is m avium intracellulare
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infection of cervical lymph nodes in an immuno competent host. treatment is surgery
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what is m avium intracellulare?
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found commonly in aids patients, severe Gi infection
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what is m ulcerans?
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"burunndi' ulcer
prolonged incubation required for growth |
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what is m fortuitum/m chelonei?
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injection related abscesses
associated with wound infections following heart surgery |
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what are the basic characteristics of Legionella?
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gram negative
aerobic pleomorphic motile use amino acids for energy |
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what diseases does Legionella pneumophila cuase?
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legionnaire's disease
pontiac fever |
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what are symptoms of legionnaire's disease?
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pneumonia
fatal if not treated treated with erythromycin |
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what are symptoms of pontiac fever?
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flu-like
milder than legionnaire's disease self limiting myalgia no pneumonia |
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how is legionella transmitted?
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contaminated air and water supply
not spread person to person |
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what are the three main types of Legionellae?
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Legionella pneumophila
Legionella micdadei other types |
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what is the most sensitive way to diagnose Legionella?
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DFA = direct fluorescent antibody
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what are other ways of diangosing Legionella?
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antigen detection in urine
serology fatty acid profiling nucleic acid amplification (PCR) antibody detection |
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what must growth media contain to grow Legionella?
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iron
cystein buffer charcoal yeast extract (BCYE) |
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how is Legionella treated?
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microlides: azithromycin
fluoroquinolones: Levofloxacin |
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what are the basic characteristics of Neisseria?
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gram negative
non motile oxidase + catalase + produce acid by oxidation |
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what does gonorrhea use for energy?
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transferrin-bound and lactoferrin-bound iron
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how does gonorrhea divide?
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binary fission
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what are methods of pathogenesis of gonorrhea?
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porin proteins- Opa, Opc, Rmp
lipooligosacchaide (LOS- o antigen subuntis) blebs, cytokines protease that cleaves IgA |
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how does gonorrhea enter cells?
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bacteria mediated endocytosis (pili help in attachment)
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what are oral infections caused by gonorrhea?
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painful, inflamed gingiva
lesions on tongue/soft palate fever usually present fetid odor |
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what metastatic infections can occur due to gonorrhea?
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endocarditis
arthritis dermatitis parotitis meningitis reproductive tract infections conjunctivitis |
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how is n. gonorrhea distinguished bw othe rsimilar neisseria?
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production of 3 enzymes: a glycosidase and 2 aminopeptidases
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what sugars are oxidized by neisseria meningitidis?
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glucose and maltose
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what are the basic characteristics of neisseria meningitidis?
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gram -
non-motile aerobic oxidase and catalase positive glucose and maltose oxidized to acid |
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where is neisseria meningitidis found in healthy individuals?
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nasopharynx of healty individuals
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what are pathogenic mechanisms of neisseria meningitidis?
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pili adherence- allow movement across BBB
absence of antibodies avoids phagocytosis- IgA protease endotoxin-LOS blebbing capsule cause vascular damage, thrombosis, dissiminated intravascular coagulation |
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what clinical manifestations occur due to neisseria meningitidis?
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DIC
waterhouse-Friderickson syndrome meningitis gangrene pericarditis arthritis |
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how is neisseria meningitidis diagnosed?
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inoculation of primary culture media
gram - coffee bean shape cocci oxidase reaction + |
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what is the only pathogenic gram negative cocci?
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neisseria
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what 2 main diseases are caused by neisseria?
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meningitis
gonorrhea |
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what are the virulence factors of Neisseria meningiditis?
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1. capsule
2. endotoxin (LPS) 3. IgA1 protease |
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which serotypes of n. meningiditis cause meningitis?
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A,B,C
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what is the purpose of the endotoxin in n. meningiditis?
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causes blood vessel destruction and sepsis, seen as petechiae. can damage adrenal glands
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what kind of culture medium does Neisseria grow best on?
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chocolate agar. Thayer-Martin medium which is chocolate agar with antibiotics
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what kind of organisms does vancomycin kill?
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gram positive
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what are the virulence factor of neisseria gonorrhea?
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pili
protein II- outer membrane protein involved in adherence to host cells |
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what are three unusual treatments for syphillus?
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mercury, arsenic, and malaria
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What is the Tuskegee Syphilis study?
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an example of ethical misconduct where patients with syphilis were denied treatment
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what is NOT a way to contract syphilis?
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blood transfusion, because refrigeration of the blood kills the bacteria
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how long does it take to test positive for syphilis?
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1-4 weeks
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what is the primary stage of syphilis?
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before primary lesion develops
incubation period = 3 weeks chancre develops (single, painless lesion). lesion heals in 2-6 weeks occurs 3-90 days after exposure at inoculation site. |
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what are signs of secondary syphilis?
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rash on palms and soles
oral lesions appear lesions recur every 2-3 years |
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compare the sensitivity of the tests at each stage
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primary- possibility of a false negative
secondary- 100% sensitivity. if you have it you will test positive |
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how are primary and secondary syphilis treated?
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benzathine
doxycycline ceftriaxone |
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what are signs of latent syphilis?
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seroreactive but no overt disease
organisms can decrease or disappear |
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what are signs of tertiary syphilis?
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3-10 y after secondary disease disappears
few organisms slow, immunological destruction arthrigis, glossitis, oeteitis, osteomyelitis or TGN |
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what are symptoms of CNS syphilis?
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cranial nerve dysfunction, meningitis
increase in CSF protein, decrease in CSF glucose |
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what are some signs of symptomatic parenchymatous neurosyphilis?
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Paresis
personality, affect, reflexes, eye, sensorium, intellect, speech |
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what happens to the feet in symptomatic parenchymatous neurosyphilis?
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tabes dorsalis
demyelinization of posterior columns, dorsal roots and ganglia. foot slap, wide gait, loss of pain bladder dysfunction |
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how is CNS syphilis treated?
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aqueous PCN
procain PCN + probenecid |
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how does cardiovascular syphilis develop?
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10-40 years after primary disease manifest
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how do you treat cardiovascular syphilis?
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benzathine PCN
doxycycline |
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when does congenital syphilis occur?
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anytime before birth
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what are some manifestations of congenital syphilis?
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jaundice, anemia, damaged long bones, underdeveloped face, delayed tooth eruption, hutchinson incisors, mulberry molars
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what is the body's immune response to syphilis?
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antibodies don't help
cell mediated immunity is inhibited early on but does strengthen in secondary and tertiary disease |
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what are the screening tests for syphilis looking for?
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VDRL and Wasserman variants, rapid plasma reagin card test, automated reagin test are all looking for complement to phospholipids, nto teh specific organism
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which tests are definitive for a syphilis diagnosis?
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TPI = treptomonal pallidum
FTA-ABS = fluorescent TPHA (micro) = humoigglutination IgM-FTA-ABS |
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what is measured in reagin Abs tests for syphilis?
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IgG and IgM Abs directed against a lipoidal Ag which comes from host tissues interacting with T. pallidum or T. pallidum itself
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what are some reasons for false positives in syphilis tests?
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epstein barr virus
people who have had treatment but are serologically positive |
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which test is used to monitor response to prescriptions?
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VDRL (non-treptomonal)
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which are teh quick, simple tests for syphilis?
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non-treptomonal reaginic tests like RPR card and TRUST
15-25% of people who are treated with antibiotics during primary syphilis will test positive on these tests for 2-3 years |
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what are some symptoms of Lyme diseas?
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rash, flu-like symptoms, mirgratory joint pain, neurological problems, loss of vision
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what microorganism is responsible for causing Lyme disease?
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B. burgdorferii
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how is syphilis treated?q
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penicillin (can kill congenital)
OR erythromycin + doxycycline (does not kill congenital) |
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how is lyme disease treated?
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doxycycline or penicillin
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what are examples of anarobic, non-spore forming, gram positive bacteria?
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actinomyces
lactobacillus proprionibacterium morbiluncus |
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what are the two types of fimbriae associated with actinomyces?
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type 1- attach to teeth
type 2- attach to other bacteria |
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what are the human species of actinomycosis?
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actinomyces israelii
a. naeslundii a. odontolyticus a. viscosus a. meyeri |
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are actimomyces acid fast?
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NO
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which microorganism causes sulfur granules?
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actinomyces
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what are the 5 clinical manifestations of actinomycosis?
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cervicofacial
abdominal cutaneous thoracic genital |
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what infection is seen in women who use IUDs?
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genital actinomyces
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what is the treatment for actinomyces?
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surgical debridement of infected tissue
prolonged antibiotics- penicillin |
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what is the treatment of propionibacterium acnes?
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erythromycin, clindamycin, topical benzoyl peroxide
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which spcies of Nocardia is invasive?
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N. asteroides
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which nocardia species is found on the skin?
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N. brasiliensis
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what is the cause of bovine mastitis?
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Nocardia
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what are some clinical manifestations of Nocardosis?
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bronchopulmonary disease
mycetoma lymphocuteaneous disease cellulitis brain abscess |
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what is the treatment for Nocardial infections?
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TMP-SMZ (trimethoprim-sulfamethoxazole
surgical drainage as needed |
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what are some basic characteristics of streptococcus?
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gram positive
divide along long axis non-motile facultative anaerobe |
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what are the catalase, fermentation, and growth characteristics of streptococcus?
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catalase negative (different from staph)
ferment carbohydrates some grow in capnophilic fashion (need CO2 for growth) |
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how do strep pyogens, strep pneumoniae and staph aureus divide?
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pyogens divides into a chain
pneumoniae divides into pairs staph aureus divides into clusters |
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what are teh hemolytic classifications of streptococcus?
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alpha- incomplete hemolysis
beta- complete hemolysis gamma- no hemolysis |
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what is lancefield grouping?
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to differentiate b-hemolytic strains A-G
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what is the peak age of incidence of streptococcus pyogens?
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5-15 years
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what is the serologic classification of streptococcus pyogens?
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beta group, type A
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what do class I and class II M protein do?
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class I = pathogenicity
class II = survival |
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what does M protein do?
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it is the first defense for bacteria against the immune system. It binds to H factor, inactivates complement, so phagocytic function is gone.
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what are the toxins of S. pyogens?
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streptococcal Pyrogenic exotoxins
streptolysin S strepgolysin O |
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what are the enzymes of S. pyogens?
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streptokinase
deoxyribonucleases C5a peptidase hyaluronidase disphosphopyridine nucleatidase DPNase |
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where is the natural habitat for streptococcal diseases?S
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throat, pharynx
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what are suppurative streptococcal disease examples?
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pharyngitis
erysipelas scarlet fever pyoderma (impetigo) cellulitis necrotizing fascitiitis bacteremia streptococcal toxic shock syndrome rheumatic fever acute glomerulonephritis |
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how is streptococcus pyogens treated?
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penicillin
if mixed with staph infections, add vancomycin or oxacillin |
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what is the only species that carries group B antigens?
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strep agalactiae
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what is the most important virulence factor of strep agalactiae?
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polysccharide capsule
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where does strep agalactiae colonize?
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lower Gi tube or urinary/genital system
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when is neonatal disease early onset?
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1 day to 1 week
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how do you treat strep agalactiae?
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penicillin
vancomycin if resistant |
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what are important beta hemolytic streptococci?
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strep anginosus
strep dysgalatiae |
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what is unique to teh cell wall of S. pneumoniae?
|
phosphocholine
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what causes tissue destruction by strep pneumoniae?
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teichoic acid, peptidoglycan fragments, amidase, pneumolysin, H202, phosphocholine
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what are clinical manifestations of pneumococcal pneumonia?
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onset abrupt
chest pains chills labored breathing |
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what are clinical diseases caused by streptococcus pneumoniae?
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sinusitis and otitis
meningitis bacteremia |
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how can you differentially diagnose between streptococcus mitis and streptoccocus pneumoniae?
|
streptococcus pneumoniae is lysed by bile
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how do you diagnose strep pneumoniae with 100% sensitivity?
|
antigen detection with pneumococcal C polysaccharide
reacts with CRP in serum. 100% sensitive in patients with pneumococcal meningitis |
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how do you treat strep pneumoniae?
|
penicillin
OR fluoroquinolone or vancomycin + cetriaxone |
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what are enterococci?
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colonists of human large intestine, cause UTI
grow in high concentrations of NaCl and bile salts |
