Microbiology Flashcards
what is the most common immunologic method?
latex agglutination
what is a DNA probe?
identify the bug and the way to attack it
which antibodies form first?
IgM (7-14 days in)
why would you use a 2 titer approach?
are you in acute phase of disease or are you getting better?
streptococci
gram positive in chains
Group A beta hemolytic strep
S. pyogenes
DOC penicillin and amoxicillin
dx by culture and rapid ID test
serological dx by anti-treptolysin (ASO)
what dz are assoc with S. pyogenes?
glomerulonephritis (rare) rheumatic fever (rare) pharyngitis scarlet fever cellulitis TSS necrotizing fascitis
what happens if strep is untreated in some of the situations?
rheumatic fever and glomerulonephritis
Group B beta hemolytic strep
S. agalactiae
causes neonatal septicemia and meningitis
source in maternal genital tract
dx with maternal vaginal culture
intradelivery antibiotics for positive mothers
what is also assoc with group B strep?
post partum endometritis
Group C beta hemolytic strep
primarily animal pathogens but may be normal human flora
Group F beta hemolytic strep
dental abscesses, but infection uncommon
Group G beta hemolytic strep
animal pathogen, but can be normal human flora
S. viridans
alpha hemolytic strep
gram +
most common skin contaminant but normal in oral, throat, GI
what is S. viridans also assoc with?
opportunistic infections, wounds, bacteremia
what is the most common cause of bacterial endocarditis?
S. viridans
S. pneumoniae
alpha hemolytic gram +
community acquired pneumonia
and pneumococcal bacteremia if left untreated
most strains sensitive to penicillin
what is assoc with S. pneumoniae?
otitis media, meningitis, in children and older adults
what do you do with S. pneumoniae infection?
C&S and latex agglutination of CSF
Group D non hemolytic strep
S. bovis (affects animal handlers)
Enterococcus
E. faecalis and E. faecium
causes 20% of bacterial endocarditis and 10% of UTI
also causes nosocomial infections producing vancomycin-resistant strains (VRE)
staphylococci
gram positive in clusters
Staph aureus
assoc with purulent inflammation and causes abscesses
*most common cause of bacterial endocarditis in drug users
causes endotoxin with causes TSS
what is MRSA?
methicillin resistant staph aureus
-cause of nosocomial infections
staph epidermidis
normal flora on skin
mostly assoc with indwelling devices (catheters, vascular grafts, joint prosthetics)
skin contaminant and eye surgery infection
staph saprophyticus
common cause of bacterial UTI
often antibiotic resistant
what color is gram positive?
blue
what color is gram negative?
red
neisseria gonorrhoeae
gram negative diplococci causes gonorrhea typically asx in females, but not in males strains are becoming resistant causes PID or salpingitis
neisseria meningitidis
most common type of meningitis in adults
dx by C&S and agglutination of CSF
moraxella catarrhalis
gram negative diplococci found in URI
most common with ear and sinus infection
E. coli
most common cause of UTI
most common cause of neonatal meningitis
E. coli O157:H7
hemorrhagic colitis
Klebsiella pneumoniae
a/w pneumonia in alcoholics and older adults
aspirated vomit
proteus
cause of UTI in pts in hospital
P. mirabilis and P. vulgaris
normal flora of GI
pseudomonas aeruginosa
nosocomial with UTI and septicemia
a/w severe burns, otitis externa and cystic fibrosis infections
known for high resistance and mortality
gardnerella vaginalis
causes bacterial vaginosis
dx by clue cells in wet mount of discharge
haemophilus
gram negative coccobacilli
H. influenzae
most important species of croup
a/w otitis media (children), sinusitis, meningitis, bacteremia and pneumonia
H. aegyptius
purulent conjunctivitis
H. ducreyi
causes venereal chancroid
pasteurella multocidas
dogs and cat bites
cellulitis occurs if left untreated
H. pylori
mucus covering gastric mucosa
dx with gastric biopsy culture, urea breath test
acute and chronic gastricits, duodenal ulcer and gastric CA
corynebacteria
gram positive bacilli
C. diphtheriae
most important corynebacteria
lactobacillus
normal genital tract flora
listeria monocytogenes
causes infection from contaminated food (cheese, salads)
dx by culture
most common presents with meningitis and bacteremia
clostridium perfringens
most common cause of gas gangrene
deep tissue wounds are more susceptible
clostridium tenani
causes tetanus (produces spores) puncture wounds are at higher risk
clostridium botulinum
produces botulism
produces an endotoxin (spores germinate in anaerobic conditions)
clostridium difficile
pseudomembraneous colitis
a/w antibiotic use
major nosocomial infection
chlamydia
coccobacillary organism
can only be grown in living cells
chlamydia psittaci
associated with birds
chlamydia pneumoniae
causes about 10% of pneumonia
chlamydia trachomatis
causes lymphogranuloma venereum STD
huge lymph nodes in their groin
serology test
can cause urethritis and endocervicitis
mycoplasma pneumoniae
atypical pneumonia
chest x-ray is LL mottled infiltrates
most common in college freshman and military recruits
mycobacterium TB
acid fast bacillus
what is the dx value of bacteria in UTI?
> 100,000 cfu/mL
why is sputum culture difficult?
can be contaminated with oropharyngeal bacteria
