Bacteria Flashcards
gram positive cocci
staph, strep
gram negative cocci
neisseria
gram positive rods
clostridium, corynebacterium, bacillus, listeria, mycobacterium, gardnerella
branching filamentous gram positives
actinomyces, nocardia (weakly acid fast)
pleomorphic gram negatives
rickettsiae, chlamydiae
spiral gram negatives
spirochetes (borrelia, leptospira, treponema)
bacteria that do not gram stain well
These Microbes May Lack Real Color
- treponema, mycobacteria, mycoplasma, legionella (intracellular), rickettsia (intracellular parasite), chlamydia (intracellular parasite)
mycobacteria
contains mycolic acid, high lipid content
mycoplasma
no cell wall - contains sterols
Giemsa stain bugs
Certain Bugs Really Try my Patience
- chlamydia, borrelia, Rickettsia, Trypanosomes, Plasmodium
Ziehl-Neelsen
acid-fast organisms - nocardia, mycobacterium
PAS
tropheryma whipplei
india ink stain
cryptococus neoformans
silver stain
legionella, fungi (pneumocystis), H pylori
chocolate agar with factors V and X
H influenzae
Thayer Martin (VPN media)
neisseria
- Vancomycin, Polymixin/colistin, Nystatin
Bordet-Gengou (potato agar)
B. pertussis (Bordet for Bordetella)
tellurite agar, Loffler medium
C. diptheriae
Lowenstein-Jensen agar
M. tuberculosis
Eaton agar, requires cholesterol
M. pneumoniae
MacConkey agar
lactose-fermeting enterics
- e coli is also grown on eosin-methylene blue with green metallic sheen
- MacConKEE’S agar: citrobacter, klebsiella, e coli, enterobacter, serratia
charcoal yeast agar buffered with cysteine and iron
legionella
Sabouraud’s agar
fungi
obligate aerobes
Nagging Pests Must Breathe
- nocardia, psuedomonas, MycoBacterium tuberculosis
facultative intracellular
Some Nasty Bugs May Live FacultativeLY
- salmonella, neiseeria, brucella, mycobacterium, listeria, francisella, legionella, yersinia pestis
obligate intracellular
rickettsia, chlamydia
obligate anaerobes
Anaerobes Can’t Breathe Air
- clostridium, bacteroides, actinomyces
- lack catalase or superoxide dysmutase - susceptible to oxidative damage
- aminO2glycosides are effective because they require O2 to enter the cell
encapsulated organisms
SHiNE SKis
- strep pneumo, HiB, Neisseria meningitidis, E coli, Salmonella, Klebsiella pneumonia, group B Strep
(first three bugs secrete IgA protease to colonize respiratory mucosa)
catalase-positive organisms
You need PLACESS for your CATs
- chronic granulomatous disease have increased infections with these bugs because they lack NADPH oxidase
- pseudomonas, listeria, aspergillus, candida, E coli, S aureus, Serratia
urease positive bugs
PUNKSS Can Handle urease
- Proteus, Ureaplasma, Nocardia, Klebsiella, S epidermidis, S saprophyticus, Cryptococus, H pylori
diptheria toxin
- secreted by c. diphtheriae, inactivates elongation factor (EF-2)
- presents with pharyngitis with pseudomembranes in throat and severe lymphadenopathy (bull neck)
exotoxin A
- secreted by pseudomonas aeruginosa, inactivates elongation factor (EF-2)
- leads to host cell death
shiga toxin
- secreted by shigella spp. and inactivates 60s ribosome by removing adenine from rRNA
- GI mucosal damage –> dysentery
- ST also enhances cytokine release, causing HUS
shiga-like toxin
- secreted by EHEC and inactivates 60s ribosome by removing adenine from rRNA
- enhances cytokine release, causes HUS
- unlike shigella, does not invade host cells
heat-labile toxin (LT)
- secreted by ETEC, overactivates adenylyl cyclase, increased cAMP, increasing Cl secretion in gut
- watery diarrhea
- “Labile in the Air, Stable on the Ground”
heat-stable toxin (ST)
- secreted by ETEC, overactivates guanylate cyclase, increasing cGMP, decreasing NaCl and H20 absorption in the gut
- watery diarrhea, “Labile in the Air, Stable on the Ground”
edema factor
- secreted by bacillus anthracis
- mimics adenylate cyclase (inc cAMP), resulting in edema surrounding black eschar
cholera toxin
- secreted by vibrio cholerae, overactivates adenylate cyclase, inc cAMP, by permanently activating Gs –> Cl secretion into the gut
- voluminous “rice-water” diarrhea
pertussis toxin
- overactivates adenylate cyclase (inc cAMP) by disabling Gi, impairing phagocytosis to permit survival of microbe
- whooping cough, unknown if related to toxin
tetanospasmin
- produced by clostridium tetani, protease that cleaves SNARE proteins required for NT release
- spasticity, risus sardonicus, and “lockjaw”
- toxin prevents release of inhibitory NTs from Renshaw cells in spinal cord
botulinum toxin
- produced by clostridium botulinum, protease that cleaves SNARE proteins required for NT release
- flaccid paralysis, floppy baby, toxin prevents release of stimulatory Ach signals and NMJ
alpha toxin
- produced by clostridium perfringens, phospholipase (lechithinase) degrades tissue and cell membranes
- leads to myonecrosis (“gas gangrene”) and hemolysis (“double zone” of hemolysis on blood agar)
streptolysin O
- produced by strep pyogenes, its a protein that degrades cell membranes
- lyses RBCs, contributes to b hemolysis, Abs used to diagnose rheumatic fever
toxic shock syndrome toxin (TSST-1)
- produced by staph aureus, brings MHC II and TCR in proximity to outside antigen binding site to cause overwhelming release of IFNgamma and IL 2 –> shock
- TSS, scalded skin syndrome, food poisoning
exotoxin A
- produced by strep pyogenes, brings MHC II and TCR in proximity to outside antigen binding site to cause overwhelming release of IFNgamma and IL 2 –> shock
- TSS
Endotoxin effects
ENDOTOXIN
- edema, NO, DIC, Outer membrane, TNFa, O-antigen, eXtremely heat stable, IL-1, Neutrophil chemotaxis
strep pneumo most common cause of…
MOPS
- meningitis, otitis media in kids, pneumonia, sinusitis
- Most are OPtochin Sensitivte
EIEC
invades intestinal mucosa and causes necrosis and inflammation. clinical manifestations similar to shigella
EHEC
- shiga-like toxin, HUS, does not ferment sorbitol like other e coli
EPEC
no toxin produced, adheres to apical surface and prevents absorption
- common in Pediatrics
ETEC
produces heat stable and heat labile enteroToxins
- watery travelers diarrhea
salmonella typhi
causes typhoid fever
- rose spots on the abdomen, fever, headache, diarrhea
- can remain in the gallbladder in carrier state
yersinia enterocolitica
transmitted via pet feces, contaminated milk, pork
- can mimic Chrons or appendicitis
H pylori
- catalase, oxidase and urease +
- creates an alkaline environment
- triple therapy: PPI + clarithromycin + amox or flagyl
VDRL false positives
viruses (mono, hepatitis), drugs, rheumatic fever, lupus/leprosy
reheated rice toxin
B. cereus
reheated meat dishes infection
C. perfringens
meats, mayo, custard preformed toxin
S. aureus
contaminated seafood infection
V. parahaemolyticus and V. vulnificus
campylobacter diarrhea
comma or S shaped organisms, growth at 42C
E histolytica diarrhea
protozoan, amebic dysentery, liver abscess
salmonella diarrhea
lactose neg, flagelar motility, has animal reservoir, esp poultry and eggs
Y enterocolitica diarrhea
day care outbreaks, pseudoappendicitis
causes of watery (non-bloody) diarrhea
C diff, C perfringens, ETEC, V. cholerae, rotavirus, norovirus, protozoa (giardia, cryptosporidium)
most common causes of pneumonia in neonates
E coli, GBS
most common causes of pneumonia in kids (4 weeks-18yrs)
Runts May Cough Chunky Sputum
- RSV, Mycoplasma, C. trachomatis, C. pneumoniae, Strep pneumo
most common causes of pneumonia in adults 18-40
Mycoplasma, C pneumoniae, S pneumoniae
most common causes of pneumonia in adults 40-65
S pneumo, H flu, anaerobes, viruses, mycoplasma
most common causes of pneumonia in the elderly
S pneumo, influenza, anaerobes, H flu, GNR
bugs causing pneumonia in alcoholic
s. pneumo, klebs, staph
bugs causing pneumo in CF
pseudomonas, s. aureus, s. pneumo
bugs causing pneumo in immunocompromised
staph, enteric GNR, fungi, viruses, PCP
bugs causing post-viral pneumonia
staph, H flu, s. pneumo
common causes of meningitis in 0-6mo
GBS, E coli, listeria
common causes of meningitis in 6 mo - 6 years
S. pneumo, N meningitidis, HiB, enteroviruses
common causes of meningitis 6 years - 60 years
s. pneumo, N. meningitidis, enteroviruses, HSV
common causes of meningitis 60+
S. pneumo, GNR, listeria
UTI bug with red pigment
serratia
UTI bug with “swarming” and associated with struvite stones
proteus
congenital toxo
chorioretinitis, hydrocephalus, intracranial calcifications
congenital rubella
PDA, cataracts, deafness +/- blueberry muffin rash
congenital CMV
hearing loss, seizures, petechial rash, “blueberry muffin” rash
congenital HIV
recurrent infections, chronic diarrhea
congenital HSV
encephalitis, herpetic vesicular lesions
congenital syphillis
stillbirth, hydrops, saddle nose, saber shins, CN VIII deafness, Hutchinson teeth