Microbio Flashcards
peptidoglycan function and structure
- protects against osmotic pressure
- sugar backbone with peptide side chains cross-linked by transpeptidase
periplasm is the location for what?
hydrolytic enzymes, including b-lactamases
Unique to gram (-) or gram (+)
gram (+): lipoteichoic acid
gram (-): porins, endotoxin/LPS (outer membrane), periplasmic space
Special cultures (H. flu, N. gonorrhoeae, Legionella)
H flu - chocolate agar (requires factors X hematin and V NAD+)
N gonorrhoeae - Thayer-Martin ( Very Typically Cultures Neisseria - vanc + trimethoprim + colistin + nystatin)
Legionella - charcoal yeast
Aerobes - Nagging Pests Must Breathe
Require O2 to generate ATP
Nocardia, Pseudomonas, MycoBacterium tb
Anaerobes - Frankly Can’t Breathe Air
normal in GI tract, can’t use aminoglycosides (which require O2 to enter cell)
Fusobacterium, Clostridium, Bacteroides, Actinomyces
Encapsulated bacteria (SHiNE SKiS)
Strep pneumo, H. flu, N. meningitidis, E. coli, Salmonella, Klebsiella, group b Strep
Bacterial virulence proteins - Protein A, IgA protease, Protein M
Protein A - binds Fc region of IgG, Staph aureus
IgA protease - cleaves IgA, SHiN (S. pneumo, H. flu, N.m)
Protein M - prevent phagocytosis by decreased activation of alternate complement pathway, group A strep
ENDOTOXIN
Edema Nitric Oxide DIC/Death Outer membrane TNF-a O-antigen eXtremely heat stable IL-1 Neutrophil chemotaxis
Gram-positive algorithm
bacilli vs. cocci
catalase + (clusters) –> coagulase
catalase - (chains) –> hemolysis
then sensitivities (coag -: novobiocin, cat -/a-hemolytic: optochin, cat-/B-hemolytic: bacitracin)
Strep bovis (bovis in the blood = ?)
Group D strep
Bovis in the blood = cancer in the colon
Diphtheria ABCDEFG
ADP-ribosylation B-prophage Corynebacterium Diphtheriae Elongation Factor-2 Granules (intracellular, polyphosphate)
Gram positive rod
Clostridia toxins (Gram positive rod)
tetani - cleave SNARE proteins, block release of NTs (spastic paralysis)
botulinum - block Ach release (floppy baby)
perfringens - alpha toxin = lecithinase - phospholipid breakdown (also, myonecrosis by collagen breakdown)
dificile - toxin A: enterotoxin. Toxin B: cytotoxin (depolymerizes actin filaments) (pseudomembranous colitis)
Listeria bacteria features
facultative intracellular Gram positive rod
rocket tails - actin polymerization, rapid movement
neonatal meningitis!
grows at 4 degrees (contaminates refrigerated food, food = most common transmission)
Leprosy (mycobacterium)
- cool temperature distribution (glove and stocking)
- tx: dapsone and rifampin
- lepromatous: low immunity (Th2)
- tuberculoid: high immunity (Th1)
Gram-negative algorithm
diplocoi vs. coccoid rods vs. cocci
- maltose fermentation vs. not
- lactose fermentation or not
- oxidase + (pseudomonas) vs. not
Lactose fermenters (Klebsiella and E. coli)
MacConkey’s agar
Lactose is key with MacConKEY’s agar
Neisseria gono vs. mening
GoNO - no polysaccharide capsule, no maltose fermentation, no vaccine, FHC syndrome
Mening - maltose fermentation, W-F syndrome
H. flu leads to what?
hEMOPhilus
haEMOPhilus causes: Epiglottitis Meningitis Otitis media Pneumonia
Legionella
use silver stain on charcoal culture with iron and cysteine (silver helmet over campfire with iron dagger - not a sissy!)
aerosol transmission
Pseudomonas is associated with what?
PSEUDDO Pneumonia Sepsis otitis Externa UTIs Drugs/Diabetes Osteomyelitis
think pseudomonas in burn victims!
exotoxin A -
E. coli subtypes (I, T, P, H)
EIEC: invasive
ETEC: enteroToxins, Traveler’s (watery, heat-stable vs. heat-labile)
EPEC: Pediatrics
EHEC: O157:H7, Shiga-toxin, HUS (anemia, thrombocytopenia, renal failure due to damaged endothelium)
Klebsiella (4A’s)
Aspiration pneumonia
Abscesses (lung/liver)
Alcoholics
diAbetics
Campylobacter
Bloody diarrhea
Gullain-Barre
reactive arthritis (arthritis, conjunctivitis, urethritis)
Undercooked meat!
Cholera mechanism
Enterotoxin that permanently activates Gs, causing increased cAMP activity
Leptospirosis (surfers, tropics)
flu-like symptoms
myalgias (calves!)
jaundice
photophobia
Lyme symptom progression (FACE)
early - flu-like, classic rash, facial nerve palsy (bilateral)
later - arthritis, AV nodal block, neurologic
Lyme pie to the FACE: Facial nerve palsy, Arthritis, Cardiac block, Erythema migrans
False positives on VDRL
Viruses
Drugs
Rheumatic fever
Lupus/leprosy
Animal transmission
cat scratch - Bartonella
armadillo - leprosy
dog tick - rickettsia (RMSF)
sheep amniotic fluid - Coxiella (Q fever)
Gardnerella
bacterial vaginosis
clue cells
KOH whiff test
Palms and soles rash
CARS
Coxsackie A
RMSF
Syphillis
E’s and R’s of chlamydia
Elementary body is enfectious, enters cell through Endocytosis
Reticulate body Replicates in cell by fission, Reorganizes into elementary bodies for spread to other cells
Reactive arthritis - uveitis/conjunctivitis, arthritis, urethritis
Chlam subtypes
ABC - Africa, blindness, chronic infection
D-K - everything else!
High titer of cold agglutinins (IgM)
Mycoplasma pneumoniae
X-ray is worse than patient
antigenic similarity with RBCs, so immune response destroys RBCs!
no cell wall
Systemic Mycoses (HBCP)
Histo - hides within macrophages
Blasto bus broadly
Coccidio crowds (spherule filled with spores)
Paracoccidio parasails with captain’s wheel to Latin America
Tinea versicolor mechanism
degradation of lipids produces acids that damage melanocytes and cause hypopigmentation
Opportunistic fungal infections (6 total)
Candida - superficial or systemic (no pulm involvement)
Aspergillus - invasive; ABPA (asthma and CF, look for eosinophilia); aspergilloma (post-TB infection). A for Acute Angles in Aspegillus.
Cryptococcus - heavily encapsulated, latex agglutination (polysaccharide capsular antigen test)
Mucor/Rhizopus - rhinocerebral, frontal lobe abscess, CST
Pneumocystis - diffuse ground-glass opacities, disc-shaped yeast
Sporothrix - ascending lymphangitis (rose in the pot)
GI protozoa
Giardia - foul-smelling, fatty
Entamoeba - liver abscess (anchovy paste), RBCs in cytoplasm, cysts with 4 nuclei
Cryptosporidium - severe diarrhea in AIDS
CNS protozoa
Toxo - congenital (chorioretiniti, calcifications, hydrocephalus), AIDS (brain abscess)
Naegleria - rapidly fatal, freshwater lakes
Trypanosoma brucei (African sleeping) - lymph nodes, recurring fever, somnolence. “Sure is nice to sleep with Melatonin” tx = suramin, melarsoprol
Heme protozoa
Malaria (Plasmodium) - fevers are 48 hrs apart in vivax/ovale, look for spots in RBCs, quinidine = watch for G6PDH def.!
Babesia - same tick as Lyme, hemolytic anemia, Maltese cross in RBC, predilection for asplenia!
Other protozoa
Chagas dz (trypanosoma cruzi) - dilated cardiomyopathy + achlasia/megacolon + unilateral periorbital swelling, kissing bug feces Leishmaniasis - sandfly, fevers/HSM/pancytopenia
Trichomonas (what does cervix look like?)
strawberry cervix, foul-smelling, treat pt and partner!
roundworm treatment (pinworms, hookworms, etc.)
Bendazoles are bendy for intestinal infection
Biliary tract dz -cholangiocarcinoma (parasite)
Clonorchis sinensis (undercooked fish), pigmented gallstones
Brain cysts/seizures (parasite)
Taenia solium (cysticercosis) when eggs are ingested
Hematuria, bladder SCC (parasite), less likely =
Schistosoma haematobium, lives in snails!
Liver hydatid cysts (parasite)
Echinococcus (dog feces, sheep, kill daughter cysts before removal with ethanol)
Microcytic anemia (parasite)
Ancylostoma (blood sucker!)
Myalgias (parasite)
Trichinella (undercooked meat)
Perianal pruritis (parasite)
Enterobius (pinworm)
Portal hypertension (parasite)
Schistosoma mansoni, schistosoma japonicum
Vitamin B12 deficiency (parasite)
Diphyllobothrium latum (raw freshwater fish)
Match the food to the bug Rice Canned food/honey Undercooked meat Poultry/meat/eggs Meats/mayonnaise Seafood
Rice - bacillus cereus Canned food/honey - C. botulinum Undercooked meat - E. coli Poultry/meat/eggs - Salmonella, Campylobacter Meats/mayonnaise - Staph aureus Seafood - Vibrio
HIV + diseases
<100: Aspergillus (pleuritic pain), Crypto (meningitis), Candida (esophagitis), CMV (retinitis, colitis, enceph), EBV (oral hairy leukoplakia, B-cell lymphoma), Histo (const. sx), MAC (non-specific sx)
Three prion diseases
CJD: rapidly progressive dementia
Bovine spongiform encephalopathy: mad cow disease
Kuru: human cannibalism
Diarrhea etiologies
Bloody: Campy, Enteamoeba, EHEC, EIEC, E. coli, Salmonella, Shigella, Yersinia
Watery: Clostridium (diff/perf), ETEC, Giardia/Crypto, Vibrio, Rota/Noro/Adeno
Special pneumonia groups (alcoholics, atypical, CF)
Alcoholics: Klebsiella
Atypical: Mycoplasma, Legionella, Chlam
CF: Pseudomonas, S. aureus
Brain abscess
Viridans strep
Staph aureus
Toxo reactivation
Osteomyelitis special risk factors (generally S. aureus, except…)
Sickle cell - Salmonella, S. aureus
Vertebral involvement - M. tuberculosis
Cat/dog bites - Pasteurella
UTI bugs
E. coli - green metallic sheen on EMB agar
Staph sapro
Klebsiella - + urease test
Congenital infections (ToRCHeS)
Toxo - chorioretinitis, hydrocephalus, intracranial calcs
Rubella - PDA, cataracts, deafness
CMV - hearing loss, seizures, petechial rash
HSV-2 - encephalitis
Syphilis - facial abnormalities
Red rashes of childhood
Coxsackie Type A - HFM dz
HHV-6 (roseola) - fever followed by rash
Measles (rubeola) - 3 C’s, descending rash
Rubella - post-auricular adenopathy, descending rash
Strep pyogenes - scarlet fever, sandpaper-like rash
VZV - lesions of different ages
Random bug hints
asplenia, branching rods, chronic granulomatous dz, currant jelly sputum, dog/cat bite, health care provider, neutropenia, organ transplant, PAS +, palms/soles rash, surgical wound, traumatic open wound
SHiN - strep pneumo, H. flu, Neisseria Actinomyces (oral infections) catalase + (S. aureus, Burkholderia) Klebsiella Pasteurella HBV Candida, Aspergillus CMV Tryponema Whipplei CARS: coxsackie A, Rickettsia, Syphillis Staph aureus Pseudomonas
