7. Micro Flashcards
What bacterial structure mediates adherence of bacteria to the surface of a cell?
fimbria
What bacterial structure protects against phagocytosis
capsule
What bacterial structure provides rigid support to bacterial cell and protects against osmotic pressure
peptidoglycan
What bacterial structure is the space b/w the inner and outer cellular membranes in gram negative bacteria?
periplasmic space
What bacterial structure allows motility?
flagella
What is the bacterial form which provides resistance to dehydration, heat, and chemicals?
spore
what forms attachment b/w two bacteria during transfer of DNA material (aka conjucation)
pilus
What is the name of independent pieces of genetic material within bacteria that may contain genes for abx resistance?
plasmid
What stain is required to see Cryptococcus neoformans?
india ink
What stain is required to see PCP?
silver stain
What stain is required to see Chlamydia?
Giemsa stain
Which organisms are not well visualized with Gram stain? (4)
- treponema
- legionella
- mycoplasma (b/c no cell wall)
- mycobacteria (b/c of high lipid content)
Which bacteria are encapsulated?
- Strep pneumo
- H. influenzae type B
- Neisseria meningitidis
- E. coli
- Salmonella
- Klebsiella pneumoniae
- GBS
By what method are plasmids exchanged b/w bacteria?
conjugation (via pilus)
What exotoxin matches each of the following characteristics?
- inhibits ACh release –> flaccid paralysis
botulinum toxin (clostridium botulinum)
What exotoxin matches each of the following characteristics?
- phospholipase that causes gas gangrene
alpha toxin (clostridium perfringens)
What exotoxin matches each of the following characteristics?
- inhibits the inhibitor of adenylate cyclase –> increased cAMP –> impairing phagocytosis; whooping cough
Pertussis toxin (Bordetella pertussis)
What exotoxin matches each of the following characteristics? (2)
- stimulates adenylate cyclase –> increasing Cl and water secretion into gut –> diarrhea
Heat-labile ETEC toxin Cholera toxin (Vibrio cholerae)
What exotoxin matches each of the following characteristics? (2)
- destroys leukocytes
- gamma-hemolysin (S. aureus)
2. Panton-Valentine leukocidin (tissue destruction with MRSA)
What exotoxin matches each of the following characteristics?
- composed of edema factor, lethal factor, and protective antigen
Anthrax toxin (Bacillus anthracis)
What exotoxin matches each of the following characteristics?
- enterotoxin causing rice-water diarrhea
Cholera toxin
What exotoxin matches each of the following characteristics?
- causes Scarlet fever
pyogenic/exotoxin A (GAS)
What exotoxin matches each of the following characteristics?
- causes toxic shock syndrome
TSST-1 (S. aureus)
What exotoxin matches each of the following characteristics?
- inactivates EF-2 –> pseudomembranous pharyngitis
Diphtheria toxin (Corynebacterium diphtheriae)
What exotoxin matches each of the following characteristics?
- blocks release of inhibitory neurotransmitter (GABA and glycine)
tetanospasmin (Clostridium tetani)
What 6 bacteria secrete enterotoxins (exotoxins that causes water and electrolyte imbalances of intestinal epithelium resulting in diarrhea)?
- Vibrio cholerae
- ETEC
- S. aureus
- Shigella
- Yersinia
- C. diff
What is the function of catalase?
Hydrogen peroxide –> water + o2
One hour after eating potato salad at a picnic, an entire family began to vomit. After 10 hrs, they were better. What is the organism?
S. aureus
What very common aerobic skin colonizer is responsible for many indwelling foreign device infections?
S. epidermidis
What types of disease processes are caused by Strep pyogenes? (3)
- Pyogenic (pharyngitis, cellulitis, impetigo, erysipelas)
- Toxin-mediated (scarlet fever, toxic shock-like syndrome, necrotizing fasciitis)
- Immune mediated (rheumatic fever, glomerulonephritis)
Which gram positive organism causes scalded skin syndrome?
S. aureus (exfoliative toxin)
Which gram positive organism cause gray-white membrane in the posterior pharynx of an unvaccinated child?
Corynebacterium diphtheriae
Which gram positive organism cause pharyngitis resulting in glomerulonephritis
GAS
Which gram positive organism is the most common cause of meningitis?
Strep. pneumo
Which gram positive organism is the most common cause of osteomyelitis?
S. aureus
Which gram positive organism cause serious newborn infections
GBS, listeria, E.coli
Which gram positive organism cause infants with poor muscle tone?
Clostridium botulinum
Which gram positive organism cause resp distress in a postal worker?
Bacillus anthracis
Which gram positive organism cause otitis media in children
strep. pneumo
Which gram positive organism cause cellulitis? (2)
s. aureus, GAS
Which pts are susceptible to Listeria monocytogenes?
old, young, pregnant, immunocompromised
Which bacteria are spore formers? (3)
Bacillus, clostridium, coxiella burnetti
A culture reveals gram negative, oxidase positive diplococci. What is the likely organism? (3)
- Moraxella catarrhalis (COPD)
- Neisseria gonorrhoeae (urethral discharge from college student)
- N. meningitidis (CSF)
A 50 yo male smoker presents with a new cough and flu-like symptoms. Gram stain of the sputum shows no organisms but silver stain shows rods. What is the diagnosis?
legionella pneumophila
What gram-negative organism cause sepsis, DIC, adrenal hemorrhage?
N. meningitidis (Waterhouse-Friderichsen syndrome)
What gram-negative organism cause 5 yo with pharyngitis, drooling, and x-ray revealing thumb sign?
H. influenzae type B
What gram-negative organism cause burn wound infection?
pseudomonas
What gram-negative organism cause life-threatening meningitis + purpura?
N. meningitidis
What gram-negative organism cause septic arthritis in young, sexually active patients?
N. gonorrhoeae
Which form of E.coli causes HUS?
EHEC (0157:H7)
What infectious agent cause diarrhea caused by gram-negative, non-motile organism that does NOT ferment lactose?
Shigella
What infectious agent cause rice-water stools (2)
Vibrio cholerae, ETEC
What infectious agent cause diarrhea caused by S-shaped organism?
Campylobacter
What infectious agent cause diarrhea transmitted from household pet?
Yersinia (pet feces)
What infectious agent cause diarrhea caused by gram-negative motile organism that does not ferment lactose
Salmonella
Most common cause of traveler’s diarrhea
ETEC
What infectious agent cause bloody diarrhea after eating undercooked hamburger meat?
EHEC (O157:H7)
What infectious agent cause diarrhea and RLQ pain mimicking appendicitis?
Yersinia
What infectious agent cause diarrhea after consuming eggs or handling raw chicken? (2)
Salmonella, campylobacter
What infectious agent cause osteo in sickle cell patient?
Salmonella
What organism cause LAD with new kitten?
Bartonella
What organism is associated with dog bite?
Pasturella
What organism is associated with ixodes tick?
Borrelia burgdorferi
What organism is associated with rabbit hunter?
Francisella tularensis
What organism is associated with pet prairie dog?
Yersenia pestis
What is the treatment for latent TB?
Isoniazid alone for 9 months (+B6)
What ist he treatment for active TB?
RIPE for first 2 months
Just rifampin+isoniazid for next 4 months
What abx is used for ppx of MAC in AIDS patients? When should this begin?
Azithromycin
when CD4+
What is the distinction b/w Ghon complex and Ghon focus? Are these seen in primary or reactivated TB?
Ghon focus: lung lesion from primary TB
Ghon complex: Ghon focus + hilar LAD
What is the Rickettsial triad of symptoms?
- HA
- Fever
- Rash
25 yo with mycoplasma atypical pneumonia exhibits ANEMIA due to cold agglutinins. What type of immunoglobulins is responsible for the anemia?
IgM antibodies
note: cold agglutinins are non-specific IgM ab to erythrocytes. can agglutinate (lyse) RBCs in cold environments
Which abx should be used to treat mycoplasma pneumoniae?
tetracycline or macrolide (azithromycin)
Which abx should be used to treat rocky mountain spotted fever
doxy
Which abx should be used to treat bacterial vaginosis?
metronidazole
Which penicillin drug would you use given the following infection?
- syphilis
penicillin G (IV)
Which penicillin drug would you use given the following infection?
- UTI
aminopenicillins, like amoxicillin (better gram (-) coverage)
Which penicillin drug would you use given the following infection? (3)
- pseudomonas
- ticarcillin
- carbenicillin
- piperacillin
What extended coverage do ampicillin or amoxicillin have? (7)
HEELPSS
- H. influenzae
- E coli
- Enterococci
- Listeria
- Proteus mirabilis
- Salmonella
- Shigella
What are the 2 diff. mechanisms of resistance bacteria use against penicillin agents?
- production of beta-lactamase
- alteration of penicillin-binding protein (ex. MRSA)
What are the beta-lactamase inhibitors? (3)
- clavulanic acid
- sulbactam
- tazobactam
Which generation of cephalosporin would you choose to use for each of the following infections?
- UTI prevention
1st
Which generation of cephalosporin would you choose to use for each of the following infections?
- Serratia UTI
2nd (remember, HENS PEcK)
Which generation of cephalosporin would you choose to use for each of the following infections?
- N. meningitidis
3rd
Which generation of cephalosporin would you choose to use for each of the following infections?
- Pseudomonas
4th (cefepime)
or ceftazidime (3rd)
Which generation of cephalosporin would you choose to use for each of the following infections?
- resistant otitis media
cefdinir (oral 3rd gen)
What side effect would you be concerned about if a patient is receiving both ceftriaxone and gentamicin?
nephrotoxicity
Classify the following cephalosporins in their generation: cefepime
4th
Classify the following cephalosporins in their generation: cephalexin
1st
Classify the following cephalosporins in their generation: cefuroxime
2nd
Classify the following cephalosporins in their generation: ceftazidime
3rd
Classify the following cephalosporins in their generation: ceftaroline
5th
What is the MoA of cephalosporins?
Binds to penicillin-binding protein –> inhibition of synthesis and cross-linking of peptidoglycans
What cell wall inhibitor matches each of the following statements?
- aminoglycoside pretender
Aztreonam (monobactam)
What cell wall inhibitor matches each of the following statements?
- broad-spec coverage for appendicitis
imipenem + cilastin OR
meropenem
How does an organism develop resistance to vancomycin?
amino acid modification; D-ala D-ala –> D-ala D-lac
A patient is receiving an IV infusion of an abx and the nurse calls you when his face becomes flushed 15 min after the infusion started. What is the treatment for this patient?
- stop vanco
- antihistamines
- restart @ slower infusion
What are the side effects of aminoglycosides?
NOT
- nephrotoxicity
- ototoxicity
- teratogenic
What drugs have photosensitivity reactions?
SAT for photo
- Sulfonamides
- amiodarone
- tetracyclines
What causes gray baby syndrome? Gray man syndrome? Red man syndrome?
a. Chloramphenicol
b. amiodarone
c. vanco
What are the clinical uses for macrolides?
PUS
- pneumonia (atypical)
- URI
- STD: chlamydia, gonorrhea
What agent is used for ppx of gonorrhea
ceftriaxone
What agent is used for ppx of syphilis
penicillin G
What agent is used for ppx of recurrent UTIs (3)
- TMP-SMX or
- nitrofurantoin or
- cephalexin
What agent is used for ppx of PCP pneumonia
TMP-SMX
What agent is used for ppx of exposure to H. influenzae type B meningitis
rifampin
What agent is used for ppx of endocarditis prevention in pt with turbulent flow heart disease?
amoxicillin
What are the major side effects of the IV polymyxins? (2)
- neurotoxicity
- nephrotoxicity
What is the MoA of sulfamethoxazole (SMX)?
inhibits dihydropteroate synthase
What is the MoA of trimethoprim?
inhibits dihydrofolate reductase
What is the MoA of levofloxacin?
inhibits DNA gyrase (topoisomerase III)
What is the MoA of nitrofurantoin
inhibits bacterial ribosomes (only effective in urine)
What is the MoA of metronidazole
forms toxic free radicals that damage DNA
What is the MoA of polymyxin B?
cation detergent
What 2 organisms are important causes of pneumonia and meningitis in neonates?
GBS
e. coli
A group of picnic goers develop vomiting 2 hrs after eating. What is the most likely cause?
S. aureus
What infection matches each of the following descriptions?
- green frothy vaginal discharge with flagellated cells on wet prep
Trichomonas vaginalis
What infection matches each of the following descriptions?
- koilocytes on biopsy of lesion
HPV
What infection matches each of the following descriptions?
- multiple tender vesicles which becomes shallow ulcers
Herpes simplex virus
What infection matches each of the following descriptions?
- painless genital ulcer followed by rash on palms and soles
syphilis
What infection matches each of the following descriptions?
- mucopurulent cervical discharge with cervical motion tenderness
PID
Which TORCHeS infections is the most likely cause?
chorioretinitis, hydrocephalus, intracranial calcifications
toxo
Which TORCHeS infections is the most likely cause?
hydrops fetalis
parvo virus B19
Which TORCHeS infections is the most likely cause?
PDA, cataracts, deafness
rubella
Which TORCHeS infections is the most likely cause?
saddle nose, snuffles, Hutchinson teeth, saber shins
syphilis