CLINICAL MICRO Flashcards
Compare the rash of tick-borne rickettsia to that of louse-borne rickettsia
Tick = RMSF = palms and soles to trunk (centripetal); Louse = epidemic typus (R. prowazekii) = trunk to palms and soles (centrifugal)
What disease has morulae in granulocyte cytoplasm)
Anaplasmosis (monocyte would be Ehrlichia)
What is the natural reservoir of Borrelia burgdorferi?
mouse
What bug can you get from cattle and sheep amniotic fluid?
Coxiella burnettii (Q fever); veteranarians
What stabilizes the membrane of Mycoplasma pneumoniae?
sterols (no cell wall)
What causes neonatal staccato cough?
Pneumonia caused by C. trachomatis D-K serotypes
Which type of E. coli ferments sorbitol?
Everything but EHEC
What is the vector for Rickettsia prowazekii?
louse
What is Elek’s test?
The test for diphtheria toxin
What serotypes of C. trachomatis cause lymphogranuloma venereum?
L1, L2 , and L3
How do you treat C. trachomatis?
Azithromycin (or doxy) with Ceftriaxone for likely Gonorrheal co-infection
Name 3 diseases that have a palm and sole rash
Rickettsia rickettsii (RMSF), Coxsackie A16 (hand foot and mouth), Secondary syphilis
What are the 3 main genera of spirochetes?
Leptospira, Treponema, and Borrelia
Chronic pneumonia in CF patients is usually caused by _________ and the most important virulence factor here is __________
P. aeruginosa; Biofilm
What 2 Chlamydial spp. Cause atypical pneumonia?
C. pneumoniae and C. psitiacci
What is another name for Weil’s disease?
Icterohemorrhagic leptospirosis
What bacteria does someone likely have if the X-ray looks worse than the patient?
Mycoplasma pneumoniae
Which type of E. coli flattens villi?
EPEC (P for Peds)
What causes diabetic osteomyelitis and sickle cell osteomyelitis?
DM = P. aeruginosa (prob an extension of skin infection of an ulcer) HbS = Salmonella enteriditis
How would you know if an infectious facial palsy was Ramsay-Hunt or Lyme disease?
Ramsay-Hunt syndrome is a VZV bell’s palsy and is unilateral with blistering; Lyme disease is bilateral
What is the cause of undulant fever?
Brucella
What are 2 possible outcomes of streptococcal pharyngitis that self resolves?
Rheumatic fever and PSGN
What is the gram stain of a bug causing a cherry red epiglottis?
Gram negative coccobacillus
The bacteria grown on Eaton’s agar is common in what 2 demographics?
M. pneumoniae is common in military recruits and prisons
What do C. trachomatis serotypes L1, L2 and L3 cause?
Lymphogranuloma venereum
What serotypes of C. trachomatis cause blindness in Africa? What is the pathogenesis here?
A, B, and C? Flies transmit the bug and it causes conjunctivitis with scarring, this occurs over and over again until blind
What causes aortic aneurysm in tertiary syphilis?
arotitis with destruction of vasa vasorum
What bacteria are carried by these ticks A) Ixodes B) Lone star C) Dermacentor
A) Babesia and B. burgdorferi B) E. chaffeensis C) R. ricketsii (RMSF)
What are your 2 options for treating Mycoplasma pneumoniae?
Macrolide or fluoroquinolone (NO beta lactams bc no cell wall)
What bug causes mediastinal widening?
Pulmonary anthrax
What 2 antibiotics are frequently implicated in pseudomembranous colitis?
ampicillin (beta lactam) and clindamycin (50 S ribosome peptidyltransferase inhibition)
What are the pros and cons to having Anti-M protein antibodies?
Pros: enhances defenses against S. pyogenes, Cons: causes rheumatic fever and PSGN
Everyone knows that alcoholics and DM are the ones who get Klebsiella pneumoniae? BUT WHY?
It is a normal flora of the intestine thus, it gets aspirated? Alcoholics are notorious for aspirating. I’m guessing the DM is because they have autonomic neuropathy and therfore diabetic gastroparesis leading to increased likelihood of aspiration
What is the largest spirochete? What is the thinnest?
Borrelia; Leptospira (lepto = thin)
What is the presentation of primary syphilis? Secondary syphilis?
Primary = painless chancre; Secondary = copper colored maculopapular rash with condyloma lata
What bug is transmitted by the lone star tick?
Eherlichia chaffeensis
What are the vectors for the 2 spp of Borrelia?
B. burgdorferi = ixodes tick; B. recurrentis = louse
How do you kill spores as in ones that may be leftover on surgical equipment?
Autoclave at 121 C for 15 min
What 2 exotoxins are produced by Clostridium difficile?
Toxin A = enterotoxin causing diarrhea? Toxin B = cytotoxin that damages cytoskeleton of enterocytes = pseudomembranous colitis
How do you differentiate the Group D strep?
Enterococci grows in 6.5% NaCl and bile; S. bovis only grows in bile
How do you treat Listeria monocytogenes?
Ampicillin? But usually only infants, IC pts, and in empirical Tx of meningitis because Listeria gastroenteritis in adults is self-limiting
What do both M. meningitidis and M. gonorrhoeae ferment?
Glucose but meningitidis also metabolizes maltose
In which portion of the bacterial growth curve is an endospore going to form, why?
Stationary phase (top of curve) because this is when growth = death, this is because nutrients are sparse, when nutrients are sparse they initiate survival mode = spore
How do you Tx gonorrhea?
Ceftriaxone (3rd gen) with Azithromycin for likely Chlamydial co-infection
What do serotypes A, B, and C for C. trachomatis cause?
Blindness in Africa
Which type of E. coli produces similar Sx to Shigella but does NOT produce toxin?
EIEC, the invasion causes bloody diarrhea like Shigella
2 diseases that may present with a saddle nose
Congenital syphilis and Lepromatous leprosy (destruction of septum)
What are the neurological and cardiac manifestations of Lyme disease?
Neuro = bilateral facial palsy (early) and encephalopathy/polyneuropathy (late); Cardiac = AV node block
What bacteria contains a cell wall lacking muramic acid?
Chlamydia
What is the treatment of the 2 filamentous gram positive rods?
Actinomyces = ampicillin; Nocardia = sulfonamides
What are 4 signs of congenital syphilis?
Mulberry molars, Saber shins, CN VIII deafness, and Saddle nose
Which bacterium inhibits the release of neurotransmitters from Renshaw cells?
C. tetani? Renshaw cells in the spinal cord release inhibitory NTs (GABA and Glycine). Tetanospasmin inhibits their release = spastic paralysis
What is the Tx of Lyme disease (2 drugs), why can’t they go in the sun?
Doxycycline and Ceftriaxone (Doxycycline = a tetracycline, phototoxicity is a notorious AE for this drug)
What chemical is added to elicit a positive whiff test for BV?
KOH
What is the screening test for Syphilis? Confirmatory?
VDRL and RPR; FTA-ABS
What is the vector for Rocky Mountain Spotted Fever?
Dermacentor tick
Which infectious agent leads to a glove and stockings loss of sensation? What disease more commonly does this?
Hansen’s disease (leprosy); Diabetes mellitus
Which antibiotics require O2 for uptake and are ineffective against anaerobes?
Aminoglycosides
What kind of media can Vibrio cholerae grow in? What is the most important aspect of MGMT?
alkaline; REHYDRATION
Aside from the bacitracin test, what are 2 other tests you can use to identify S. agalactiae?
Hippurate test positive and CAMP positive
What causes a thumbprint sign on CXR? Steeple sign?
Thumbprint sign = Haemophilus influenzae B epiglottitis; Steeple Sign = Croup, parainfluenza virus
What shape of gram negative organisms do you use lactose fermentation as an initial measure for differentiation?
Rods? If you have diplococci then you use maltose, if you have coccobacilli then you are dealing with some weird organisms that are fairly fastidious
What is the Tx of Psudeomonas (2 drugs)?
Aminoglycosides and extended spectrum penicillins (Ticarcillin and Piperacillin)
What is carried by the Dermacentor tick?
Rocky mountain spotted fever (Ricketssia ricketsii)
What 2 Bacillus spp. Can cause GI Sx?
B. cereus and don?t forget B. anthracis can also cause GI anthrax!
Which group D strep grow in 6.5% NaCl and and bile?
Enterococci grows in 6.5% NaCl and bile; S. bovis only grows in bile
How do you detect recent strep infection?
ASO titer
E. coli fimbrae are most important for what infections?
Cystitis and pyelonephritis
Triple therapy for H. pylori consists of:
Clarithromycin, metronidazole, PPI
FTA-ABS is a confirmatory test for what?
Treponema pallidum
How can you use maltose to differentiate the gram negative diplococci?
N. meningitidis metabolizes maltose whereas gonorrhoeae does not
Where does TB usually go when it reactivates and why?
apices of lung because higher ventilation
What causes Traveler’s diarrhea?
ETEC
What do C. trachomatis serotypes D_ _ K cause?
urethritis and PID, ectopic pregnancy, neonatal conjunctivitis/pneumonia (pneumonia = staccato cough)
Why doesn?t S. aureus require a damaged valve or a pre-existing thrombotic (noninfectious) endocarditis to form bacterial endocarditis while S. epidermidus does?
Because it contains coagulase and can form a fibrin clot around itself which allows it to stick to the valve? S. epi can bind if the valve is damaged and a thrombus has formed on it.
Why is S. pneumoniae good at infecting mucosal surfaces?
IgA protease
What is the vector for Ricketssia typhi?
Flea (endemic typhus)
What is the vector for Ehrlichia chaffeensis? What is the typical inclusion body seen?
Lone star tick; morulae
Which member of enterococci is an important cause of nosocomial infection?
VRE
Which toxin causes Scarlett fever? What part of the body is spared?
Exotoxin A, Face
What immune cell infiltrate will you find in the crypts of Salmonella infections vs. Shigella infections?
Salmonella = monocytic; Shigella = PMN
Which S. aureus virulence factor inhibits complement fixation and phagocytosis by binding to Fc of IgG?
Protein A
What bug can mimic Crohn’s or appendicitis?
Yersenia enterocolitica
Which TB virulence factor inhibits phagolysosomal fusion?
Sulfatides (surface glycolipids)
Why are Chlamydia obligate intracellular?
Cannot synthesize ATP because have no NAD or CoA (like Ricketssia)
What disease has morulae in monocyte cytoplasm?
Erhilichiosis (granulocytes would be Anaplasmosis)
How can you differentiate EHEC from other E. coli?
EHEC does not ferment sorbitol
What are the JONES criteria?
for rheumatic fever: J = joints (migratory polyarthritis) O = pancarditis (ALL layers affected), N = nodules, E = Erythema marginatum, S = Sydenham’s chorea (chorea = caudate or at least the striatum in general)
If you ran an electrolyte panel on a patient with Legionairres’ what would you see?
Hyponatremia
How do you get Brucellosis?
Unpasteurized milk
Clarithromycin, metronidazole, and omeprazole are a useful therapy in treating a bug that causes what 2 cancers?
Gastric adenocarcinoma and lymphoma (this is triple therapy for H. pylori)
What E. coli virulence factors are the most important for pneumonia and neonatal meningitis
K capsule
A cherry red epiglottis is likely caused by what organism? What sign on CXR?
Haemophilus influenzae B; Thumbprint sign (Steeple sign = Croup, parainfluenzae)
What are the reservoirs for Salmonella vs. Shigella?
Salmonella = animals (chickens, turtles); Shigella = humans and primates only
Tetanospasmin inhibits the release of GABA and glycine from these cells ________
Renshaw cells