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Amitha's Micro test 3


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What is the major route of infection in UTIs?
Retrograde ascent up the urethra/ureters
What is the normal protective vaginal flora?
Gram positive lactobacilli
What are 3 things secreted by normal flora that deters the growth of other organisms?
Hydrogen peroxide lactic acid to lower pH, and bacteriocins to prevent infection
What hormone promotes growth of vaginal flora?
What virulence factor promotes E. coli UTI's?
pilus that binds epithelial cells
What virulence factor promotes Staph saprophyticus infections of the urinary tract
lipoteichoic acid
What orgainsim accounts for 85% of UTI's?
E. coli
Which orgainsims are mainly responsible for hematogeous spread of UTI's?
Staph aureus or candida
What two things are tested for with a dipstick urinalysis?
Leukocyte esterase levels (indicating neutrophils in the urine) and Nitrate reduction to Nitrate (performed only by enterobacteriaceae)
In the microscopic examinationof urine, how many White cells/ high power field indicate pyuria?
> 5 per high power field
which anaerobic gram-positive spore-forming rod makes an enterotoxin produced in the small intestine which causes transport disturbances and secretory diarrhea?
Clostridium perfringens
What 3 syndromes are caused by Salmonella enterica?
Enteric fever, enterocolitis, and bacteremia
Are salmonella lactose positive or negative?
lactose negative
Campylobacter is a gram (neg/pos?) (cocci/rod?)
Gram negative curved rod
Gram negative bacilli, lactose positive, indole positive, sorbitol negative
E. coli O157 (enterohemorrhagic)
What lactose negative organism is closely related to E. coli
What food borne pathogen causes an appendicitis-like syndrome and causes mucosal ulcerations in the terminal ileum?
Yersinia enterocolitica
What organism that is responsible for many duodenal and gastric ulcers will produce urea and thus an increase in pH in a urease media?
Helicobacter pylori
Which enterobacteriaceae does not causes GI symptomes but causes bubonic and pneumonic plague?
Yersinia pestis
What organism causes most of the cases of tuberculosis?
Mycobacterium tuberculosis
What is the major difference that distinguishes Mycobacterium tuberculosis from other bacteria?
60% of the dry wall weight is lipid--responsible for the acid fast stain specificity.
What cell type ingests Mycobacteria tuberculosis in a non-immune host? What intracellular compartment do the bacteria reside in?
pulmonary alveolar macrophages, reside intracellularly in phagosomes
What is a Ghon focus?
Local lung parenchymal infection caused by mycobacterium bacilli.
What is a Ghon complex?
Ghon focus (site of parenchymal infection plus intrathoracic lymphangitis with draining regional node involvement
What makes up the TB granulomas?
langhans giant cells, lymphocytes, and granulation tissue (fibroblasts and capillaries)
What type of necrosis occurs in the tissue as a result of TB?
caseation necrosis
Can those with a latent infection of TB transmit the disease?
Which 4 drugs are given as initial first line theraphy in TB patients?
Isoniazid, rifampin, pyrazinamide, and ethambutol
What common fluroquinolone would not be given up front to treat UTIs because it is not excreted in the urine?
Moxifloxacin. Other fluoroquinolones are commonly given to treat cystitis
Which 3 organisms can cause food poisoning illness by ingestion of preformed toxins?
S. Aureus, B. Cereus, C. botulinum.
What is the most common cause of traveler's diarrhea?
enterotoxigenic E. coli
Vibrio cholerae causes diarrhea by what mechanism?
irreversible activation of adenylate cyclase-> produces cAMP-> water and electrolyte secretion in gut -> secretory diarrhea
What is the morphology of Borrelia?
elongated, spiral shaped bacteria
What is the natural reservoir of endemic relapsing feber caused byBorrelia? What vector is it transmitted by?
Rodents, fly
What is the natural reservoir of epidemic relapsing fever caused by Borrelia? What vector is it transmited by
Humans, louse born
How does Borrelia evade the immune system?
Gets sequestered into organs of the reticuloendothelial system and re-emerges antigenically modified after a period of quiescence.
What is the best way to diagnose relapsing fever? With what stain?
blood films with arcidine orange stain you can see a small squigly organism
What antibiotics can be used to treat relapsing fever caused by Borrelia?
Tetracycline or erythromycin
What is a Jarish herxheimer reaction?
A reaction seen a few afters antibiotics are given to treat borrelial or spirochete organisms. It causes a febrile reaction because of the antigens released after the bacteria have been killed.
What is Lyme disease?
A systemic infection caused by Borrelia burgdorferi that is spread by the bite of Ixodes ticks. Has a life cycle similar to syphillis
What is the primary reservoir of Borrelia burgdorferi
white footed mouse
At which stage in its life cycle is a tick most likely to transmit lyme disease to humans?
small nymph stage
What are the characteristics of the first stage or primary stage of lyme disease
Erythema migrans and acute flu like or meningitis like symptoms
What are the characteristics of the secondary stage of lyme disease?
A disseminated infection that occurs weeks to months later, can present with arthritis, cardiac (prolonged P-R interval)or neurological symptoms (bells palsy)
What are the characteristics of the chronic or persistent stage of lyme disease?
chronic skin conditions, neurologic changes (encephalitis, dementia, spastic paraparesis, transverse myelitis)
How are Rocky mountain spotted fever and erllichiosis transmitted?
What is the hallmark of roky mountain spotted fever?
small vessel vasculitis- porliferation of the organisms around the endothelium of small vessels with a large inflammatory response
What is the clinical presentation of Rocky Mountain Spotted Fever?
traid of fever, headache, and myalgias. A rash appears on the 3rd day of illness. May have hemmorhagic manifestations of petechia and ecymoses. Also thrombocytopenia
What are the drugs of choice used for Rocky Mountain Spotted Fever
tetracycline and chloramphenicol
What organism causes Rocky Mountain Spotted Fever?
R. rickettsii
What is the organism, vector and host for epidemic typhus?
Rickettsia prwazekii, louse, human
What is the organism, vector, and host for endemic typhus?
Ricketsia typhi, flea, rats and opossums
What is Brill Zinsser disease?
A recrudescence of typhus
What is a morrula?
A group of replicating bacteria in the white blood cells.
What is the organism responsible for Q-fever?
Coxiella burnetti
How is Q-fever transmitted?
Transmitted by inhalation-it is infectious for long periods outside the host.
What is the treatment for Q fever?

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