Micro - STD & UTI
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- Where is N. meningitidis normally found?
- Normal flora of nasopharynx
- What are the sx. of meningicoccemia?
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*diseeminated infection
*petechial rash
*pupura
*DIC
*shock - What are the symptoms of meningitis caused by N. meningitidis?
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*H/A
*stiff neck
*mental status changes - What is the treatment for meningitis caused by N. meningitidis?
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*rapid tx. w/ceftriaxone, PCN, cefotaxime
*rifampin prophylaxis for close contacts - Is there a vaccine for N. meningitidis? What is a drawback?
- A vaccine is available for adults only but it doesn't protect against the B serotype.
- What are some bacterial characteristics and virulence factors of N. meningitidis?
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*G- diplococci
*antiphagocytic capsule
*blebbing outer membrane
*pili and adhesins
*LPS - Which Neisseria organism can be part of the normal flora?
- N. meningitidis can be found in the URT, but n. gonorrheae is never part of the normal flora.
- Describe the surface structure of N. gonorrheae.
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*G- diplococci
*hypervariable surface structure
*NO capsule
*expresses pili, adhesins, and invasins - What kinds of symptoms can uncomplicated N. gonorrheae cause in men? Women? Infants?
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*M: urethritis, purulent discharge, epididymitis
*W: cervicitis w/exudate, salpingitis, PID
*I: conjunctivitis - What are the hallmarks of DGI with N. gonorrheae?
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*septic arthritis
*septicemia
*skin lesions - Describe the pathogenesis of N. gonorrheae.
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*attacks non-ciliated cells
*taken up by endocytosis
*forms microcolonies
*rarely penetrates past subepithelium - Infection with N. gonorrheae carries other risks - what are they?
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*increased susceptibility to HIV and other STD
*increased transmissibility of HIV - Should N. gonorrheae be treated with PCN?
- No b/c of resistance problems. Ceftriaxone is the preferred tx.
- How is gonorrhea diagnosed?
- Culture, gram stain, or rapid screening test.
- What triggers a bout of bacterial vaginosis?
- Any change in the normal flora of the vagina which results in supression of lactobacilli and growth of gardnerella, mycoplasma hominis, et al.
- What is the primary symptom of bacterial vaginosis? What causes this?
- Fishy smelling discharge. Bacteria secrete proteases that break proteins into polyamines.
- How is bacterial vaginosis diagnosed?
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*presence of clue cells
*vaginal p > 4.5
*discharge appearance and odor - Why is it important to treat BV? What is the preferred treatment?
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*numerous OB/GYN sequelae if untreated
*metronidazole, probiotics - What is the most common agent of UTI? What determines the site of infection with this organism?
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*uropathogenic E. coli
*type of adhesin expressed and receptors on tissue - What is a Type 1 pili?
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*expressed by UPEC
*binds mannose-containing receptors
*assoc. w/cystitis - What is the P pili?
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*expressed by UPEC
*binds digalactoside residues in kidney
*assoc. w/pyelonephritis - What does the S pili bind?
- *sialic acid
- What does the Dr adhesion bind?
- *DAF
- Give two reasons as to why women may be more susceptible to UTI than men.
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1.Shorter urethra
2.Prostatic fluid is protective - How might choice of contraception influence susceptibility to UTI?
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*use of diaphragms increases risk
*use of condoms decreases risk - What is cystitis? What are the symptoms? How is it treated?
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*infection of the lower urinary tract
*burning, painful urination
*turbid urine that may have blood
*tx. w/short course of antibiotics - What is pyelonephritis? What are the symptoms? How is it treated?
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*infection with kidney involvement
*may lead to systemic bacteremia
*fever, chills, pain at the costovertebral angle
*may cause renal scarring
*tx w/long course of antibiotics - How can T. pallidum be visualized?
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*Gram staining does not work
*silver stain
*dark field microscopy - Describe the membrane structure of T. pallidum.
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*similar to G-
*smooth outer membrane
*periplasmic flagella - What are three modes of transmission for T. pallidum?
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*needles
*sex
*congenital - Describe the 5 stages of disease by T. pallidum. At which stages is the pt infectious?
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1.incubation
2.Primary: painless chancre
3.Secondary: rash (on palms and soles), mucus patches
4.Latent phase
5.Tertiary: CV, neuro, gummatous
*infectious at stages 1,2,3 - How is syphilis diagnosed?
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*non-treponemal screening test
*highly specific treponemal confirmatory test - How is T. pallidum studied?
- Animals must be used - no in vitro culture.
- What are the 3 main serovars of Chlamydia trachomatis?
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1.Ocular
2.Genital
3.Lymphogranuloma venereum (LGV) - What animal reservoir is Chlamydia psittaci associated with? How is it spread among humans?
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*Birds - shed in feces
*there is no p-p spread - Describe 2 disease states associated with Chlamydia psittaci.
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*respiratory infection with atypical pneumonia
*gestational psittacosis: premature labor, sponatneous abortion - Chlamydia pneumoniae caused what percentage of community acquired pneumonia?
- 10-20%
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T/F:
Chlamydia is able to colonize the epithelial surface or invade and replicate within cells. - False: Chlamydia is an obligate intracellular pathogen, so it can only live inside of cells.
- What are the two forms of the chlamydia organism? Which is infectious? Which is metabolicallly active?
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*elementary body: highly infectious, metabolically inactive
*reticulate body: noninfectious, metabolically active - What is an "inclusion"?
- An intracellular vesicle filled with reticulate and elementary bodies of Chlamydia. It is released by exocytosis or host cell lysis.
- How is tissue damage mediated in a Chlamydia infection?
- By chronic inflammatory response.
- How is a chlamydia infection diagnosed?
- Typically by urine screening test.
- When considering treatment for chlamydia what ia essential?
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*the rx must be able to penetrate the cell
*doxycycline and azithromycin are recommended - What are clue cells?
- Exfoliated epithelia wiith large numbers of Gardnerella attached; diagnostic of bacterial vaginosis