22. STDs – Microbiology – Flashcards
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| What STIs are considered Curable? |
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| - Chlamydia - Gonorrhea - Trichomoniasis - Syphilis - Chancroid |
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| Which STIs are incurable? |
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| - HIV/AIDS - HPV - Hepatitis B - Herpes |
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| Consequences of STIs for women |
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| - Pelvic Inflammatory Disease - Infertility, ectopic pregnancy - Cervical cancer - Adverse pregnancy outcomes |
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| Consequences of STIs in infants |
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| - Eye infections - Blindness - Death |
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| Consequences of STIs in men |
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| - Infertility - Narrowing of urethra |
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| What is the prognosis of HIV/AIDS? |
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| eventually fatal (even with treatment) |
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| What kind of bacteria is gonorrhoea? |
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| - Aerobic Gram negative diplococci - very fastidious - Often appear intracellular on a gram stain |
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| What are some risk factors for N. gonorrhoea? |
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| - Age < 25 - Street youth, homeless - New sexual partners - > 2 sexual partners/year - Non-barrier contraception |
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| What are the risks of transmission of N. gonorrhea in the following situations: - Infected female to male - Infected male to female - Anal sex |
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| - 20% per episode - 50% per episode - not well quantified but also high |
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| What are some clinical manifestations of gonorrhoea? |
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| - Acute urethritis/cervicitis - Ano-rectal or pharyngeal gonorrhea - PID - Septic arthritis |
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| What are the major virulence factors associated with N. gonorrhoea? |
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| 1. Pili --> helps the bacteria adhere to the mucosal surface and inhibit killing by neutrophils 2. Outer membrane --> outer membrane proteins facilitate invasion of epithelial cells --> LPS posses and endotoxin activity that results in ciliary death |
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| What type of cells does N. gonorrhoea infect? |
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| columnar or cuboidal epithelial cells |
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| How long does it take for epithelial cells to be penetrated by gonorrhoea? |
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| 20-24 hours |
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| Where can the N. gonorrhoea infection spread? |
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| - the proximal genital tract - Bloodstream - joints |
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| We used to be able to treat gonorrhoea with penicillin but now it is resistant to it. What are treatment alternatives? |
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| - Plasmid mediated beta-lactamaes (fluoroquinolones and tetracycline have very high resistance) |
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| What does the CDC recommend for gonorrhoea treatment? |
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| - Cefixime which is a cephalosporin - It is the only oral agent for uncomplicated url-genital or rectal gonorrhea |
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| What needs to be on your plate when culturing for gonorrhoea? |
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| - Some antibiotics to suppress the normal flora |
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| Gonorrhoea doesn't grow on sheep blood agar plates, but it does grow on ____ plates |
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| CHOCOLATE |
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| It is more common to use PCR techniques to test for gonorrhoea. What samples do we use for males and females? |
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| Males: 1st voided urine (want to get the bacteria that have built up in the urethra...don't care about what is in the bladder) Females: vaginal swabs that can be self collected |
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| IF doing a culture for gonorrhoea, what type of samples do you need? |
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| A urethral swab for males (ouch) and a cervical swab for females |
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| What are the three species of Chlamydia? and which one do we care about? |
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| 1. C. psittaci 2. C. pneumoniae 3. C. trachomatis --> care about this one since it usually the cause of chlamydia |
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| Describe the life cycle of C. trachomatis |
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| - It is biphasic - It has an elementary body which is the inactive form - And a reticular body which divides |
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| Chlamydia commonly causes urethritis in men. What is the incubation period and what % of men are asymptomatic? |
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| - incubation period is 7-21 days - as many as 25% of men are asymptomatic |
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| Cervicitis and PID are common complications of chlamydia. What % of women with cervicitis are asymptomatic? |
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| 80% |
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| What are the first and second line therapy for Chlamydia? What is the benefit to the 1st line therapy? |
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| 1st: 1 gram of Azithromycin (It's a single dose! Yay! We call this direct observed therapy or DOT) 2nd: 100 mg BID of doxycycline (10 day course - no one likes that!) |
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| How do we diagnose Chlamydia in the lab? |
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| - Antigen detection - Immunofluorescence - Cell culture - PCR (used most! male urine/female vaginal swab) |
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| What kind of virus is Herpes simplex? |
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| - An enveloped, ds-DNA virus with an icosahedral capsid |
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| What percentage of the US population has HSV-2? |
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| 24%...but that may just be the tip of the iceberg (since many are unrecognized or asymptotic) |
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| HSV-1 is most frequently associated with --> |
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| oral and ocular infections (causing more genital infections! 340% increase) |
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| HSV-2 is most frequently associated with --> |
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| genital infections |
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| Describe % transmission through viral shedding of HSV during asymptomatic vs. symptomatic outbreak |
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| asymptomatic = 70% symptomatic = 30% |
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| What % of people who are over the age of 30 in the US are HSV2 +? |
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| 25%! |
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| Explain why newly recognized outbreaks in a monogamous couple does not equal infidelity. |
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| Many recognizes first outbreaks may actually be reoccurrences (also keep in mind latency) |
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| Which HSV (1 or 2) involves more relapses? |
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| HSV-2 (90% have 1 reoccurrence, 28% have 6 or more, 20% have 20 or more) |
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| When is neonatal herpes transmitted? |
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| In utero it is very rare Intrapartum is 75-80% |
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| What complications can arise from neonatal herpes? |
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| - Severe disseminated infections - Encephalitis - 80% fatal without treatment |
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| What happens if a woman has recurrent break outs of herpes and gets pregnant? |
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| - will give prophylaxis - may opt for a C section |
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| How do we diagnose Herpes Simplex virus? |
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| - Viral culture - Serology --> but you can't differentiate between HIV-1 and HIV-2 - PCR --> way more sensitive and quite specific |
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| What kind of virus is human papilloma virus? |
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| - Naked icosahedral virus - Circular double stranded viral DNA |
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| How many types of HPV viruses are there? |
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| > 100 types |
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| What kind of Skin-to-skin HPV infections are common? What types cause it? |
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| 1, 2, 3 and others --> plantar and common warts |
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| What mucosal HPV infections are low risk and what types cause it? |
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| 6 and 11 --> associated with genital warts |
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| What mucosal HPV infections are high risk and what types cause them? |
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| - invasive cancers --> HPV 16, 18 and others |
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| How long does the development of cervical cancer take? |
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| 10 years |
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| Can you detect HPV using a pap smear? |
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| Nope, you look for changes in the cervix cause by the virus |
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| Is there a risk of getting HPV from the vaccine? |
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| NO Because to make the vaccine, they excise a gene from the virus that codes for the nuclear capsid... put it in a eukaryotic cell and build the capsid. There is no genetic material inside --> inject it into the patient and antibodies will be made in response |
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| What strains does the HPV vaccine target? |
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| 16, 18, 6, 11 |
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| When do you get your HPV vaccine doses? |
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| 0, 2 and 6 months |
