GU infections Flashcards
Double stranded DNA
Enveloped
Space between envelope and capsid is packed with tegument proteins
Alpha-Herpesvirus
Two life cycles of HSV
- Quiescent latent infection = limited to neurons (sacral ganglion), not associated with clinical symptoms
- Lytic replication = active, many infectious viruses are produced, happens at the mucosa/skin at the site of initial inoculation
Can HSV be transmitted if there are no lesions present?
Yes - on any given day have 25% chance of shedding virus even without lesions
Diagnosis of HSV
Clinical presentation - vesicles
Detection of virus in lesions – culture, IFA, PCR
Detection of HSV-1 or HSV-2 specific antibodies
Treatment of HSV
Famciclovir, Acyclovir – antivirals, nucleotide analogs that specifically target viral DNA polymerase and inhibit replication
NO TREATMENT for latent infection and no vaccine
Very large linear double stranded DNA fused at both ends – Poxvirus family
Molluscum Contagiosum
Where does Molluscum Contagiosum replicate?
In the cytoplasm of infected cells – unique for DNA virus
How is Molluscum Contagiosum diagnosed and treated?
Diagnosis based on presentation of lesions and histology (large eosinophilic cytoplasmic inclusions)
Treated with scraping, liquid nitrogen, or iodine
More severe disease in immunocompromised patients can be treated with ritonavir or cidofovir. No vaccine.
Small double stranded DNA virus
Papovavirus family
Icosahedral capsid, not enveloped
Human Papillomavirus
How does HPV lead to disease?
Replicates in the upper level of epithelium – virus DNA has to be maintained as an episome for productive replication
Replication stimulates cellular division– etiology of HPV-induced genital warts
How can HPV lead to cancer?
Accidental integration of broken viral DNA terminates virus replication –> abortive infection or cancer
Viral DNA integration that disrupts E2 gene increases risk of cancer along with expression of E6 and #7
Treatment of HPV
Wart destruction in office by cryotherapy, or application of acid or removal with laser
Vaccine against high-risk strains (6, 11, 16, 18)
Pleomorphic gram negative rods (coccobacilli)
Haemophilus ducreyi
What does haemophilus ducreyi infection lead to?
Painful, ulcerated lesion with lymphadenopathy
Uncommon in US
How is H. ducreyi diagnosed?
Culture or nucleic-acid based detection
How is H. ducreyi treated?
Azithromycin, ceftriaxone, ciprofloxacin
Pleomorphic gram negative rods
Part of normal vaginal flora in many sexually active women
Gardnerella vaginalis
How does G. vaginalis cause disease?
Disturbance of normal flora leads to outgrowth, causing disease
Vaginal lactobacillus keeps G. vaginalis in check
Can synergize with anaerobes to cause disease
How does G. vaginalis present?
Vaginitis, pruritis, dysuria, foul smelling copious vaginal discharge with fishy odor
What is the diagnostic criteria of bacterial vaginosis?
Amsels criteria = Vaginal pH greater than 4.5 Presence of clue cells in vaginal fluid Milky, homogeneous vaginal discharge Release of amine (fishy) odor after addition of 10% NaOH
Treatment for BV?
Nitroimidazoles (metronidazole and tinidazole) or clindamycin
Recurrence is common regardless of therapy
Smallest free-living bacteria
Has no cell walls – gram stain and B-lactams are useless
Slow rate of growth
Ureaplasma urealyticum
Treatment for ureaplasma urealyticum
Erythromycin
Doxycycline
Gram negative spirochete
Extra outer membrane
Periplasmic flagella
Treponema pallidum
What are the stages of sphyillis caused by Treponema pallidum?
Primary stage = painless chancre at inoculation site – highly infectious
Secondary stage = systemic spread to multiple organs and CNS
Latent = asymptomatic and noninfectious, can relapse to secondary or remain asymptomatic
Tertiary = immune system driven damage to multiple organs (skin, bones, vessels, nerves)
How is syphilis diagnosed?
Cannot be cultured on conventional medium or seen on light microscopy
Darkfield microscopy, serology and nucleic acid-based approaches
Treatment of syphilis
Benthazine penicillin – modified for slow absorption and long half life, not effective against tertiary stage
Gram negative obligate intracellular bacteria
Chlamydia trachomatis
2 forms of Chlamydia
Elementary body = metabolically inactive, cannot replicate, but infectious and stable
Initial body = aka reticulate bodies, forms intracellular inclusions, metabolically active, intracellular non-infectious form, can divide and make more of itself
Treatment for Chlamydia
Azithromycin and doxycycline
Gram negative oxidase and catalase positive diplococci
Neisseria gonorrhea
Diagnosis of Neisseria gonorrhea
Chocolate agar - nonselective
Thayer-Martin - selective
Culture
Nucleic acid based used more now
Treatment of Neisseria gonorrhea
Ceftriaxone
Protozoa
Trophozoite
Males asymptomatic
Females mild scant watery discharge or vaginitis with itching, burning and painful urination
Trichomonas vaginalis
Diagnosis of Trichomonas vaginalis
Microscopic examination of vaginal or urethral discharge – usually highly motile in urine
Treamtent for Trichomonas vaginalis
Metronidazole (flagyl)
Yeast
Commonly in immunocompromised
Can cause vaginitis
Candida albicans
Diagnosis of candida albicans
KOH prep of skin scrapping
Treatment of candida albicans
Imidazole vaginal suppositories or single oral dose of fluconazole
