Bacterial STDs Flashcards
What is the etymology of the term “clap”?
It comes from a French word for brothel.
List the prevalence of STDs in the U.S.?
Chlamydia: 1,500,000
Gonorrhea: 400,000
Syphilis: 24,000
______________ is a facultative intracellular pathogen.
Neisseria gonorrhoeae
Remember the red cushions on the white chairs in the Sketchy scene.
If you have high specificity, then you have low ___________.
false positives
With low sensitivity, what will you have a lot of?
False negatives
____________ describes what percent of people without the disease will test negative.
Specificity
Oropharyngeal samples might test positive (falsely) for ______________.
Neisseria, because there are commensal bacteria that are intracellular Gram-negative diplococci
Gram stains for Neisseria gonorrhoeae have low _____________.
sensitivity (meaning high rate of false negatives)
Which strains of Neisseria are encapsulated?
N. meningitidis
(In the Sketchy scenes, the evidence in the college dorms is covered with glass domes, while in the nightclub scene the glass is broken on the floor!)
What virulence factor causes inflammation in Neisseria meningitidis?
Lipooligosaccharide (remember the LOS envelopes that are burning in the Sketchy college student’s dorm); these are the same as LPS but without the O sidechain
Neisseria require ___________ to grow.
5% CO2
Colonies turn ____________ in positive oxidase tests.
black
Both strains of Neisseria can ferment __________.
glucose
What two things are generally needed for a diagnosis of gonorrhea?
- Either mucopurulent cervical discharge or exposure to an infected person
- Growth on susceptible agar, PCR, or Gram stain showing Gram-negative diplococci
True or false: more men than women are asymptomatic carriers of gonorrhea.
False. Many more women are asymptomatic carriers (about 50%).
PID occurs in about _______ percent of female gonorrhea infections.
10
Untreated, gonorrheal conjunctivitis can cause __________.
corneal perforations
What age group has the highest incidence of gonorrhea?
15 - 24 (over 50%)
What mechanism allows Neisseria to escape the immune system?
- Antigenic variation from amino acid switching in pili (can make up to 1,000,000 different forms)
- Phase variation (on-off switching for expression of genes)
In the 1970s, Neisseria gonorrhea became resistant to _________________.
penicillins (due to expression of beta-lactamases)
______________ are no longer recommended for treatment of Neisseria gonorrhoeae due to widespread resistance.
Fluoroquinolones
_______________ is the only recommended therapy for gonorrhea.
Ceftriaxone and azithromycin
The macrolide can cover Chlamydia, but tetracycline can be substituted.
Chlamydia are much _________ than Streptococcus.
smaller
Which strains of Chlamydia are specific to humans?
C. trochomatis and C. pneumoniae
How does Chlamydia survive inside cells?
It inhibits phagolysosome formation (meaning it is non-fusogenic).
Most people infected with Chlamydia are ____________.
asymptomatic
_____________ reproduce via transverse fusion.
Spirochetes
________________ cannot be cultured in vitro.
Treponema pallidum
Tertiary syphilis is ____________ transmissible.
not
Syphilis initially travels by _____________.
lymphatics
Describe the timeline of syphilis.
Infection Incubation period: 3 weeks Primary syphilis: 2-6 weeks Asymptomatic period: 2-24 weeks Secondary syphilis: 2-6 weeks Latent syphilis: 3-30 years Tertiary syphilis
What percent of people recover from syphilis infection?
~25%
Describe the symptoms of each stage of syphilis.
Primary: painless chancre at site of lesion (usually as macule to papule to ulcer) and lymphadenopathy
Secondary: maculopapular rash, lymphadenopathy, alopecia, condyloma lata
If you suspect syphilis but a person has a painful chancre, what organism might have caused this?
Haemophilus ducreyi
The only sign or symptom of latent syphilis is _____________.
positive serologic testing
What microscopy technique is needed to identify Treponema pallidum?
Darkfield microscopy
____________ is more common in females and ___________ is more common in males.
Chlamydia; syphilis
Rates of gonorrhea are about the same between genders.
Neisseria undergo rapid autolysis at ____________.
25º C or alkaline pH
The best screening test for Chlamydia and N. gonorrhoeae is ____________.
NAAT (basically PCR)
In someone with gonorrhea, it is important to contact and treat those who’ve had sex with that person in the past __________.
60 days
How should gonorrhea be treated?
With intramuscular ceftriaxone and oral azithromycin (the latter for Chlamydial coinfection)
Which stain helps identify Chlamydia?
Giemsa (like the GEMS from the Sketchy scene)
How does Chlamydia cause conjunctivitis?
It causes the eyelids to turn inward, thereby scraping the eye continually and leading to conjunctivitis.
Lymphogranuloma venereum can mimic ____________.
ulcerative colitis (because it can spread through the peritoneum)
What is unique about Treponemal growth?
They divide by transverse fission.
Can treponema persist in the environment?
Mostly no. They of course had to come from somewhere, but infection by fomites has not been documented.
Which of the bacterial STDs is on the rise?
Syphilis
The incidence in 2015 was three times the incidence in 2005.
Leptospirosis presents with damage to what organs?
Liver and kidney
Which are larger, reticulate bodies or elementary bodies?
Reticulate
What percent of untreated patients will develop tertiary syphilis?
30%
Note: this is now rare because antibiotics during the primary or secondary phase prevent this complication.
Other than presence of pain, how can you distinguish H. ducreyi from syphilis?
H. ducreyi present with multiple ulcers while syphilis presents with a single indurated ulcer.
Which immune pathway is responsible for the elimination of syphilis?
T-cells
The Jarisch-Herxheimer reaction occurs in the ____________ stages of syphilis.
first and second
Neisseria obtained a beta-lactamase from _________.
E. coli
