Bacterial STDs Flashcards
What is the most common bacterial STD in the US?
Chlamydia
Gonorrhea is number 2
Neisseriaceae characteristics
Gram negative diplococci
Aerobic
REQUIRES 5% CO2 for growth
Oxidase positive
Glucose only (N. gonorrhea), glucose and maltose (N. meningitidis), or glucose, maltose and lactose (N. lactamica)
Causes direct mucosal infection
Media for Neisseria
Chocolate agar or Thayer-Martin Chocolate Agar in CO2 incubator
NOT blood agar
Gonorrhea in male
90% have symptoms
Urithritis
Purulent discharge
Dysuria
Most common complication: acute epidyimitis
Gonorrhea in females
50% asymptomatic
Infection of cervix urethra
Vaginal discharge, dysuria
Ascending infection in 45%
PID, infertility, fallopian tube scarring, ectopic pregnancy
Disseminated gonorrhea
Swelling and pain in joints
Rash
Conjunctivitis
Virulence factors for gonorrhea
Pili: initiate binding to epithelial cells, antigenic and phase variation
Opa proteins (Outer membrane Proteins): important for intimate attachment. Antigenic and phase variation
IgA protease
What is antigenic and phase variation?
Antigenic: changing of amino acid sequence of surface proteins (one patient can have different pili from same infection!)
Phase: On-off control of expression of surface proteins
Both are used by N. gonorrhea to avoid host defense mechanisms
Antibiotic resistance of gonorrhea
Were very susceptible to penicillin, then had Beta-lactamase, then chromosomal mutations
Now cephalosporins are last line of defense for treating gonorrhea
Current guidelines for treatment of N. gonorrhea
Third generation cephalosporins plus azithromycin or doxycycline
NO more Quinolones (e.g. Ciprofloxacin)
Patients treated for N. gonorrhoeae should also be treated for Chlamydia trachomatis
Treat all sexual partners
Lipo-oligosaccharide (LOS)
N. gonorrhea
Equivalent of the lipopolysaccharide (LPS) of gram-negative bacteria, but without the long O-side chains.
8 or more types of LOS
Toxic for ciliated cells in tissue cultures. LOS is probably responsible for many of the inflammatory processes seen during an infection.
Diagnosis of N. gonorrhea
Gram stained smears of urethral or endocervical exudates reveal many diplococci WITHIN polymorphonuclear cells (PMNs).
Sensitivity: 90% for men, 50% for women. Specificity: 99% for men, 90% for women.
This is true only for urogenital infections with N. gonorrhoeae. It is NOT true for other kinds of infection (e.g. oral pharyngeal infections).
Culture identification of N. gonorrhoeae including a positive oxidase test and the oxidative utilization of glucose, but not maltose or sucrose is the “Gold Standard” for laboratory diagnosis of gonorrhea.
Chlamydia
Obligate intracellular
Highly infectious/ very prevalent
Cocci/coccobacilli
Gram negative
VERY small (0.2-0.8 um diameter)
Dependent on host cell for ATP
What percent of men and women are asymptomatic with C. trachomatis
75% women
50% men
Comparison of incidence of gonorrhea, chlamydia, and syphillis in men vs women
Chlamydia: women have it more than men
Gonorrhea: equal in men and women
Syphilis: High rate in men and less in women
Symptoms of C. trachomatis
Impossible to distinguish from gonorrhea
What is the most common cause of neonatal conjunctivitis
C. trachomitis
Lymphogranuloma venereum
caused by C. trachomitis (serovariants L1-L3)
Sexually transmitted
Small ulcer disseminates to inguinal lymph nodes
Africa and S. America
Treatment for C. trachomitis
Azithromyin
or
Doxycycline
Treat partners
Not same problems with antibiotic resistance seen with gonorrhea
Chlamydia lifecycle
Biphasic
Elementary bodies (EB’s) measuring about 0.3 µm in diameter have a condensed chromosome and are the infectious form. EB’s can be recognized by their electron-dense centers. EB’s enter the cell by endocytosis.
Reticulate bodies (RB’s), which measure 1 µm in diameter, are the vegetative forms that multiply intracellularly. RB’s develop within the membrane-bound vacuole through a process of metabolic changes and reorganization of chromosome. The molecular basis of this process is not understood. Energy for replication is derived from the ATP generated by the host cell.
After 24 to 72 hours of intracellular growth, RB’s reorganize and condense to form multiple new EB’s. The host cell ruptures and frees the EB’s, which are capable of infecting other host cells.
Trachoma
Caused by C. trachomitis
Chronic keratoconjunctivitis that begins with acute inflammatory changes in the conjunctiva and cornea and progresses to scarring and blindness.
Hand to eye contact
Inclusion conjunctivitis
Caused by C. trachomitis
Inclusion conjunctivitis is an acute disease that occurs throughout the world in both infants and adults. It is the most common form of neonatal conjunctivitis in the United States.
What is the most frequently reported infectious disease in the US?
C. trachomitis
What is the most sensitive and specific test for C. trachomitis right now?
NUCLEIC ACID AMPLIFICATION TECHNIQUES (NAAT)
Chlamydial cell wall
NO muarmic acids
How can you visualize chlamydia?
Giemsa stain
What do the different serotypes of C trichomitis cause?
A-C: blindness
D-K: STI
L1-L3: LGV
Spirochetes
spiral, motile bacteria
Gram-negative but don’t have LPS
Reproduce by transverse fission
Pathogenic treponema Can’t culture in vitro
Four stages of syphilis
Primary: Primary lesion or chancre (usually painless). Can test seronegative for syphilis. Highly infectious.
Secondary: Several weeks after primary chancre. Mucocutaneous lesions. High titer serologic tests. Alopecia. Condylomata lata. Lesions ARE infectious.
Latent: No symptoms, but serum positive.
Tertiary: 30% untreated pts progress to tertiary syphillis in 1-20 years. Sero-positive. Due to immune response. Gummatous lesions, cardiovascular syphilis, neurosyphilis. Lesions are NOT infectious.
Neurosyphilis
Can occur at any stage of syphilis
Clinical manifestations can include acute syphilitic meningitis, meningovascular syphilis, and ocular involvement
How to diagnose Ab to syphilis?
Rapid Plasma Reagin (RPR) Card Test for Syphilis
How to treat syphilis?
Penicillin (no resistance, but higher doses than previously needed)
Doxycycline or tetracycline if allergic to penicillin
Resistance to azithromycin for people allergic to penicillin has been reported
JARISCH-HERXHEIMER REACTION
A reaction that that develops 2-24 hours after penicillin treatment in patients infected with Spirochetes (e.g. syphilis, Lyme disease).
Fever Chills Headache Nausea General joint aches General muscle aches Increased heart rate (tachycardia)
