(From Micro, 10 Oct 2000, by Brian Buschman)
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Chlamydia (can Rickettsia) are intracellular parasites that cannot make ATP but must grab it from their host. Chlamydia also exists as an elementary body as they move from one host to another and as a reticular body (or initial body) when inside. The RB is small and like a spore in that it does nothing because it has no ATP source. The initial body is what undergoes metabolism and divides.
Chlamydia is epically fond of columnar epithelia so it can be found in the conjunctiva, cervix and trachea. This means that they do not grow well in the squamous epithelia of the vagina but like to infect the glands. Also to culture it you need McCoy’s tissue culture.
C. trachomatis is an infection of eyes and genitals. In males it causes NGO (non-gonococcus urethritis) and in females it can lead to PID. If a baby is born to an infected mom the kid will get inclusion conjunctivitis without erythromycin eye drops.
It can also lead to trachoma which is an eye infection that causes eyelashes to grow inside and scar the cornea. It is very preventable.
It also causes some infant pneumonia. Dx is by McCoy’s agar, antibody fixation and PCR. You must treat with tetracycline or erythromycin because Chlamydia is often associated with gonorrhea or ureaplasma urealyticum.
The disease is mostly carried in birds causing atypical pneumonia. The lungs sound normal on ascultation except for a few cracks but the lungs are filled with junk that can be seen on x-ray.
Treponema is a small corkscrew that has no toxins and most of the damage is from the host’s defenses. They are very hard to see and you must use silver staining, dark field microscopy or Ab fluorescence.
It works antigenically by stimulation production of Abs that attack the host cell’s plasma membrane.
1o syphilis involves a painless chancre (ulcer) that forms where they multiply. It is usually on the penis in males or cervix and external genitallia in females, but it can be anywhere. It develops 6 weeks after inoculation and heals on it’s own in about six more weeks.
2o syphilis comes about 6 weeks after the ulcer goes away unless the patient is treated. At this point bacteremia begins. It has widespread effects like fever, lymphadenopathy and involvement of skin. Especially red dots on the palms and soles of feet. Hair loss is seen on affected skin.
It also has a wart called condyloma latum which is very contagious if it ruptures. Usually on the scrotum or vulva. It goes away in about 6 more weeks.
Latent syphilis is where occasional relapses can occur but usually the disease sits dormant for 6-40 years. 66% of patients clear up completely on their own during this phase. (They never develop 3o syphilis.)
3o syphilis has three man parts:
1) Gummas syphilis are granulomastous legions that become necrotic and fibrotic. Usually in the skin and bone.
2) Cardiovascular syphilis occurs with an aortic aneurysm.
3) Neurosyphilis involves:
a. Asymptomatic neurosyphilis which appears normal but CSF shows syphilis.
b. Meningitis
c. Meningovascular syphilis shows a blocking of meningeal vessels.
d. Tabes dorsalis is a loss of the dorsal column showing loss of vibratory and proprioception.
e. General paresis.
f. Argyll-Robertson pupil. Pupilary contraction for accommodation but not in response to light.
Congenital syphilis is from placental transfer and causes mortality and late stage syphilis.
Diagnosis is in addition to dark field microscopy you can test for syphilis with VDRL (venereal disease research laboratory)or RPR (rapid plasma reagin) based on fluorescence but they have lots of false positives with cross reaction with other bugs. FTA-ABS (indirect immunoFluorescent Treponemal Antibody Absorption) and MHA-TP are confirmatory tests.
Treatment is with penicillin.
Chancroid is caused Haemophilus ducreyi. It involves rows of gram-negative coccobacillary rods causing lymph node rupture and painful genital rupture. Remember syphilis ulcer is painless. Treat with erythromycin.
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