1. Chlamydia trachomatis Sexually Transmitted Infections
Funmi Adewale
MLS Microbiology

2. Objectives After the presentation, the audience will be able to:
Summarize the natural history of the sexually transmitted infection Chlamydia
Outline the life cycle of the bacterial species Chlamydia trachomatis
Determine which serotypes of Chlamydia trachomatis are most associated with STIs
Propose explanations for the recent trends in Chlamydia prevalence
Discriminate between the various diagnostic methods for Chlamydia trachomatis according to their targets, specificities and sensitivities
Assess which specimens are acceptable and which diagnostic methods are recommended given the patient circumstances
Describe treatment options for patients diagnosed with Chlamydia trachomatis STIs
Predict future trends in prevalence based on public health prevention efforts

3. Chlamydia
2nd most common sexually transmitted infection (STI) in US after HPV; most common bacterial STI
Caused by infection with Chlamydia trachomatis
Obligate intracellular parasite (cannot make ATP)
Infects non-ciliated columnar cells (conjunctiva, urogenital tract, rectum, pharynx)
Transmitted through sexual intercourse
Most initial infections are asymptomatic; last for months to years
Repeat infections are common
Easily treated
Retrieved from Mahon, C., Lehman, D. & Manuselis, G. (2015). Textbook of diagnostic microbiology. Maryland Heights, Missouri: Elsevier/Saunders.

4. Risk Factors Age (< 25)
Race (infection 5 times greater in blacks compared to whites)
Sexual Activity
# of partners
new partners
Men who have sex with men (MSM)*
Retrieved from Torrone, E., Papp, J., & Weinstock, H. (2014). Prevalence of Chlamydia trachomatis Genital Infection Among Persons Aged Years - United States, MMWR: Morbidity & Mortality Weekly Report, 63(38),
*not much known (~6% positivity rate as of CDC’s monitoring in 2005)

5. Clinical Presentation
Retrieved from
Clinical Presentation
Majority of infections are asymptomatic
Primary symptoms
Cervicitis in women
Nongonococcal urethritis in men (progresses to epididymitis)
Sequelae include:
Pelvic inflammatory disease (infection/inflammation of uterus, fallopian tubes, ovaries, peritoneal cavity)
Ectopic pregnancy
Tubal infertility
Lymphogranuloma venerium (a more severe disease caused by L1-3 serovars, rarely seen in the US)
In neonates, can lead to:
Pneumonia
Conjunctivitis
Retrieved from
Mucopurulent discharge
Upper tract infection; Most common cause of epididymitis
LGV is invasive (lymphatics) and rarely seen in US

6. Life Cycle of C. trachomatis
Retrieved from Mahon, C., Lehman, D. & Manuselis, G. (2015). Textbook of diagnostic microbiology. Maryland Heights, Missouri: Elsevier/Saunders.
Elementary body (EB): infectious, metabolically inactive, extracellular and enveloped (Gram-negative elements = LPS)
Reticulate body (RB): non-infectious, metabolically active, intracellular
Diagnostic text

7. Structural & Genetic Features
Serotyping based on:
Major outer membrane protein (MOMP), species specific
Serovars D-K responsible for non-LGV STIs
Lipopolysaccharide (LPS), genus specific
Genetics
Cryptic plasmid (>99% of C. trachomatis)
Retrieved from Land, J. A., Van Bergen, J. E., Morre, S. A., & Postma, M. J. (2010). Epidemiology of chlamydia trachomatis infection in women and the cost-effectiveness of screening. Human Reproduction Update, 16(2),
Unknown purpose

8. Diagnosis: Methods Culture Non-culture
Recommended method for diagnosis and legal investigation of code 600 in children
Culture
Shell vial method
96-well microtiter plate method
Non-culture
Surface Antigens (MOMP or LPS)
Direct fluorescent antibody (DFA) tests
Enzyme immunoassays
Nucleic Acid
Nucleic acid probe tests
Nucleic acid amplification testing
Recommended method for screening/diagnosis (code 600 in adults)
Shell vial is more accurate than 96-well b/c it requires more inoculum and has less risk of cross-contamination
Blind pass: 1st incubation monolayer is disturbed and used to reinoculate 2nd monolayer to improve sensitivity
Analysis: light microscopy visualization for cytopathic effect, stain w/ fluorescein-conjugated mAb for visualization
Issues w/ culture: turnaround time, poor standardization, labor intensive, requires technical skill, highly-dependent on specimen quality
DFA: specimen rolled onto slide, flooded with a stain of fluorescein-labeled mAb that react with either MOMP or LPS (cross-reactivity!) antigens
EIA: antibodies react with LPS (cross-reactivity!), then detected through enzyme assay (e.g. HRP)

9. Diagnosis: Methods
Retrieved from Mahon, C., Lehman, D. & Manuselis, G. (2015). Textbook of diagnostic microbiology. Maryland Heights, Missouri: Elsevier/Saunders.
Culture has poor sensitivity (missing a lot of infections), but excellent specificity (gold standard)

10. Diagnosis: Specimens
Specimen of choice (according to CDC recommendations)
Men: urine (as good as or superior to urethral swabs)
Women: vaginal swab (as good as endocervical swabs)
In women, urine is acceptable for screening, but may reduce sensitivity (up to 10 percent of infections missed)
Extragenital sites: rectal and oropharyngeal (not much research, but amplification tests recommended)
Collection, transport and storage
Transport media for swabs varies depending on diagnostic method
Regardless of method, should be refrigerated (4°C) immediately
Long-term storage ranges from -10°C to -30°C for varying durations
And less invasive

11. Prognosis & Treatment
Excellent prognosis, given of treatment compliance
Single-dose oral azithromycin OR 1-week course of doxycycline
Expedited partner therapy: prescribing medication for sexual partner of diagnosed patient without examining partner
Proven to reduce repeat infections in females
Sanctioned by the CDC
As of 2010, only legal in 27 states

12. Prevention: Screening
CDC recommends annual screening for:
ALL sexually-active women under the age of 25
Sexually-active women 25 and over IF determined to be at increased risk (e.g. new or multiple sexual partners)
Men who have sex with men (MSM)
CDC also recommends screening for repeat infection months after initial diagnosis
No screening recommended for heterosexual men UNLESS:
High prevalence settings (e.g. correctional facilities)
Partners of infected women
Barriers to screening: insurance (young adults), privacy (adolescents), awareness, provider-failure to offer screening
BYOP (bring your own partner; when patients are called and informed of positive results, advised to bring partner with them during follow-up)

13. Chlamydia trachomatis STIs: Summary
Most prevalent bacterial STI in United States
Obligate intracellular parasite of columnar epithelium
Serovars D-K cause most of the infections seen in US
Nucleic acid amplification testing is recommended diagnostic method (except in children)
Theoretically easy to reduce prevalence
Easy to prevent transmission (safe sex practices e.g. free condoms by mail in CA)
Easy to minimize spread (sensitive diagnostic methods => less invasive specimen collection => increased screening/more accurate diagnostic testing)
Easily treated
Areas that need improvement
Increasing initial screening rates, especially in at-risk populations (under age of 25, blacks, MSM)
Free, at home test-kits by mail in Los Angeles
Increasing reinfection testing by providers 3-12 months after initial infection
CA Health Dept (Family Health Council)
LA Health Dept

14. References
Abram, S. (2014, July 22). Rise in chlamydia, gonorrhea cases renew call for std home test kits for women. LA Daily News. Retrieved from CDC Grand Rounds: Chlamydia Prevention: Challenges and Strategies for Reducing Disease Burden and Sequelae. (2011). MMWR: Morbidity & Mortality Weekly Report, 60(12), Holmes, K. (2008). Sexually transmitted diseases. New York: McGraw-Hill Medical. Land, J. A., Van Bergen, J. E., Morre, S. A., & Postma, M. J. (2010). Epidemiology of chlamydia trachomatis infection in women and the cost-effectiveness of screening. Human Reproduction Update, 16(2), Mahon, C., Lehman, D. & Manuselis, G. (2015). Textbook of diagnostic microbiology. Maryland Heights, Missouri: Elsevier/Saunders. Papp, J. R., Schachter, J., Gaydos, C. A., & Van Der Pol, B. (2014). Recommendations for the Laboratory-Based Detection of Chlamydia trachomatis and Neisseria gonorrhoeae MMWR Recommendations & Reports, 63(2), Steinberg, J. (2015, February 18). Free condom-by-mail program set for san bernardino county. San Bernardino County Sun. Retrieved from Torrone, E., Papp, J., & Weinstock, H. (2014). Prevalence of Chlamydia trachomatis Genital Infection Among Persons Aged Years - United States, MMWR: Morbidity & Mortality Weekly Report, 63(38),