Case Study
Pathogenic Bacteriology
2009
Case #3
Mamadou Diallo
Anne Roberts
Case Summary
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Patient is 16 year old female
Complaints of ongoing abdominal pain for days and
vaginal bleeding
No nausea or vomiting and denies urinary tract
infection symptoms, chills or fever
Abdominal pain increased 24 hours before being
admitted to the emergency room
Upon examination, exquisite tenderness in the upper
right and lower left quadrants of the abdomen, and
had a fever of 38.3°C (101 °F)
Cervical motion tenderness present upon pelvic
examination as well as right and left adnexal (ovary)
tenderness
Key Information Pointing to
Diagnosis
PHYSICAL EXAMINATION
 Fever of 38.5°C or greater
 Abnormal vaginal discharge
 Lower abdominal tenderness when felt
 Tenderness when cervix is moved
 Tenderness in female organs
Pelvic Inflammatory Disease (PID) believed to be the cause of the symptoms.
2 organisms known to cause PID:
Neisseria gonorrhoeae and Chlamydia trachomatis
LABORATORY EXAMINATION
 Endocervical swab obtained from patient used to inoculate McCoy cells. After
incubation, cells were stained and showed the presence of inclusions.
The Diagnosis for Case #3
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After results from the physical examination and a laboratory examination
that determined the presence of elementary and reticulate body
inclusions in inoculated cells it was established that Chlamydia
trachomatis was the infectious agent.
Classification,Gram Stain Results, and Microscopic
Appearance of Chlamydia trachomatis
Chlamydia trachomatis
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Gram indeterminate – cannot be stained with Gram stain (no
peptidoglycan), structurally organism is Gram negative (outer /
inner membrane & LPS)
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Family:
Chlamydiaceae
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Genus:
Chlamydia
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Species:
C. trachomatis
Diseases and Pathogenesis of
Disease – C. trachomatis
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Chlamydia is a STD. It is an OBLIGATE intracellular bacteria.
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Alternate between two development stages with different functions:
 1. Elementary Bodies (EB) – Infectious form
 Spore-like to permit survival outside of host cell
 Metabolically inert , Dense, compacted chromosomes
 Infect non-ciliated, epithelial cells by phagocytosis
 2. Reticulate Bodies (RB) – Non-infectious form
 Active metabolism, and divides rapidly
 To complete the cycle, the RB must develop into EB
before exiting the host.
 Cell will lyse and release the EB
DISEASES CAUSED BY Chlamydia
 Eye infections - Infant conjunctivitis and Trachoma (Chronic eye infection)
 Lymphogranuloma Venereum (STD where organism disseminate to lymph
nodes and result in buboes)
 Urethritis, epididymitis, prostatitis, cervicitis
Methods to Isolate/Identification/Detect C.trachomatis
MOST SENSITIVE / SPECIFIC
• Culture organism in tissue/cells where Giemsa stain is used
• Considered the “gold standard” for specificity / sensitivity
OTHER METHODS
• DIRECT FLUORESCENT ANTIBODY
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ENZYME IMMUNOASSAY
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Detects outer membrane LPS chlamydial antigen
Significantly less sensitive than culture, but high in specificity
ANTIBODY DETECTION
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Mainly used for Trachoma / Conjunctivitis
Highly sensitive/specific but technically demanding
Least sensitive and specific – Individuals have antibodies from previous infection
Used as a complementary diagnostic tool in certain scenarios
NUCLEIC ACID AMPLIFICATION TESTS (NAATS)
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Detect organism specific DNA/RNA sequences
Used more today due to higher sensitivity than the other non culture methods
Therapy, Prevention and Prognosis of Patient Infected
with C.trachomatis
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LONG TERM THERAPY NECESSARY!
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Doxycycline, Azithromycin, Erythromycin and
Tetracycline used
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Beta Lactam drugs are… NOT effective for treatment
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No peptidoglycan in the organism!!!
Beta Lactam drugs can be used in addition to the
antibiotics above to treat patient for concomitant
infection with Neisseria gonorrhoeae
Primary Research Article – C. trachomatis
Kevin Hybiske and Richard Stephens. Mechanisms of Host Cell Exit by the Intracellular Bacterium
Chlamydia. PNAS. Vol. 104: 11430-11435. 2007.
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EXPERIMENTAL
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HeLa cells generated to express cytosolic GFP gene.
HeLa cells infected with C.trachmatis.
Visualization of real-time inclusion dynamics by fluorescence microscopy took place to
determine mechanism of host cell exit.
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WHAT WAS FOUND
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2 mutually exclusive pathways of release take place in the inclusion:
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Lysis – rupture of membrane, destructive mode of release mediated by Ca+2
activated proteases.
Extrusion – packaged elementary bodies released, no conclusive results as to how
mediated
Conclusion
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Rate of inclusion release was
reduced when cells treated with
protease inhibitors
 Rate of lysis duration was
increased when host cells placed
in Ca2+ free conditions
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Deciphering the cellular exit
mechanisms of C. trachomatis
will be of fundamental
importance to understanding
Chlamydia pathogenesis. This is
because cellular release directly
affects its ability to infect new
cells and transmit to new hosts
Take Home Message
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PID often involves infection with Chlamydia trachomatis…
Typical symptoms fever, severe abdominal tenderness, cervical/ovary
tenderness, vaginal bleeding/discharge
Pathogen is an OBLIGATE INTRACELLULAR ORGANISM with a
complex life cycle
Diagnostics include culture in cells, enzyme immunoassays, direct
fluorescent antibody test, NAATs
Therapy is based on long term antibiotic treatment
Prognosis is based on patient symptoms and inclusions of organism
within host cells
Prevention of organism is through use of condoms, talking openly with
sexual partners, etc.
Transmission is via sexual contact or through infected mothers to their
babies
Threats associated with this disease include ectopic pregnancy,
infertility, blindness
References
CDC – Chlamydia Factsheet. <http://www.cdc.gov/std/Chlamydia/STDFactChlamydia.htm> Department of Health and Human Services. Dec 20, 2007.
March 1, 2009.
Hybiske, Kevin and Richard Stephens. Mechanisms of Host Cell Exit by the
Intracellular Bacterium Chlamydia. PNAS. Vol. 104: 11430-11435. 2007.
Mahon, Connie, Donald Lehman, George Manuselis. Textbook of Diagnostic
Microbiology. 3rd Edition. Saunders-Elsevier, St. Louis, Missouri, 2007.
University of South Carolina School of Medicine – Microbiology / Immunology Online.
http://pathmicro.med.sc.edu/mayer/chlamyd.htm The Board of Trustees of the
University of South Carolina. April 11, 2007. March 8, 2009.