Microbiology: Chlamydia and Mycoplasma Quiz

Chlamydia and Mycoplasma

Chlamydia

• Primary mode of transmission: Sexual contact
• Caused by: Chlamydia trachomatis, a type of bacterium
• Most common symptom in women: Asymptomatic, but can cause abnormal vaginal discharge, burning sensation while urinating, or abdominal pain

Mycoplasma

• Characteristic: Lacks a cell wall
• Typically found in: Respiratory tract, particularly in the mucous membrane of the lungs

Chlamydiae Characteristics

• Possess DNA and RNA
• Multiply via binary fission
• Susceptible to several antibiotics
• Small, variable shape (generally rounded)
• Unusual replicative cycle

Life Cycle

• Elementary body: small, extracellular, infectious stage
• Enters via endocytosis and resides within phagosome
• Metabolically active and reorganizes within one hour of infection into reticulate body

Reticulate Body

• Larger, intracellular, non-infectious
• Cannot survive outside of cell
• Uses host ATP to divide
• After 24-72 hours, becomes elementary body
• Replicates within cytoplasm of host cells
• Intracellular inclusions can be seen by light microscope
• Between 48-72 hours, cell ruptures and infective elementary bodies are released

Virulence Factors

• Not completely known
• Produce heat-labile toxins
• Compete with host cell for nutrients
• Cause tissue damage and cell death

Chlamydia Trachomatis

• Divided into 3 biovars
• Cause eye infections (two forms): trachoma and inclusion conjunctivitis

Trachoma

• Caused by serotypes A, B, Ba, and C
• Chronic keratoconjunctivitis
• More common in developing countries
• Transmission through droplet, hands, fomites, and flies
• Leading cause of preventable blindness in developing countries

Inclusion Conjunctivitis

• Acute inflammation of conjunctiva seen in adults and infants
• Common in populations with high numbers of Chlamydia genital infections
• Neonatal form results from direct contact with infected cervical secretions
• Presents as acute, copious, mucopurulent eye discharge
• Symptoms can resolve without treatment

Genital Infection

• Most frequent cause of STD in U.S.
• Treatment: antimicrobials, tetracycline, erythromycin, sulfonamides, and rifampin
• Control: treat known cases, prevent exposure

Diagnostics

• Isolation: most sensitive and specific method
• Direct staining: Giemsa, iodine, or immunofluorescence
• ELISA: used to detect organisms in clinical samples
• Serology: used to diagnose acute infections, must show 4-fold titer increase, high IgM suggestive of recent infection

Chlamydophila Pneumoniae

• Worldwide distribution
• Infections seen between 7-30 years of age
• Infections usually mild to moderate, but can be severe in elderly
• Associated with pneumonia, bronchitis, pharyngitis, sinusitis, and flu-like illness
• Diagnosis based on clinical presentation and laboratory tests

Mycoplasmataceae

• Urogenital infections: Mycoplasma hominis, Ureaplasma urealyticum, and Ureaplasma parvum
• Respiratory infections: M. pneumoniae
• Distinct venereal disease from C. trachomatis
• One of 5 common STDs: gonorrhoeae, syphilis, herpes, chancroid

LGV (Lymphogranuloma Venereum)

• Systemic manifestations: hepatitis, pneumonitis, meningoencephalitis
• Diagnosis: characteristic appearance, laboratory tests
• Two stages: genital lesion, lymph adenitis

Chlamydophila (Chlamydia) Psittaci

• Cause of psittacosis among psittacine birds
• Parrot fever
• Diagnosis: based on history of exposure to psittacines, serology