Cell Wall Defective Bacteria

Chlamydia

Filename: Chlamydia.ppt

Chlamydia

Chlamydia
Obligate intracellular coccoid parasites contain DNA and RNA, and ribosomes lack ATP, biosynthetic pathways cell wall but peptidoglycan absent - use disulfide bonds non motile

Obligate Parasites

Obligate intracellular parasites of mammals and birds not transmitted by arthropods. incorrectly called the PLT viruses or Bedsonia or basophilic viruses, Multiply in the cytoplasm of the host cell. generally epithelial cells Basophilic inclusions

Similar to Viral Infections

The methods used to study Chlamydia are those of the virologist rather than the bacteriologist. The clinical features, pathogenesis, pathology and epidemiology of chlamydial infections are similar to those of viral infections.

Energy Parasites

The cells can synthesize DNA, RNA and protein. No flavoproteins or cytochromes. lack of ATP-generating ability need to obtain ATP from the host cell.


Three species:
C. trachomatis C. psittaci C. pneumoniae

Ecology

Chlamydia form two main ecological groups. Infect only humans Subgroup A trachoma, inclusion conjunctivitis, and lymphogranuloma venereum Zoonotic Infections Subgroup B Respiratory tract infections

Zoonotic Infections

transmitted to man About 100 species of birds are naturally infected with chlamydia. 71 species of parrots finches, pigeons, chickens, ducks, turkeys and seabirds.

C trachomatis

Trachoma conjunctivitis proctitis urethritis salpingitis Lymphogranuloma venereum
C psittaci & C pneumoniae
Upper respiratory infection Bronchitis Pneumonia

Chlamydial Morphologies

Elementary body 0.25 - 0.3 um diameter electron-dense nucleoid Released from ruptured infected cells. Human to human & bird to human. Reticulate Body Intracytoplasmic form 0.5 - 1.0 um Replication and growth. ( Inclusion body ) without a dense center.

Developmental Cycle of Chlamydia

C trachomatis elementary bodies

C trachomatis inclusions
Glycogen Inclusions

Subgroups

Subgroup A Mammalian parasites Compact inclusions Glycogen synthesized Folates synthesized Sensitive to D-cycloserine Restricted host range Chlamydia trachomatis
Subgroup B Primarily bird parasites Diffuse inclusions Glycogen not synthesized Folates not synthesized Resistant to D-cycloserine Broadening of host range Chlamydia psittaci

Evolution of Chlamydia

Gram-negative cocci Facultative intracellular parasites of mammals Obligate intracellular parasites Host range restricted to rodents Restricted virulence (compact inclusions) Folates synthesized (sulfonamide susceptible) Glycogen synthesized and deposited in inclusions

Conjunctivitis

Inclusion conjunctivitis: Transmitted by infectious secretions of the genitourinary tract autoinoculation Infantile conjunctivitis: Acquired in the birth canal -- 5-12 days after birth most common type of conjunctivitis Antibiotic prophylaxis: erythromycin, tetracycline.

Chlamydial Infection of Ocular Conjunctiva

Trachoma
infection of conjunctival epithelial cells. subepithelial infiltration of lymphocytes. Infected epithelial cells contain cytoplasmic inclusion bodies Cell infiltrations to cornea cause clouding Trichiasis: abnormal inward growth of eyelashes.

Predisposing factors:

climate - hot , dry shortage of water standards of hygiene low Transmitted by flies, dirty towels, fingers, cosmetic eye pencils. Initial infection in childhood mostly by 10-15 years of age.

Trachoma

Almost six million people have become blind and another 540 million almost 10% of the world’s population are at risk

Trachoma Incidence

Chlamydia trachomatisClinical disease
lymphogranuloma venereum nongonoccal urethritis (NGU) epididymitis salpingitis mucopurulent cervicitis pelvic inflammatory disease (PID) Reiter's syndrome neonatal chlamydia

Chlamydia: Rates by Gender

Chlamydia Symptoms In Men
Symptoms usually appear between 7 and 28 days after infection, usually with mild burning when urinating, a more frequent need to urinate, and a white discharge from the penis. Occasionally, blood may appear in the urine. The symptoms occur most frequently in the morning.

Erythematous meatus and urethra with balanitis

Hyperlink to original

Chlamydial Urethritis in Males

Nongonococcal urethritis (NGU) - Reiter's syndrome
Swollen, painful right knee in which needle aspiration for synovial fluid was performed (yellow discoloration from the betadine prep)
Hyperlink to original site

Lymphogranuloma venereum LGV

200 reported cases per year. Incubation period is 5 to 20 days. Lesion: Transient vesicles on penis or vagina that are often unnoticed and patients do not usually seek medical advice.

Bilateral inguinal adenopathy with overlying erythema

R Roberts MD

LGY: "Groove sign"

Pompart's ligament is preserved despite the involvement of multiple inguinal nodes
R Roberts MD

LGV: Microscopy

lymph node shows both necrosis and granulomatous reaction (dimorphic necrotizing granulomatous reaction)
R Roberts MD

Chlamydia pneumoniae

This bacterium was first recognized in 1983 as a respiratory pathogen, after isolation from a college student with pharyngitis. Pneumonia or bronchitis, gradual onset of cough with little or no fever. Less common presentations are pharyngitis, laryngitis, and sinusitis.

Incidence

Each year an estimated 50,000 adults are hospitalized with pneumonia in the United States. The overall incidence is unknown.

Transmission

Person-to-person transmission by respiratory secretions. Risk Groups All ages at risk but most common in school-age children. By age 20 years, 50% of population have evidence of past infection. Reinfection throughout life appears to be common.



C. pneumoniae Associations
Associated with Heart Disease infection may be associated with atherosclerotic vascular disease Proposed Associations Alzheimer's diseases, asthma, and reactive arthritis

Treatment Chlamydia

Adults Conjunctival, urethral, cervical, rectal: Azithromycin 1 gm x 1 dose Doxycycline 100 mg BID for 7 days Ofloxacin 300 mg po BID for 7 days Erythromycin 500 mg QID for 7 days Amoxacillin 500 mg TID 7-10 days
Children < 45 kg, urogenital & rectal: erythromycin 50 mg/kg/day in 4 doses for 10-14 days Neonates (ophthalmia, infants born to infected mothers): erthromycin 50 mg/kg/day in 4 doses for 10-14 days

Chlamydia Antigens

Antigens: group specific & species specific Major outer membrane protein (cysteine-rich) Eucaryotic cell binding protein Host response: damage to specific tissues

Laboratory Diagnosis

Isolate the organism from infected tissue. Inoculate the yolk sac of seven-day chick embryos Inoculate McCoy human cells. Characteristic cytoplasmic inclusion bodies in infected cells.

Immunofluorecent tests

Microimmunofluorescent tests patients with eye infections Check tears for the presence of anti-chlamydia antibody. Direct immunofluorescence of conjunctive cells with fluorescein - conjugated monoclonal antibody is sensitive and specific. In neonatal conjunctivitis and early trachoma

Serological diagnosis:

Immunofluorecent tests Delayed Type Skin Reaction Antibodies to Family antigen


FREI Test
Delayed-type skin reaction to killed organisms in genitourinary infections

Antibodies to Family antigen

Rising titer of antibody against the chlamydial family antigen in lung infections. Complement fixation test Fluorescent antibody test.

DONE!!!