Chlamydia

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Chlamydia
Filename Chlamydia.ppt
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Chlamydia
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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

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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

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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.

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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.

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Three species

• C. trachomatis
• C. psittaci
• C. pneumoniae

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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

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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.

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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.

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Developmental Cycle of Chlamydia
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C trachomatis elementary bodies
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C trachomatis inclusions
Glycogen Inclusions
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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

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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

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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.

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Chlamydial Infection of Ocular Conjunctiva
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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.

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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.

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Trachoma

• Almost six million people have become blind and
  another 540 million almost 10 of the worlds
  population are at risk

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Trachoma Incidence
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Chlamydia trachomatisClinical disease

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

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Chlamydia Rates by Gender
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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.

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Erythematous meatus and urethra with balanitis
Hyperlink to original
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Chlamydial Urethritis in Males
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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
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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.

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Bilateral inguinal adenopathy with overlying
erythema
R Roberts MD
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LGY "Groove sign"

• Pompart's ligament is preserved despite the
  involvement of multiple inguinal nodes

R Roberts MD
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LGV Microscopy

• lymph node shows both necrosis and granulomatous
  reaction (dimorphic necrotizing granulomatous
  reaction)

R Roberts MD
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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.

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Incidence

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

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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.

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C. pneumoniae Associations

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

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Treatment Chlamydia

• Children lt 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

• 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

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Chlamydia Antigens

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

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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.

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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

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Serological diagnosis

• Immunofluorecent tests
• Delayed Type Skin Reaction
• Antibodies to Family antigen

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FREI Test

• Delayed-type skin reaction to killed organisms
  in genitourinary infections

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Antibodies to Family antigen

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

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DONE!!!