Clinical
Microbiology
Chlamydia
Chlamydia spp.
• 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
Bed Sonia 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.
Three species:
C. trachomatis
C. psittaci.
C. pneumoniae.
Pathology
Chlamydiaceae Family
(species that cause disease in humans)
Species (genus) Disease
Trachoma, NGU,
C. trachomatis
MPC, PID,
2 bio vars, non- conjunctivitis,
LGV
Infant pneumonia,
LGV
LGV
Pharyngitis,
C. Pneumoniae bronchitis,
pneumonia
C. Psittaci Psittacosis
6
) )لالطالعSubgroups
• Subgroup A • Subgroup B
• Mammalian parasites. • Primarily bird parasites
• Compact inclusions. • Diffuse inclusions
• Glycogen synthesized. • Glycogen not synthesized
• Folates synthesized. • Folates not synthesized
– Sensitive to D-cycloserine – Resistant to D-cycloserine
• Restricted host range • Broadening of host range
• Chlamydia trachomatis • Chlamydia psittaci
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 (EB):
–electron-dense nucleoid
–Released from ruptured infected cells .
- Human to human , & bird to human.
• Reticulate Body (RB):
–Intracytoplasmic form 0.5 - 1.0 um
–Replication and growth( Inclusion
body ).
Developmental Cycle of Chlamydia
C trachomatis elementary bodies
C. trachomatis inclusions
Glycogen 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.
–sub epithelial infiltration of
lymphocytes.
–Infected epithelial cells contain
cytoplasmic inclusion bodies
–Cell infiltrations to cornea cause
clouding
• Trichiasis: abnormal inward growth of
eyelashes.
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 trachomatis
Clinical disease
• lymphogranuloma venereum
• Nongonoccal urethritis (NGU)
• Epididymitis
• Salpingitis
• Mucopurulent cervicitis
• Pelvic inflammatory disease (PID)
• Reiter's syndrome
• Neonatal chlamydia
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.
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)
LGY: "Groove sign"
• Pomp art's
ligament is
preserved despite
the involvement
of multiple
inguinal nodes
LGV: Microscopy
• lymph node shows
both necrosis and
granulomatous
reaction (dimorphic
necrotizing
granulomatous
reaction) .
Normal Cervix
25
Clinical Manifestations
Clinical Syndromes Caused by C. trachomatis
Local Infection Complication Sequelae
Conjunctivitis Chronic arthritis
Men Reiter’s syndrome
Urethritis (rare)
Epididymitis
Prostatitis Infertility (rare)
Infertility
Conjunctivitis Endometritis Ectopic pregnancy
Urethritis Salpingitis Chronic pelvic
Women
Cervicitis Perihepatitis pain
Proctitis Reiter’s syndrome Chronic arthritis
(rare)
Conjunctivitis
Pneumonitis Chronic lung
Infants Rare, if any
Pharyngitis disease?
26 Rhinitis
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.
Transmission
• Person-to-person transmission by respiratory
secretions.
• 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.
Treatment Chlamydia
• Adults Conjunctival,
urethral, cervical, • Children < 45 kg,
rectal: urogenital & rectal:
– Azithromycin 1 gm x 1 – erythromycin 50
dose mg/kg/day in 4 doses
for 10-14 days
– Doxycycline 100 mg BID
for 7 days • Neonates (ophthalmia,
– Ofloxacin 300 mg po BID infants born to infected
for 7 days mothers):
– Erythromycin 500 mg – Erythromycin 50
QID for 7 days mg/kg/day in 4 doses
– Amoxacillin 500 mg TID for 10-14 days
7-10 days
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
DONE!!!
