CHLAMYDIA
Group 14
Course overview
• Introduction
• MEDICALLY IMPORTANT SPECIES
• LIFE CYCLE
• Pathogenesis & Clinical Findings
• Diseases
 C. trachomatis
 C. psittaci
 C. pneumoniae
• Transmission
• Laboratory Diagnosis
• TREATMENT AND PREVENTION
• Summary
• References and citations
INTRODUCTION
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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
Similar to 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.
MEDICALLY IMPORTANT SPECIES
Three species: C. trachomatis C.
psittaci C. pneumoniae
C.trachomatis causes
Trachoma conjunctivitis proctitis,
Lymphogranuloma venereum,
Urethritis, pneumonia
C.psittaci & C.pneumoniae Upper
respiratory infection Bronchitis
Pneumonia
LIFE CYCLE
Pathogenesis & Clinical Findings
Chlamydia infect
primarily
epithelial cells of
the mucous
membranes or the
lungs. They rarely
cause invasive,
disseminated
infections.
Diseases
Chlamydia trachomatis causes eye
(conjunctivitis, trachoma),respiratory
(pneumonia), and genital tract
(urethritis,lymphogranuloma venereum)
infections.
Chlamydia trachomatis is the most
common bacterial cause of sexually
transmitted disease
Infection with C. trachomatis is also
associated with Reiter’s syndrome,
an autoimmune disease
Chlamydia pneumoniae causes atypical
pneumonia. Chlamydia psittaci causes
psittacosis, also a disease characterized
mainly by pneumonia
CHLAMYDIA TRACHOMATIS
has more than 15 immunotypes (A–L). Types A, B, and C
cause trachoma, a chronic conjunctivitis endemic in
Africa and Asia. Trachoma may recur over many years and
may lead to blindness but causes no systemic illness.
Types D–K cause genital tract infections. In men, it is a
common cause of nongonococcal urethritis ,which is
characterized by dysuria and a watery, nonpurulent urethral
discharge.
The discharge may be slight, detectable only by staining of
underwear overnight. This infection may progress to
epididymitis,prostatitis, or proctitis. In women, cervicitis
develops and may progress to salpingitis and pelvic
inflammatory disease (PID).
Nongonococcal urethritis.
Note watery, nonpurulent
discharge caused by
Chlamydia trachomatis.
CHLAMYDIA TRACHOMATIS
LYMPHOGRANULOMA VENEREUM:
C.trachomatis serotypes L1,L2 and L3
causes lymphogranuloma venereum(LGV),
more invasive sexually transmitted disease.
It is uncommon in USA but endemic in
Asia,Africa,and South America. LGV is
characterized by transient papules on the
genitalia,and perirectal lymph nodes.
Adenopathy(swelling of the lymph nodes).
Trachoma conjunctivitis
LYMPHOGRANULOMA VENEREUM
CHLAMYDIA PNEUMONIAE
• Chlamydia pneumoniae causes upper and lower respiratory tract
infections, especially bronchitis and pneumonia, in young adults. Most
infections are mild or asymptomatic.
• The clinical picture resembles other atypical pneumonias, especially that
caused by Mycoplasma pneumoniae. It is unclear whether C.pneumoniae
causes upper respiratory infections such as sinusitis and otitis media.
CHLAMYDIA PSITTACI
• Chlamydia psittaci infects the lungs primarily. The infection may be
asymptomatic (detected only by a rising antibody titer) or may
produce high fever and pneumonia.
• Human psittacosis is not generally communicable from human to human.
• Although most infections are mild, some are quite severe
• and involve organs other than the lung. The respiratory infection
typically manifests with fever, cough, dyspnea,myalgias, and headache.
The most common extrapulmonary
• organs involved are the liver (hepatomegaly, jaundice), heart
(myocarditis, pericarditis), and nervous system (hearing loss, transverse
myelitis, and encephalitis)
Transmission
Chlamydia trachomatis infects only humans and is usually
transmitted by close personal contact (e.g., sexually or by passage
through the birth canal)
Individual with asymptomatic genital tract infections are an
important reservoir of infection for others.
In trachoma, C. trachomatis is transmitted by finger-to-eye or
fomite-to-eye contact.
Chlamydia pneumoniae infects only humans and is transmitted
from person to person by aerosol/ respiratory droplets.
Chlamydia psittaci infects birds (e.g., parrots, pigeons, and
poultry, and many mammals including humans).
Humans are infected primarily by inhaling organisms in airborne
dry bird feces.
LABORATORY DIAGNOSIS
• C.trachomatis
• Inclusions in epithelial cells seen with Giemsa stain or by
immunofluorescence; also cell culture
• C.pneumoniae
• Serologic test
• C.psittaci
• Serologic test (cell culture rarely done)
TREATMENT AND PREVENTION
• C.trachomatis
• Doxycycline,
• Erythromycin
• C.pneumoniae
• Doxycycline
• C.psittaci
• Doxycycline
REFERENCES AND
CITATIONS
• Review of medical microbiology and immunology, Warren
Levinson, Fourteenth Edition, chapter 25 page 208
• https://www.slideserve.com/dkenny/chlamydia-powerpointppt-presentation