lecture 29 chlamydia

الرحمن الله الرحمن بسم الله بسمالرحيمالرحيم

GENUS: CHLAMYDIAProf. Khalifa SifawGhenghesh

Small Gram-negative bacteria (Stain poorly with Gram’s stain)

Like Bacteria Have both DNA and RNA, Ribosomes, a Cell

wall, and Divide by Binary fission Like Viruses

Obligate intracellular parasites Differ from Bacteria

Have no peptidoglycan in their cell wall Can not produce their own ATP Require to use host ATP (Energy parasite)

Chlamydia species

C. trachomatis 3 biovars

Those causing trachoma and inclusion conjunctivitis (TRIC)

Those causing lymphogranuloma venereum (LGV)

The one causing mouse pneumonitis (MoPn)

C. psittaci > Infect both mammals and birds C. pneumoniae > both humans and animals C. pecorum > Some infect mammals

Trachoma biovars 14 Serovars: A-K

Serovars A, Ba, B, C Classic trachoma

Serovars D-K Inclusion conjunctivitis and Genital

infections

LGV biovars 3 Serovars: L1, L2, L3

Can be stained with Giemsa stain Elementary body (EB)

Extracellular, infectious metabolically inert form of chlamydiae

Reticulate body (RB) Intracellular, non-infectious,

metabolically active particle

Infection to Humans

Ocular infection Trachoma > in countries where sanitation

and hygiene standards are poor Spread by eye seeking flies, or fingers,

from one patient to another Blindness

“Trachoma belt” > North Africa to South-East Asia

Adult inclusion conjunctivitis (paratrachoma)

Acute stage >> follicular conjunctivitis Self-limited

Chlamydial ophthalmia neonatrum (inclusion blennorrhoea)

5-21 days after birth If not treated > after 1 year > secondary bacterial infection > ocular damage and even blindness

Source: infected genital tract of the mother

Genital infection C. trachomatis is the Commonest

cause of non-gonococcal urethritis in males (30%)

LGV In both males and females in tropics and subtropics

In females Mucopurulent cervicitis and urethritis

Vaginitis and vaginal discharge Asymptomatic females if not treated

Ascending infection >> Pelvic inflammatory disease (endometritis or salpingitis or both)

Tubal damage >> ectopic pregnancy and infertility

Infection in pregnancy C. psittaci

Miscarriage or intra-uterine death Patients had contact with sheep

C. trachomatis Isolated from abortion products

Respiratory infection C. pneumoniae

3rd or 4th cause of pneumonia Pharyngitis, bronchitis, otitis and

sinusitis

C. psittaci Psittacosis in humans from avian

strains Disease ranges from an influenza-like

illness, to severe illness with typhoidal state ad pneumonia.

C. trachomatis Pneumonitis in neonates (infection acquired from the mother)

Laboratory Diagnosis

Cultivation MacCoy cells treated with

cycloheximide Organism detected by staining for

inclusions or EBs Detects only living cells

Antigen detection Using probes for DNA or mRNA that

identify the infected cells PCR

Amplification of parts of the genome

Chlamydia trachomatis from a urethral scrape

Serology Micro-immunofluorescence test

Using Ags from all chlamydial strains to detect species-specific and serovar-specific Ab

Complement fixation test Detecting Ab in serum directed against group Ag

Chlamydia psittaci Direct FA stained mouse brain impression smear

Treatment and Control

Chemotherapy Tetracycline in adults and

Erythromycin in babies For 3 weeks

Azithromycin Single dose

Contact tracing Partners of index cases (even if

clinically normal) Neonatal infection

Both parents should be treated

Animal contact Avoidance of contact with sources of

infection (specially pregnant women) Sheep, milking and shearing

Control of importation of psittacine birds

Hygiene