mycoplasma ii mbbs dr ekta chourasia microbiology, gmca

MYCOPLASMA

II MBBS

Dr Ekta ChourasiaMicrobiology, GMCA

19/02/2008 Dr Ekta,Microbiology, GMCA

Key Words

MycoplasmaNo cell wallPleomorphismFried egg coloniesDiene’s stainPrimary atypical/

walking pneumoniaGenital infections

Cold agglutination test

Cell culture contamination

UreaplasmaHydrolysis of urea

19/02/2008 Dr Ekta,Microbiology, GMCA

MYCOPLASMASmallest (<1µ) free-living micro organisms,

lack cell wall.

1st member of this group – isolated by Nocard & Roux (1898) – caused bovine pleuropneumonia.

Later, many similar isolates were obtained from animals, human beings, plants & environmental sources – called as “pleuropneumonia like organisms”(PPLO).

19/02/2008 Dr Ekta,Microbiology, GMCA

MYCOPLASMA

1956- PPLO replaced by Mycoplasma.– Myco : fungus like branching filaments– Plasma : plasticity

highly pleomorphic – no fixed shape or size - Lack cell wall.

Can pass through bacterial filters.

19/02/2008 Dr Ekta,Microbiology, GMCA

Mycoplasmas of Humans Parasitic1. Established pathogens: M.

pneumoniae2. Presumed pathogens: M. hominis,

U. urealyticum3. Non pathogenic: M. orale, M. buccale,

M. genitalium, M. fermentans Saprophytic – present mainly on skin

& in mouth.

19/02/2008 Dr Ekta,Microbiology, GMCA

Pathogenicity Produce surface infections – adhere

to the mucosa of respiratory, gastrointestinal & genitourinary tracts with the help of adhesin.

Two types of diseases:1. Atypical Pneumonia2. Genital infections

19/02/2008 Dr Ekta,Microbiology, GMCA

Mycoplasmal pneumonia

Also called Primary Atypical Pneumonia/ Walking pneumonia

Seen in all ages Incubation period: 1-3 wksTransmission: airborne droplets of

nasopharyngeal secretions, close contacts (families, military recruits).

19/02/2008 Dr Ekta,Microbiology, GMCA

Mycoplasmal pneumoniaGradual onset with fever, malaise,

chills, headache & sore throat.

Severe cough with blood tinged sputum (worsens at night)

Complications: bullous myringitis & otitis, meningitis, encephalitis, hemolytic anemia

19/02/2008 Dr Ekta,Microbiology, GMCA

Laboratory Diagnosis

Specimens – throat swabs, respiratory secretions.

Microscopy –

1. Highly pleomorphic, varying from small spherical shapes to longer branching filaments.

2. Gram negative, but better stained with Giemsa.

19/02/2008 Dr Ekta,Microbiology, GMCA

Laboratory Diagnosis Isolation of Mycoplasma (Culture) –1. Semi solid enriched medium containing

20% horse or human serum, yeast extract & DNA. Penicillium & Thallium acetate are selective agents. (serum – source of cholesterol & other lipids)

2. Incubate aerobically for 7 -12 days with 5–10% CO2 at 35-37°C. (temp range 22- 41°C, parasites 35- 37°C, saprophytes – lower temp)

19/02/2008 Dr Ekta,Microbiology, GMCA

Laboratory Diagnosis

3. Typical “fried egg” appearance of colonies - Central opaque granular area of growth extending into the depth of the medium, surrounded by a flat, translucent peripheral zone.

4. Colonies best seen with a hand lens after staining with Diene’s method.

5. Produce beta hemolytic colonies, can agglutinate guinea pig erythrocytes.

19/02/2008 Dr Ekta,Microbiology, GMCA

Fried egg coloniesFried egg colonies

19/02/2008 Dr Ekta,Microbiology, GMCA

Identification of Isolates

Growth Inhibition Test – inhibition of growth around discs impregnated with specific antisera.

Immunofluorescence on colonies transferred to glass slides.

Serological diagnosis PCR

19/02/2008 Dr Ekta,Microbiology, GMCA

Identification of Isolates Serological diagnosis1. Specific tests – IF, HAI2. Non specific serological tests –

cold agglutination tests (Abs agglutinate human group O red cells at low temperature, 4C).

1:32 titer or above is significant.

19/02/2008 Dr Ekta,Microbiology, GMCA

Ureaplasma urealyticumStrains of mycoplasma isolated from

the urogenital tract of human beings & animals.

Form very tiny colonies - hence called T strain or T form of mycoplasmas.

Hydrolyzes urea

19/02/2008 Dr Ekta,Microbiology, GMCA

Genital InfectionsCaused by M. hominis & U. urealyticumTransmitted by sexual contactMen - Nonspecific urethritis, proctitis,

balanoposthitis & Reiter’s syndromeWomen – acute salpingitis, PID,

cervicitis, vaginitisAlso associated with infertility,

abortion, postpartum fever, chorioamnionitis & low birth weight infants

19/02/2008 Dr Ekta,Microbiology, GMCA

Mycoplasma & HIV infectionSevere & prolonged infections in HIV

infected & other immunodeficient individuals

19/02/2008 Dr Ekta,Microbiology, GMCA

Mycoplasma as cell culture contaminants

Contaminates continuous cell cultures maintained in laboratories

Interferes with the growth of viruses in these cultures.

Mistaken for viruses.

Eradication from infected cells is difficult.

19/02/2008 Dr Ekta,Microbiology, GMCA

TreatmentTetracycline, Erythromycin &

Clarithromycin – drug of choice

Resistant to antibiotics which interfere with bacterial cell wall synthesis.

Newer macrolides & quinolones being used now.