MYCOPLASMA II MBBS Dr Ekta Chourasia Microbiology, GMCA

19/02/2008Dr Ekta,Microbiology, GMCA Key Words  Mycoplasma  No cell wall  Pleomorphism  Fried egg colonies  Diene’s stain  Primary atypical/ walking pneumonia  Genital infections  Cold agglutination test  Cell culture contamination  Ureaplasma  Hydrolysis of urea

19/02/2008Dr Ekta,Microbiology, GMCA MYCOPLASMA  Smallest (<1µ) free-living micro organisms, lack cell wall.  1 st 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).

19/02/2008Dr Ekta,Microbiology, GMCA MYCOPLASMA  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.

19/02/2008Dr Ekta,Microbiology, GMCA Mycoplasmas of Humans  Parasitic 1. Established pathogens: M. pneumoniae 2. Presumed pathogens: M. hominis, U. urealyticum 3. Non pathogenic: M. orale, M. buccale, M. genitalium, M. fermentans  Saprophytic – present mainly on skin & in mouth.

19/02/2008Dr 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 Pneumonia 2. Genital infections

19/02/2008Dr Ekta,Microbiology, GMCA Mycoplasmal pneumonia  Also called Primary Atypical Pneumonia/ Walking pneumonia  Seen in all ages  Incubation period: 1-3 wks  Transmission: airborne droplets of nasopharyngeal secretions, close contacts (families, military recruits).

19/02/2008Dr Ekta,Microbiology, GMCA Mycoplasmal pneumonia  Gradual 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

19/02/2008Dr 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.

19/02/2008Dr 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 days with 5– 10% CO 2 at 35-37°C. (temp range °C, parasites °C, saprophytes – lower temp)

19/02/2008Dr 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.

19/02/2008Dr Ekta,Microbiology, GMCA Fried egg colonies

19/02/2008Dr 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

19/02/2008Dr Ekta,Microbiology, GMCA Identification of Isolates  Serological diagnosis 1. Specific tests – IF, HAI 2. Non specific serological tests – cold agglutination tests (Abs agglutinate human group O red cells at low temperature, 4  C). 1:32 titer or above is significant.

19/02/2008Dr Ekta,Microbiology, GMCA Ureaplasma urealyticum  Strains 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

19/02/2008Dr Ekta,Microbiology, GMCA Genital Infections  Caused by M. hominis & U. urealyticum  Transmitted by sexual contact  Men - Nonspecific urethritis, proctitis, balanoposthitis & Reiter’s syndrome  Women – acute salpingitis, PID, cervicitis, vaginitis  Also associated with infertility, abortion, postpartum fever, chorioamnionitis & low birth weight infants

19/02/2008Dr Ekta,Microbiology, GMCA Mycoplasma & HIV infection  Severe & prolonged infections in HIV infected & other immunodeficient individuals

19/02/2008Dr 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.

19/02/2008Dr Ekta,Microbiology, GMCA Treatment  Tetracycline, Erythromycin & Clarithromycin – drug of choice  Resistant to antibiotics which interfere with bacterial cell wall synthesis.  Newer macrolides & quinolones being used now.