MYCOPLASMAClass: Mollicutes (“soft skin” – no cell wall)Genus: MycoplasmaSpecies: Mycoplasma pneumoniae – human respiratory pathogenMycoplasma homonis – human genital tract pathogenMycoplasma incognitus – associated with AIDS patientsPAP:- Resembles a viral or rickettsial pneumonia- Initial symptoms not suggestive of pneumonia- Not identified from Gram stain- Penicillin is not prescribedMicroscopic Morphological AppearanceNot able to be Gram stainedToo small to be viewed with light microscopePleomorphic shapeLimited Biosynthetic AbilitiesSmallest and simplest self-replicating bacteriaLack enzymatic pathways for purine and pyrimidine synthesis“Surface parasite”Growth ConditionsFastidiousComplex or Enriched MediumSupplemented Beef Infusion Broth 1. peptone or yeast extract2. glucose3. horse serum4. penicillum or thallium acetateMesophileFacultative anaerobe or aerobeUnique colony appearance – “fried egg”- mulberry appearanceSlow grower – 1 to 3 weeksMycoplasma pneumoniae – surface parasite adhering to the respiratory epitheliumCausative agent of – primary atypical pneumonia (PAP)Transmission: Aerosol dropletsMode of Infection1. Inhalation2. Attachment – specific binding of P1 (protein/adherence) protein to sialic acid receptor of respiratory cells inhibition of ciliary action and epithelial cell injury (attachment: virulence)3. Tight adherence – bacteria not freed by mucous secretionsa. parasitic lifestyleb. limited biosynthetic abilities 4. Multiplication and colonization of respiratory epithelium – Local accumulation of mycoplasmal metabolites enzymes, hydrogen peroxide, ammonia localized tissue damage localized surface infection5. Colonization of “upper” respiratory tracta. Cilliostasis – disruption of ciliary function1b. allows microbes to colonize “lower” respiratory tractEarly Symptoms fever, headache, unproductive cough, sore throat, malaiseLater Symptoms – tracheobronchitis, or PAP – “walking pneumonia” blood-streaked sputum, chest pain, earacheMorbidity /Mortality: pneumonia self resolvesFrequency of infections with M. pneumoniae- only 3% of the cases result in pneumonia- 20% are asymptomatic- 77% are infections of the upper respiratory tract only- epidemics occur every 4 – 8 yearsRisk Groups 1. children, young adults2. outbreaks – crowded conditions3. increased frequency summer and fall monthsConvalescence/Immunity1. Initial resistance – mucosal surfaceNon-specific factors – complement and phagocytic cells2. Specific antibody productionIgM class – initial antibodyIgG class – convalescent antibody3. Cold agglutinins – non-specific convalescent antibodya. Cold agglutinins-non specificb. IgG-specific4. Prior natural infection – best immunity but short livedDiagnosis/IdentificationCulture impractical – (2 – 3 weeks) before growth is noted. Microscopy – useless- Has to be gram stained to see in microscopyClinical observation is non-specificsputum smearsleukocyte countsX-raysSerological tests definitive at convalescent stagecomplement fixationELISAIndirect hemagglutinationSerum cold agglutination – 65% reliabilityPolymerase Chain Reaction – (PCR)Initial studies using PCR for diagnosis with DNA are being performedRadiolabeled DNA probe – 90% sensitivityTreatmentBroad spectrum antibiotics – erythromycin or tetracyclineNot an effective drug - --lactam antibioticsPrevention/ControlAvoid contact with ill patients; avoid droplet nucleiAdminister antibodies directed against surface membrane proteinsInactivated or attenuated live vaccines – disappointing; protective immunity conferred is very lowMycoplasma hominis – surface parasite adhering to the urogenital epitheliumCausative agent of – pelvic inflammatory disease, kidney inflammation and vaginitis2Transmission – sexual contactTreatment – Broad spectrum antibiotic – tetracycline Prevention/Control – Avoid sexual activity, use condomsMycoplasma incognitos – intracellular pathogenAssociated with HIV-positive individualsAssumed to be a co-factor accounting for rapid deterioration and cell deathAssociated with HIV-negative individualsCauses a flu-like illness that suppresses the immune system*************************************************************************************LEGIONELLAFamily: LegionellaceaeGenus: LegionellaSpecies: Legionella pneumophila – human respiratory pathogenMicroscopic Morphological AppearanceGram negative pleomorphic bacillusGram stains poorly – Giminez Silver Impregnation Stain or Dieterle Silver StainMotile – (+) flagella – Virulence FactorNon-spore formerGrowth conditionsFastidiousSpecialized Media1. Buffered Charcoal Yeast Extract (BCYE)2. Mueller-Hinton + L-cysteine HCl and soluble ferric pyrophosphateNecessary additives to Media1. Iron2. L-cysteineMesophileAerobeBiochemical Characteristics(-) carbohydrate fermentation(+) --lactamase(+) catalase(+) hemolysinLegionella pneumophilaCausative agent of Legionnaire Disease (primary atypical pneumonia)TransmissionAerosol formNo person to personEnvironmental source3Mode of Infection1. Inhalation – target organ lung2. Engulfment by alveolar macrophages and leukocytes3. Growth and multiplication within alveolar macrophages and leukocytes – (intracellular parasite)4. Destroy macrophages – release of host cellular enzymes (phosphatase, lipase, nuclease) and toxins result in localized tissue damageEarly symptoms (mild bronchopneumonia) diarrhea, weakness, headache, muscle ache, dry coughLater symptoms - 104- F temperature, recurrent chills, chest pain (lung consolidation), stupor or deliriumCritical symptoms – multi-system disease - infecting liver, gastrointestinal tract, central nervous system and kidneysRisk Groups1. middle-aged to older men2. cigarette smokers3. alcoholics4. immunocompromised5. hospitalized individuals6. increased frequency of infection in summerDiagnosis/Identification1. Culture Identification useless- slow grower, no visible colonies noted for 3 to 5 days2. Serological testsc. antigen detectionDirect fluorescent antibody (DFA) test – sputum sampleELISA or radioimmunoassay – detection of Legionella antigens in urine sampled. antibody detectionCompare antibody levels to Legionella in two blood samples obtained 3 to 6 weeks apart3. Chest X-raysHeavy lung damage, large pockets of fluid in alveoli, suggestive of pneumonia4. Pathology of