What are the characteristics of mycoplasma?
-No cell wall, no peptidoglycan
-Boundary is cytoplasmic membrane with sterols
-Undefined cell shape, cells pass through filters
What are the cultural characteristics of mycoplasma?
-Smallest agent scultivable on cell-fee medium
-Difficult to cultivate
-Mycoplasma and ureaplasma require sterols to be added to medium to gro
-Ureaplasma requires urea in culture medium, energy yielding
How does mycoplasma stain?
-Not visible in gram stain b/c no peptidoglycan and too small to visualize with light microscope
-Colonies on media can be stained and visualized
What is the major mycoplasma human pathogen?
-Mycoplasma pneumonia: common cause of CAP
---Primary atypical pneumonia
---General walking pneumonia
What is the clinical course of M. pneumonia?
-2 wk incubation period
-Early phase: fever, headache, chills, sweats, non-productive cough
-Late phase: pulmonary infiltrates
-Low mortality rate: even if untreated
What is the speculative pathology of M. pneumonia?
-Attch to cell mem and ciliated epithelial cells
-Destroys ciliated epithelial cells that inhibits cellular catalases and peroxidases so RoS destroys epi cells
What diagnostic lab tests are used for mycoplasma?
-Culture: sputum, bronchoscopy specimens, throat swabs
---Problem: few labs provide culture service, results take wk.s, too long
-Immunofluorescence: detects organisms in sputum and bronchoscopy specimens
---Problem: specific, not sensitive, few labs
-EIA: detects Ag.s in sputum and bronchoscopy specimens, specific and sensitive
---Prob: best rapid test but few labs
-Old test: cold agglutins for serum Ab.s but not sensitive
What is the epidemiology of mycoplasma?
-Worldwide endemic, incidence more in winter
-Humans are only hosts
-Transmission by inhalation of respiratory aerosols
-Effects range from inapparent to severe compromise of pulmonary fxn
What therapy is for mycobacteria?
-Antimicrobials decrease infectivity
-Little effect on s/m.s
-No cell wall so no cell wall antimicrobials
What are other Mycoplasma pathogens?
-both can be found in GU tract of M/F
-Associated w/urethritis, cervicitis and post-partem fevers
-Chlamydia more common w/same effect
What are the characteristics of Mycoplasma fermentans?
-Controversial cause for progression from HIV to AIDS
-Present: attention in literature, no mainstream literature
What are the characteristics of legionella?
-9 serotypes of L. pneumophila
-Special growth media needed w/charcoal, cysteine and yeast extract
-Water hapitat in ponds/streams, air-conditioners, hot-water systems
What are the lab characteristics of legionella?
-Grows slowly in lab
-Visualized poorly on gram stain
-Need carbol-fuchsin as counterstain
-Use half-a-Gram stain w/odecolorizer and counterstain
What is legionellosis?
-15% of community-acquired pnemonia cases
-May have high mortality rate but generally lower mortality rate
What is the clinical picture of legionellosis?
-2-10 day incubation period
-High fever, chills, non-productive cough
-If cough becomes productive sputum is not purulent
-Possible GI s/m.s
-Organism isolated from blood cultures, multiple organ systems
-Chest radiograph findings non-specific
How is the lab d/g done for legionellosis?
-Gram stain used to rule out others
---Culture common, days for results
-Direct immunofluorescence: sputum or broncheolar lavage but only + in 20%
-Urine Ag test: + in 90% of infections, early and remains for weeks, detects type 1 only, results w/in 48 hours
What is the therapy for legionellosis?
-Respiratory support necessary
-Antimicrobials: not susceptible to broad-spectrum ICU-type antimicrobials
-Macrolides and fluoroquinolones are effective
-Partly explains excess mortality
What is the summary points of mycoplasma?
-Difficult definitive diagnosis
-No peptidoglycan so therapy hard
What are the summary points of legionella?
-Urinary Ag test: fastest and most reliable d/g for type 1 L. pneumophilia
-Not susceptible to broad-spectrum ICU antimicrobials