Chlamydia which does have a little bit Metabolism - facultativebut mainly fermentative- complex nutritional requirements (due to small genome) > require external supplies of nucleotides, AAs, FAs & sterols - fastidious (takes 2-3 wks to grow in culture) Among smallest free-living organisms (genome = 500Kd) Other Unique Features - genome is only 500 kD! - no antigenic variation Virulence - P1 adhesinV(binds NANA on epithelial cells in respiratory tract)ciliastasis & epithelial necrosis Transmission - spread via droplets to upper respiratory tract- ~2 million cases/yr & 100,000 pneumonia-associated hospitalizations - Humoral immunity(IgG & IgA) control infxn > protection correlated w/ acquisition of serum IgG > C’ fixation, anti-attachment & opsonization > Cell-mediated Immunity is not protective > life-long immunity after infxn Associated Diseases * Tracheobronchitisw/nonproductive cough * 1oAtypical Pneumonia- children & young adults * cold agglutinin response(60% of infxns) - IgM antibodies to I antigen on RBC membrane possible intravascular hemolysis * rareextrapulmonary manifestations (possibly autoimmune mechanism) > myocarditis > pericarditis > encephalitis > neuropathies > rashes > tender joints & muscles > polyarthritis Diagnosis - C’ fixation test(measures early IgM & IgG) - ELISA(measures IgM & IgG to P1 adhesin) - Ag-EIA (Ag Capture Enzyme Immunoassay) - PCR(detects genomic DNA) Treatment(s) - intrinsic resistance to ß-lactam Ab’s (b/c no PDG) * erythromycin/ doxycycline as empiric tx for atypical pneumonia * alternatives = long-acting macrolides & quinolones Shigella dysenteriae member of EnterobacteriaceaeLab ID &MetabolismG- rod non-motile unlike most Enterobacteria! catalase (-)unlike other Enterobacteria! cannot ferment lactose colorless colonies on MacConkey’s agar No H2S (differentiates from Salmonella) facultative oxidase (-); utilizes alternative cytochrome for ETC ferments glucose pyruvate+ [end productsS] Other Unique Features - reduces nitrite nitrate- notinhibited by bile salts (can grow in GI tract) - 1° pathogen but usu not beyond the colon - all species are obligate human pathogens - low infective dose 10-200 Virulence - most virulence factors are plasmid encoded - antiphagocytic capsule(“K” antigen) - Shiga toxinV(chrom-encoded S. dysenteriaand phage-encoded EHEC) > 2 component toxin > cleaves adenosine residue in 23S rRNA part of 60s ribosomal sb inhibits protein synthesis cell death > assoc w/ HUS, TTP- plasmid encoded TTSSinvade cells deliver proteins actin rearrangements -invades through the gut M Cells multiplies and spreads to adjacent cells Associated Diseases - Human reservoir - Phase 1: pain, fever, watery diarrhea - Phase 2: low volume stools w/ pus, blood Inflammatory diarrhea Treatment(s) None or fluoroquinolones Lactose Nonfermenters: all the bad ones, not meant to be in your gut. Get them outta there!