Medical Microbiology

308 4 BacteriaasHumanPathogens

Diagnosis.Histopathological,culturaland,molecularidentificationofthe

bacteriainstomachliningbiopsies.Anoninvasivebreathtestinvolvingin-

gestionof^13 C-labeledureaandmeasurementof^13 CO 2 intheexpelledair.

Antigendetectioninstool.AntibodiescanbeidentifiedwithanELISAorWes-

ternblotting.

Therapy.Inpatientswithulcersand/orgastritissymptoms,atriplecombina-

tiontherapywithomeprazole(protonpumpblocker),metronidazole,and

clarithromycinlastingsevendaysissuccessfulin 90 %ofcases.

Epidemiology.BasedonseroepidemiologicalstudiesweknowthatH.pylori

occurworldwide.Generalizedcontaminationofthepopulationbeginsin

childhoodandmayreach 100 %inadultsinareaswithpoorhygiene.Thecon-

taminationlevelisabout 50 %amongolderadultsinindustrializedcountries.

Transmissionisbythefecal-oralroute.

Spirillumminus.......................................

Thisspeciesisamotilebacteriumonly0.2lmthickand 3 – 5 lmlongwith

twotothreespiralwindings.Itcannotbegrownonculturemediums.S.minus

causesspirillaryratbitefever,alsoknownassodoku.Thisdiseaseoccurs

worldwide,withahighlevelofincidenceinJapan.Theorganismistrans-

mittedtohumansbythebitesofrats,mice,squirrels,anddomesticanimals

thateatrodents.Followinganincubationperiodofsevento 21 daysafebrile

conditiondevelopswithlymphangitisandlymphadenitis.Ulcerouslesions

developattheportalofentry.Diagnosiscanbedonebyusingdarkfield

orphasecontrastmicroscopytodetectthespirillainbloodorulcerousma-

terial.PenicillinGisusedtotreattheinfection.

Pseudomonas,Stenotrophomonas,Burkholderia...................

&PseudomonadsareGram-negative,aerobic,rod-shapedbacteriawith

widespreadoccurrenceinnature,especiallyindampbiotopes.Themostim-

portantspeciesfromamedicalpointofviewisPseudomonasaeruginosa.Free

O 2 isrequiredasaterminalelectronacceptortogrowtheorganismincul-

tures.ThepathogenesisofPseudomonasinfectionsiscomplex.Theorganism

canuseitsattachmentpilitoadheretohostcells.Therelevantvirulencefac-

torsare:exotoxinA,exoenzymeS,cytotoxin,variousmetalproteases,and

twotypesofphospholipaseC.Ofcourse,thelipopolysaccharideoftheouter

membranealsoplaysanimportantroleinthepathogenesis.Pseudomonas

infectionsoccuronlyinpatientswithweakenedimmunedefensesystems,

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Kayser, Medical Microbiology © 2005 Thieme