Medical Microbiology

244 4 BacteriaasHumanPathogens

characterofthesepathogens.Recentlyobservedepidemicsonintensivecare

wardsinvolvedstrainsthatwereresistanttoallstandardanti-infective

agentsincludingtheglycopeptidesvancomycinandteicoplanin.

Gram-Positive,AnaerobicCocci....................................

Gram-positive,strictlyanaerobiccocciareincludedinthegeneraPeptococcus

andPeptostreptococcus.TheonlyspeciesinthefirstgenusisPeptococcusniger,

whereasthelattercomprisesanumberofspecies.Theanaerobiccocciare

commonlyobservedinnormalhumanflora.Inapathogeniccontextthey

areusuallyonlyencounteredascomponentsofmixedfloraetogether

withotheranaerobesorfacultativeanaerobes.Thesebacteriainvadetissues

throughdermalormucosalinjuriesandcausesubacutepurulentinfections.

Suchinfectionsareeitherlocalizedintheheadarea(cerebralabscess,otitis

media,mastoiditis,sinusitis)orlowerrespiratorytract(necrotizingpneumo-

nia,pulmonaryabscess,empyema).Theyarealsoknowntooccurintheabdo-

men(appendicitis,peritonitis,hepaticabscess)andfemalegenitals(salpin-

gitis,endometriosis,tubo-ovarianabscess).Gram-positiveanaerobiccocci

mayalsocontributetosoft-tissueinfectionsandpostoperativewoundinfec-

tions.Seep. 31 7ff.forclinicaldetailsofanaerobeinfections.

Bacillus.............................................................

&ThenaturalhabitatofBacillusanthracis,aGram-positive,sporing,obligate

aerobicrodbacterium,isthesoil.Theorganismcausesanthraxinfectionsin

animals.Humaninfectionsresultfromcontactwithsickanimalsoranimal

productscontaminatedwiththespores.Infectionsareclassifiedaccordingto

theportalofentryasdermalanthrax(95%ofcases),primaryinhalational

anthrax,andintestinalanthrax.Sepsiscandevelopfromtheprimaryinfec-

tionfocus.Laboratorydiagnosisincludesmicroscopicandculturaldetection

ofthepathogeninrelevantmaterialsandbloodcultures.Thetherapeutic

agentofchoiceispenicillinG. &

ThegeneraBacillusandClostridiumbelongtotheBacillaceaefamilyofspor-

ingbacteria.TherearenumerousspeciesinthegenusBacillus(e.g.,B.cereus,

B.subtilis,etc.)thatnormallyliveinthesoil.Theorganisminthegroupthatis

ofveterinaryandhumanmedicalinterestisBacillusanthracis.

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Kayser, Medical Microbiology © 2005 Thieme