Page 237 - konishipaper

ThecurentJapaneseregulatorysafetylevelforLegionelainbathwater，whichisset belowthedetectionlimitofculturetechniques(10cfu/100ml)，shouldbeapropriateto
asociatedlegionelosis.Ifmorethanasinglecolonywhichhas1x105 preventbathwater
四
Legionelabacteriaisdetachedfromglaswalanddispersedintoabathtubcontaining 1000literofwater，thenumberoflegionelaeasilyexcedstherequiredsafetyregulations of 10 c白100 m.l Also，biofilm detachment and the interaction ofLegionela with αcanthamoebaeenhancethemultiplicationofLegionelathatsignificantlyincreasedthe riskoflegionelosis(2).
TheemergenceofL.pneumophilabetween5.7and630C innaturalenvironmentshas demonstrated the ability of the pathogen to survive over a wide temperature range (7).
OptimumgrowthofL.pneumophilainwaterocuredat370C，andgrowthwasprevented at420C(23)(24)
Inourstudy，werevealedthatthetemperaturebetween370C and420C influenceon biofilmformationandbacterialengthontheglaswalinliquidflowchamber，ontheglas wal l in static liquid and on B C Y E開 αagar plate. W e found that the equivalent outer diameter，atachedcirculardiameterandemptinesincreasedwiththetempe1'ature(Fig.6， Fig.7，Table2).TheL.pnewηophilacelgrowthwasinhibitedover420C，the1'eforewe consideredthatthegrowthofbiofilmsmightalsobeinhibited.
Otherbacteria，Seratiamarcescens，forexample，gothroughasimila1' reproduction procesofatachment，agregation，microcolonydevelopment，hollowcolonyformation， anddispersa.lHoweve，'1 theirreproductionocursatlowertemperatureandinashorter pe1'iodoftimethanLegionela.HollowcoloniesofSelγσtiamarcescenswereobservedin flowcelbiofilmsafter3to4daysat300C(20)(2).
Inourstudy，hollowcolonieswereobservedat370C(Fig.6A)，400C(Fig.6B)inιdays. Thebiofilmsincubatedat420C (Fig.6C)exhibitdispersalstagesonsurfacesandrelease celsintotheenvironmenttocolonizenewsites.Thus，weconsiderthathighertemperature maycont1'ibutetobiofilmmaturationofL.pneumophila.ThelengthofL.pneumophila bacteriainstaticliquidandonBCYE四 αagarplateincreasedwiththeriseoftemperature， thebacterialengthdidnotchangeasthetemperaturechangedinliquidflow(Fig.8，Fig.9， Table3).Inthestaticliquid(Fig.8B)andonBCYE-αaga1' plate(Fig.8C)， ariseof temperaturecausedL.pneumophilacelelongation，i.e.filamentouscels.Onthecontrary， inliquidflow，celskept1'odshapedinspiteofthechangesofincubationtemperature (Fig.9).
Ot t et a.l revealed that flagel lation of Legionel lae was also temperature regulated between37oCto41oC(25).Whenthegrowthtemperatureofvirulentandavirulentofstrain L.pneumophilawasshifted・白om30oCtoeither37or41oC，adecreaseinthepercentage offlagelatedbacteriawithinthepopulationwasobserved.AnotherstudyshowedthatClpP wasrequiredforoptimalgrowthofL.pneumophilaathightemperaturesandunderseveral other stres conditions(26). They observed that cels devoid ofClpP exhibited cel elongation，incompleteceldivisionandcompromisedcolonyformation.
Piaoeta.lexaminedforbiofilmfo1'mationoffiftyst1'ainsrepresenting38speciesofthe genusLegionelawereonglas，polystyrene，andpolypropylenesurfacesinstaticcultures at 250 C，370 C，and 420 C (27). They revealed that biofilms formed at 370 C 01' 420 C were mycelialmatlikeandwerecomposedoffilamentouscels，whileat250C，celswererod shaped.Planktoniccelsoutsideofbiofilms01' inshakenliquidcultureswererodshaped. However，theyalsoshowedthatfilamentouscelswereabletorapidlygiverisetoalarge number of ShOli rods in a fi'esh liquid culture at 370 C. The nutrient