RoleofGammaRadiation,β-lactamaseandOuterMembranePermeabilityintheResistanceofSomePathogenicBacterialIsolatestoDifferentβ-lactamAntibiotics

Abstract

Roleofgammaradiation,β-lactamaseandoutermembranepermeabilityintheresistanceofsomepathogenicbacterialisolatestodifferent β-lactamantibiotics. TheaimofthepresentstudywastodevelopnewstrategiesforrevertingresistanceofpathogenicGram-negativebacillibycombinationofantibiotics,potentpermeabilizersandnaturalbetalactamaseinhibitorsinenhancingtheactivityofdifferentantibiotics. Thepresentstudyincludedcollectionof105clinicalsamplesandspecimensfromdifferentsites.Outofthem,(31urinesamples(29.52%),30asciticfluidsamples(28.57%),18bloodsamples(17.14%),7sputumsamples(6.67%),7throatswab(6.67%),9wound(pus)swabs(8.57%),and3stoolspecimens(2.86%))fromoutpatientsofdifferentpublicandprivatehospitalsandNationalcancerInstitute(NCI),Cairo,Egypt. Fromthetotalcollectedsamplesandspecimens,therewere66cases(62.86%)positiveformicrobialinfectionwithdifferentsexandageand39cases(37.14%)werenegativeformicrobialgrowth. AlltheisolatesofpathogenicbacteriawereidentifiedbyusingtheMicroScanWalkAway-  Summary 19 6 96SISystem.Theresultsrevealedtheisolationof16speciesofpath ogenicbacteriabelongingto8genera,themostcommonwasEsche richiawhichrepresent(37.97%),thiswasfollowedbyAcinetobac ter(16.46%),comenextinrankbothofPseudomonasandKlebsiel laeachrepresent(11.39%),(7.59%),alsotherewasoccurrenceof Enterobacter,Proteus,Citrobacterbutwithsmallextent. Alltheisolatesofpathogenicbacteriaweresubjectedtosens itivitytestusing23differentantibioticswithdifferentmodeofacti ons;theseantibioticsbelongto5maingroupsofantibioticsaccordi ngtotheirmodeofactiononmicrobialcells. Theobtainedresultsrevealedthat,thehighestpercentageof antibioticresistanceofGramnegativebacterialisolateswasagainsterythromycinE( 100%),pi peracillinPRL(84.85%),thencefoperazoneCFP(83.33%),aztre onamATM(78.79%),ampicillinsulbactamSAMandcefotaxime CTXshowedthesamepercentageofantibioticresistancetobacter ialisolates(74.24%),whilelessresistanttocefepimeFEP(48.48% ),colistinsulfateCT(31.82%),meropenemMEM(10.61%),finall yimipenemIPM(6.06%). Allidentifiedisolatesweretestedtodetectiftheseisolatespr oducingextendedspectrumbetalactamase(ESBL)enzymeornot, theresultsrevealedthat,42(63.64%)isolateswerepresumptively consideredpositive(ESBLs)accordingtothescreeningmethodsu sedforidentifyingpotentialESBLs.  Summary 19 7 Different concentrations of these phytochemicals were tested for its antibacterial activity against the selected bacterial isolates. The obtained results revealed that gallic acid (≤600μg/ml), ellagic acid (≤40μM), thymol (≤500 μg/ml), chitosan (≤100ppm), EDTA (≤0.1mM) and sorbic acid (≤5mM) did not show any antibacterial activities against all selected bacterial isolates. Therefore, these concentrations were selected for further studies.