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dc.contributor.advisorDe Kock, M. J.
dc.contributor.authorMaqutu, Lennox Makhelane
dc.date.accessioned2017-06-21T07:05:03Z
dc.date.available2017-06-21T07:05:03Z
dc.date.issued2005-05
dc.identifier.urihttp://hdl.handle.net/11660/6391
dc.description.abstractEnglish: This study was designed to elucidate the epidemiology, nature and extent of β-lactam resistance in urinary tract infections caused by Escherichia coli isolates in Bloemfontein hospitals. To reach this goal it was necessary to phenotypically characterise and re-identify the E. coli isolates by the Mastascan identification system. Pure cultures were obtained by streaking single colonies onto MacConkey agar containing 50 µg / ml ampicillin. Single colonies were then picked off and inoculated into Mueller-Hinton broth, grown overnight at 37°C and re-streaked onto MacConkey agar containing 50 µg / ml ampicillin. Three colonies were then picked and stored at -20°C in a freeze mixture of 10 % proteose and 10 % glycerol. E. coli isolates were mated to a universal recipient strain (162) in pre-warmed Mueller- Hinton broth. Transconjugants were selected on MacConkey agar supplemented with 50 µg / ml ampicillin and 50 µg / ml nalidixic acid. Lactose-negative colonies resistant to nalidixic acid and ampicillin were inoculated into Mueller-Hinton broth, incubated for six hours and restreaked onto MacConkey agar containing ampicillin. Lactose-negative colonies were picked and considered to be transconjugants. It was found that fifty four (45 %) out of 120 ampicillin-resistant isolates transferred ampicillin-resistance determinants to an E. coli recipient (162) by conjugation. Seventy-five percent of ampicillin-resistant isolates were from female patients, indicating that urinary tract infections are more prevalent in females than in males. The National Committee for Clinical Laboratory Standards* agar dilution method was used to determine minimum inhibitory concentration (MIC) distributions of 12 β-lactam antimicrobial agents (ampicillin, amoxycillin, piperacillin, augmentin, cefoxitin, cefotaxime, cefepime, ceftazidime, cephazolin, ceftriaxone, cefuroxime and imipenem). Strains found to be resistant had MICs that overlapped the range where susceptibility was normally assumed. This was due to inducible β-lactamase producer strains, which go undetected by the Kirby- Bauer disk diffusion method but can be identified by using the Jarlier double-disk method. MIC frequency distributions for the penicillins showed that elevated doses should be administered in order to maximise antibiotic concentration at the site of infection or that a second antibiotic agent or inhibitor should be used in combination therapy. Beta-laetam susceptibility profiles were determined by the Kirby-Bauer disk diffusion method. This method was also used to determine the correlation of MIC values with the inhibition zone diameters in order to predict treatment outcomes from inhibition zone diameters. The Jarlier double-disk technique was used to detect extended-spectrum β-lactamaseproducing organisms and the frequencies at which they occurred. There was no difference between the ratios of ESBL-producers in hospitalised and non-hospitalised patients, although the absolute numbers were different. This was probably due to the 48 hour cut-off point used to define hospitalisation. Samples taken before 48 hours were considered to be nonhospitalised. There were many more female than male patients with urinary tract infections in the Bloemfontein hospitals during the period of the study. The extent of joint resistance to β-lactam antibiotics among E. coli isolates was assessed by comparing two agents at a time. The observed incidence of joint resistance was compared to the rate of double resistance expected if it had been acquired as two independent events. It was found that even amongst two antibiotics that are biologically cross-resistant (ampicillin and augmentin) a close correlation exists between the concentrations of the two agents required to inhibit individual E. coli strains.en_ZA
dc.description.abstractAfrikaans: Hierdie studie is ontwerp om die epidemiologie, aard en omvang te ondersoek van β- laktam weerstandigheid in Escherichia coli isolate wat urienweginfeksies in Bloemfonteinse hospitale veroorsaak. Om in hierdie doel te slaag was dit nodig om die E. coli isolate fenotipies te karakteriseer en te her-identifiseer d.m.v. die Mastascan identifikasie stelsel. Suiwer kulture is verkry deur uitstreping van enkel kolonies op MacConkey agar wat 50 µg / ml ampisillien bevat het. Enkel kolonies is hiervandaan afgeneem en in Mueller-Hinton sop geïnokuleer. Na oornag-inkubasie by 37°C is die kulture weer op MacConkey agar wat 50 µg / ml ampicillin bevat, uitgestreep. Drie kolonies is hiervandaan afgeneem en geberg by -20°C in 'n vriesmengsel bestaande uit 10 % proteose en 10 % gliserol. E. coli isolate is in voorafverwarmde Mueller-Hinton sop met 'n universele ontvangerstam (162) gepaar. Transkonjugante is vanaf MacConkey agar wat aangevul is met 50 µg / ml ampicillin en 50 µg / ml nalidiksiese suur, geselekteer. Laktose-negatiewe kolonies wat weerstandig is teen ampisillien en nalidiksiese suur is afgeneem en geïnokuleer in Mueller- Hinton sop. Na 6 uur se inkubasie is die kulture weer uitgestreep op ampisillienbevattende MacConkey agar. Laktose-negatiewe kolonies is afgeneem en as transkonjugante geklassifiseer. Vier en vytig (45 %) transkonjugante uit 120 ampisillien-weerstandige isolate is geselekteer in die E. coli J62 ontvanger. Vyf en sewentig persent van die ampisillienweerstandige isolate was vanaf vroulike pasiënte afkomstig, wat daarop dui dat urienweginfeksies meer algemeen in vroue as in mans is. Die ''National Committee for Clinical Laboratory Standards" (NCCLS)* se agarverdunnings metode is gebruik om die minimum inhibitoriese konsentrasie (MIK) verspreidings van 12 β-Iaktam antibiotiese verbindings (ampisillien, amoksisillien, piperasillien, augmentin, kefoksitien, kefotaksiem, kefepiem, keftasidiem, kefasolien, keftriaksoon, kefuroksiem en imipenem) te bepaal. Weerstandige stamme se MIKs mag die bestek oorvleuel waar gevoeligheid gewoonlik verwag word. Dit is die gevolg van induseerbare β-Iaktam produserende stamme wat nie deur die Kirby-Bauer skyfie diffusiemetode waargeneem word nie. Hierdie stamme kan egter deur Jarlier se dubbelskyfle-tegniek aangetoon word. MIK frekwensie-verspreidings vir die penisilliene wys dat verhoogde dosisse gebruik moet word om die antibiotikum-konsentrasie by die infeksiepunt te verhoog, of dat 'n tweede antibiotikum of 'n inhibeerder in kombinasie gebruik moet word. Beta-laktam gevoeligheidsprofiele is d.m.v. die Kirby-Bauer skyfie diffusie-metode bepaal. Hierdie metode is ook gebruik om die korrelasie met MIK-waardes te bepaal sodat behandelingsuitkomste vanaf inhibisiesone-deursnitte voorspel kan word. Die Jarlier dubbelskyfie-tegniek is gebruik om verlengde-spektrum β-laktamaseproduserende (VSBL) organismes en hul voorkomsfrekwensie te bepaal. Geen verskil tussen die verhoudings van VSBL produseerders in hospitaal- en nie-hospitaal pasiënte kon aangetoon word nie, hoewel die absolute getalle verskillend was. Dit is moontlik as gevolg van die 48 uur afsnypunt wat gebruik is om hospitalisasie te definieer. Monsters wat voor 48 uur geneem is, is beskou as afkomstig van nie-hospitaal pasiënte. Daar was tydens die duur van die ondersoek baie meer vroulike as manlike pasiënte met urienweginfeksies in die Bloemfonteinse hospitale. Die omvang van kruisweerstandigheid teen β-laktam antibiotika by E. coli-isolate is bepaal deur twee middels op 'n slag met mekaar te vergelyk. Die waargenome voorkoms van kruisweerstandigheid is vergelyk met dit wat verwag word indien dit onafhanklik sou onstaan. Selfs tussen twee antibiotika wat biologies kruis-weerstandig is (ampisillien en augmentin) is 'n noue verwantskap gevind tussen die konsentrasies wat die twee middels benodig om individuele E.coli-stamme te inhibeer.af
dc.description.sponsorshipNational Manpower Development Secretariaten_ZA
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectEpidemiologyen_ZA
dc.subjectResistanten_ZA
dc.subjectSensitiveen_ZA
dc.subjectDonoren_ZA
dc.subjectTransconjuganten_ZA
dc.subjectMinimum inhibitory concentrationsen_ZA
dc.subjectExtended-spectrum β-lactamasesen_ZA
dc.subjectCross-resistanceen_ZA
dc.subjectCoefficient of determinationen_ZA
dc.subjectβ-laetam antibioticsen_ZA
dc.subjectUrinary tract infections -- Treatmenten_ZA
dc.subjectEscherichia coli infectionsen_ZA
dc.subjectAnti-infective agentsen_ZA
dc.subjectDissertation (M.Med.Sc. (Medical Microbiology))--University of the Free State, 2005en_ZA
dc.titleBeta-lactam resistance profiles in urinary tract infection among Escherichia coli isolates in Bloemfonteinen_ZA
dc.typeDissertationen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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