Effect of aminglycoside administration on the occurrence and multiplication of resistant bacteria [Utjecaj uporabe aminoglikozida na nastanak i širenje otpornih bakterija]

Milas, Josip and Kalenić, Smilja and Milas, Vesna and Miškulin, Maja and Vuković, Dubravka and Rudan, Stjepan and Puntarić, Dinko (2009) Effect of aminglycoside administration on the occurrence and multiplication of resistant bacteria [Utjecaj uporabe aminoglikozida na nastanak i širenje otpornih bakterija]. Collegium Antropologicum, 33 (2). pp. 579-585. ISSN 0350-6134

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Abstract

In the prospective study the susceptibility of 41 Escherichia coli strains and 55 Pseudomonas aeruginosa strains to gentamicin, netilmicin and amikacin was tested at a 2-year interval (period I April 1998 to March 1999, and period II April to July 2001). Genotyping was performed by pulsed-field gel electrophoresis, and a clone based on 80% or 90% similarity was determined for each of the study bacteria. In 24 (32.0%) clones, strains showed no variation over 2-year interval, supporting the hypothesis on a priori susceptible strains. Transformation from susceptibility in period I to resistance in period II was demonstrated in 5 (6.7%) clones, a pattern consistent with the concept of bacterial development of resistance under the influence of antibiotics. However, there were 10 (13.3%) clones whose strains exhibited an inverse pattern. Accordingly, two-way transformation of susceptibility took place during the study period. The utilization of the study aminoglycosides had no major impact on the variation of microbial susceptibility. Changes in microbial susceptibility were found to follow some regular patterns, which were not influenced by the study aminoglycosides. Two phenomena were observed: (i) there were stable clones that did not develop resistance in spite of selective antibiotic challenge; and (ii) changes of susceptibility in isolated bacteria from both inpatient and outpatient strains of the same clone were two-way and reversible.

Abstract in Croatian

U razmaku od 2 godine (1998/1999 i 2001) ispitana je osjetljivost 41 soja Escerichie coli (E. coli), 55 sojeva Pseudomonas aeruginosa (P. aeruginosa) na gentamicin, netilmicin i amikacin. Za genotipizaciju korištena je pulsfieldgelektroforeza (PFGE). Klonovi su za svaku bakteriju određeni na temelju sličnosti od 80%, odnosno 90%. Cilj je ispitivanja promatrati djelovanje aminoglikozida na dinamiku promjena osjetljivosti sojeva nekog klona u razmaku od 2 godine u navedenim bakterijama i iz bolničkih i iz izvanbolničkih uzoraka. Najveći je broj klonova čiji su sojevi pronađeni samo u jednom ispitanom razdoblju (36, 48%) te se za njih nije mogla odrediti promjena osjetljivosti između dva razdoblja od 2 godine. U 24 klona (32%) sojevi u razmaku od 2 godine nisu mijenjali osjetljivost. Ovi podaci govore u prilog hipotezi da a priori postoje osjetljivi i otporni sojevi. U 5 (6,7%) klonova dokazana je promjena od osjetljivosti sojeva u prvom razdoblju prema otpornosti u drugom razdoblju. Ovakvo ponašanje je sukladno shvaćanju da bakterije razvijaju otpornost pod djelovanjem antibiotika. Međutim, dokazano je i postojanje 10 (13,3%) klonova čiji sojevi pokazuju suprotno: otporni sojevi iz prvog razdoblja »gube« otpornost i postaju osjetljivi u drugom razdoblju. Dakle, u promatranom su vremenu promjene osjetljivosti dvosmjerne. 88% klonova sadrže sojeve i iz bolničkih i iz izvanbolničkih uzoraka što ukazuje da nema više zatvorenih sredina. Potrošnja ispitanih aminoglikozida ne utječu na promjenu osjetljivosti.

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