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Medycyna Doświadczalna i Mikrobiologia 2018, 70(1): 49-56

Oporność typu MLSB u klinicznych izolatów Bacteroides i Parabacteroides
[MLSB resistance in clinical isolates of Bacteroides and Parabacteroides]

Marta Kierzkowska, Anna Majewska, Ksenia Szymanek-Majchrzak, Anna Sawicka-Grzelak, Andrzej Młynarczyk, Grażyna Młynarczyk

STRESZCZENIE

Zgodnie z rekomendacjami EUCAST pałeczki Bacteroides sp. fenotypowo wrażliwe na klindamycynę i jednocześnie z wartością MIC erytromycyny >32 mg/L należy raportować jako oporne na klindamycynę. W prowadzonym badaniu 42% izolatów prezentowało w/w profil. Wykazano jednak, że zaledwie 7,2% takich izolatów posiada geny erm związane z opornością typu MLSB. W pozostałych przypadkach oporność na erytromycynę, ale nie na klindamycynę, może być spowodowana aktywnym wypompowywaniem leku z komórki przez pompy błonowe.

ABSTRACT

Introduction: The MLSB resistance (to macrolides, lincosamides and streptogramin B) is associated with the presence of erm genes (ermF, ermB, ermG). The aim of the study was to check the presence of the mechanism MLSB resistance in Bacteroides spp. and Parabacteroides spp. isolates originated from clinical specimens.

Methods: The study involved 200 clinical isolates collected from 190 patients hospitalized in the years 2007-2012. The mechanism of resistance was assessed using E-tests, test with two disks (clindamycin 15 μL, and erythromycin 2 μL) and then erm genes (ermB, ermF, ermG) have been detected.

Results: Overall 42% of the isolates tested was susceptible to clindamycin (MIC≤ 4 mg/L) but resistant to erythromycin (MIC > 32 mg/L). According to EUCAST recommendations, such strains should be reported as resistant to clindamycin. However, in only 7.2% of them the erm genes (mainly ermF) were detected. Resistance to clindamycin was present in 31% of all tested isolates. Additionally, it was observed that the proportion of clindamycin resistant strains increased from 20% in 2007 to 40% in 2012.

Conclusions: In our investigations it was shown that the resistance to clindamycin of isolates of Bacteroides spp. and Parabacteroides spp. obtained from patients of Warsaw hospital has steadily increased. It is in accordance with studies of other European laboratories which show high levels of resistance to clindamycin. In our study, resistance was mainly detected in B. ovatus, P. distasonis, B. uniformis, and B. fragilis. The proportion of resistant B. fragilis increased more than twice (from 15% to 36.6%) during the period considered. The clindamycin MIC in each case had an extreme value of 256 mg/L. For this reason, empirical therapy should be always implemented on the basis of a clinical assessment of the course of infection and of the antimicrobial drug resistance pattern in the hospital and ward and then modified on the basis of the results of the drug susceptibility tests. Sensitivity to clindamycin should be routinely monitored in medical laboratories.

Key words: Bacteroides spp., anaerobes, clindamycin, MLSB, Parabacteroides spp.

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