Characterization of macrolide resistance in bacteria isolated from macrolide-polluted and unpolluted river sediments and clinical sources in Croatia

Milaković, Milena; Križanović, Stela; Petrić, Ines; Šimatović, Ana; Gonzalez-Plaza, Juan Jose; Gužvinec, Marija; Tambić Andrašević, Arjana; Pole, Lucia; Mrkonjić Fuka, Mirna; Udiković-Kolić, Nikolina (2020) Characterization of macrolide resistance in bacteria isolated from macrolide-polluted and unpolluted river sediments and clinical sources in Croatia. Science of the Total Environment, 749 . ISSN 0048-9697

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Abstract

Environments polluted with excessively high levels of antibiotics released from manufacturing sites can act as a source of transferable antibiotic resistance (AR) genes to human commensal and pathogenic bacteria. The aim of this study was to evaluate AR of bacteria isolated from the Sava river sediments (Croatia) at the discharge site of effluents from azithromycin production compared to those from the upstream site and isolates collected in Croatian hospitals. A total of 228 environmental strains of azithromycin-resistant bacteria were isolated and identified, with 124 from the discharge site and 104 from the upstream site. In addition, a total of 90 clinical, azithromycin-resistant streptococcal and staphylococcal isolates obtained from the Croatian Reference Center for Antibiotic Resistance Surveillance were analyzed. PCR screening of isolates on 11 relevant macrolide- resistance genes (MRGs) showed that discharge isolates had greater detection frequencies for 4 gene targets (ermB, msrE, mphE and ermF) compared to upstream isolates. Among clinical isolates, the most frequently detected gene was ermB, followed by msrD, mefE and mefC. The discharge site demonstrated a greater abundance of isolates with co-occurrence of two different MRGs (predominantly msrE-mphE) than the upstream site, but a lower abundance than the clinical sources (most commonly msrD-mefE). The simultaneous presence of three or even four MRGs was specific for the discharge and clinical isolates, but not for the upstream isolates. When MRG results were sorted by gene mechanism, the ribosomal methylation (erm) and protection genes (msr) were the most frequently detected among both the discharge and the clinical isolates. Following sequencing, high nucleotide sequence similarity was observed between ermB in the discharge isolates and the clinical streptococcal isolates, suggesting a possible transfer of the ermB gene between bacteria of clinical and environmental origin. Our study highlights the importance of environmental bacterial populations as reservoirs for clinically relevant macrolide- resistance genes.

Item Type:	Article
Uncontrolled Keywords:	antibiotic resistance; manufacturing; sediment; macrolide-resistance genes; environment; bacteria
Subjects:	NATURAL SCIENCES > Biology > Biochemistry and Molecular Biology NATURAL SCIENCES > Biology > Microbiology NATURAL SCIENCES > Interdisciplinary Natural Sciences NATURAL SCIENCES > Interdisciplinary Natural Sciences > Environmental Science BIOMEDICINE AND HEALTHCARE > Clinical Medical Sciences BIOMEDICINE AND HEALTHCARE > Clinical Medical Sciences > Medical Microbiology
Divisions:	Division for Marine and Enviromental Research
Projects:	Project title Project leader Project code Project type Istraživanje utjecaja otpadnih voda iz farmaceutskih industrija na sastav i profil antibiotičke rezistencije izloženih mikrobnih zajednica u slatkovodnim sedimentima Nikolina Udiković-Kolić UIP-2014-09-9350 HRZZ projekt Proučavanje povezanosti zagađenja okoliša antibioticima i razvoja rezistencije na antibiotike u ljudskih patogena Nikolina Udikovi-Kolić UNSPECIFIED Projekt Zaklade ADRIS
Depositing User:	Milena Milaković Obradović
Date Deposited:	04 Nov 2020 13:43
URI:	http://fulir.irb.hr/id/eprint/5971
DOI:	10.1016/j.scitotenv.2020.142357

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