Investigation of genetic relatedness, antimicrobial resistance, biofilm formation, biofilm-related virulence genes and integron-related genes of Stenotrophomonas maltophilia isolates obtained from bovine milk samples with mastitis
No Thumbnail Available
Date
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Treatment of infections caused by the opportunistic pathogen Stenotrophomonas maltophilia is com-plicated by the bacterium's ability to produce biofilms and high antibiotic resistance. This study aimed to investigate the prevalence of genetic relatedness, antimicrobial resistance, biofilm formation, biofilm-related genes with virulence and integron-related genes among isolates of S. maltophilia recovered from bovine milk with subclinical mastitis. In this study, bacterial identification was performed using conventional methods. The smeT gene-based Polymerase Chain Reaction (PCR) was used for bacterial identification. PCR was also used to detect virulence and integron-related genes, too. The quantitative Microplate Test (MP) method was used to determine the phenotypic biofilm production capacity of the isolates. The resistance patterns of the isolates against nine antibiotics belonging to nine antimicrobial families were examined using the disk diffusion method. Isolates resistant to at least three drug classes from various antimicrobial drug classes were defined as multi-drug resistant (MDR). The genetic linkage of S. maltophilia isolates was investigated by Enterobacterial Repetitive Intragenic Consensus (ERIC) PCR. Chi-square (chi 2) test was used to reveal statistical difference between MDR and integron-related gene prevalances as well as biofilm formation capacity of isolates and biofilm-related virulence genes. In the study, a total of 312 milk samples with subclinical mastitis were taken from 27 farms. Ten isolates from five farms were phenotypically and genotypically identified as S. maltophilia. All isolates were resistant to cefepime and imipenem. 80% of the isolates carried at least one of the integron-related genes and 70% were MDR. The phenotypically biofilm-forming capacity identified in isolates was detected at 80%. The prevalence of the studied virulence genes was rpfF 60%, rmlA 70%, spgM and smf1 80%. There was no signifi-cant relationship between the biofilm-forming capacity of the isolates and the prevalence of biofilm-related virulence genes and MDR with integron-related genes. In the UPGMA analysis performed, a total of five genotypes were found, two single and three multiple according to 18% similarity coefficient. The presence of same isolates on the same farm and closely related isolates on different farms may suggest a clonal spread. ERIC-PCR can be useful in identifying S. maltophilia isolates with epidemic potential. S. maltophilia isolates were detected simply and quickly, using PCR based on the smeT gene, from bovine milk samples for the first time in Turkey.