Characterization of Aminoglycoside Resistance and Virulence Genes among Enterococcus spp. Isolated from a Hospital in China

Abstract

This study investigated the aminoglycoside resistance phenotypes and genotypes, as well as the prevalence of virulence genes, in Enterococcus species isolated from clinical patients in China. A total of 160 enterococcal isolates from various clinical samples collected from September 2013 to July 2014 were identified to the species level using the VITEK-2 COMPACT system. The antimicrobial susceptibilities of the identified Enterococcus strains were determined by the Kirby-Bauer (K-B) disc diffusion method. PCR-based assays were used to detect the aminoglycoside resistance and virulence genes in all enterococcal isolates. Of 160 Enterococcus isolates, 105 were identified as E. faecium, 35 as E. faecalis, and 20 isolates were classified as “other” Enterococcus species. High-level aminoglycoside resistance (HLAR) for gentamicin, streptomycin, and both antibiotics was identified in 58.8, 50, and 34.4% of strains, respectively. The most common virulence gene (50.6% of isolates) was efaA, followed by asa1 (28.8%). The most prevalent aminoglycoside resistance genes were aac(6')-Ie-aph(2''), aph(2')-Id, aph(3')-IIIa, and ant(6')-Ia, present in 49.4%, 1.3%, 48.8% and 31.3% of strains, respectively. Overall, E. faecium and E. faecalis were most frequently associated with hospital-acquired enterococcal infections in Zhejiang Province. All aminoglycoside resistance genes, except aph(2'')-Id, were significantly more prevalent in HLAR strains than amongst high level aminoglycoside susceptible (HLAS) strains, while there was no significant difference between HLAR and HLAS strains in regard to the prevalence of virulence genes, apart from esp, therefore, measures should be taken to manage infections caused by multi-drug resistant Enterococcus species.

A study of high level aminoglycoside resistant enterococci

“…On the other hand, Aph (2//)-Ib and Aph (2//)-Id were not detected in any isolates. This was in agreement with Wanxiang et al (2015) and Li et al (2015) who stated that 94.4% of HLAR enterococci were Aac (6/)-Ie-aph (2//)-Ia positive and in contrast to our results he detected Aph (2//)-Id in 1.3% of his HLAR enterococcal isolates and none of their strains were positive to Aph (2//)-Ic or Aph (2//)-Ib. Padmasini et al (2014) stated that Aac (6/)-Ie-aph (2//)-Ia found in 68.4% of their HLAR enterococcal isolates, while none of other genes were detected and attributed.…”

Distribution of acquired antibiotic resistance genes among Enterococcus spp. isolated from a hospital in Baotou, China

“…Moreover, 8.1% of the HLGR enterococcal isolates did not carry any of the examined AME genes. This was lower than that previously reported by Li et al [19].…”

Effects of two novel amino acid substitutions on the penicillin binding properties of the PBP5 C-terminal from Enterococcus faecium

“…Institutional ethical clearance was obtained. The specimens were isolated from various clinical samples, as described previously (10), including urine (9/13), orotracheal fluid (1/13), vaginal/semen swab (1/13), pus (1/13) and blood (1/13). A VITEK 2 Compact system (BioMérieux, Ltd., Marcy l'Etoile, France) and polymerase chain reaction (PCR) analysis were used to identify E. faecium.…”