High-level aminoglycoside resistance and virulence characteristics among Enterococci isolated from recreational beaches in Malaysia

Abstract

We report the first study on the occurrence of high-level aminoglycoside-resistant (HLAR) Enterococci in coastal bathing waters and beach sand in Malaysia. None of the encountered isolates were resistant to high levels of gentamicin (500 μg/mL). However, high-level resistance to kanamycin (2,000 μg/mL) was observed in 14.2 % of tested isolates, the highest proportions observed being among beach sand isolates. High-level resistance to kanamycin was higher among Enterococcus faecalis and Enterococcus faecium than Enterococcus spp. Chi-square analysis showed no significant association between responses to tested antibiotics and the species allocation or source of isolation of all tested Enterococci. The species classification of encountered Enterococci resistance to vancomycin was highest among Enterococcus spp. (5.89 %) followed by E. faecium (4.785) and least among E. faecalis. A total of 160 isolates were also tested for virulence characteristics. On the whole, caseinase production was profoundly highest (15.01 %) while the least prevalent virulence characteristic observed among tested beach Enterococci was haemolysis of rabbit blood (3.65 %). A strong association was observed between the source of isolation and responses for each of caseinase (C = 0.47, V = 0.53) and slime (C = 0.50, V = 0.58) assays. Analysis of obtained spearman's coefficient showed a strong correlation between caseinase and each of the slime production (p = 0.04), gelatinase (p = 0.0035) and haemolytic activity on horse blood (p = 0.004), respectively. Suggestively, these are the main virulent characteristics of the studied beach Enterococci. Our findings suggest that recreational beaches may contribute to the dissemination of Enterococci with HLAR and virulence characteristics.

Phenotype–Genotype Correlations and Distribution of Key Virulence Factors in Enterococcus faecalis Isolated from Patients with Urinary Tract Infections

“…A clear zone around the colonies, observed after 24-hour incubation at 37 °C, indicated hemolytic activity. 26 , 27 …”

The prevalence of aminoglycoside-modifying enzyme and virulence genes among enterococci with high-level aminoglycoside resistance in Inner Mongolia, China

“…Recently, high-level gentamicin resistance (HLGR) (MIC ≥500 μg/ml) and high-level streptomycin resistance (HLSR) (MIC ≥2000 μg/ml) have been reported worldwide. 3 , 4 , 5 , 6 , 7 , 8 Clinical experience supports the use of aminoglycosides along with cell-wall inhibitors for treating serious enterococcal infections. 9 However, high-level resistance of clinical isolates of Enterococcus species to aminoglycosides negates the synergism between cell-wall inhibitors and aminoglycosides, making the treatment of serious enterococcal infections difficult.…”

Natural transformation of the filamentous cyanobacterium Phormidium lacuna

“…500 µg/ml Kn, respectively. In an extensive literature survey we found a report about an environmental Enterococcus strain that was resistant up to 2 mg/ml Kn (45), but no report about higher Kn resistance. Thus, transformed Phormidium lacuna has probably the strongest Kn resistance reported so far.…”