Assessment of pheromone response in biofilm forming clinical isolates of high level gentamicin resistant <i> Enterococcus faecalis</i>

Abstract

Twenty Þ ve clinical isolates of high level gentamicin resistant Enterococcus faecalis were tested for their bioÞ lm formation and pheromone responsiveness. The bioÞ lm assay was carried out using microtiter plate method. Two isolates out of the 25 (8%) were high bioÞ lm formers and 19 (76%) and four (16%) isolates were moderate and weak bioÞ lm formers respectively. All the isolates responded to pheromones of E. faecalis FA2-2 strain. On addition of pheromone producing E. faecalis FA2-2 strain to these isolates, seven of 19 (37%) moderate bioÞ lm formers developed into high bioÞ lm formers. Similarly one of the 4 (25%) weak bioÞ lm formers developed into high level bioÞ lm former. Twelve (48%) of the 25 isolates were transconjugated by cross streak method using gentamicin as selective marker. This proves that the genetic factor for gentamicin resistance is present in the pheromone responsive plasmid. Among these twelve transaconjugants, seven isolates and one isolate were high bioÞ lm formers on addition of E. faecalis FA2-2 and prior to its addition respectively. Out of the total 25 isolates, eight transconjugants for gentamicin resistance could turn to high bioÞ lm formers on addition of the pheromone producing strain. All the isolates were resistant to more than two antibiotics tested. All the isolates were sensitive to vancomycin. The results indicate the signiÞ cance of this nosocomial pathogen in bioÞ lm formation and the role of pheromone responding clinical isolates of E. faecalis in spread of multidrug resistance genes.

Characterization of Bacterial Etiologic Agents of Biofilm Formation in Medical Devices in Critical Care Setup

“…Acinetobacter , Pseudomonas, Klebsiella, Staphylococcus, Enterobacter, and E. coli are the most common causes of nosocomial infections, and that may be common cause of colonization in indwelling medical devices even responsible for biofilm production [10, 11]. These microorganisms survive in hospital environments despite unfavorable conditions such as desiccation, nutrient starvation, and antimicrobial treatments.…”

“…A study by Donlan et al showed that the organisms most commonly isolated from central venous catheter biofilms are Staphylococcus epidermidis, S. aureus, Candida albicans, P. aeruginosa, K. pneumoniae, and Enterococcus faecalis [9, 10]. Stickler et al [17] showed that the organisms commonly contaminating this urinary catheter and developing biofilms are S. epidermidis, Enterococcus faecalis, E. coli, Proteus mirabilis, P. aeruginosa, K. pneumoniae, and other gram-negative organisms [2, 9–11]. The study of different mechanisms of drug resistance showed isolates commonly found positive for ESBL, carbapenemase production in gram-negative organism and MRSA, vancomycin resistance among gram-positive organisms.…”

Basic research In vitro antibacterial activity of seven Indian spices against high level gentamicin resistant strains of enterococci

“…These isolated strains were considered clinically significant when obtained in pure culture from the clinical samples or in significant numbers as part of mixed cultures. The isolates were further identified in accordance with the standard procedure [ 9 , 10 ].…”

“…The possession of diverse virulence factors has been an important benefit for enterococci, since possessing any of them may change the severity of infections caused by these bacteria. On the other hand, it is believed that nosocomial enterococci might have virulence elements that increase their ability to colonize hospitalized patients [ 4 , 8 , 9 ]. Resolution of the high level gentamicin resistant enterococci infections is further complicated by the presence of virulence factors present in these organisms [ 9 ].…”