Antimicrobial susceptibility and virulence genes of clinical and environmental isolates ofPseudomonas aeruginosa

Abstract

Background Pseudomonas aeruginosa is ubiquitous, has intrinsic antibiotic resistance mechanisms, and is associated with serious hospital-associated infections. It has evolved from being a burn wound infection into a major nosocomial threat. In this study, we compared and correlated the antimicrobial resistance, virulence traits and clonal relatedness between clinical and fresh water environmental isolates of P. aeruginosa.Methods219 P. aeruginosa isolates were studied: (a) 105 clinical isolates from 1977 to 1985 (n = 52) and 2015 (n = 53), and (b) 114 environmental isolates from different fresh water sources. All isolates were subjected to ERIC-PCR typing, antimicrobial susceptibility testing and virulence factor genes screening.ResultsClinical and environmental isolates of P. aeruginosa were genetically heterogenous, with only four clinical isolates showing 100% identical ERIC-PCR patterns to seven environmental isolates. Most of the clinical and environmental isolates were sensitive to almost all of the antipseudomonal drugs, except for ticarcillin/clavulanic acid. Increased resistant isolates was seen in 2015 compared to that of the archived isolates; four MDR strains were detected and all were retrieved in 2015. All clinical isolates retrieved from 1977 to 1985 were susceptible to ceftazidime and ciprofloxacin; but in comparison, the clinical isolates recovered in 2015 exhibited 9.4% resistance to ceftazidime and 5.7% to ciprofloxacin; a rise in resistance to imipenem (3.8% to 7.5%), piperacillin (9.6% to 11.3%) and amikacin (1.9% to 5.7%) and a slight drop in resistance rates to piperacillin/tazobactam (7.7% to 7.5%), ticarcillin/clavulanic acid (19.2% to 18.9%), meropenem (15.4% to 7.5%), doripenem (11.5% to 7.5%), gentamicin (7.7% to 7.5%) and netilmicin (7.7% to 7.5%). Environmental isolates were resistant to piperacillin/tazobactam (1.8%), ciprofloxacin (1.8%), piperacillin (4.4%) and carbapenems (doripenem 11.4%, meropenem 8.8% and imipenem 2.6%). Both clinical and environmental isolates showed high prevalence of virulence factor genes, but none were detected in 10 (9.5%) clinical and 18 (15.8%) environmental isolates. The exoT gene was not detected in any of the clinical isolates. Resistance to carbapenems (meropenem, doripenem and imipenem), β-lactamase inhibitors (ticarcillin/clavulanic acid and piperacillin/tazobactam), piperacillin, ceftazidime and ciprofloxacin was observed in some of the isolates without virulence factor genes. Five virulence-negative isolates were susceptible to all of the antimicrobials. Only one MDR strain harbored none of the virulence factor genes.ConclusionOver a period of 30 years, a rise in antipseudomonal drug resistance particularly to ceftazidime and ciprofloxacin was observed in two hospitals in Malaysia. The occurrence of resistant environmental isolates from densely populated areas is relevant and gives rise to collective anxiety to the community at large.

Detection of virulence and multidrug resistance operons in Pseudomonas aeruginosa isolated from Egyptian Baladi sheep and goat

“…The results indicated that the isolates were susceptible to both ciprofloxacin 13 (100%) and norfloxacin 12 (92.3%), while completely resistant to ampicillin, bacitracin, erythromycin, streptomycin, tetracycline, trimethoprim-sulfamethoxazole, and tobramycin, most of the isolates were resistant to amikacin, chloramphenicol, and gentamycin. These findings agreed with the other previous studies which illustrated that the organism is resistant to all used antibiotics except quinolones [32-35].…”

Antibiotic resistance, virulence factors and genotyping of Pseudomonas aeruginosa in public hospitals of northeastern Mexico

“…The analyzed samples in this study were found in different anatomical sites such as urinary, respiratory and auditive tract, wounds from different parts of the body, in addition to bloodstream samples. P. aeruginosa was mainly isolated from the respiratory and urinary tract, as well as from wounds, in consistence with other studies where they have also been found in these sites and wounds of severely burnt patients [30]. Regarding antibiotic resistance, in this The abbreviations correspond to the origin and code of the strains, labeled with each of the sampling site of the isolate) UC, urine culture, RTS, respiratory tract secretions, BAL, bronchoalveolar lavage, E, ear, W, wound.…”

Carbapenem-Resistant Pseudomonas aeruginosa Strains-Distribution of the Essential Enzymatic Virulence Factors Genes

“…The environmental antimicrobial susceptible P. aeruginosa strains are also infectious for human but it is likely that they become resistant during the infection, possibly with the influence of antimicrobial therapy pressure [ 14 ]. A growing number of reports on the increased virulence of multi-drug resistant P. aeruginosa isolates, when compared to more susceptible strains, can be found in the available literature [ 15 , 16 , 17 , 18 , 19 ].…”

“…It has also been recently shown that particular resistance mechanisms can easily and favorably co-exist with virulence genes in particular sets of strains [ 13 , 21 , 22 ]. Other authors, on the contrary, have suggested that the virulence of antibiotic-resistant P. aeruginosa strains (including carbapenem-resistant isolates) has somehow been reduced [ 16 , 17 , 18 , 19 ]. One of the explanations of this phenomenon is that bacterial cells somehow selectively activate genes, when necessary from the survival point of view, while silencing other ones.…”