جستجوی مقالات مرتبط با کلیدواژه "phenotypic" در نشریات گروه "پزشکی"

Carbapenem resistance among Pseudomonas aeruginosa strains is alarming. This study aimed to investigate the relative frequency of carbapenem-resistant P. aeruginosa strains by phenotypic and genotypic methods.

he antibiotic susceptibility pattern of 60 P. aeruginosa isolates was determined by disk diffusion method (Kirby-Bauer). BD Phoenix automated microbiology system was used to identify carbapenem-resistant isolates, and the minimum inhibitory concentration (MIC) was determined using E-Test. In addition, mCIM (modified carbapenem inactivation method) phenotypic test was performed to evaluate carbapenem resistance genes in P. aeruginosa isolates. The prevalence of metallo-beta-lactamase (MβL) genes in carbapenem-resistant P. aeruginosa isolates was determined using conventional polymerase chain reaction (PCR).

The frequency of carbapenem-resistant P. aeruginosa isolates was 36% (22 of 60). The highest resistance was observed to imipenem and meropenem (36.6%), and the highest sensitivity was observed to amikacin (75%). All carbapenem-resistant P. aeruginosa isolates were confirmed by the BD Phoenix automated system (MIC> 8 µg/mL for imipenem and meropenem), E-test (MIC ˂32 µg/mL), and mCIM assay (the growth inhibition zone diameter was 6-8 mm).  In carbapenem-resistant P. aeruginosa isolates, the frequency of blaVIM, blaIMP, and blaSPM genes was 9.1% (2 of 22), 4.5% (1 of 22), and 4.5% (1 of 22), respectively. BlaKPC and blaNDM genes were not found in any of the isolates.

Based on the present study results, all phenotypic tests used to identify carbapenemase-producing isolates had the same sensitivity (100%) and specificity (100%).

The occurrence of asymptomatic verocytotoxin (VT)-producing Escherichia coli (VTEC) infections among humans in recent years is posing a high risk to public health. Thus, the role of asymptomatic human carriers as a source of dissemination should not be underestimated. This study aimed to elucidate the phenotypic and genotypic characteristics of E. coli in the stool samples collected from indigenous individuals in Malaysia.  E. coli strains (n=108) were isolated from stool samples obtained from 41 indigenous individuals. All strains were subjected to Repetitive Extragenic Palindromic-Polymerase Chain Reaction (REP-PCR) typing and confirmation of VTEC variants. Non-duplicate strains were selected based on REP-PCR profiles and further subjected to antimicrobial susceptibility test (AST). The genotypic and phenotypic characteristics of the strains were then correlated with the demographic data of the subjects.   A total of 66 REP-PCR profiles grouped in 53 clusters (F=85%) were obtained. Four genetically distinct strains were confirmed as VTEC (eaeA-positive). The predominant resistance was against ampicillin (34.2%), followed by trimethoprim-sulfamethoxazole (32.9%), ampicillin-sulbactam (5.5%), and ciprofloxacin (1.4%). All isolates were sensitive to amoxicillin-clavulanate, cefuroxime, ceftriaxone, imipenem, and meropenem.  Genetically diverse E. coli and VTEC strains were found to colonize the intestines of the indigenous populations. This study is important for the prospective surveillance of E. coli among the indigenous individuals in Malaysia, especially in asymptomatic VTEC infection and antimicrobial resistance phenomenon.

Salmonella typhi infection occurs in most endemic areas. Patients suspected of typhoid fever located in the Badda and Shantinagar localities of Dhaka were the studied population. A total of 107 blood specimens were collected.
This study attempted to determine the antibiotic susceptibility pattern of Salmonella typhi among different age and gender groups having clinical symptoms of typhoid fever.

 The microorganisms obtained from blood specimens were identified by phenotypical and biochemical tests following standard protocols. Antibiotic susceptibility test was done by the Agar-disc-diffusion method to understand antibiotic susceptibility of the isolates. All the Salmonella typhi isolates were serologically confirmed using a commercial antisera kit.

Out of 107, 74 Salmonella typhi isolates showed multidrug-resistant properties. Nalidixic acid, ampicillin, azithromycin, and ciprofloxacin showed high antibiotic resistance percentage. On the other hand meropenem, amikacin, gentamycin showed low antibiotic resistance. Age and sex groups also revealed significant attributes to the multidrug-resistant isolates. Multidrug-resistant pattern of the clinical isolates of Salmonella typhi of the current study has presented a matter of great public health concern in Dhaka city, Bangladesh. The first line of antibiotics can be prescribed, taking into consideration of age and gender. The sources of Salmonella typhi infection and mode of transmission must be identified.

Escherichia coli is a common enteric pathogen of human and livevestock. Antibiotic resistance is the main concern of public health. The aim of this study was to detect this bacterium in stool samples of diarrheal patients and identify the phenotypic and genotypic characterizations of antibiotic-resistant isolates such as dfrA1, sul1, citm, tetA, qnr, aac(3)-IV in Shahrekord. Two hundred fifty diarrheal stool samples from patients were collected. Microbiological and biochemical examinations were done to detect E. coli. Phenotypic and genotypic antibiotic resistance of the isolates were determined using dick diffusion method and polymerase chain reaction (PCR), respectively. Among 114 E. coli isolates, the least resistance was for gentamicin (0%) and the most resistance was for trimethoprim (79.8%). The resistance to sulfamethoxazole, ciprofloxacin, ampicillin, and tetracycline were 71.05%, 10.5%, 52.63%, and 3.5% respectively. The results of PCR assay revealed that 10 isolates contain sul1, 49 isolates harbor citm, 8 isolates tetA, 36 isolates dfrA1, 11 isolates qnr genes but there was no isolate with aac(3)-IV gene. In comparison between phenotypic and genotypic of the isolates revealed that citm, tetA, dfrA1, qnr, sul1, aac(3)-IV genes covered 42.98%, 7.01%, 31.57%, 9.64%, 8.7%, 0% of the antibiotic resistance, respectively. Our results revealed that all isolates harbor one or more antibiotic resistance genes and that the PCR is a fast practical and appropriate method to determine the presence of antibiotic resistance genes.

Food-borne pathogenic is a group of micro -organis ms that caus e food -borne illnes s thus , the res earch for finding effective drugs agains t this infection is neces s ary. Staphylococcus aureus is the major caus e of food -borne and nos ocomial infection in las t decade and methicillin res is tant S. aureus (MRSA) has emerged as a major clinical problem. The aim of the pres ent s tudy was to compare different phenotypic methods with genotypic method by polymeras e chain reaction (PCR) for the detection of MRSA s trains . Sens itivity to methicillin was als o inves tigated by oxacillin, methicillin, cefotetan, cefoxitin, cefmetazole dis ks , the data tab, and dis k diffus ion method and oxacillin s trip. Minimum inhibitory concentration (MIC) of thes e is olates was determined by us ing micro-broth dilution. A total of 186 is olates of S. aureus with PCR method (gold s tandard) were detected. About 95 is olates were methicillin -s ens itive S. aureus , and 91 is olates were MRSA. Among the diagnos tic methods s tudied, micro - broth dilution and cefoxitin dis k had the mos t s pecificity with 98.9% and 94.7%, res pectively. The s ens itivity of them was 100.0% and 98.9%, res pectively. Furthermore, the concordance with PCR was 98.9% and 93.6%, res pectively. The cefotetan and cefmetazole dis ks had the lowes t concordance with the res ults of PCR. Due to the neces s ity of us ing s imple, reliable and low-cos t methods in routine diagnos tic laboratories it s eems us e of cefoxitin dis k s till be cons idered as one of recommended methods for detecting MRSA is olates.

Extended-spectrum beta-lactamases (ESBLs) are a group of enzymes that hydrolyze antibiotics, including those containing new cephalosporins, and they are found in a significant percentage of Escherichia coli and Klebsiella pneumoniae strains. With the widespread use of antibiotics, difficulties with infection therapy caused by drug resistant organisms, especially those that have acquired resistance to beta-lactams, such as broad-spectrum cephalosporins, have amplified the above-mentioned organisms.. This study was conducted to characterize ESBLs among E. coli and K. pneumonia isolates by molecular and phenotypic methods.. Different strains of E. coli and K. pneumonia were collected from patients with urinary tract infections. The ESBL phenotype was determined by a double disk diffusion test (DDDT). In addition, polymerase chain reaction (PCR) analysis specific for β-lactamase genes of the TEM and SHV family was carried out. The PCR products were run on agarose and examined for DNA bands.. A total of 245 E. coli and 55 K. pneumonia strains were isolated from different samples. In total, 128 of the 300 isolates were confirmed as potential ESBLs producers as follows: 107 (43.67%) E. coli and 21 (38.18%) K. pneumonia. ESBLs genes were found in 24 isolates (18.75%): 21 E. coli and 3 K. pneumonia isolates. The TEM gene was present in 13 (12.14%) E. coli strains, but it was not detected in K. pneumonia. In addition, the SHV gene was present in 8 (7.47%) E. coli and 3 (14.28%) K. pneumonia isolates. Five (4.67%) of the E. coli isolates harbored both TEM and SHV genes. All isolates (100%) were susceptible to imipenem. The lowest rates of resistance to other antibiotics were observed for; piperacillin-tazobactam (6.25%), amikacin (12.5%) and gentamicin (14.84%). The rates of resistance to other antibiotics were as follow: nitrofurantoin (16.4%), nalidixic acid (23.43), co-trimoxazole (25%), cefepime (32%), ciprofloxacin (55.46%), ampicillin (69.53%), ceftazidime (100%), and cefotaxime (100%).. The results of this study indicate the widespread prevalence of ESBLs and multiple antibiotic resistance in E. coli and K. pneumoniae. Therefore, beta-lactam antibiotics and beta-lactamase inhibitors or carbapenems should be prescribed based on an antibacterial susceptibility test..