Extended-spectrum Beta-lactamase Positivity Research Articles

Extended spectrum beta-lactamase (ESBL) production and antibiotic resistances of Escherichia coli and Klebsiella spp. strains isolated from urine cultures

Objective: It was aimed to determine extended spectrum beta-lactamase (ESBL) production and antibiotic resis­tance rates of Escherichia coli and Klebsiella spp. strains isolated from urine cultures of patients admitted to vari­ous outpatient clinics and inpatient clinics of our hospital between December 2011 and August 2012. Methods: E.coli and Klebsiella spp. strains isolated from urine cultures were identified by conventional methods. Antibiotic susceptibilities were determined by using Kirby- Bauer’s disk diffusion method according to Clinical and Laboratory Standards Institute (CLSI) recommendations. Extended spectrum beta-lactamase (ESBL) producing E.coli and Klebsiella spp. strains were detected by using “double disk sinergy method”. Results: During the study period, 308 E.coli and 54 Kleb­siella spp. strains were isolated from urine cultures. ESBL production was detected in 64 (20.8%) of E.coli strains and 21 (38.9%) of Klebsiella spp. strains. ESBL positivity was encountered the most frequently in urine samples of patients who were from outpatient clinics of pediatrics and urology, it was followed by internal clinics and intensive care units. Imipenem resistance was found to be 4.7% and amikacin resistance was 7.8% in ESBL-positive E.coli strains. There was no resistance to carbapenems in ESBL-positive Klebsiella spp. strains, but their amika­cin resistance was 4.8%. Piperacillin tazobactam resis­tance rate in ESBL-positive E.coli and Klebsiella spp. was 17.2% and 14.3%, respectively. Conclusion: Selection of antibiotics should be made by considering results of antibiotic susceptibility tests for treatment of urinary tract infections. Also, determination of ESBL production and reporting it with antibiotic suscep­tibility tests will enhance the success of treatment.

Characterization of CTX-M type extended spectrum β- lactamases of Escherichia coli isolated from urinary tract infections in Southern Turkey: The first report of CTX-M-14 producing Escherichia coli from Turkey

The aim of this study was to investigate the frequency of CTX-M type extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli strains which have become emerging etiologic agents of urinary tract infections (UTIs). A total of 310 E. coli isolates recovered from UTIs were screened for ESBL production by VITEK2 system and the double-disk synergy tests. In addition, ESBL positive isolates were selected for typing of blaCTX-Mgenes by PCR screening followed by DNA sequencing analysis permitting the differentiation of the CTX-M subtypes. A pulsed-field gel electrophoresis (PFGE) assay was also performed to check for a possible clonal relation among these isolates. ESBL positivity was detected in 77 (24.8%) of isolates. Subsequently, 46 (14.8%) of ESBL positive E. coli isolates were shown to be carrying blaCTX-M genes of which 30 (9.6%) were found to be CTX-M-15 producers, while the remaining 16 (5.1%) were CTX-M-14 producers. No major clonal relationship among these blaCTX-M producers was found. Wedemonstrated the presence of CTX-M-14 producer E. coli strains for the first time in Turkey and provided epidemiologic data suggesting the evidence for the ongoing dissemination of CTX-M type ESBLs. Key words: CTX-M-14, extended-spectrum beta-lactamase (ESBL), Escherichia coli, pulsed-field gel electrophoresis (PFGE)

Frequency of extended spectrum beta lactamase producing enterobacteriaceae among urinary pathogen isolates.

To determine the frequency of extended-spectrum beta lactamase (ESBL) producing Enterobacteriaceae in urinary isolates. Observational study. Ziauddin University Hospital, Karachi, from February to October 2008. All members of Enterobacteriaceae isolated from urinary samples of in-patients were included and identified using standard biochemical tests. Urinary samples from out-patients were excluded. Detection of ESBL was carried out by double disk diffusion technique. Statistical analysis was performed by SPSS version 10. A total of 289 isolates of Enterobacteriaceae were identified during the study period. Of those 190/289 (65.7%) of the isolates were found to be ESBL producing. ESBL positivity within individual organism group was highest in Klebsiella species 84.16%, followed by Escherichia coli 68.55%, Enterobacter species 36.84%, and Proteus mirabilis 28.55%. Mean age of patients with ESBL producing organisms was 58.69 ± 18.97 years. ESBL production was almost similar in all age groups. A high frequency of ESBL producing organisms especially Klebsiella species and Escherichia coli amongst the hospital obtained urinary isolates was documented particularly in the older age group. The data points towards an urgent need for regular screening and surveillance for ESBL producing organisms in this region.

Investigation and analysis of nosocomial infection in neonates

To investigate the incidence of nosocomial infections of newborn infants in neonates and to explore the risk factors and strategies of infection control. There were 433 confirmed cases of nosocomial infection in the neonatal ward of the authors' hospital from January 2007 to December 2009. Their data of epidemiological and clinical characteristics, results of etiological examinations and antibiotic resistance were retrospectively analyzed. During the study, the number of hospitalizations were 6437. Nosocomial infection occurred in 433 patients 513 times. The overall nosocomial infection rate was 6.82%. The overall hospitalization days were 73 663 and nosocomial infection patient-day rates were 6.96‰. The VAP infection rate was 28.7‰. The CRBSI rate was 3.5‰. Gestational age (OR = 1.049), mechanical ventilation (OR = 1.810), umbilical vein catheter (OR = 1.106), hospitalization days (OR = 1.081), premature rupture of membrane (OR = 1.433) were the risk factors for the development of nosocomial infection. There were 197 (38.4%) cases of pneumonia, which was the most common nosocomial infection in Neonatal Ward. There were 129 cases of ventilator-associated pneumonia (VAP), which accounts for 65.5% of pneumonia and 24.4% of cases treated with ventilator. The next was sepsis, 124 cases (24.2%) and 64 cases of diarrheal disease (12.7%). One hundred and eighty two (54.4%) strains of isolates were Gram-negative bacteria, which accounted for the highest proportion. The predominant pathogens of Gram-negative bacteria were Klebsiella pneumoniae (19.6%), followed by Acinetobacter baumannii (8.1%), Pseudomonas aeruginosa (7.2%), Stenotrophomonas maltophilia (4.8%) and Escherichia coli (4.8%). The isolation rates of Klebsiella pneumoniae and Escherichia coli with positive extended-spectrum beta-lactamases (ESBLs) were 91.4% and 75%, respectively. Those two bacteria were universally resistant to cephalosporins. The rate of resistance to imipenem of Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa were 1.5%, 11.1% and 41.7%. The isolation rates of methicillin-resistant Staphylococcus aureus and methicillin-resistant coagulase-negative Staphylococcus were 28.6% and 95.5%. It is important to identify the high risk factors for nosocomial infections in newborn infants. To shorten time for mechanical ventilation and hospitalization days, removal of the central venous catheter as early as possible would be conducive to reducing the morbidity of nosocomial infection. The main pathogens were Gram-negative bacteria. The multidrug resistance of Enterobacteriaceae and Non-fermenters is serious.

Frequency of extended spectrum beta-lactamase (ESBLs) producing Escherichia coli and Klebseilla pneumonia isolated from urine in an Iranian 1000-bed tertiary care hospital.

Betal-lactam antibiotics are the most frequently prescribed antibiotics. Emerging resistance to these antibiotics among gram-negative bacilli limited their utility. This study was done to determine the frequency of extended spectrum beta-lactmase (ESBLs) producing Escherichia coli and Klebsiella pneumoniae isolated from urine in Milad Hospital of Tehran. This study was done on 735 urine gram-negative bacilli isolates including 620 strains of E. coli and 115 strains of K. pneumoniae in microbiology laboratory of Milad Hospital in Tehran, Iran. ESBls resistance was detected in 132 (21%) of isolates of E. coli and 18 (12%) in those with K. pneumoniae. Of 150 patients which had positive ESBLs isolates, 104 were outpatients and 46 others were hospitalized. Nearly 80% ESBls isolates were resistant to co-trimoxazole and nitrofuantion was the most effective antibiotic against ESBLs producing isolates. Our study revealed that there is a high frequency isolates of ESBls producing strains of E. coli and K. pneupmiae in both community and hospital. This has a significant implication for patients’ management. Further drug resistance surveillance in our hospitals and molecular characteristics of ESBls isolates in our country is necessary. Key words: Extended spectrum beta-lactamase (ESBLs), Escherichia coli,Klebseilla pneumonia, urinary tract.

Extended Spectrum Beta Lactamase Frequency In Cefhtazidime Resistant Pseudomonas Aeruginosa Strains

One of the resistance mechanisms of Pseudomonas aeruginosa, which is an increasing resistance problem to antibiotics, is beta lactamase production. Especially it becomes more and more difficult to apply a treatment to the infections developed by extended spectrum beta lactamase (ESBL) producing strains. It is of importance for the success of the treatment that ESBL is determined in P. aeruginosa and reported to the clinician. In recent years, some ESBL types such as PER-1 in class A and OXA group in class have been determined in P. aeruginosa. These enzymes hydrolyze third generation cefhalosporins and some of them hydrolyze especially cefhtazidimes. In the study, ESBL existence was researched in ceftazidime-resistant (n:50) and cefhtazidim-sensitive (n:20) 70 P. aeruginosa strains with double disc synergy test. ESBL existence was determined in 35 (50%) of the strains. ESBL positivity was reported in cefhtazidime-resistant strains, but not in cephtazidime-sensitive ones. ESBL should be remembered in P. aeruginosa infections not treated with other beta lactam antibiotics except for carbapenem and waste of costs and treatments should be avoided by researching ESBL existence with the help of routine antibiogram tests and double disc synergy method.

Investigation of the presence of extended spectrum beta-lactamases (ESBL) in multiresistant strains of E. Coli and salmonella species originated from domestic animals

Bacterial strains which possess genes to produce ESBL most often are multiresistant and also carry genes responsible for the resistance to most other antibiotics, including aminoglycosides, sulfamethoxazole+trimethoprim and fluoroquinolones. Therefore, practically the biggest contemporary clinical problem are infections of humans and animals caused by ESBL-producing strains of E. coli, Kleibsiella, Enterobacter, Proteus, Serratia, Citrobacter, Salmonella and Shigella species. The investigation of the ESBL presence was completed on multiresistant E. coli and Salmonella strains originating from dogs, cats, cattle, sheep, goats, pigs and poultry. The investigated strains were isolated from ear, skin, vaginal, faecal, urine, egg and eggshell swabs, from healthy and diseased individual animals of various ages and breed categories. The sum of 112 E. coli and 45 Salmonella strains was investigated. All strains resistant to 3 or more antibiotics were categorized as multiresistant, which led to a conclusion that 35 E. coli and 6 Salmonella strains out of all investigated were multiresistant to antibiotics. The largest number of multiresistant E. coli strains was discovered in cattle - 12 in total, and the minimal number in goats and sheep, with two strains each. All multiresistant Salmonella strains belonged to the Salmonella Enteritidis species (S. enterica subsp. enterica serovar Enteritidis). The sum of multiresistant Salmonella strains compared to all investigated strains was relatively low (13.3%), but the resistance prevalence for some antibiotics in these strains was extremely high, for ampicillin and amoxicillin with clavulanic acid as high as 100%, and for tetracycline 83.3%. For the control in this investigation were used ESBL positive E. coli strains originated in human urine specimens. No presence of positive ESBL strains was established. However, when the screening investigation was performed, almost all the strains were suspect, thus a confirmatory test had to be performed for all strains.

Plasmid-mediated, carbapenem-hydrolysing beta-lactamase, KPC-2, in Klebsiella pneumoniae isolates.

Four isolates of Klebsiella pneumoniae obtained from patients at a Maryland medical centre exhibited reduced susceptibility to carbapenems and were found to produce the novel, class A, plasmid-mediated, carbapenem-hydrolysing enzyme, KPC-2. This enzyme has 99% identity with the plasmid-mediated, carbapenem-hydrolysing enzyme KPC-1, reported previously in a North Carolina K. pneumoniae isolate. The KPC-2-producing isolates were either susceptible or intermediate to imipenem and meropenem, unlike the KPC-1-producing isolate, which was resistant to these agents. Detection of KPC-2 may be a problem for clinical laboratories because in this study it was associated with positive extended-spectrum beta-lactamase (ESBL) confirmation tests (clavulanate-potentiated activities of ceftriaxone, ceftazidime, cefepime and aztreonam). Therefore, a failure to recognize the significance of reduced carbapenem susceptibility in the isolates that remained susceptible to imipenem or meropenem could have resulted in the isolates being incorrectly identified as ESBL producers.

Antimicrobial Resistance Surveillance of Gram-Negative Bacteria Isolated from Intensive Care Units of Four Different Hospitals in Turkey

Background: The aim of this study was to determine the antimicrobial resistance of gram-negative rods (GNRs) isolated from surgical intensive care units and to establish the prevalence of extended-spectrum beta-lactamases (ESBLs) and inducible beta-lactamases (IBLs). We also wished to determine the widespread beta-lactam substrate in ESBL-positive GNRs by two different E-test strips and to discuss the value of the routine utilization of these substrates together. Methods: Out of 348 nosocomial gram-negative strains isolated with similar methods, 236 strains with resistance to the beta-lactam group of antimicrobials using the E-test method were included in this study. Two different strips were used for the detection of ESBLs: cefotaxime/cefotaxime + clavulanic acid (CT/CTL) and ceftazidime/ceftazidime + clavulanic acid (TZ/TZL). For IBLs, the double-disk method was used. Results: The order of frequency of the strains, starting with the most frequent, was Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. In the 236 strains, the ESBL positivity rate was found to be 19.5% with TZ/TZL and CT/CTL strips, while it was 13.2% for IBL in 348 strains. Seventy-one percent of ESBL-positive strains gave parallel results with TZ/TZL and CT/CTL. ESBL positivity with only TZ/TZL or only CT/CTL was found to be 18 and 8%. Conclusions: Our study showed that except for imipenem, amikacin and ciprofloxacin, there was a high resistance to other antimicrobials, and multiresistance rates were increased in the strains in which ESBLs and IBLs were detected. In particular, the increasing prevalence of ESBLs in K. pneumoniae and IBLs in P. aeruginosa emphasizes the importance of the problem of infection control and antibiotic administration policies. Although it was seen that the prevalence of substrate templates in the detection of ESBL positivity was similar, we think that it is more useful to use two different strips together to obtain precise results.

Detection and Typing of Extended-Spectrum β-Lactamases in Clinical Isolates of the Family Enterobacteriaceae in a Medical Center in Turkey

To determine and type the extended-spectrum beta-lactamases (ESBLs) among the family Enterobacteriaceae in a medical center, a total of 668 clinical isolates were screened. Of the 668 isolates, the 80 strains were presumptively defined as ESBL producers according to the result of disk method using ESBL marker antibiotics (aztreonam, ceftazidime, and cefoxitin). These 80 strains were retested with the double-disk synergy test (DDST), the E-test ESBL strip, a 5-microg ceftazidime disk, and agar dilution MICs of ceftazidime with and without clavulonic acid. Isoelectric focusing was performed to confirm ESBL production and type the beta-lactamases. By evaluation of the results of all tests used for ESBL detection together with isoelectric focusing, 33 (4.9%) of the 668 isolates were described as ESBL producer. The positive results of the agar dilution test, DDST, the E-test strip, and 5-microg ceftazidime disk were 32, 26, 27, and 26 of the 33 strains, respectively. ESBL positivity was 48.8% in Klebsiella species, 15.4% in Citrobacter species, 4.9% in Enterobacter species and 1.1% in Escherichia coli strains. The ESBL enzymes frequently determined were SHV-2/6-like (pI 7.6), SHV-5-like (pI 8.2), SHV-4-like (pI 7.8), and SHV-3-like (pI 7). SHV-derived enzymes were commonly observed in Klebsiella spp whereas TEM-related enzymes were seen in E. coli strains. The results of this study indicated that SHV-2/6-derived (pI 7.6) ESBL expression among the isolates of the family Enterobacteriaceae is an important problem in our medical center.