Spectrum Β-lactamase Production Research Articles

Phenotypic and Genotypic Characterization of Extended Spectrum β-Lactamase-producing (ESBL) Salmonella species isolated from poultry and human in Egypt

This study was carried out in Alexandria Province for a period of 12 months from July 2022 to June 2023 for isolation and molecular identification of extended - spectrum β-Lactamase producing (ESBL) Salmonella isolated from human and poultry. A total of 125 cloacal swabs were collected by sterile swabs from 25 poultry farms (5 samples / farm) located in Behera province including broilers, layers, breeder chicken and ducks. In addition, 50 human stool samples have been obtained from diarrheal individuals. It was recorded that the overall rate of isolation of Salmonella from poultry after molecular detection of invA gene in biochemically identified Salmonella isolates was 10.4% and it was 8, 6, 20 and 25 % in flocks of broilers, layers, breeders and ducks, respectively. Also, serological identification of 13 Salmonella strains revealed the presence of S. Kentucky (9 isolates), S. Anatum (2 isolates) and S. Bloomsbury (2 isolates). Distribution of antibiogram pattern of Salmonella isolates obtained from poultry samples using β -lactam antibiotics revealed that the highest resistance rate was recorded in Ceftazimide (100%), followed by Cephalexin and Cefadroxil (92.31% for each) then Ceftriaxone and Imipeneme (84.62% for each) then Piperacillin and Cefotaxime (76.92 % for each) while the least resistance rate was recorded in using Amoxicillin + Clavulanate (69.23%) and ESBLs resistant genes were identified in Salmonella strains where CTX gene was detected in 9 isolates, AmpC gene was detected in 10 isolates and IMP gene was detected in 11 isolates. On the other hand, it was recorded that the overall rate of isolation of Salmonella from diarrheic human stools was 6% (3 isolates) after detection of invA gene and serological identification revealed the presence of S. Kentucky (2 isolates) and S. Bloomsbury (1 isolate). Distribution of antibiogram pattern of Salmonella isolates (n=3) obtained from human using β -lactam antibiotics revealed that the highest resistance rate was recorded in Ceftazimide and Piperacillin (100%), followed by Ticarcillin, Amoxicillin + Clavulanate, Piperacillin/Tazobactam, Ticarcillin/clavulinic acid and Cefotaxime (66.67%) while the least resistance rate was recorded in using Cefepime, Aztreonam, Imipenem, Meropenem and Cefoxitin and ESBLs resistant genes were identified in Salmonella strains where CTX, AmpC and IMP gene was detected in 2 isolates while they could not be detected in the remained isolate.

Phenotypic and genotypic characterization of Extended Spectrum β-lactamases producing Proteus mirabilis isolates.

Background: The Extended spectrum β-lactamases (ESBLs) production is one of the most essential mechanism of drug resistance in Proteus mirabilis (P. mirabilis). Objective: Phenotypic and genotypic detection of extended spectrum β -lactamases production in P. mirabilis and its antimicrobial resistance among clinical isolates. Methods: A total of Sixty P. mirabilis clinical isolates were tested for Extended spectrum β lactamase production by modified double disc synergy test (MDDST). Polymerase chain reaction (PCR) was done to detect Extended spectrum β-lactamases genes in the clinical isolates. Antimicrobial susceptibility testing was done by means of Kirby Bauer disc diffusion method. Results: Out of the 60 P. mirabilis clinical isolates, 17 isolates (28.33%) were ESBL producers by phenotypic test. Genotypically; ESBLs genes were detected and the most prevalent ESBL resistance gene was TEM (91.7%) followed by SHV (75%), CTX-2-59 (56.7%) and CtxM-15 (51.7%). Moderate level of resistance to ofloxacin, ciprofloxacin, amoxicillin/ clavulanic acid, cefotaxime and ceftazidime (60.0%, 58.3%, 45.0%, 41.7% and 40.0% respectively) was recorded. In addition, 73.33% of isolates were classified as multidrug resistant (MDR). Conclusion: Monitoring of Extended spectrum β-lactamase producing P. mirabilis is very important because of its high prevalence among urinary tract infections. Also; increasing awareness for clinicians and enhancing laboratories

Analysis of blood stream infections: Antimicrobial susceptibility and associated types of extended spectrum β-lactamases

Purpose: To investigate the antimicrobial susceptibility and extended spectrum β-lactamase (ESBL) production by clinical isolates of Escherichia coli (ESBL-EC) and Klebsiella species (ESBL-KP) associated with blood stream infections (BSIs).Methods: Bacteria isolation and identification were carried out using basic bacteriological and biochemical techniques. Antimicrobial susceptibility test was performed according to the guidelines of the Clinical Laboratory Standard Institute (CLSI). Vitek 2 Compact automated system was used toconfirm the identifications (ID) and antimicrobial susceptibility test (AST). The ESBL produced by E. coli and K. pneumoniae isolates were phenotypically characterised using Modified Double Disc Synergy Test (MDDST), as recommended by CLSI.Results: All (100 %) isolates were sensitive to imipenem and meropenem, while susceptibility to other antibiotics varied. ESBL genotypes, viz, blaTEM, blaSHV and blaCTX were encountered in the BSIs. For ESBL-EC, TEM, SHV and CTX producers accounted for 33, 16.67 and 58.3 %, respectively, while 75, 91.7 and 100 % of ESBL-KP were TEM, SHV and CTX producers, respectively. In ESBL-KP, 67 % coexisted with all three genotypes (blaTEM, blaSHV, and blaCTX, while 8.3 % of ESBL-EC coexisted with the three encoding genes (CTX, SHV and TEM).Conclusion: ESBL E. coli and K. pneumoniae associated with BSI have been identified as TEM, SHV and CXT producers, with more ESBL-KP coexisting with all three than ESBL-EC.
 Keywords: β-Lactamases, Genes, Klebsiella pneumoniae, Escherichia coli

Prevalence of antibiotic resistance and biofilm formation in Klebsiella pneumoniae carrying fimbrial genes in Egypt

Biofilm formation is closely related to the pathogenic processes of Klebsiella pneumoniae, which frequently causes infections that are difficult to treat with antimicrobial agents. The aim of this study was to evaluate biofilm formation ability among clinical Klebsiella pneumoniae isolates from Egypt, and to study its antibiotic resistance, extended spectrum β-lactamases (ESBLs) production and fimbrial genes occurrence. A total of 90 clinical Klebsiella pneumoniae isolates were collected from different sources. Antimicrobial susceptibility, phenotypic and genotypic detection of ESBLs and biofilm assay were determined. SEM was applied to confirm K. pneumoniae biofilm formation. PCR assay was performed to investigate the distribution of fimbrial, as well as β-lactamases genes which were further confirmed by DNA sequencing. The results reveal high prevalence of multidrug resistance (86.66%) and biofilm formation ability (51%) among Klebsiella pneumoniae isolates. Furthermore, ESBL producing Klebsiella pneumoniae isolates had a higher ability to form a biofilm compared to non-ESBL forming ones. The occurrence of blaCTX-M and blaTEM among ESBLs-biofilm producers demonstrated high predominance of isolates harboring blaCTX-M. The distribution of fimbrial (mrkD and fimH) among biofilm former isolates were 100% and 86.95% respectively. The present study revealed high prevalence of multi-drug resistance (MDR) among Klebsiella pneumoniae in Egypt, in addition to biofilm formation, and also conclude that ESBL producing Klebsiella pneumoniae isolates had a higher ability to form a biofilm in comparison with non-ESBL forming ones. In addition, our study strongly supports that type 3 fimbriae strongly promote biofilm formation in Klebsiella pneumoniae.

Resistance prevalence profile of Klebsiella pneumoniae in the Intensive Care Units of Al-Shatby Pediatric Hospital, Alexandria, Egypt

Klebsiella pneumoniae has been identified as an opportunistic pathogen associated with both community-acquired and nosocomial infections mainly among patients admitted to the Intensive care units (ICUs). Some resistant genes were transferred vertically or horizontally within many microbial communities, directly between bacteria through plasmids or integrin. Different techniques including; phenotypic and genetic ones were used to evaluate the presence of β-lactamases among the isolated strains of K. pneumoniae. This bacterial species is the most commonly isolated pathogen (95 isolates) from all the examined samples (51.35%). Current results revealed that 30 and 14 strains of K. pneumoniae are positive to Extended spectrum β-lactamase (ESBL) production, and AmpC β-lactamase producers, respectively. On the other hand, modified carbapenem inactivation and modified Hodge test (MHT) were used to assess the carbapenem resistant strains. It is observed that all the β-lactamase producers’ strains are also carbapenemase producers, whereas only nine strains (30%) are MHT positive. The Polymerase Chain Reaction (PCR) technique revealed that TEM, BETA, NDM and IPM genes are found on the bacterial plasmid (100%). However the presence of the β-lactamase genes on the bacterial DNA varied among the different strains. The presence of the resistance genes on the bacterial plasmid may signify the resistance acquired upon the previous exposure of this bacterium to the different antibiotics. The aims of the current work were to isolate K. pneumonia from Al-Shatby hospital ICUs, to determine the incidence of its β-lactamases, and to decide the frequency of acquisition of 12 different genes among ESBL K. pneumoniae isolates.

Fosfomycin : A Promising Therapeutic Option for Urinary Tract Infections in the Era of Antibiotic - Resistant Uropathogens

Background: The distressingly rising antibiotic resistance amongst uropathogens figures a foremost health challenge. The role of fosfomycin in eradicating such superbugs has been rampantly studied nowadays. Objectives: This study was designed to (1) investigate the in vitro susceptibility of Gram negative uropathogens to fosfomycin and (2) compare fosfomycin efficacy with other antibiotics commonly prescribed for treatment of urinary tract infections (UTIs). Methodology: A prospective cohort study was performed over a period of 12 months. Urine samples were collected from patients admitted to the Oncology Center of Mansoura University (OCMU), Egypt, and processed at the Microbiology Diagnostics and Infection Control Unit (MDICU), Faculty of Medicine, Mansoura University, Egypt. Antimicrobial susceptibility was determined by the Kirby-Bauer's disc diffusion method. The minimum inhibitory concentrations (MICs) of fosfomycin were evaluated by agar dilution (AD) method. Phenotypic confirmation of extended spectrum β-lactamase (ESBL) production was done by the double-disc synergy test (DDST). The modified Hodge test (MHT) was used as a screening method for carbapenemase-producing isolates. Results: A total of 171 Gram negative uropathogens were recovered. Fosfomycin was the most active antibiotic with an overall susceptibility of 92.4%. The MICs of fosfomycin ranged from 0.25 to ≥ 256 μg/mL. Amongst the ESBL-producing isolates, 87.5% were fosfomycin-sensitive, while 61.5% of the carbapenemase-producing uropathogens were susceptible. Conclusion: Fosfomycin has a feasible in vitro activity against Gram negative uropathogens, including ESBL- and carbapenemase-producing isolates. Thereby, fosfomycin could be a relevant therapeutic approach for UTIs caused by resistant strains. Nonetheless, future studies should be executed to explore the underlying mechanisms of fosfomycin resistance.

Detection of Extended Spectrum B-Lactamases Among Bacteria Isolated from Snacks Sold Within Kaduna State Metropolis Northwest Nigeria

Extended spectrumβ-lactamses (ESBL) are a group of plasmid mediated, diverse, complex, and rapidly evolving enzymes that are posing a major therapeutic challenge today in the treatment of hospitalized and community patients. Due to non-regulation of snacks, people are exposed to pathogenic bacteria. The aim of this study is to detect extended spectrum β-lactamases among bacteria isolates from snack foods sold in Kaduna metropolis Nigeria. A total of 144 samples comprising of meat-pie, doughnut, egg-roll, buns, samosa, burger and pizza were cultured on blood agar, McConkey agar and Cysteine Lactose Electrolyte Defficient Agar, for the presence of pathogenic bacteria. The isolated organisms were subjected to biochemical tests for identification using standard procedures. The isolates were screened for Extended Spectrum β-lactamase (ESBLs) production using the Clinical Laboratory Standard Institute (CLSI) break point using ceftriazone (30µg) and cefotaxime (30µg). Suspected ESBLs producing organisms from screening tests were subjected to double disc synergy test (DDST) for confirmation and standard discs of Augmentin (30µg). Out of the 144 snack samples analysed, 24 Gram negative entericbacteria were isolated and these includes: Citrobacter freundii 6(25%), Echerichia coli 1(4.2%), Enterobacter sp. 2(8.3%), Klebsiella pneumonia 7(29.2%), Proteus mirabilis 1(4.2%), Serratia marcenscens 4(16.7%), Morganella morganii 1(4.2%), providencia sp. 1(4.2%) and Shigella sp. 1(4.2%). Detection of ESBL among Gram-negative isolates based on CLSI revealed that 16(66.7%) of the isolates were ESBL producers while 37.5% were confirmed as ESBLs producers using Double Disc Synergy Test. Statistically, there was a significant relationship between the different beta-lactamases producing isolates (P<0.05). It also showed a significant relationship between the occurrences of beta-lactamase producing isolates among the different snacks (P<0.05) This study indicated that snack foods can be contaminated by ESBLs producing bacteria and may result to infections following consumption by humans which have public health implications for the general public.

Molecular identification and antimicrobial resistance analysis of a new hypervirulent variant of Klebsiella pneumoniae

Objective To investigate the infection case and drug resistance patterns of new hypervirulent (hypermucoviscous) clinical variant of Klebsiella pneumoniae(hvKP)strains, and the virulence and resistance mechanisms. Methods Retrospective study.Two hundred and ten Klebsiella pneumoniae isolates were collected in the First Affiliated Hospital of Nanchang University from January 2011 to December 2013, and 12 hvKP were identified. Multilocus sequence typing (MLST) and enterobacterial repetitive intergenic consensus (ERIC)-PCR were used to type the hvKP isolates. The extended spectrum β-lactamase and carbapenemase producing Klebsiella pneumoniae were screened by the double disc synergy test and the modified Hodge test, respectively. PCR and DNA sequencing were carried out to detect their resistance related genes, serotype and virulence genes. Hypermucoviscosity phenotype (HM) of all strains was determined by string test. Results HvKP were resistant to 15 antibiotics and the extended-spectrum beta-lactamase producing rate was 8/12. In addition, one strain was detected positive by the modified Hodge test. Among the 12 hvKP strains, five ERIC-MLST molecular types were identified, of which A/ST23 and B/ST263 were the most predominant types, accounting for 5/12 and 4/12, respectively. The results of PCR and DNA secquencing showed that 2 were positive for blaKPC-2 (2/12), 9 positive for qnrA1 (9/12), 6 positive for qnrB4 (6/12), 8 positive for qnrS1 (8/12), 6 positive for blaCTX-M-3 (6/12), 7 positive for blaCTX-M-14 (7/12), 10 positive for blaTEM-1 (10/12), and 4 positive for blaSHV-12 (4/12). Eleven hvKP strains were serotype K1, while only one strain was serotype K2. Serotype K3, K5, K20, K54 and K57 were not detected. The positive rate of virulence genes magA, rmpA and aerobactin were 11/12, 9/12 and 9/12, respectively. In addition, the positive rate of kfu, mrkD, wabG and allS were 9/12, 10/12, 4/12 and 2/12, respectively. The positive rate of HM was 8/12. Conclusions The resistance mechanism of hvKP strains was complex and diverse, in which strong toxicity serotype and multiple virulence genes exist, which need attention from clinic. Effective infection control measure should be conducted in order to control the outbreak of resistant hvKP strains. (Chin J Lab Med, 2015, 38: 392-396) Key words: Klebsiella pneumoniae; Virulence; Drug resistance, bacterial; Serotyping

Bloodstream infections and antimicrobial resistance patterns in a South African neonatal intensive care unit

Background:Bloodstream infections remain a leading cause of morbidity and mortality in neonatal intensive care units (NICU) worldwide. Commonly isolated NICU pathogens are increasingly resistant to standard antimicrobial treatment regimes.Objectives:The primary aim of this study was to determine the burden of bloodstream infections (BSI) in an NICU in a low-to-middle-income country and to describe the spectrum of pathogens isolated together with their drug susceptibility patterns.Methods:This retrospective, descriptive study included NICU patients admitted to the Tygerberg Children’s Hospital, Cape Town, between 1 January and 31 December 2008. All blood culture samples submitted to the reference laboratory were extracted and clinical data on patients were obtained by hospital record review.Results:There were 78 culture-confirmed episodes of BSI in 54/503 (11%) patients admitted; median gestational age was 31 weeks (IQR 29–37) and birth weight 1370 g (IQR 1040–2320). Common isolates included coagulase-negative Staphylococcus (22/78, 28%), Klebsiella spp. (17/78, 22%), Acinetobacter spp. (14/78, 18%), Candida spp. (9/78, 11·5%) and methicillin-resistant Staphylococcus aureus (5/78, 6%). There was a predominance of gram-negative organisms (38/78, 48·7%). All Staphylococcus aureus isolates were methicillin-resistant and 59% of Klebsiella pneumoniae isolates were extended spectrum β-lactamase (ESBL) producers. Acinetobacter baumanii isolates showed low susceptibility to the aminoglycosides, carbapenems and cephalosporins. Of 54 infants admitted to the NICU with BSI, 25 (46%) died; 9/25 deaths (36%) were attributable solely to infection.Conclusion:Compared with overall mortality in the NICU, that attributable solely or partly to BSI was high. Many bacterial BSI isolates were resistant to current empiric antibiotic regimens. Regular microbiological and clinical surveillance of BSI in NICUs is required to inform appropriate antibiotic protocols and monitor the impact of infection prevention strategies.

English

The rising rate of antimicrobial drug resistance in Enterobacteriaceae reduces the number of reliably effective drugs that can be used to treat infections. Gram negative bacteria producing β-lactamases that are resistant to many other antibiotics and very few antimi- crobial agents remain effective as treatment option. Since the initial description of Extended Spectrum β-lactamases (ESBLs) production by Klebseilla pneumonia & Escherichia coli in the 1980s, strains of Enterobacteriaceae resistant to third-generation cephalosporins are increasingly being recognized globally. ESBL-producing Enterobacteriaceae strains have been frequently implicated in outbreaks in all intensive care units especially pediatric Intensive Care Unit (PICUs) and Neonatal Intensive Care Unit (NICU). Therefore, there have been many recent calls to intensify current infection control efforts aimed at reducing the emergence and dissemination of infections caused by antibiotic-resistant bacteria. The widespread use of Cefriaxone and/or cefotaximine has been proposed as a reason for the emergence of CTX-M enzymes. The increased frequency of isolation & reporting of CTX-M ESBLs is alarming and is likely to represent only the tip of iceberg for the underdeveloped continents where molecular technology for the analysis of ESBL enzymes is scares. To further delineate the mode of successful dissemination of ESBLs CTX-M-15 and to gain insights into the mechanism underlying this phenomenon we de- signed this study to assesses clonality & diversity of Enterobacteriaceae strains isolated from PICUs and NICUs of our hospital. Total of 100 blood samples were received from PICU and NICU during the study period of two months. 10 ESBLs were isolated from total 55 Gram negative bacteria, of that five were possessing CTX-M-15 by PCR methods.

Determination of correlation between biofilm and extended spectrum β lactamases producers of Enterobacteriaceae

Background: Biofilm is a complex aggregate of microorganisms in which cells adhere to each other to a surface in a self-produced matrix of extra-cellular polymeric substance. Antibiotic resistance of bacteria in the biofilm mode of growth contributes to the chronicity of infections. Aims: This study was aimed to find out the prevalence of biofilm producers among the microorganisms isolated from our setup and to find out their antimicrobial susceptibility pattern with special reference to Extended Spectrum β-lactamase (ESBL) and AmpC producers. Settings and Design: It is a prospective, analytic study. Materials and Methods: The study included 169; non-repeat, clinical isolates of Enterobacteriaceae collected over a period of 6 months. All isolates were tested for biofilm production by tube adherence methods. Any bacterial species which showed resistance to any of third generation cephalosporin was tested for ESBL production and AmpC production. Statistical Analysis: Statistical analysis was carried out by taking percentage and simple ratios. Results: Among 169 isolates, 100 (59.2%) were biofilm producers. In our study, 44 (26%) and 43 (25%) isolates were ESBL and AmpC producers respectively. Of 44 ESBL producers, 42 (95.4%) and of 43 AmpC producers 39 (90.7%) were biofilm producers. Conclusions: Among 169 isolates, 26% and 25% were ESBL and AmpC producers. Of which, more than 90% were biofilm producers, which showed high resistance to commonly used antibiotics. Disabling biofilm resistance may enhance the ability of existing antibiotics to clear infections involving biofilms that are refractory to current treatments.

Bacteriological profile of cholectystitis and their implication in causing post-operative wound infections

Background: Cholecystitis is a common indication for major abdominal surgeries. It may occur with or without obstruction of common bile duct. Obstruction leads to secondary bacterial infection of bile. Bactibilia is an important predisposing factor for post-operative complications. Hence, this study was designed to determine the prevalence of bacteria in bile samples of cholecystitis patients and to correlate bactibilia and post-operative wound infection. Materials and Methods: Bile samples collected intra-operatively were subjected to gram stain, culture, and antibiotic sensitivity testing. The patients were followed-up for post-operative complications. If post-operative wound infection was found, cultures were done and correlated with bacteria isolated from bile samples. Results: Bactibilia was found in 27/50 (52%) of patients. Polymicrobial flora was found in 10% of bile samples. Escherichia coli, Klebsiella pneumoniae and Enterococcus faecalis were the predominant organisms isolated. None of the anaerobes were isolated. Extended spectrum β-lactamase and AmpC β-lactamase (AmpC) production was seen in 47% and 31.5% of Enterobacteriaceae isolates respectively. Post-operative wound infection was found in six (12%) patients who had bactibilia. Combination of piperacillin-tazobactam and amikacin was most effective in prophylactic regimen. Conclusion: The organisms responsible for bactibilia were found to cause post-operative infections in the same patient warranting the use of prophylactic antibiotics in every patient undergoing cholecystectomy. All patients undergoing open cholecystectomy should receive prophylactic antibiotics to prevent post-operative wound infections.

Urinary tract infections caused by extended spectrum -lactamase (ESBL) producing Escherichia coli and Klebsiella pneumoniae

Emerging antibiotic resistance due to extended spectrum β-lactamase (ESBL) production limited the use of β-lactam antibiotics against Escherichia coli andKlebsiella pneumoniae. This observational study was conducted at the Microbiologydepartment of the Children’s Hospital, Lahore Pakistan, from June, 2009 to November, 2010 to determine the frequency and antimicrobial resistance of ESBL producing E. coli and K. pneumoniae. A total of 13638 urine samples were processed for culture and antimicrobial sensitivity testing. E. coli and K. pneumoniaewere identified using API 20E. A double disk synergy test (DDST) was performed to determine ESBL production. ESBL production was detected in 312 (57.4%) E. coliand 386 (71.7%) K. pneumoniae. A multidrug resistance pattern was seen in ESBL producing E. coli and Klebsiella pneumoniae. ESBL producing E. coli showed maximum resistance to cefotaxime (100%), ceftazidime (99.4%) and cefuroxime (93.3%) while minimum resistance was seen with meropenem (1.3%), piperacillin/tazobactam (10.3%) and nitrofurantoin (27.6%). ESBL producing K. pneumoniae showed maximum resistance to ceftazidime (100%), cefotaxime (98.7%) and cefuroxime (98.1%) while minimum resistance was seen withmeropenem (3.6%), piperacillin/tazobactam (17.6%), and nitrofurantoin (28.5%). In ESBL producing bacteria, high prevalence of antibacterial resistance of non-β-lactam antibiotics is a serious matter of concern. Monitoring of ESBL production and antimicrobial susceptibility testing are necessary to avoid treatment failure in patients with urinary tract infection (UTI). Key words: Extended spectrum, beta-lactamases, urinary tract infections,Escherichia coli, Klebsiella pneumoniae.

Characterization and Molecular Epidemiology of Extended Spectrum Beta-Lactamase ProducingEnterobacter cloacaeIsolated from a Tunisian Hospital

In 2009, out of the 66 nonrepetitive Enterobacter cloacae collected at Charles Nicolle hospital in Tunisia, 44 were extended spectrum β-lactamase (ESBL) producers. The aim of the current study was to detect and characterize the genes encoding the ESBLs including blaTEM, blaSHV, and blaCTX-M groups by polymerase chain reaction and sequencing. Pulsed-field gel electrophoresis (PFGE) analysis was used to determine the genetic relatedness between isolates. All strains were susceptible to carbapenems. They were resistant to fluoroquinolones, gentamicin, tobramycin, and trimethoprim+sulfamethoxazole but variably resistant to netilmicin, amikacin, and tetracyclines. Sequence analysis of the polymerase chain reaction products revealed the presence of blaCTX-M-15 (39 strains), blaSHV-12 (6 strains), and blaSHV-27 (1 strain). The coexistence of two ESBLs was observed in two isolates harboring, respectively, SHV-12+CTX-M-15 and SHV-27+CTX-M-15. PFGE revealed 36 unrelated profiles. Diffusion of E. cloacae producing CTX-M-15 ESBL in our hospital is the consequence of dissemination of identical or related plasmids harboring the CTX-M-15 gene.

High Prevalence of Extended Spectrum Beta-Lactamase Production Among Klebsiella pneumoniae Strains Isolated at a University Hospital in Turkey

β-lactam susceptibility and β-lactamase patterns of a random sample of 44 Klebsiella pneumoniae strains that had been isolated from nosocomial infections at Dokuz Eyliil University Hospital in Izmir, were investigated. All strains were amoxycillin resistant but in the presence of clavulanic acid 26 became sensitive. Similarly 39 of the strains were resistant to ceftazidime and cefo-taxime; clavulanic acid restored sensitivity to ceftazidime in 28 and to cefo-taxime in 25 of these resistant strains. Extended spectrum β-lactamase (ESBL) production was positive in 84% of the isolates as determined by the double disk synergy test. Isoelectric focusing revealed that each strain produced one to four β-lactamases, pI 7.6 enzymes being the most prevalent. Other enzymes with pIs of 8.4, 8.2, 5.4, 7.8 were also detected. Resistance to ceftazidime was transferred from 18 of the 44 isolates to the recipient Escherichia coli K-12 at 37°C. The transconjugants were examined for their plasmid content and the plasmids were characterized by their size and resistance profile. Fourteen different restriction pattern groups were identified with Eco R1. The results indicate a high prevalence of ESBL production in nosocomial K. pneumoniae isolates in Izmir and have major implications concerning the clinical use of later generation cephalosporins.