Prevalence Of ESBL Research Articles

Neonatal Sepsis in a Tertiary Care Hospital in South India: Bacteriological Profile and Antibiotic Sensitivity Pattern

To identify the common bacterial pathogens associated with neonatal sepsis and their antibiotic susceptibility pattern. This prospective observational cohort study was done in a tertiary care teaching hospital located in South India for a period of 2years. All the admitted inborn and out born neonates during this study period were screened for sepsis based on the clinical features and septic screening. All infants satisfying the criteria for sepsis were subjected to blood culture. Growths, if any, were noted and standard antibiotic sensitivity testing was done by Kirby-Bauer disk diffusion method. The Chi-square test or Fisher's exact test was used to compare two groups. Out of the 120 clinically suspected and positive screening test cases of neonatal sepsis, 41.6% (50 of 120) were culture-proven cases of neonatal sepsis. Klebsiella pneumoniae was isolated from 66% of culture positive cases followed by Coagulase-negative staphylococci in 12% of cases. Klebsiella pneumoniae was resistant to most of the antibiotics tested except amikacin and meropenem. Of the total 33 Klebsiella pneumoniae isolates, 16 (32.0%) were ESBL producers. The prevalence of ESBL producing Klebsiella pneumoniae during two month outbreak and rest of the study period was 83.3% (15 of 18) and 20% (3 of 15) respectively (P value 0.0010). Klebsiella pneumoniae was the most common agent causing both early-onset and late-onset sepsis and significantly associated with sepsis in inborn babies. Amikacin should be used along with the third-generation cephalosporins for empirical treatment of gram-negative neonatal sepsis.

Resistance phenotype-genotype correlation and molecular epidemiology of Citrobacter, Enterobacter, Proteus, Providencia, Salmonella and Serratia that carry extended-spectrum β-lactamases with or without plasmid-mediated AmpC β-lactamase genes in Thailand

Extended-spectrum β-lactamases (ESBLs) and plasmid-mediated AmpC β-lactamases (pAmpCs) have been increasingly reported among less commonly encountered genera of Enterobacteriaceae. However, little is known regarding the genetic characteristics of resistance genes and epidemiology of these genera. Lack of accurate ESBL and pAmpC detection may adversely affect therapeutic outcomes. This study investigated resistance phenotype-genotype correlation and molecular epidemiology among six genera of Enterobacteriaceae ( Citrobacter, Enterobacter, Proteus, Providencia, Salmonella and Serratia) that carried ESBL with or without pAmpC genes at a university hospital in Thailand. From a total of 562 isolates, 105 isolates (18.7%) had ESBL-positive phenotype whilst 140 isolates (24.9%) harboured one or more ESBL genes. CTX-M and TEM were common ESBL-related bla genes among these isolates. The sensitivity and specificity of ESBL phenotypic detection as opposed to ESBL gene detection were 70.7% and 98.6%, respectively. pAmpC genes were detected in 96 ESBL gene-carrying isolates (68.6%) and significantly caused false negative detection of ESBL. Molecular typing based on pulsed-field gel electrophoresis revealed several clones that may be endemic in this hospital. This study indicated a high prevalence of ESBLs and pAmpCs among less common members of the family Enterobacteriaceae in Thailand and these resistant bacteria need to be monitored.

Faecal carriage of multidrug-resistant Gram-negative bacilli during a non-outbreak situation in a French university hospital

To determine the prevalence of multidrug-resistant (MDR) Gram-negative bacilli and extended spectrum β-lactamase (ESBL)-producing isolates in stool specimens obtained from patients hospitalized for acute diarrhoea in a French university hospital. Bacteria in stool specimens were screened for ESBL production on Drigalski agar supplemented with ceftazidime, ESBL CHROMagar(®) and CTX CHROMagar(®) media and confirmed by the double-disc synergy test. Genetic detection was performed by PCR and sequencing with bacterial DNA extracted from isolates. The presence of MDR bacteria was markedly high (96 of 303 patients, 31.7%). The majority of MDR bacteria were Enterobacter cloacae (44, 38%) and Escherichia coli (32, 28%). Moreover, the prevalence of ESBL and CTX-M producers among all included patients was 15.8% and 5.9%, respectively. The clone E. coli O25b : H4-ST131 was detected in 63% of CTX-M strains. Surprisingly, 16 carbapenemases (5.3% of patients) were isolated. The study revealed the wide dissemination of MDR bacteria, including carbapenemase producers, in a French hospital during a non-outbreak situation. Public health efforts to combat emergence and dissemination of MDR organisms need to be developed.

Prevalence of extended spectrum beta lactamases in Salmonella species isolated from patients with acute gastroenteritis

Extended-spectrum β-lactamases (ESBLs) continue to be a major problem world wide, conferring resistance to the expanded-spectrum cephalosporins. They are increasingly associated with genus Salmonella. This study aimed to determine the prevalence of ESBLs in Salmonella isolates in our region by phenotypic methods. One thousand stool samples of acute gastroenteritis patients were screened and 42 strains of Salmonella (19 S. typhimurium, 14 S. enteritidis, 5 S. typhi, 3 S. paratyphi B 3 and 1 S. infantis) were detected. In the 3rd generation cephalosporin resistant Salmonella stains, ESBL was detected by double disc synergy test in ten isolates and by phenotypic confirmatory test in eight isolates of Salmonella. Drug resistance to various antibiotics was noted both among ESBL producers and non-ESBL producers. Resistance to chloramphenicol, nalidixic acid, norfloxacin and ciprofloxacin was noted in ESBL producers (n=4, 3, 8 and 8 of eight cases respectively) and in non-ESBL producers (n=10, 9, 16 and 13 of 34 cases, respectively). Quinolone resistance was significantly higher in ESBL producers while imipenem and cotrimoxazole resistance was significantly higher in non-ESBL producers. ESBL positive Salmonella isolates were found to be sensitive to amikacin and amoxyclav. The proper and regular monitoring of drug resistance ESBL production among Salmonella strains were necessary for the effective therapeutic outcome.

High prevalence of blaCTX-M extended-spectrum β-lactamase genes in Escherichia coli isolates from pets and emergence of CTX-M-64 in China

As a cause of community-acquired infections, extended-spectrum β-lactamase (ESBL)-producing Escherichia coli constitute an emerging public-health concern. Few data on the molecular epidemiology of ESBL-producing E. coli isolates from pets are available in China. Detection and characterization of ESBL genes (blaCTX-M, blaSHV and blaTEM) was conducted among 240 E. coli isolates recovered from healthy and sick pets in South China from 2007 to 2008. The clonal relatedness of ESBL-producing E. coli isolates was assessed by pulsed field gel electrophoresis. ESBL-encoding genes were identified in 97 (40.4%) of the 240 isolates and 96 (40.0%) of them harbored CTX-M. The most common CTX-M types were CTX-M-14 (n = 45) and CTX-M-55 (n = 24). The recently reported CTX-M-64 was identified in three isolates. Isolates producing CTX-M-27, -15, -65, -24, -3 and -9 were also identified. Ten isolates carried two or three CTX-M types, with the combination of CTX-M-14 and CTX-M-55 being the most frequent (n = 6). ISEcp1 was identified in the upstream region of 93 out of the 107 blaCTX-M genes (86.9%). The sequence of the spacer region (45 bp) between ISEcp1 and the start codon of all blaCTX-M-55 genes (except four) was identical to that of blaCTX-M-64. No major clonal relatedness was observed among these CTX-M producers. It is suggested that the horizontal transfer of blaCTX-M genes, mediated by mobile elements, contributes to their dissemination among E. coli isolates from pets. Our finding of high prevalence of ESBL in E. coli of companion animal origin illustrates the importance of molecular surveillance in tracking CTX-M-producing E. coli strains in pets.

Antibiotic susceptibility of unselected uropathogenic Escherichia coli from female Dutch general practice patients: a comparison of two surveys with a 5 year interval

To optimize empirical treatment of urinary tract infections (UTIs), regular evaluation of the antibiotic susceptibility of the most common uropathogen, Escherichia coli, is necessary. We compared the antibiotic prescription rate for UTIs in women and the E. coli antibiotic susceptibility results, including the prevalence of extended-spectrum β-lactamase (ESBL)-producing strains, in 2009 with data collected 5 years earlier. Urinary samples from female patients with symptoms of uncomplicated UTI in 42 general practices were collected over a 6 month period. Uropathogens were identified and the antibiotic susceptibility of E. coli was determined. We analysed 970 urine cultures, of which 785 (81%) were considered positive (≥ 10(3) cfu/mL). E. coli accounted for 72% of the isolates. ESBLs showed an increase between the two surveys (0.1% versus 1%; P < 0.001), while no difference in antibiotic susceptibility to the commonly used antimicrobial agents for UTIs was observed. A significantly lower susceptibility rate to co-amoxiclav was observed in the eastern region of the Netherlands, as compared with the northern region (80% versus 92%; P < 0.05). Consistent with national guidelines, the prescription rate of trimethoprim decreased over time (19% versus 5%; P < 0.05) whereas nitrofurantoin and fosfomycin rates showed an increase (58% versus 66% and 0% versus 6% respectively, both P < 0.05). Over a 5 year period, the antibiotic susceptibility of uropathogenic E. coli did not change in female patients with uncomplicated UTI in the Netherlands, but ESBL prevalence increased. With respect to the prescription of antimicrobial agents, compliance with national UTI guidelines was good.

Nosocomial blood-stream infections from extended-spectrum-beta-lactamase-producing Escherichia coli and Klebsiella pneumonia from GB Pant Hospital, New Delhi

Nosocomial septicemia due to extended spectrum beta-(Beta)-lactamase (ESBL) producing Klebsiella pneumoniae and Escherichia coli are a therapeutic challenge due to resistance. Knowledge of disease burden and resistance patterns is required for proper and timely management. We report the prevalence and antimicrobial susceptibility of ESBL producing E. coli and K .pneumoniae from septicemia at a tertiary care hospital. A total of 2,870 blood samples of suspected cases of septicemia were studied between January and December 2009. Antimicrobial susceptibility was determined by Kirby Bauer's disc diffusion method and MICs for imipenem, meropenem, and ertapenem were determined using the E-test. All isolates of E. coli and K. pneumoniae were tested for ESBL production by E-test method. Forty-one (70.7%) K. pneumoniae isolates and ten (41.7%) E. coli isolates were ESBL producers. Two (5%) of ESBL producing K. pneumoniae isolates, but no E. coli isolates, were resistant to carbapenems. In vitro, all ESBL producers were sensitive to tigecycline. Our data indicated that the prevalence of ESBL-producing E. coli and K. pneumonia strains isolated from blood cultures from hospitalized patients is high. ESBL-producing organisms were found to be more susceptible to meropenem than to imipenem and ertapenem. Tigecycline is active against all the ESBL or multidrug resistant (MDR) E. coli and Klebsiella spp. isolates.

Studies on multidrug resistant Pseudomonas aeruginosa from pediatric population with special reference to extended spectrum beta lactamase

A total of 53 isolates of Pseudomonas aeruginosa were obtained from 250 clinical samples from pediatric populations in Chennai. The isolates were obtained from clinical specimens viz . the throat swab, ear swab and urine sample. The isolates of P. aeruginosa were subjected to antibiotic sensitivity test. Among various antibiotics tested, the strains showed highest resistance to ampicillin (85%), followed by amikacin (62.2%), norfloxacin (60.3%) and ciprofloxacin (50.9%). The data on ESBL production indicated overall production of 25% among MDR strains. MIC values for the antibiotics ranged from 3.9 μg/ml to 256µg/ml. These data suggest that the prevalence of ESBLs which are very important as these strains may often cause outbreaks in the pediatric population and causes increased morbidity and mortality in patients underlying diseases or limit therapeutic options due to the high degree of multidrug resistance.

Prevalence and types of extended-spectrum β-lactamases among urinary Escherichia coli and Klebsiella spp. in New Zealand

The aims of this survey were (i) to determine the prevalence of extended-spectrum β-lactamases (ESBLs) among urinary Escherichia coli and Klebsiella spp. in New Zealand (NZ), (ii) to identify the relative prevalence of ESBL types and (iii) to investigate clonality among ESBL-producing E. coli and Klebsiella spp. During a 4-week period in 2006, 86% of NZ hospital and community diagnostic microbiology laboratories participated in the survey and referred isolates to the national reference laboratory. A total of 86 ESBL-producing isolates were identified, comprising 55 E. coli and 31 Klebsiella spp. (all Klebsiella pneumoniae), equating to prevalence rates of 0.7% and 4.2%, respectively. The majority of the ESBL-producing E. coli (80.0%) and K. pneumoniae (58.6%) were reported to be from community-acquired urinary tract infections. CTX-M-15 and CTX-M-14 accounted for 75.9% and 13.3%, respectively, of the ESBL types identified. A novel ESBL, designated CTX-M-68, was identified. Most CTX-M-15-producing isolates were multiresistant to three or more antibiotic classes. Pulsed-field gel electrophoresis typing identified a wide diversity of strains among the ESBL-producing E. coli, whereas the K. pneumoniae were more clonal. The results of this survey show that the prevalence of ESBLs has increased in recent years in NZ, that CTX-M ESBLs are almost wholly dominant and that ESBL-producing organisms are already established as community-acquired pathogens.

Detection of VEB-1, OXA-10 and PER-1 genotypes in extended-spectrum β-lactamase-producing Pseudomonas aeruginosa strains isolated from burn patients

Resistance of Pseudomonas aeruginosa strains to the broad-spectrum cephalosporins may be mediated by the extended-spectrum β-lactamases (ESBLs). These enzymes are encoded by different genes located on either chromosomes or plasmids. This study aimed to investigate the prevalence of ESBLs and antimicrobial susceptibilities of P. aeruginosa isolated from burn patients in Tehran, Iran. Antimicrobial susceptibility of 170 isolates to cefpodoxime, aztreonam, ciprofloxacin, ofloxacin, ceftazidime, cefepime, imipenem, meropenem, cefotaxime, levofloxacin, piperacillin–tazobactam and ceftriaxone was determined by disc agar diffusion test. Polymerase chain reaction (PCR) amplification of the genes encoding OXA-10, PER-1 and VEB-1 was also performed. All isolates (100%) were resistant to ceftazidime, cefotaxime, cefepime and aztreonam. Imipenem and meropenem were the most effective anti-pseudomonal agents. The results revealed that 148 (87.05%) of the isolates were multidrug resistant and 67 (39.41%) of the isolates were ESBL positive. Fifty (74.62%), 33 (49.25%) and 21 (31.34%) strains among 67 ESBL-producing strains amplified bla OXA-10, bla PER-1 and bla VEB-1 respectively. In conclusion, the high prevalence of multidrug resistance (87.05%) and production of OXA-10, PER-1 and VEB-1 genes in P. aeruginosa isolates in burn patients confirm that protocols considering these issues should be considered in burn hospitals.

Detection of Extended Spectrum β-lactamase Production Among Uropathogens

Background:Detection of extended spectrum β-lactamase (ESBL) production among uropathogens is an important marker of endemicity.Aim:Intervention of this endemic transmission is important for the control of initial outbreak of ESBL producing organisms in a hospital or specialized unit of hospital.Materials and Methods:During the study period of one and a half months, 1,551 urine samples were processed for significant bacteriuria. Two hundred gram negative bacterial isolates were tested for ESBL production. Antimicrobial sensitivity pattern was ascertained for ESBL producing isolates.Results:ESBL production was seen in 36% of isolates. All the isolates were multidrug resistant with uniform sensitivity to imipenem.Conclusion:This study reveals the significant prevalence of ESBL producing organisms in this north Indian tertiary care hospital. Constant revision of antibiotic policies with infection control interventions is suggested.

In-Vitro Activity of Ertapenem Against Extended-Spectrum Beta Lactamase (ESBL) Producing Gram-Negative Bacilli (GNB) Seen in Indian Medical Centers

Background: ESBL producing GNB causing blood stream infections (BSI), skin and soft tissue (SSTI) and respiratory tract infection (RTI) are widely prevalent in Indian medical centers. We compared the in-vitro activity of five commonly used antimicrobials to treat such infections against the recently introduced carbapenem - ertapenem (ERT). Methods: From a collection of 776 clinically significant isolates prospectively collected (2005–2007) from seven medical centers, 238 GNB isolates (Escherichia coli [EC], = 122, Klebsiella spp. [KS], = 107 and Enterobacter spp. [ES] = 9) obtained from RTI (n = 75), BSI (n = 74), SSTI (n = 70) and urinary tract (n = 19) were tested. ESBL screen was performed by disc diffusion using cefotaxime (CTX) and ceftazidime (CZD), confirmed using CTX and CZD discs with and without clavulanic acid and Etest ESBL strips. Antimicrobial resistance to levofloxacin (LEV), amikacin (AMK), piperacillin/tazobactam (P/T), imipenem (IMP), meropenem (MER) and ERT was determined by agar dilution and Etest. Isolates were considered multi-drug resistant (MDR), if resistant to >2 classes. Polymerase Chain Reaction (PCR) was done to determine beta lactamases (bla)TEM, SHV and CTX-M among 120 isolates. Results: In this study, 221(93%) GNB were confirmed ESBL producers (range between centers, 74 to 99%) of which 94% were nosocomial in origin. ESBL in intensive care unit (ICU) and non-ICU patients was 86% and 98% respectively. Among ESBLs in ICU, 13.5% were community acquired. Resistance to LEV was 73.3% > P/T 27.3% and > AMK 12.3%. No resistance to IMP and MER seen. Overall 61% were MDR. Four KS (1.7%) isolates were resistant to ERT. PCR showed blaCTX-M in 73%, blaTEM in 56% and blaSHV in 38%. Multiple genes were present in 60%. Conclusion: Prevalence of ESBL among GNB causing infections continues to be high in Indian medical centers. ERT shows good activity equivalent to the tested Group 2 carbapenems and may be considered for treatment of such infections.

Survey of ESBL Producing Escherichia coli and Klebsiella pneumoniae and MRSA in a Tertiary Care Facility in United Arab Emirates

Introduction: There are no reports to date on prevalence of extended-spectrum ˇ-lactamase (ESBL) producing strains in the UAE. The aim of this study was to evaluate the prevalence of extended-spectrum ˇ-lactamase producing E. coli and K. pneumoniae and MRSA in UAE. Methods: Retrospective analysis of microbiology laboratory data between January 2005 and 30 November 2006 was carried out. ESBL production was confirmed by double disk diffusion approximation test or by the combined disk method. Isolates from the same patient in one month and the same site of isolation with the same antimicrobial susceptibility were considered as duplicates and eliminated. The values for the year 2005 and 2006 were compared. Statistical analysis was carried out by SPSS software. Results: In 2005, 7.3% (64/883) of total E.coli isolates and 7.3% (21/286) of K. pneumoniae isolates were ESBL producers. In 2006 this value significantly increased for E. coli to 11.2% (96/854), while K. pneumoniae remained unchanged at 7.3% (20/276). Inpatient isolates were significantly higher than in outpatients. ESBL production in E.coli for outpatients increased from 4.15%(27/650) in 2005 to 6.91%(42/608) in 2006 (P = 0.043). There was a trend towards increasing ESBL production among inpatients for K. pneumoniae (9.8 to 14.2%) and for E. coli (15.9 to 22%). The MRSA rates for the years 2005 and 2006 were 6.7% (41/616) and 7.0% (34/484) respectively. There was no significant change in MRSA prevalence in inpatients (9 Vs. 10.7%) or outpatients (4.4 Vs. 4.5%). Conclusions: This study shows that there is a relatively high prevalence of ESBL E. coli and K. pneumoniae in our institution which is comparable to that reported from other countries in this region. This is likely driven by the unrestricted use of antimicrobials particularly 3rd generation cephalosporins. Antimicrobial stewardship programs and good infection control practices are required to stem the increasing resistance.

High Prevalence of the aac(6′)-Ib-cr Gene and Its Dissemination among Enterobacteriaceae Isolates by CTX-M-15 Plasmids in Bulgaria

Since 1998, three mechanisms of plasmid-mediated quinolone resistance (PMQR) have been reported: Qnr-mediated topoisomerase protection (6), enzymatic modification of ciprofloxacin and norfloxacin by the aminoglycoside acetyltransferase AAC(6′)-Ib-cr (10), and active efflux due to QepA (8). PMQR genes confer low-level quinolone resistance and are frequently cotransmitted with extended-spectrum β-lactamase (ESBL) genes (9). We report the prevalence of aac(6′)-Ib-cr and its association with qnr genes in ESBL-producing Enterobacteriaceae isolates in a Bulgarian hospital. A total of 163 ESBL-producing enterobacteria (4.6% of 3,516 consecutive isolates) were recovered among 10 species at increasing overall prevalence rates between 2000 and 2005 (Table ​(Table1).1). These increases reflected the increasing rates of ESBL production in Escherichia coli (from 1.2% in 2000 to 10.0% in 2005), whereas similar rates of ∼7% in Klebsiella pneumoniae and the irregular appearance of ESBL production in other species have been observed during the study period. As shown in Table ​Table1,1, using primers 5′-ACTGAGCATGACCTTGCGATGC-3′ and 5′-TTAGGCATCACTGCGTGTTCG-3′, aac(6′)-Ib was detected in 99 (60.7%) of the ESBL producers distributed among nine species. Of these, 52 (52.5%) were found to carry the cr variant by sequencing, including 2 Citrobacter freundii isolates; one isolate each of Enterobacter aerogenes, Morganella morganii, and K. pneumoniae (all from 2005); and 47 E. coli isolates recovered since 2002, increasing from 0% to 67% during that period. For seven C. freundii isolates, including the two aac(6′)-Ib-cr-positive isolates, PCR for qnrA, qnrB, and qnrS (11, 12) yielded amplicons only for qnrB, identified as qnrB10 (GenBank accession number {type:entrez-nucleotide,attrs:{text:DQ631414,term_id:110226166,term_text:DQ631414}}DQ631414), qnrB13 (GenBank accession number {type:entrez-nucleotide,attrs:{text:EU273755,term_id:161579477,term_text:EU273755}}EU273755), and qnrB18 (GenBank accession number {type:entrez-nucleotide,attrs:{text:AM919399,term_id:161338643,term_text:AM919399}}AM919399) by using sequencing (1). The overall prevalence of qnrB (7/163; 4.3%) was sevenfold lower than that of aac(6′)-Ib-cr (52/163, 31.9%), and the coexpression of QnrB and AAC(6′)-Ib-cr occurred only in two (1.4% of all) isolates. TABLE 1. Distribution of aac(6′)-Ib-cr and qnrB genes among 163 ESBL-producing enterobacterial isolates at the National Oncology Center, Sofia, Bulgaria, from 2000 to 2005 and the respective ESBL prevalence rates The 52 aac(6′)-Ib-cr-positive isolates were characterized by antibiotic susceptibility testing and bla content determination as previously described (3, 13). Forty-three isolates were resistant to ciprofloxacin, 41 to gentamicin, and 25 to trimethoprim-sulfamethoxazole. All isolates were resistant to tobramycin and exhibited reduced susceptibility to amikacin, but worrisomely, 39 (75%) of the isolates were classified as amikacin susceptible according to CLSI breakpoints. Fifty isolates had both blaCTX-M-15 and blaOXA-1. Of these, 2 isolates also carried blaSHV-12 and 32 carried blaTEM-1. The remaining two aac(6′)-Ib-cr-positive isolates expressed ESBLs not of the TEM, SHV, CTX-M, VEB, PER, or GES type, associated with the TEM-1 enzyme. Thirty different XbaI-pulsed-field gel electrophoresis patterns were observed among the 47 E. coli isolates (data not shown). These findings suggest that the high prevalence of aac(6′)-Ib-cr was not solely due to the spread of a specific E. coli clone. Transferability of AAC(6′)-Ib-cr determinant in broth and on filters was examined using rifampin-resistant recipient E. coli ML4909 (F− galK2 galT22 hsdR metB1 relA supE44 Rifr) (4). Transconjugants were selected on bromothymol blue lactose agar containing rifampin (200 μg/ml) and kanamycin (25 μg/ml). Conjugative transfer of aac(6′)-Ib-cr was achieved for 42 of the 52 isolates, including one isolate each of K. pneumoniae and M. morganii, two C. freundii isolates, and 38 E. coli isolates. aac(6′)-Ib-cr was mostly cotransferred with blaCTX-M-15 and blaOXA-1, variably with blaTEM-1, but not with blaSHV-12 and qnrB. This is the first report of qnrB and aac(6′)-Ib-cr in clinical Enterobacteriaceae isolates from a Bulgarian hospital. The aac(6′)-Ib and its cr variant were highly prevalent in ESBL-producing E. coli. CTX-M-15 plasmid-mediated dissemination of aac(6′)-Ib-cr among Enterobacteriaceae isolates was particularly observed, as has been found in other countries (2, 5). In this work, qnrB had a low prevalence and was not cotransferred with the aac(6′)-Ib-cr gene. This result supports previous findings suggesting that aac(6′)-Ib-cr might already be widespread and substantially more prevalent than qnr genes (7, 10). Most of the isolates carrying the aac(6′)-Ib-cr variant were resistant to ciprofloxacin, probably reflecting its ability to promote higher-level quinolone resistance mutations (10).

PP-025 Prevalence of ESBL and AmpC producing strains among Gram-negative isolates at a teaching hospital in Nepal

PP-025 Prevalence of ESBL and AmpC producing strains among Gram-negative isolates at a teaching hospital in Nepal

Susceptibility patterns of bacterial isolates from hospitalised patients with respiratory tract infections (MOXIAKTIV Study)

The objective of this study was to determine: (i) the prevalence of resistance in current clinical isolates of Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, Moraxella catarrhalis and Klebsiella pneumoniae; (ii) the prevalence of production of extended-spectrum β-lactamases (ESBLs) and methicillin resistance in S. aureus; and (iii) regional differences in the prevalence of ESBL production and clonality of K. pneumoniae isolates. Pathogens causing respiratory tract infections in hospitalised patients were prospectively collected from all over Germany. Drugs tested by Etest included moxifloxacin, levofloxacin, amoxicillin/clavulanic acid, cefuroxime, clarithromycin and penicillin G. ESBL production by K. pneumoniae was determined using cefotaxime/ceftazidime ± clavulanic acid. Deutsches Institut für Normung (German Institute for Standardisation)/European Committee on Antimicrobial Susceptibility Testing (DIN/EUCAST) breakpoints were used where applicable. Overall, 1859 pathogens were analysed. For all species tested the fluoroquinolones achieved the highest overall susceptibility rate (92.8%) compared with clarithromycin (60.5%), amoxicillin/clavulanic acid (85.7%) and cefuroxime (89.6%). From 438 K. pneumoniae isolates, 13.0% produced an ESBL. The ESBL prevalence was 38.8% in Eastern Germany with a trend towards clonality in some centres, but ranged from 4.7% to 7.1% in Southern, Northern and Western Germany. Among the methicillin-susceptible S. aureus isolates, 10.1% were moxifloxacin- and levofloxacin-resistant. Of the S. pneumoniae isolates, 99.3% were moxifloxacin- and levofloxacin-susceptible, 93.9% were penicillin G-susceptible and 85.7% were clarithromycin-susceptible. With a MIC 90 value (minimal inhibitory concentration for 90% of the isolates) of 0.19 mg/L, moxifloxacin was more potent than levofloxacin (MIC 90 = 1 mg/L) against S. pneumoniae. Haemophilus influenzae and M. catarrhalis were almost 100% susceptible to the quinolones; 100% of the M. catarrhalis but only 4.5% of the H. influenzae strains were clarithromycin-susceptible. Moxifloxacin was the most active agent amongst the drugs tested, in particular against Gram-positive pathogens.

INCREASED PREVALENCE OF EXTENDED SPECTRUM βLACTAMASE PRODUCERS IN NEONATAL SEPTICAEMIC CASES AT A TERTIARY REFERRAL HOSPITAL

Emergence of extended spectrum βlactamases (ESBLs) producing strains of gram negative bacteria, as one of the leading cause of septicaemia often complicates the clinical and therapeutic outcome. The present study was undertaken to investigate the prevalence of ESBLs in bacteria isolated from neonatal septicaemic cases along with their antimicrobial sensitivity pattern. Blood samples were collected from 243 suspected cases of neonatal septicaemia. Apart from susceptibility testing, all the gram negative isolates were subjected to phenotypic tests for ESBL production. Amongst the positive test samples (n = 115), 84 were gram negative rods. ESBL was detected in 26 (32%) isolates. Results indicate that routine ESBL detection should be made imperative and empirical use of third generation cephalosporins must be discouraged.

Expanded-Spectrum β-Lactamase PER-1 in an Environmental Aeromonas media Isolate from Switzerland

Aeromonas spp. are environmental reservoirs of resistance determinants to different classes of antibiotic molecules (1, 3, 7). Intrinsic resistance to β-lactams among this genus may arise from the expression of chromosomal β-lactamases and/or efflux pumps (5). Acquired β-lactamases conferring resistance to narrow-spectrum β-lactams, such as OXA-type enzymes and the penicillinases TEM-1 and SHV-1, have been identified in that genus as well as in a single report of the extended-spectrum β-lactamase (ESBL) TEM-24 (2, 4). The aim of this study was to evaluate the prevalence of ESBLs among Aeromonas sp. strains recovered from several rivers, lakes, and activated sludges from the southern part of the Swiss Alps. Water samples were collected between 2002 and 2005 from the rivers Ticino and Vedeggio, from the lakes Cadagno and Lugano, and from activated sludges, all located in the Tessin county of Switzerland. The water samples were plated and growing bacteria identified by conventional biochemical methods (API-NE system; bioMerieux, Marcy-l'Etoile, France). All of the 50 Aeromonas sp. strains recovered were tested for ESBL detection by a synergy test using disks of ticarcillin-clavulanic acid, ceftazidime, cefotaxime, and aztreonam. The susceptibility testing of isolates was performed using Etest strips (AB Biodisk, Solna, Sweden). A single isolate, A72, recovered from an activated sludge located in Bioggio, displayed an ESBL phenotype. This isolate was resistant to most β-lactams, except cephamycins and carbapenems (Table ​(Table1).1). PCR amplifications performed as described previously (9), using primers specific for ESBL-encoding genes, followed by sequencing identified the blaPER-1 gene. Genotyping of isolate A72, according to the results of gyrB sequencing (10), identified Aeromonas media, a waterborne species known to cause diarrhea in humans (6). TABLE 1. MICs of antimicrobial agents for Aeromonas media A72, E. coli J53 harboring natural plasmid p72, and E. coli reference strain J53 A 70-kb plasmid (pAM) harboring the blaPER-1 gene was transferred by conjugation into the Escherichia coli J53 recipient strain, using a selection made of ceftazidime (10 μg/ml) and sodium azide (100 μg/ml). Transconjugant E. coli J53(pAM) showed an antimicrobial susceptibility pattern mirroring that of A. media A72 (Table ​(Table11). PCR mapping performed as described previously (9) identified the blaPER-1 gene as part of a Tn1213 composite transposon, as previously found (9). In addition, this Tn1213 structure was bracketed by the aphA6 and strA genes (encoding resistance to aminoglycosides) of transposon Tn5393d, as already observed in an Alcaligenes faecalis clinical isolate producing PER-1 recovered from Italy. In that latter isolate, the Tn5393d transposon was inserted into a Tn501 backbone carrying a mercury resistance transposon (8) that was not identified in A. media A72 by PCR mapping. Our study constitutes the first identification of an ESBL-producing environmental Aeromonas sp. strain. The occurrence of blaPER-1 on a conjugative and broad-host-range plasmid, inside a genetic context similar to that described for an A. faecalis clinical isolate recovered in a neighboring country, may indicate that Aeromonas spp. may act as vehicles for spreading such an antibiotic resistance determinant. These findings also strengthen the role of Aeromonas spp. as reservoirs or vectors of antimicrobial resistance determinants of clinical relevance, as recently exemplified by the identification of the plasmid-mediated quinolone resistance qnrS2 gene in Aeromonas punctata and A. media from the Seine River, Paris, France (1).

Extended-Spectrum β-Lactamase–Producing Enterobacteriaceae in Bulgarian Hospitals

The aim of the study was to describe the emergence, the spread, and the prevalence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in Bulgaria. Over eight years (1996-2003), 442 ESBL-screen-positive isolates were collected in nine medical institutions in four Bulgarian towns. Class A ESBLs of the SHV, TEM, and CTX-M groups were identified in seven species. SHV-type enzymes persisted during the whole study period, TEM-ESBLs appeared first in 1999, and CTX-M-types appeared first in 2001. The rate of CTX-M enzyme producers increased rapidly between 2001 and 2003, while the rate of SHV producers decreased. Six different ESBL-types were identified, namely, SHV-2, -5, and -12, CTX-M-3 and -15, and a new TEM-3-like variant (TEM-139). The most widespread enzymes were SHV-12, CTX-M-15, and CTX-M-3 found in seven centers. TEM-139 was identified mainly in one center. A trend for strains harboring more than one ESBL gene, for example, CTX-M + SHV, was observed since 2002. Plasmid fingerprinting and random amplified polymorphic DNA analysis typing revealed wide dissemination of identical plasmids among different bacterial species and hospitals, as well as clonal spread of ESBL producers. Our data contribute to clarify the dynamics in the prevalence of ESBLs in Bulgaria and demonstrate the importance of molecular procedures for their analysis.

High prevalence of CTX-M-15-producing Klebsiella pneumoniae among inpatients and outpatients with urinary tract infection in Southern India

Sir, The population of India of over one billion represents a potentially vast reservoir of antimicrobial resistance genes including those encoding extended-spectrum β-lactamases (ESBLs). Occurrence of ESBL-producing Enterobacteriaceae has been described in India mostly using phenotypic detection methods alone. The present study was conducted to identify the occurrence of ESBL genes in urinary isolates of Klebsiella pneumoniae collected in Southern India. The study was conducted at two hospitals, one in Gulbarga and the other in Raichur, between July 2005 and March 2006. The two cities are ~150 km away from each other and have populations of ~440 000 and 160 000, respectively. A total of 1288 non-duplicate urine specimens were collected from 642 inpatients and 646 outpatients. K. pneumoniae was identified by standard biochemical tests including citrate, urease, indole, Voges–Proskauer, glucose and inositol. As a result, K. pneumoniae was recovered from 270 of 1288 urinary specimens. Among them, 115 (43%) were from inpatients and 155 (57%) were from outpatients. ESBL production was confirmed in 260 (96%) isolates using the disc method defined by the CLSI (2007). All these isolates produced ≥5 mm increase in zone diameters with either cefotaxime or ceftazidime discs when clavulanic acid was added. They represented 95% and 97% of the inpatient and outpatient isolates, respectively. Of those, 255 isolates were resistant to cefotaxime and were assigned to phenotypic Group I, which was further classified into subgroups depending on susceptibility to ceftazidime and cefepime (Table 1). Another five isolates with resistance to ceftazidime but not to cefotaxime were assigned to phenotypic Group II. The remaining 10 non-ESBL-producing isolates susceptible to both cefotaxime and ceftazidime were assigned to phenotypic Group III. For non-β-lactam antimicrobials, 92% and 95% of the inpatient and outpatient isolates were resistant to ciprofloxacin, respectively. High rates of resistance to gentamicin (79% and 83% in inpatient and outpatient isolates, respectively) and amikacin (66% and 69% in inpatient and outpatient isolates, respectively) were also observed. Resistance to chloramphenicol, which is still commonly prescribed for infections caused by K. pneumoniae in India, was observed in 90% and 92% of the inpatient and outpatient isolates, respectively. All the study isolates were susceptible to ertapenem, except for one isolate which was intermediately resistant. No resistance to imipenem was identified. Table 1 Phenotypic and genotypic characteristics of the K. pneumoniae clinical isolates A total of 35 isolates from all phenotypic groups and subgroups were subjected to PFGE analysis using restriction enzyme XbaI (New England Biolabs, Ipswich, MA, USA) and CHEF III DR electrophoresis system (Bio-Rad, Hercules, CA, USA). Forty-five percent of the isolates in the phenotypic Group I that were examined by PFGE belonged to pulsotype A (Table ​(Table1).1). This pulsotype was commonly observed regardless of the source hospitals or the patient locations. The isolates in the phenotypic Group II belonged to pulsotype D. A total of 60 isolates from various pulsotypes were then subjected to PCR analysis for the detection of blaTEM, blaSHV and blaCTX-M, as described previously.1,2 All the isolates belonging to the phenotypic Group I yielded amplicons consistent with blaCTX-M. The gene was confirmed as blaCTX-M-15 in representative isolates by sequencing the entire open-reading frame using the following external primers: CTX-M-15-SF, 5′-CACACGTGGAATTTAGGGACT-3′ and CTX-M-15-SR, 5′-GCCGTCTAAGGCGATAAACA-3′. These results were consistent with the findings in a previous study reporting the predominance of blaCTX-M-15 in a small number of isolates from Southern India.3 Some of the Group I isolates were positive for blaTEM or blaSHV. The sequences of representative amplicons were consistent with blaTEM-1 and either blaSHV-1 or blaSHV-28, respectively, all of which are non-ESBL genes. All five isolates in Group II were positive for blaSHV-12, an ESBL gene, and negative for blaTEM or blaCTX-M. The prevalence of ESBL producers in this study was strikingly high, particularly given the fact that more than half of the isolates were obtained from outpatients. One of the reasons contributing to the high prevalence of ESBL may be the crowded hospital conditions precluding implementation of optimal hygiene practices. The epidemic in the community is then likely fuelled by unrestricted use of antimicrobials that may be purchased without prescription.4 A recent study reported that ESBL-producing Enterobacteriaceae, including K. pneumoniae, were responsible for community-onset infections in India.5 Dissemination of ESBL-producing K. pneumoniae in the community has a serious implication in the empirical management of complicated urinary tract infections caused by this organism, given their tendency for co-resistance to non-β-lactam classes of antimicrobials, as was observed in the present study. CTX-M-15 is known to be an ESBL that has peculiar association with community-onset Escherichia coli infections.6 It may therefore be speculated that CTX-M-15-producing E. coli is already established in the community in this area and that the responsible gene is being exchanged between E. coli and K. pneumoniae by means of conjugal transfer, both in the healthcare and in the community environments.