Presence Of Extended-spectrum Beta-lactamase Research Articles

Acinetobacter baumannii clonal lineages I and II harboring different carbapenem-hydrolyzing-β-lactamase genes are widespread among hospitalized burn patients in Tehran.

The aim of this study was to analyze antimicrobial resistance patterns and their encoding genes and genotypic diversity of Acinetobacter baumannii isolated from burn patients in Tehran, Iran. The presence of extended-spectrum beta-lactamase- and blaOXA-encoding genes among 37 multidrug resistant (MDR) A. baumannii strains isolated from patients hospitalized in a teaching hospital in Tehran was evaluated. Susceptibility to 7 antibiotics was tested by disk agar diffusion and to polymyxin B and colistin was tested by E-test, according to CLSI guidelines. All isolates were then analyzed by PCR for the presence of blaIMP, blaVIM, blaSIMblaOXA-23, blaOXA-24, and blaOXA-58-like carbapenemase genes, and blaOXA-51-like, blaTEM, blaSHV, blaPER, blaVEB, and blaGIM genes. Genotyping of A. baumannii strains was performed by repetitive sequence-based (REP)-PCR and cluster analysis of REP-PCR profiles. A. baumannii isolates were assigned to international clones by multiplex PCR sequence group analysis. Twenty-five A. baumannii isolates were classified as MDR, and 12 were classified as extensively drug resistant. All isolates were susceptible to colistin and polymyxin B. Eighty-one percent of the isolates was resistant to imipenem or meropenem and harbored at least one or both of the blaOXA-23-like or blaOXA-24-like carbapenemase genes. Co-existence of different resistance genes was found among carbapenem-resistant isolates. Multiplex PCR sequence group analysis most commonly assigned A. baumannii isolates to international clones I (18/37; 48.6%) and II (18/37; 48.6%). An alarming increase in resistance to carbapenems and the spread of blaOXA-23-like and/or blaOXA-24-like carbapenemase genes was observed among A. baumannii strains belonging to clonal lineages I and II, isolated from burn patients in Tehran.

Improved detection of extended spectrum beta-lactamase (ESBL)-producing Escherichia coli in input and output samples of German biogas plants by a selective pre-enrichment procedure.

The presence of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli was investigated in input (manure from livestock husbandry) and output samples of six German biogas plants in 2012 (one sampling per biogas plant) and two German biogas plants investigated in an annual cycle four times in 2013/2014. ESBL-producing Escherichia coli were cultured by direct plating on CHROMagar ESBL from input samples in the range of 100 to 104 colony forming units (CFU) per g dry weight but not from output sample. This initially indicated a complete elimination of ESBL-producing E. coli by the biogas plant process. Detected non target bacteria were assigned to the genera Acinetobacter, Pseudomonas, Bordetella, Achromobacter, Castellaniella, and Ochrobactrum. A selective pre-enrichment procedure increased the detection efficiency of ESBL-producing E. coli in input samples and enabled the detection in five of eight analyzed output samples. In total 119 ESBL-producing E. coli were isolated from input and 46 from output samples. Most of the E. coli isolates carried CTX-M-type and/or TEM-type beta lactamases (94%), few SHV-type beta lactamase (6%). Sixty-four bla CTX-M genes were characterized more detailed and assigned mainly to CTX-M-groups 1 (85%) and 9 (13%), and one to group 2. Phylogenetic grouping of 80 E. coli isolates showed that most were assigned to group A (71%) and B1 (27%), only one to group D (2%). Genomic fingerprinting and multilocus sequence typing (MLST) showed a high clonal diversity with 41 BOX-types and 19 ST-types. The two most common ST-types were ST410 and ST1210. Antimicrobial susceptibility testing of 46 selected ESBL-producing E. coli revealed that several isolates were additionally resistant to other veterinary relevant antibiotics and some grew on CHROMagar STEC but shiga-like toxine (SLT) genes were not detected. Resistance to carbapenems was not detected. In summary the study showed for the first time the presence of ESBL-producing E. coli in output samples of German biogas plants.

Houseflies (Musca domestica) as Vectors for Extended-Spectrum β-Lactamase-Producing Escherichia coli on Spanish Broiler Farms.

Flies may act as potential vectors for the spread of resistant bacteria to different environments. This study was intended to evaluate the presence of Escherichia coli strains resistant to cephalosporins in flies captured in the areas surrounding five broiler farms. Phenotypic and molecular characterization of the resistant population was performed by different methods: MIC determination, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and phylotyping. The presence of extended-spectrum beta-lactamase (ESBL) genes, their plasmid location, and the mobile genetic elements involved in their mobilization were studied. Additionally, the presence of 35 genes associated with virulence was evaluated. Out of 682 flies captured, 42 yielded ESBL-producing E. coli. Of these isolates, 23 contained bla(CTX-M-1), 18 contained bla(CTX-M-14), and 1 contained bla(CTX-M-9). ESBL genes were associated mainly with the presence of the IncI1 and IncFIB replicons. Additionally, all the strains were multiresistant, and five of them also harbored qnrS. Identical PFGE profiles were found for E. coli isolates obtained from flies at different sampling times, indicating a persistence of the same clones in the farm environment over months. According to their virulence genes, 81% of the isolates were considered avian-pathogenic E. coli (APEC) and 29% were considered extraintestinal pathogenic E. coli (ExPEC). The entrance of flies into broiler houses constitutes a considerable risk for colonization of broilers with multidrug-resistant E. coli. ESBLs in flies reflect the contamination status of the farm environment. Additionally, this study demonstrates the potential contribution of flies to the dissemination of virulence and resistance genes into different ecological niches.

Detection of Extended Spectrum Beta Lactamase (ESBL) Producing Klebsiella pneumoniae Associated with Tuberculosis Suspected Patients in Basra Governorate, South of Iraq

Objective: To investigate extended spectrum β- lactamase (ESBL) producing Klebsiella pneumoniae isolated from sputum of tuberculosis suspected patients in Basra governorate. Methods: A total of 28 (30.4 %) isolates of K. pneumoniae were recovered from 92 sputum clinical specimens at Pulmonary and Respiratory Diseases Center (PRDC) in Basra Governorate, Iraq. All these isolates were tested for ESBL production by using chromogenic media. Results: Of 28 isolates of K. pneumoniae, 6 (21.4%) were positive for ESBL production. Conclusion: This finding demonstrates a high percentage of ESBL producers among clinical isolates of K. pneumoniae. Presence of ESBL producing K. pneumoniae associated with TB patient gives a high risk factor to patients.

TEM mediated extended spectrum cephalosporin resistance in clinical & environmental isolates of Gram negative bacilli: A report from northeast India

TEM mediated extended spectrum cephalosporin resistance in clinical & environmental isolates of Gram negative bacilli: A report from northeast India

Risk factors of organ failure in cholangitis with bacteriobilia.

To identify the risk factors for organ failure (OF) in cholangitis with bacteriobilia. This study included 182 patients with acute cholangitis who underwent percutaneous transhepatic biliary drainage between January 2005 and April 2013. We conducted a retrospective analysis of comprehensive clinical and laboratory data. There were 24 cases (13.2%) of OF and five deaths (2.7%). Bile culture was positive for microbial growth in 130 out of 138 (94.2%) patients. In multivariate analysis of 130 patients with positive bile cultures, significant predictive factors for OF were the presence of extended-spectrum beta-lactamase (ESBL) organisms in blood cultures, pre-existing renal dysfunction, and choledocholithiasis as an etiology, with odds ratios of 15.376, 6.319, and 3.573, respectively. We developed a scoring system with a regression coefficient of each significant variable. The OF score was calculated using the following equation: (2.7 × ESBL organisms in blood cultures) + (1.8 × pre-existing renal dysfunction) + (1.3 × choledocholithiasis). This scoring system for predicting OF was highly specific (99.1%) and had a positive predictive value of 86.2%. ESBL organisms in blood cultures, pre-existing renal dysfunction, and choledocholithiasis are risk factors for OF in cholangitis with bacteriobilia. The OF scoring system may aid clinicians to identify a poor prognosis group.

Prevalence of blaCTX-M gene in multi-resistant Escherichia coli isolated from Urinary Tract Infections, Tehran, Iran

Background: The emergence and increase in the incidence of Extended-spectrum beta lactamase (ESBL) producing Escherichia coli (E. coli) has become an emerging challenge especially in hospitalized patients with urinary tract infection (UTI). The aim of the present study was to survey the frequency of bla CTX-M genotype in ESBL producing E. coli isolated from hospitalized patients with urinary tract infection and determination of their antibiotic resistance pattern. Materials and Methods: A total of 135 E. coli isolates were collected and isolated from patients with UTI. The isolates were subjected to confirmatory phenotype tests for the presence of ESBL. 75 E. coli isolates were confirmed as ESBL-positive by double disc synergy test. In vitro susceptibility of ESBL isolates to 15 antimicrobial agents amoxicillin, penicillin, ceftazidime, cefotaxime, cefoxitin, ceftriaxone, cefixime, cephalexin, co-trimoxazole, gentamicin, nalidixic acid, ciprofloxacin, nitrofurantoin, amikacin, and imipenem was performed by Kirby-Bauer’s Disk diffusion method according to Clinical and Laboratory Standards Institute (CLSI, 2012) guideline. PCR method was used to identify bla CTX-M gene in 75 ESBL positive strains. Results: PCR and sequence analysis showed that 75 (55.5%) isolates produced bla CTX-M genes. In vitro susceptibility of ESBL producing E. coli showed that all of them were resistant to amoxicillin and penicillin. The rates of resistance to the majority of tested antibiotics varied among 61% to 100 %, with the exception of amikacin (14.7%) and imipenem (2.7%). Our results showed that the frequency of bla CTX-M was strikingly high (93.3%) in patients with UTI. Conclusion: These data confirmed that the frequency of bla CTX-M genes was high among E. coli isolated from patients with UTI. The trend of multidrug-resistant profile has been associated with bla CTX-M gene is alarming. Therefore, it is very important to establish a routine screening of ESBL in clinical isolates to prevent dissemination of resistant isolates in health care settings.

Molecular characterisation of Escherichia coli from dead broiler chickens with signs of colibacillosis and ready-to-market chicken meat in the West Bank

1. The aim of this work was to compare a group of virulence-associated characteristics of Escherichia coli isolates from broiler chickens that had died with signs of colibacillosis against E. coli isolates from ready-to-market chicken meat in the West Bank.2. The isolates were investigated to determine the virulence factor (VF) profile, phylogenetic group and the presence of extended-spectrum beta-lactamase (ESBL). A total of 66 avian pathogenic E. coli (APEC) strains from different affected broiler farms and 21 E. coli isolates from ready-to-market chicken carcasses (hereinafter called meat strains) from 8 slaughter houses were analysed.3. The overall content of VFs was significantly higher (P < 0.05) among APEC strains, with over 75% of APEC strains having ≥4 VFs, while over 75% of the meat strains had <4 VFs. The VFs iss, astA and iucD were frequently detected in APEC and meat strains, whereas cvi, papC, vat, tsh and irp2 occurred more significantly in APEC strains. Phylogenetic typing showed that 67% of the meat strains belonged to group B2. Phylogroup D was predominant (50%) in the APEC strains. Using double disc diffusion and polymerase chain reaction (PCR), 10.6% of the APEC and 9.5% of the meat strains were determined to be ESBL positive.4. Our findings show that the VFs papC, vat, irp2 and to a lesser extent tsh and cvi are significantly more prevalent in APEC strains. The results demonstrate that chicken meat can be contaminated with APEC strains (≥4 VF). A significant percentage of the meat strains fall in the B2 group, which is a phylogroup largely associated with human pathogenic ExPEC strains. The results of ESBL screening indicated that broiler chicken products in Palestine represent a potential reservoir of ESBL genes and therefore could be considered a possible public health risk.

Adequacy of antimicrobial therapy in urinary tract infections (UTI).

Urinary tract infections are one of the most common reasons for antimicrobial prescriptions, however urine cultures are often unavailable and the choice of antibiotics is therefore empiric. The ideal antimicrobial agent must have specific pharmacokinetic and pharmacodynamic characteristics and an adequate spectrum of activity in order to obtain the potential eradication of the pathogen from the site of infection, minimizing the risk of recurrences and ensuring the best safety profile. There are several factors to be considered in the therapy choice: the type of infection, the increasing presence of extended-spectrum beta-lactamase (ESBL) producing bacteria showing resistance to most antibiotics and the problem of the bacterial internalization, that is a frequent cause of treatment failure and early recurrences. Prulifloxacin is a recent oral fluoroquinolone antibiotic approved in several European countries for the treatment of lower urinary tract infections and shows some interesting advantages in comparison with other antibiotics.

Abattoirs as non-hospital source of extended spectrum beta lactamase producers: confirmed by the double disc synergy test and characterized by matrix-assisted laser desorption/ionization time of flight mass spectrometry.

In this study, the presence of extended spectrum beta lactamase (ESBL) producing organisms in abattoirs, a non-hospital community was investigated. The presence of ESBL-producing phenotypes was confirmed by the Double Disc Synergy Test (DDST). Out of the 99 isolates screened for ESBL, 28 (28.3%) were confirmed positive. The positive isolates were characterised by using Matrix-Assisted Laser Desorption/Ionization Time of flight Mass Spectrometry. 50% of the isolates were Pseudomonas spp., the rest were different species of Acinetobacter, Stenotrophomonas and Achromobacter. Pseudomonas monteilli and Pseudomonas putida were the most occurring in the intestine. The entire positive ESBL producers were subjected to plasmid curing to ascertain the location of the resistant marker. The result of the plasmid curing indicated that the resistant genes were chromosomally borne. The findings have therefore established the presence of ESBL producing organisms in the gut of animals from abattoirs and the table were the meat are sold, and its rate of occurrence is comparable to hospital ICUs. Abattoir communities could probably be a source of human infection with ESBL expressing pathogens and possible transfer to non-ESBL producers.

Necessity of detection of extended spectrum beta-lactamase, AmpC and metallo-beta-lactamases in Gram-negative bacteria isolated from clinical specimens

Background: With increasing incidence of resistance to antibiotics carbapenems are used as the last resort because they are stable even in response to extended spectrum and AmpC beta-lactamases. However, Gram-negative bacilli producing the acquired metallo-beta-lactamases (MBL) are on the rise. Aim: The aim of the following study is to detect phenotypically the presence of extended spectrum beta-lactamase (ESBL), AmpC and MBL in Gram-negative bacteria isolated from clinical specimen. Materials and Methods: Gram-negative isolates from clinical samples were screened and confirmed for the presence of ESBLs by double disk synergy test (DDST), for AmpC by disk approximation assay and for MBL by Modified Hodge Test and imipenem-ethylenediaminetetraacetic acid DDST. Results: Among 251 isolates studied, 138 (54.98%) were ESBL producers, 49 (19.52%) were AmpC producers and 45 (17.93%) were MBL producers. Highest rates of ESBL detection was by Cefoperazone sulbactam (109/138) 78.98%. Out of 92 of the AmpC producing strains 20 (21.73%) were inducible and 72 were stably derepressed (78.26%). Out of 251 strains studied 45 (17.93%) were phenotypically identified as MBL producers, the highest no. being of Pseudomonas aeruginosa. Among the methods employed for detection of MBL production, Hodge test (62.22%) proved better than DDST (40%). Conclusions: High level of antibiotic resistance pattern exists in various clinical isolates. ESBL production should be looked for routinely in Gram-negative bacteria other than Escherichia coli and Klebsiella. A high percentage of derepressed AmpC mutants are noteworthy and alarming. We recommend phenotypic identification methods as routine practice in laboratories as genotypic methods are not cost-effective.

Extended-spectrum beta-lactamase-positive Escherichia coli causing complicated upper urinary tract infection: Urologist should act in time.

Objective:Recently, many articles reported increased incidence of urinary tract infection (UTI) due to Extended-Spectrum Beta-Lactamase (ESBL)-producing E. coli. No data are available to date regarding patients presenting with complicated upper ESBL-positive E. coli UTI and sepsis. We report the clinical presentation, management, and outcomes in seven cases.Materials and Methods:This prospective study was carried out between January 2008 and September 2011. Follow-ups varied in patients according to their disease presentation and clinical outcomes. All strains were cultured and identified by the Clinical Microbiology Laboratory and were recovered from blood and urine cultures. In-vitro presence of ESBL was confirmed with Clinical and Laboratory Standard Institute double disc method.Results:In the study period, 49 patients needed hospitalization for upper UTI. Overall, in 25 patients (51%), cultures were negative. In the remaining, seven patients (14.3%) presented positive blood and urine-culture for ESBL + E. coli. Of these, four were female and three were male. Their median age was 73 years (range 66-84). The median hospital stay of these patients was 23 days (range 13 to 45 days).Conclusions:The current situation of multiple bacterial antibiotic resistance has become a worrisome issue in UTI. Multi-drug-resistant E. coli can be readily encountered in hospital settings during daily clinical practice, and urologist should act timely. The management of such infections is extremely important for the future, with particular reference to prevention of new antibiotic resistance patterns.

The resistance rates of urinary tract infections: Our data from year 2010.

More than 95% of all urinary tract infections are caused by a single bacterium. Although E. coli is the most common bacterium causing community-acquired infections, Klebsiella spp., enteric gram-negative bacteria and S. saprophyticus have been also identified. This study evaluated the microorganisms isolated from the urine cultures of patients admitted to our outpatient clinics in 2010 and assessed E. coli resistance and the frequency of extended-spectrum beta lactamase (ESBL)-producing bacteria. In total, 7145 urine cultures were obtained from patients admitted to all clinics between 1 January 2010 and 31 December 2010. The double-disk synergy test was used to identify the presence of ESBL producers. The most frequently isolated microorganisms were E. coli (60.6%), Enterococcus spp. (10.3%), Klebsiella spp. (7.3%), Pseudomonas spp. (4.8%), and Streptococcus spp. (3.3%). E. coli strains were more resistant to ciprofloxacin (45.12%), trimethoprim-sulfamethoxazole (44.8%) and amoxicillin-clavulanate (31.6%), but they were less likely to be resistant to meropenem (0%), imipenem (0.2%), and amikacin (0.7%). The frequency of ESBL-producing E. coli strains was 14%. The choice of antibiotic treatment influences the overall success of treatment and the development of resistance, and it is also closely related to the cost of the treatment. As a result, there is a need to review the current treatment protocols. As resistance rates show regional differences, it is necessary to regularly examine regional resistance rates to determine the appropriate empiric antibiotic treatment and reduce costs.

346 Antimicrobial resistant bacteria in pig farmers in the Netherlands − a study on ESBLs

ObjectivesFarm animals may serve as a reservoir for (multi)resistant bacteria, such as extended-spectrum beta-lactamase (ESBL) producing Enterobacteriaceae. Animal to man transmission may occur through (in)direct contact during work, which may...

Improvement of modified charcoal-cefoperazone-deoxycholate agar by addition of potassium clavulanate for detecting Campylobacter spp. in chicken carcass rinse

The presence of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (E. coli) in raw poultry is one of the most common factors that interfere with the isolation of Campylobacter by cefoperazone-based selective agar. The performance of modified charcoal-cefoperazone-deoxycholate agar (mCCDA) was improved by addition of an ESBL inhibitor, potassium clavulanate (0.5mg/L). The ability of the supplemented medium (C-mCCDA) to detect Campylobacter species from chicken carcass rinse was compared with that of normal mCCDA. The isolation rate using C-mCCDA was significantly (p<0.05) higher compared with that using mCCDA (C-mCCDA, 67 out of 120; mCCDA, 38 out of 120). Furthermore, the selectivity of the C-mCCDA as assessed by comparing the number of contaminated plates (C-mCCDA, 44 out of 120; mCCDA, 110 out of 120) and growth index (C-mCCDA, 1.76; mCCDA, 2.79) of competing flora was also better (p<0.05) than that of mCCDA.

Commensal Enterobacteriaceae as reservoirs of extended-spectrum beta-lactamases, integrons, and sul genes in Portugal.

Bacteria colonizing the human intestine have a relevant role in the spread of antimicrobial resistance. We investigated the faecal carriage of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in healthy humans from Portugal and analyzed the distribution of sul genes and class 1 and 2 integrons. Faecal samples (n = 113) were recovered from healthy persons (North/Centre of Portugal, 2001–2004) and plated on MacConkey agar with and without ceftazidime (1 mg/L) or cefotaxime (1 mg/L). Isolates representing different morphotypes/plate and antibiotic susceptibility patterns (n = 201) were selected. Isolates resistant to sulfonamides and/or streptomycin, gentamicin, and trimethoprim were screened (PCR and sequencing) for sul genes (sul1, sul2, sul3) and class 1 and 2 integrons. Presence of ESBLs was inferred using the double disk synergy test (DDST) and further confirmed by PCR and sequencing. ESBL producers were selected for clonal analysis, plasmid characterization and conjugation assays by standard methods. ESBL-producing isolates were found in 1.8% (2/113) of samples, corresponding to Escherichia coli of phylogroups A (n = 1) and B1 (n = 1) carrying transferable blaCTX-M-14 and the new blaTEM-153, respectively. A 80kb IncK plasmid bearing blaCTX-M-14 was found, being highly related to that widely spread among CTX-M-14 producers of humans and animals from Portugal and other European countries. sul genes were found in 88% (22/25; sul2-60%, sul1-48%, sul3-4%) of the sulfonamide resistant isolates. Class 1 integrons were more frequently found than class 2 (7%, 14/201 vs. 3%, 6/201). Interestingly, gene cassette arrangements within these platforms were identical to those commonly observed among Enterobacteriaceae from Portuguese food-producing animals, although aadA13 is here firstly described in Morganella morganii. These results reinforce the relevance of human commensal flora as reservoir of clinically relevant antibiotic resistance genes including blaESBLs, and highly transferable genetic platforms as IncK epidemic plasmids.

Prevalence and antimicrobial susceptibility of extended-spectrum beta-lactamase producing urinary isolates of Escherichia coli in outpatients

In Gram-negative bacteria, the production of beta-lactamases is the most important mechanism of resistance to beta-lactam antibiotics. In the Banja Luka region, there were no extensive researches on the prevalence and antimicrobial resistance of the extended-spectrum beta-lactamase (ESBL) producing Escherichia coli (E. coli) isolates. The aim of the present study was to determine the presence of ESBL producing E. coli isolates as the cause of the urinary tract infections in outpatients, the distribution of these ESBL isolates according to age and gender of patients and their susceptibility to antimicrobials. Urine specimens obtained from outpatients were cultured on chromogenic CPS-ID3 media. All plates showing significant (> 10(5) cfu/ml) growth of E. coli in pure culture were further processed. Antimicrobial susceptibility testing was performed on VITEK TWO Compact using AST-GN27 cards for testing Gram negative bacteria and detection of ESBL producers. Out of 2,195 isolates, 177 (8.1%) were ESBL producers. Ninety-two isolates were obtained from female patients (5% of E. coli isolated from women) and 85 isolates from male patients (23% of E. coli isolated from men). High percentage of ESBL isolates was detected in the infant age group under one year (36.7%) and in the age group over 60 years (28.8%). All ESBL isolates were susceptible to imipenem and resistant to ampicillin, piperacillin, cefazolin, cefotaxime, ceftazidime and cefepime. There was a significant resistance to amikacin (79.1%), gentamicin (76.8%), amoxicillin/clavulanate (54.8%) and trimethoprim/sulphamethoxazole (45.8%). Resistance to nutrofurantoin was 13.6%. This study has demonstrated the presence of ESBL producing E. coli urinary isolates in outpatients, and their extensive susceptibility to imipenem and nitrofurantoin.

Detection of extended-spectrum beta-lactamase-producing Escherichia coli isolates in faecal samples of Iberian lynx

To characterize the diversity of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolates recovered within the faecal microbiota of Iberian lynx. The identification of other associated resistance genes and the analysis of clonal relationship were also focused in this study. From 2008 to 2010, 128 faecal samples of Iberian lynx (wild and captive animals) were collected. Eleven tested samples contained cefotaxime-resistant E. coli isolates (all belonging to captive animals) and 10 ESBL-producing isolates were showed. CTX-M-14 and SHV-12 ESBL-types were detected and seven different patterns were identified by pulsed-field gel electrophoresis analysis. The occurrence of unrelated multiresistant E. coli in faecal flora of captive specimens of Iberian lynx, including the presence of ESBLs, resistant genes in integrons and virulence determinants was showed in this study. The results obtained in this study highlight the environmental problem as future reintroductions of Iberian lynx could lead to a spread of resistant bacteria. Additionally, ESBL-producing bacteria can represent a health problem for this endangered species.

Prevalence of Plasmid-mediated Quinolone Resistance and Its Association with Extended-spectrum Beta-lactamase and AmpC Beta-lactamase in Enterobacteriaceae

BackgroundWe investigated the prevalence of plasmid-mediated quinolone resistance and its association with extended-spectrum beta-lactamase (ESBL) and AmpC beta-lactamase in Enterobacteriaceae.MethodsA total of 347 non-duplicated isolates of Enterobacteriaceae were collected between August and October 2006 from 2 hospitals. Qnr determinant screening was conducted using PCR amplification, and all positive results were confirmed by direct sequencing. Qnr-positive strains were determined on the basis of the presence of ESBL and AmpC beta-lactamase genes.ResultsThe qnr gene was detected in 47 of 347 clinical Enterobacteriaceae isolates. Among the 47 qnr-positive strains, Klebsiella pneumoniae (N=29) was the most common, followed by Escherichia coli (N=6), Enterobacter cloacae (N=6), Citrobacter freundii (N=5), and Enterobacter aerogenes (N=1). These isolates were identified as qnrA1 (N=6), 8 qnrB subtypes (N=40), and qnrS1 (N=1). At least 1 ESBL was detected in 38 of the 47 qnr-positive strains. Qnr-positive strains also showed high positive rates of ESBL or AmpC beta-lactamase, such as TEM, SHV, CTX-M, and DHA. DHA-1 was detected in 23 of 47 qnr-positive strains, and this was co-produced with 1 qnrA1 and 22 qnrB4. Strains harboring MIR-1T and CMY were also detected among the qnr-positive strains. Antimicrobial-resistance rates of qnr-positive strains to ciprofloxacin, levofloxacin, norfloxacin, nalidixic acid, and moxifloxacin were 51.1%, 46.8%, 46.8%, 74.5%, and 53.2%, respectively.ConclusionsThe qnr genes were highly prevalent in Enterobacteriaceae, primarily the qnrB subtypes. They were closely associated with EBSL and AmpC beta-lactamase.

Extended-Spectrum Beta-Lactamase Gene Sequences in Gram-Negative Saprophytes on Retail Organic and Nonorganic Spinach

A substantial proportion of infections caused by drug-resistant Gram-negative bacteria (GNB) in community and health care settings are recognized to be caused by evolutionarily related GNB strains. Their global spread has been suggested to occur due to human activities, such as food trade and travel. These multidrug-resistant GNB pathogens often harbor mobile drug resistance genes that are highly conserved in their sequences. Because they appear across different GNB species, these genes may have origins other than human pathogens. We hypothesized that saprophytes in common human food products may serve as a reservoir for such genes. Between July 2007 and April 2008, we examined 25 batches of prepackaged retail spinach for cultivatable GNB population structure by 16S rRNA gene sequencing and for antimicrobial drug susceptibility testing and the presence of extended-spectrum beta-lactamase (ESBL) genes. We found 20 recognized GNB species among 165 (71%) of 231 randomly selected colonies cultured from spinach. Twelve strains suspected to express ESBLs based on resistance to cefotaxime and ceftazidime were further examined for bla(CTX-M) and bla(TEM) genes. We found a 712-bp sequence in Pseudomonas teessidea that was 100% identical to positions 10 to 722 of an 876-bp bla(CTX-M-15) gene of an E. coli strain. Additionally, we identified newly recognized ESBL bla(RAHN-2) sequences from Rahnella aquatilis. These observations demonstrate that saprophytes in common fresh produce can harbor drug resistance genes that are also found in internationally circulating strains of GNB pathogens; such a source may thus serve as a reservoir for drug resistance genes that ultimately enter pathogens to affect human health.