SHV-1 Beta-lactamase Research Articles

In Silico Study of the Potential of Brazilein Sappan Wood as a Beta-Lactamase Inhibitor against Extended-Spectrum Beta-Lactamase-Encoding Genes.

Infectious illnesses are a serious health concern in Indonesia. Widespread use of self-medication by the community increases the risk of developing multi-drug resistant (MDR) bacteria. This study assessed the potential of sappan wood as an inhibitor of extended-spectrum beta-lactamase (ESBL) encoded by blaSHV, blaTEM and blaCTX-M genes. In silico testing was conducted to develop an effective and economical starting strategy. Thereby, this study significantly advances the development of novel treatments to combat antibiotic resistance. Using clavulanic acid as the benchmark medicine, the potency of the beta-lactamase inhibitor brazilein was predicted. Using the Molegro Virtual Docker computer tool, docking was performed to estimate the chemical and physical properties of the compounds, as well as the biological activity of brazilein toward the required receptor. The receptors used were SHV-1 beta-lactamase, PDB code: 2H0T; TEM-1 beta-lactamase, PDB code: 4OQG and CTX-M-14 beta-lactamase, PDB code: 6VHS. Data analysis was performed by comparing the binding energies of the docking results between the ligands and the target receptor. The more stable the bond that formed between the ligand and the target receptor, the lower the bond energy. The in silico test results on the blaSHV gene were as follows: binding energy of ligand MA4_400[A] = -100.699, brazilein = -82.206, clavulanic acid = -79.3704; in the blaTEM gene: ligand bond energy 2UL_301[B] = -107.681, brazilein = -82.0296, clavulanic acid = -103.3; in the blaCTX-M gene: X57_301[A] ligand bond energy = -86.6197, and brazilein = -88.1586, clavulanic acid = -101.933. The findings of this study demonstrate the significant potential of brazilein sappan wood to block the beta-lactamase activity of blaCTX-M.

Identification of Phytochemicals with Inhibitory Potential Against Beta-lactamase Enzymes via Computer-aided Approach

IntroductionAntibacterial drugs have been widely used for the past century to treat diseases, but their efficacy has been limited by multi-resistant pathogens, particularly those that utilize beta-lactamase enzymes. The inhibition of beta-lactamase enzymes holds great promise for reducing the influence of such pathogens. ObjectiveThis study aims to evaluate the mechanism of inhibition of phytochemicals with antibacterial activity against two classes of beta-lactamases using computational methods. Methods: To achieve this objective, a total of thirty phytochemicals were docked against SHV-1 beta-lactamase and AmpC beta-lactamase after procurement from Protein Data Bank. The pharmacokinetics (ADMET) and density functional theory (DFT) analysis study were also conducted to unravel the nature of the top six most promising compounds on each protein. ResultsThe results showed that a significant percentage of the compounds had binding affinities greater than that of avibactam, the positive control. Quercetin-3-O-rutinoside showed the most promising results against SHV-1 beta-lactamase with an affinity of −9.4 kcal/mol, while luteolin was found to be the most promising candidate against AmpC beta-lactamase with an affinity of −8.5 kcal/mol. DFT analysis demonstrated the reactivity of these compounds, and the ADMET study indicated that they were relatively safe. ConclusionIn conclusion, the study's findings suggest that the selected compounds have significant potential to inhibit beta-lactamase and may be used in combination with antibiotics against organisms that produce beta-lactamase. This study provides a basis for further research in a wet-lab setting to validate the results.

Distribution of CTX-M, TEM, SHV Beta-lactamase Gene among the Klebsiella pneumoniae Clinical Isolates from Tertiary Care Centre in Palakkad, Kerala

Resistance against the routinely used antibiotics has reached a worrying level globally. Extended spectrum β-lactamases (ESBLs) production is the major mechanism of antimicrobial resistance. These ESBLs bacteria are resistance to penicillin, cephalosporins, monobactams. TEM1&2, CTX-M, SHV are the main ESBLs genes present in Klebsiella pneumoniae, which is produced by the alteration of amino acid in the active site. The aim of this study is to determine the prevalence of ESBL genes such as blaTEM 1&2, blaCTX-M and blaSHV. The present study was carried out from April 2019 to September 2019, a total of 121 K. pneumoniae isolates were collected and subjected to phenotypic study. Among these 19 isolated was ESBL positive, genes (blaSHV, blaTEM, blaCTX-M) were detected by conventional PCR method. blaTEM (100%) was the predominant gene detected flowed by CTX-M (68.42%) and SHV (57.89%). The highest level of antimicrobial resistance towards ampicillin (93.4%) followed by ceftriaxone (28.9%), cefotaxime (24.8%) and ciprofloxacin (22.3%). However, ESBL-producing isolates were showed resistance to ampicillin (100%) followed by ceftazidime (94.74%), cefotaxime (89.47%), amikacin and amoxicillin-clavulanic acid (68%). Antimicrobial resistance of bacteria is due to the genes, especially extended spectrum beta lactamase, which is widely found in members of Enterobacteriaceae. Nevertheless, there is a paucity of studies regarding the distribution of ESBL in K. pneumoniae in Palakkad Dist., Kerala. Hence the aim of the current study determines the distribution of ESBL genes in ESBL producing K. pneumoniae isolated from various clinical samples.

Molecular Identification of CTX-M and SHV Betalactamase Genes in Escherichia Coli Clinical Isolates in Isfahan

Molecular Identification of CTX-M and SHV Betalactamase Genes in Escherichia Coli Clinical Isolates in Isfahan

Corrigendum to “Investigation of TEM and SHV Beta-Lactamase Genes in Escherichia coli Isolated from Strawberry Samples in Sanandaj, Iran” [Journal of Food Quality and Hazards Control 8 (2021) 125-130

The article's abstract is not available.

Investigation of TEM and SHV Beta-Lactamase Genes in Escherichia coli Isolated from Strawberry Samples in Sanandaj, Iran

Background: When animal manures are used, food products may include pathogenic bacteria, especially Escherichia coli. The major aim of the current study was to investigate TEM (blaTEM) and SHV beta-lactamase (blaSHV) genes in E. coli isolated from strawberry samples in Sanandaj, Iran. Methods: In this study, 150 strawberry samples were collected from farms (traditional), greenhouses, and packages in Sanandaj, Iran. E. coli contamination was done using routine culture methods. Then, isolates were investigated for Extended-Spectrum Beta-Lactamase (ESBL) production and blaTEM or blaSHV genes using phenotypic and genotypic methods, respectively. Results: The most susceptibility and resistance of E. coli to antibiotics were related to chloramphenicol and trimethoprim/sulfamethoxazole, respectively. Out of 21 isolates of E. coli, eight were resistant to ceftazidime and cefotaxime; from which, six isolates were ESBL-producer. Furthermore, Polymerase Chain Reaction (PCR) analysis of six ESBL- producing E. coli isolates showed that four isolates included blaTEM gene, while no isolates included blaSHV gene. Conclusion: In this study, multiple antibiotic resistance patterns were seen in E. coli isolates, especially ESBL patterns in E. coli isolated from strawberries produced in Iran.

Phenotypic and molecular characterization of multidrug-resistant extended-spectrum beta-lactamase-producing Salmonella prevalent in raw chicken meat vended in Nigerian markets

Abstract In Nigeria, there is still a scarcity of data on the recovery of multidrug-resistant ESBL-producing Salmonella in chicken meat. Hence this study characterized the probable multidrug-resistant extended-spectrum beta-lactamase-producing Salmonella prevalent in chilled raw chicken meat vended in Nigerian markets. Detection of Salmonella was performed by meat rinse centrifugation-plating technique. Presumptive Salmonella colonies were identified by phenotypic and 16S rRNA gene sequencing. The confirmed Salmonella isolates were tested for multidrug resistance by the Kirby Bauer disc diffusion test. Detection and confirmation of extended-spectrum beta-lactamase (ESBL) phenotypes were performed by double disc synergy and combination disc tests. PCR and DNA sequencing of the ESBL-encoding genes (bla SHV, bla TEM, and bla CTX-M) were also performed. The conserved and three-dimensional (3D) domains in ESBLs were respectively characterized by the reverse position-specific BLAST (RPS-BLAST) and Cn3D modeling tool. Of the 229 presumptive Salmonella isolates examined, 52 isolates were confirmed as Salmonella species, 46 isolates were multidrug-resistant and 41 isolates confirmed as multidrug-resistant ESBL-producing Salmonella species. The main serotypes were Salmonella enterica subsp. enterica serovar Typhimurium (35/52; 67.31%) and Salmonella enterica subsp. enterica serovar Enteritidis (17/52; 32.69%). Overall, the prevalence of chilled raw chicken meat contaminated with Salmonella was estimated at 0.17 (40/240). This value of prevalence exceeded the limits (≤ 0.1) set by the Meat Industry Guide, United Kingdom. All CTX-M, TEM, and SHV beta-lactamases produced by the Salmonella isolates were confirmed by RPS-BLAST and Cn3D modeling tool as serine-based hydrolases that consisted of two 3D domains with unique ligands such as sodium ion, formic acid, and glycerol. This study showed that multidrug-resistant ESBL-producing Salmonella was widespread in raw chicken meat vended in Nigerian markets. Thus, there is a need for relevant regulatory agencies to enforce safety.

Isolation and molecular characterization of multidrug-resistant Escherichia coli from chicken meat

Antibiotic-resistant Escherichia coli (E. coli) are common in retail poultry products. In this study, we aimed to isolate and characterize multidrug resistant (MDR) E. coli in raw chicken meat samples collected from poultry shops in Sylhet division, Bangladesh, as well as to determine correlation between resistance phenotype and genotype. A total of 600 chicken meat swabs (divided equally between broiler and layer farms, n = 300 each) were collected and the isolates identified as E. coli (n = 381) were selected. Disc diffusion antimicrobial susceptibility assay showed resistance of these isolates to ampicillin, erythromycin, tetracycline, streptomycin, trimethoprim-sulfamethoxazole, chloramphenicol, and gentamicin. Polymerase chain reaction (PCR) identified several antibiotic resistance genes (ARGs) in our isolates. Among these ARGs, the prevalence of tetA (for tetracycline) was the highest (72.58%) in broiler chicken isolates, followed by sul1 (for sulfonamide; 44.16%), aadA1 (for streptomycin; 33.50%), ereA (for erythromycin; 27.41%), aac-3-IV (for gentamicin; 25.38%), and the two genes cmlA (24.87%) and catA1 (8.63%) for chloramphenicol. On the other hand, the respective prevalence in layer chicken isolates were 82.06%, 47.83%, 35.87%, 35.33%, 23.91%, 19.02%, and 5.43%. Furthermore, 49.23% of the isolates from broiler chicken were MDR, with the presence of multiple antibiotic resistance genes, including 3 (40.11%) and 4 (9.13%) genes. On the other hand, 51.09% of layer chicken E. coli isolates were MDR, with 3, 4 or 5 ARGs detected in 36.41%, 14.13%, and 0.54% of the isolates, respectively. We also found that 12.8% of broiler chicken E. coli isolates and 7.61% of layer chicken isolates carried genes coding for extended-spectrum SHV beta-lactamases. Lastly, we report the presence of the AmpC beta-lactamase producing gene (CITM) in 4.56% and 3.26% of broiler and layer chicken E. coli isolates, respectively. We found significant correlations between most of the antimicrobial resistant phenotypes and genotypes observed among the investigated E. coli isolates. Our findings highlight the need for the prudent use of antimicrobials in chickens to minimize the development of antibiotic-resistant bacterial strains.

Antibiotic Resistant Gene Exchanged Between Escherichia coli and Staphylococcus aureus

Escherichia coli infections are becoming difficult treated because of extensive resistance to antibiotic among these organisms and manufacturing extended-spectrum beta lactamases enzymes (ESBLs) make them resistant to beta-lactam antibiotics. This study aims to offer a summary of the main horizontal transmission apparatuses between E. coli as well as Staphylococcus aureus and emergence resistance to antibiotics. Fifty of the E. coli and 50 of S. aureus isolates were examined to obtain minimum inhibitory concentration (MIC) results. These isolates were then tested by conventional polymerase chain-reaction for the existence or absence the sulfhydryl variable SHV beta-lactamase genes. About (48%) of isolated E. coli , while (32%) of S. aureus were revealed SHV gene.

Occurrence of TEM, SHV and CTX-M β Lactamases in Clinical Isolates of Proteus Species in a Tertiary Care Center.

Extended spectrum beta lactamases (ESBL) are responsible for increased resistance to third generation cephalosporins. Proteus species is an important cause of both community acquired and nosocomial infections. The Proteus species is usually susceptible to beta lactam drugs but there is progressive increase in beta lactam resistance and recently, ESBLs are also fast spreading to this species. This study was conducted to study ESBL production and occurrence of TEM, SHV and CTX-M beta lactamases in clinical isolates of Proteus species in a tertiary care center. This prospective hospital based study was carried out in Microbiology, Kasturba Medical College, Mangalore over 9 months. All non-duplicate consecutive Proteus isolates were identified and antibiotic susceptibility testing was done. ESBL detection was done by double disk synergy method and TEM, SHV, CTX-M genes were detected by PCR. 84 Proteus isolates from urine (29), blood (1), respiratory secretions (2), tissue (20) and exudates (47) were included in the study. 20.2% (17) were ESBL positive by disk synergy method. CTX-M was present in 6, TEM in 2 and both in 9 isolates. SHV was not present in any isolate. Our findings showed that 20% of clinical isolates of Proteus species were ESBL producers. 52% of ESBL positive isolates carried both TEM and CTX-M genes followed by CTX-M alone (35%) and only 11% had TEM alone. This stresses on the fact that ESBL detection should be done routinely in Proteus isolates and the genotype surveyed periodically for better management.

Antibiotic resistance in Enterobacter cloacae strains with derepressed/partly derepressed/inducible AmpC and extendedspectrum beta-lactamases in Zenica-Doboj Canton, Bosnia and Herzegovina.

Aim To investigate the prevalence of derepressed/partly derepressed/inducible and ESBL/AmpC-producing Enterobacter cloacae isolates and treatment options for infections associated with those isolates. Methods Antibiotic susceptibility was determined by disc diffusion and broth microdilution according to CLSI guidelines. Doubledisk synergy test (DDST) was performed in order to screen for ESBLs and combined disk test with phenylboronic acid to detect AmpC β -lactamases. PCR was used to detect blaESBL/blacarb genes. Genetic relatedness of the strains was determined by pulsed-fieldgel-electrophoresis (PFGE). Results Among 14 isolates with the ESBL positive E. cloaceae producing isolates, four (28.6%), nine (64.3%) and one (7.1%) isolates were derepressed/partly derepressed and inducible AmpC producers. Eleven (out of 14) isolates were resistant to cefotaxime, ceftazidime, ceftriaxone, aminoglycosides and fluoroquinolones. All isolates were susceptible to imipenem and meropenem, 79% to cefepime. Five (out of 14; 35.7%) isolates (four derepressed and one inducible AmpC carrying E. cloaceae) were negative in phenotypic test for ESBLs, but positive for broad spectrum TEM-1 β-lactamase. One (out of four derepressed) also produced CMY-2 β-lactamase. Four (out of nine) partly derepressed isolates were positive with the DDST, but did not yield PCR products with primers targeting TEM, SHV and CTX-M beta-lactamases. Four positive partly derepressed isolates carried a blaCTX-M-1 gene, two blaOXA-1 one blaCTX-M-15, OXA-1 and one blaCTX-M-28, OXA-1 (n=1). Conclusion Microbiology laboratories must be able to detect and recognize AmpC-carrying isolates in a timely manner, especially those that are falsely susceptible in vitro to drugs that may be consideredfor therapy of infected patients.

Prevalence of TEM, SHV, and CTX-M Beta-Lactamase genes in the urinary isolates of a tertiary care hospital.

Introduction:Extended-spectrum beta-lactamases (ESBLs) are the major cause of resistance to beta-lactam antibiotics such as penicillins, cephalosporins, and monobactams. They are derived from the narrow-spectrum beta-lactamases (TEM-1, TEM-2, or SHV-1) by mutations that alter the amino acid configuration around the enzyme active site.Aim:To determine the prevalence of ESBL (blaTEM, blaCTX-M, and blaSHV) genes among the members of Enterobacteriaceae.Methodology:The present prospective study was carried out from January 2015 to June 2015 in the Department of Microbiology and Molecular Medicine of a Teaching Tertiary Care Hospital. A total of 526 urine samples were studied. Seventy-eight isolates were subjected to polymerase chain reaction for detection of ESBL genes.Results:In our study, ESBL genes were detected among 18 (45%) phenotypically confirmed ESBL producers and 20 (52.5%) phenotypically confirmed non-ESBL producers. The gene that predominated was blaTEM (48.7%), followed by blaCTX-M (7.6%) and blaSHV (5.1%).Conclusion:Definitive identification of ESBL genes is only possible by molecular detection methods. Phenotypic tests need to be evaluated periodically as their performance may change with the introduction of new enzymes.

PIN9 - Increasing prevalence of ctx-m, tem and shv beta-lactamases in clinical pathogenic e. Coli causes significant health and economic losses- a perspective from pakistan

PIN9 - Increasing prevalence of ctx-m, tem and shv beta-lactamases in clinical pathogenic e. Coli causes significant health and economic losses- a perspective from pakistan

Prevalence of CTX-M, TEM and SHV Beta-lactamases in Clinical Isolates of Escherichia Coli and Klebsiella Pneumoniae Isolated From Aleppo University Hospitals, Aleppo, Syria

Background: Extended spectrum β-lactamases (ESBLs) have emerged as a major threat worldwide, with limited treatment options available. Objectives: The present study aimed to estimate the prevalence, possible types of ESBL genes and antibiotic resistant patterns of ESBL-producing Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae). Materials and Methods: A total of 199 clinical isolates of E. coli and K. pneumoniae, collected between October 2010 to March 2012, at three University Hospitals in Aleppo city center, in north Syria, were examined phenotypically and genotypically for ESBL production. Results: The ESBLs were found in (62.89%) of E. coli and (67.5%) of K. pneumoniae isolates. The majority of the typeable isolates harbored two or more ESBL genes (73%). Overall, blaCTX-M-1 was the commonest genotype (81.74%). Resistances of ESBL isolates to other antibiotics were measured: tremithoprim/sulfamethoxazole (72%), nalidixic acid (72%), tetracycline (66%), gentamicin (54%) and ciprofloxacin (53%). Conclusions: Our study showed high ESBL incidence, with CTX-M genotype as the emerging strain in our hospitals. High co-resistance to other non-β-lactam antibiotics is a major challenge for the management of ESBL infections.

Investigation of beta-lactamase genes and clonal relationship among the extended-spectrum beta-lactamase producing nosocomial Escherichia coli isolates

Extended-spectrum beta-lactamase (ESBL) producing microorganisms currently cause a major problem. Among theseCTX-M beta-lactamase producing Escherichia coli has also disseminated worldwide as an important cause of both nosocomial and community-acquired infections. The aims of this study were to determine the prevalence of the beta-lactamase genes, antibiotic susceptibilities and clonal relationships of ESBL-producing nosocomial E.coli isolates. A total of 76 ESBL-producing E.coli strains isolated from urine (n= 26), blood (n= 25) and wound (n= 25) specimens of hospitalized patients identified as nosocomial infection agents according to the CDC criteria between June 2010-June 2011 were included in the study. Antibiotic susceptibilities of the isolates were detected by Kirby-Bauer disc diffusion method according to CLSI recommendations. ESBL production was tested by double disc diffusion method, and cefotaxime/cefotaxime-clavulanic acid E-test strips (AB Biodisk, Sweden) were used for indeterminate results. Presence of TEM, SHV, CTX-M, OXA-2 group, 0XA-10 group, PER, VEB and GES beta-lactamase genes were investigated by polymerase chain reaction (PCR) using specific primers. Pulsed-field gel electrophoresis (PFGE) method was used for the detection of clonal relationships among the strains. Most of the ESBL-producing E.coli strains were isolated from samples of inpatients in intensive care (35%), internal medicine (16%) and general surgery (13%) units. All of the 76 strains were found susceptible to imipenem, meropenem and amikacin; however all were resistant to cefotaxime and ceftriaxone. The susceptibility rates of the isolates to cefoxitin, ertapenem, cefoperazone/sulbactam, piperacillin-tazobactam, gentamicin, ciprofloxacin, cefepime, amoxicillin-clavulanic acid, aztreonam and ceftazidime were 96%, 83%, 63%, 61%, 50%, 41%, 25%, 21%, 20% and 18%, respectively. Among E.coli isolates, the frequency of CTX-M, TEM, OXA-2 group, PER, SHV and OXA-10 group beta-lactamase genes were found as 89.5%, 59.2%, 15.8%, 14.5%, 11.8% and 3.9%, respectively, while none of the isolates were positive for VEB and GES beta-lactamase genes. In 1 (1.3%) strain none of the investigated genes were detected. PCR analyses of the isolates revealed that 25 harbored CTX-M and TEM genes together, while 20 harbored only CTX-M and two harbored only TEM genes. Single SHV gene was not detected in any of the isolates. PFGE demonstrated no major clonal relationship between ESBL-producing isolates. This study indicated that CTX-M type enzymes were highly endemic among ESBL-producing nosocomial E.coli strains in our hospital, with the polyclonal spread of ESBL-producing bacteria without any dominant epidemic clone. In conclusion, it was considered that further studies are needed to explain the relationship between epidemic clones and plasmids with the use of plasmid analysis and multilocus sequence typing methods.

Environmental waters and blaNDM-1 in Belgrade, Serbia: Endemicity questioned

New Delhi metallo-beta-lactamase-1 (NDM-1) will soon become the most commonly isolated and distributed metallo-beta-lactamase worldwide due to its rapid international dissemination and its ability to be expressed by numerous Gram-negative pathogens. NDM-positive bacteria pose a significant public health threat in the Indian subcontinent and the Balkans, which have been designated as endemic regions. Our study was focused on urban rivers, a lake and springheads as a potential source of NDM-1-producing strains in Serbia, but also as a source of other metallo-beta-lactamases and extended-spectrum beta-lactamase (ESBL) producing bacteria. A total of 69 beta-lactam resistant isolates, belonging to 12 bacterial genera, were collected from 8 out of 10 different locations in Belgrade, of which the most were from a popular recreational site, Ada Ciganlija Lake. Phenotypic tests revealed 7 (10.14%) ESBL-producing isolates and 39 (56.52%) isolates resistant to imipenem, of which 32 were positive for metallo-beta-lactamase (MBL) production. PCR and sequencing revealed the presence of genetic determinants for SHV (3 isolates), DHA-1 (1 isolate) and CMY-2 (1 isolate) beta-lactamases. However, we did not detect any NDM-1-producing strains (previously described cases of NDM-1 from Serbia were limited to Belgrade), so we propose that Serbian NDM-1 is in fact a transplant and a nosocomial, rather than an environmental, issue and that Serbia is not an endemic region for NDM-1.

Detection of extended spectrum beta-lactamases-producing isolates and effect of AmpC overlapping

Few reports about the prevalence and genetic basis of extended spectrum beta-lactamases (ESBLs) are available from Saudi Arabia. We sought to determine the prevalence of ESBL-producing Enterobacteriaceae in a university hospital in eastern Saudi Arabia and to characterize the ESBLs produced by these isolates at the molecular level. All clinical isolates of Escherichia coli, Klebsiella spp., and Proteus spp. collected over two years were evaluated for susceptibility to a panel of antimicrobials and were analyzed for the ESBL phenotype using screening and confirmatory tests. ESBL-positive isolates were then screened for the presence of genes encoding CTX-M, SHV, and TEM beta-lactamases by PCR. The overall prevalence of ESBL-producing isolates was 4.8% (253/5256). Most isolates (80%) were from the inpatient department. The ESBL phenotype was more frequently detected in K. pneumonia. CTX-M genes were the most prevalent ESBL genes, detected in 82% of the studied isolates. The ESBL producers demonstrated a high multidrug resistance rate (96.6%). In transconjugation assay, the same ESBL gene pattern was transmitted from 29.7% of K. pneumoniae donors to the recipient strain, and the latter exhibited concomitant decreased aminoglycosides and co-trimoxazole susceptibility. We observed the presence of ESBL screen-positive but confirmatory-negative isolates (8.9%). Phenotypic tests for the production of AmpC β-lactamase tested positive in 52% of these isolates. Further studies are needed for appropriate detection of concomitant ESBL and AmpC enzyme production among such isolates. Continued surveillance and judicious antibiotic usage together with the implementation of efficient infection control measures are absolutely required.

Genetic characterisation of extended-spectrum β-lactamases in Escherichia coli isolated from retail chicken products including CTX-M-9 containing isolates: a food safety risk factor

1. Bacterial resistance to β-lactam antibiotics has risen dramatically in Escherichia coli from food animals. In a previous study, 29 randomly selected chicken products, collected in Portugal, were analysed for the presence of extended-spectrum β-lactamases (ESBLs)-producing E. coli; and during this study the genetic characterisation of ESBLs genes was investigated. 2. The presence of genes encoding TEM, OXA, SHV, and CTX-M type beta-lactamases was studied by PCR followed by sequencing. Additionally, other mechanisms of antimicrobial resistance, phylogenetic groups and the presence of virulence determinants were evaluated among the isolates. 3. β-lactamases genes were identified as follows: bla CTX-M-14 (n = 4), bla CTX-M-1 (n = 2), bla CTX-M-9 (n = 4) and bla TEM-52 (n = 13). Mutations at positions −42, −18, −1, and +58 of ampC promoter region were identified in 4 non-ESBL-producing isolates. The tet(A) or tet(B) genes were identified in all tetracycline-resistant isolates; the aadA gene detected in 8 of 10 streptomycin-resistant isolates; the aac(3)-II gene in all gentamicin-resistant isolates; the cmlA gene in the chloramphenicol-resistant isolate; and sul1 and/or sul2 and/or sul3 genes were found in all trimethoprim-sulfamethoxazole-resistant isolates. The intI1 gene was detected in 8 trimethoprim-sulfamethoxazole-resistant isolates and the intI2 gene in 4 isolates; one gene cassette arrangements were identified among class 1 integrons (dfrA1 + aadA1) and among the class 2 integrons (dfrA1 + sat2 + aadA1). Among cefotaxime-resistant isolates, 16 belonged to A or B1 phylogenetic groups, while 11 isolates were classified into the D or B2 phylogroups. At least one virulence-associated gene (aer, fimA, or papC) was detected in 74·1% of the cefotaxime-resistant isolates. 4. Because ESBLs-producing bacteria are resistant to a broad range of β-lactams, infections caused by these organisms complicate therapy and limit treatment options.

SHV beta-lactamase in Escherichia coli clinical isolates from urinary tract infection in Mashhad

SHV beta-lactamase in Escherichia coli clinical isolates from urinary tract infection in Mashhad

Gilthead Seabream (Sparus aurata) as Carriers of SHV-12 and TEM-52 Extended-Spectrum Beta-Lactamases-Containing Escherichia coli Isolates

In recent years, bacterial resistance to beta-lactam antibiotics has risen dramatically in Escherichia coli isolated from animals that could pass through the food chain to humans. One hundred eighteen fecal samples of Sparus aurata were tested for extended-spectrum beta-lactamase (ESBL)-containing E. coli recovery. Susceptibility to 16 antimicrobial agents was performed by disk diffusion. ESBL-phenotypic detection was carried out by double-disk test, and the presence of genes encoding TEM, OXA, SHV, and CTX-M type beta-lactamases was studied by polymerase chain reaction and sequencing. The detection of other antimicrobial resistance mechanisms and phylogenetic groups was also performed in recovered isolates as well as their clonal diversity by pulsed-field gel electrophoresis. Five of the 118 fecal samples harbored ESBL-positive E. coli isolates (4.2%), and one isolate per sample was completely characterized. These five ESBL-positive E. coli isolates contained the bla(TEM-52) or bla(SHV-12) genes, as well as a variety of other resistance genes (cmlA, tetA, aadA, sul1, sul2, and sul3). Four isolates harbored class 1 integrons with the following gene cassettes in their variable region: dfrA1 + aadA1 (one isolate) and sat + psp + aadA2 (three isolates). Four unrelated pulsed-field gel electrophoresis patterns were identified among the five ESBL-positive isolates, and they were ascribed to phylogroups A and B1. The intestinal tract of S. aurata might constitute a reservoir of ESBL-producing E. coli isolates.