TEM-1 β-lactamase is one of the most well-known antibiotic resistance determinants around. It confers resistance to penicillins and early cephalosporins and has shown an astonishing functional plasticity in response to the introduction of novel drugs derived from these antibiotics. Since its discovery in the 1960s, over 170 variants of TEM-1 ...

β-Lactam antibiotics are among the most frequently prescribed antibiotics used to treat bacterial infections. However, their utility is being threatened by the worldwide proliferation of β-lactamases with broad hydrolytic capabilities, especially in multidrug-resistant Gram-negative bacteria. This review describes new β-lactams and β-lactamase inhibitors described in the patent literature primarily between ...

A multidrug-resistant Escherichia coli isolate recovered in Australia produced a carbapenem-hydrolyzing β-lactamase. Molecular investigations revealed the first identification of the bla(NDM-1) metallo-β-lactamase gene in that country. In addition, this E. coli isolate expressed the extended-spectrum β-lactamase CTX-M-15, together with two 16S rRNA methylases, namely, ArmA and RmtB, conferring a high ...

The Pseudomonas aeruginosa isolate TS-832035 was responsible for an outbreak that occurred in an Italian hospital between 1999 and 2002. It exhibited a high-level resistance to carbapenems due to the contemporary presence of two independent mechanisms: the production of a carbapenemase, coded by a bla(VIM-1) determinant carried by the chromosomal ...

We have explored the microbial community in a nonpermafrost, cold Alaskan soil using both culture-based and culture-independent approaches. In the present study, we cultured >1000 bacterial isolates from this soil and characterized the collection of isolates phylogenetically and functionally. A screen for antibiosis identified an atypical, red-pigmented strain of Janthinobacterium ...

We have investigated the antimicrobial resistance of verocytotoxin-producing Escherichia coli (VTEC) strains isolated from humans, animals, food, and the environment in Belgium. Resistance was more frequent in non-O157 strains from humans than in O157 strains from humans or other sources, and among non-O157 VTEC strains, intimin-positive strains were more resistant ...

The CMY-2, ACT-1, DHA-1, ACC-1, and FOX-1 enzymes are representative of five plasmid-mediated AmpC (pAmpC) β-lactamase clusters. Resistance to imipenem has been reported in Enterobacteriaceae as a result of pAmpC expression combined with decreased outer membrane permeability. The aim of this study was to determine the role of different pAmpCs ...

The incidence of naturally occurring AmpC β-lactamases with extended activities toward several cephalosporins was evaluated among 17 ceftazidime (CAZ)-resistant Acinetobacter baumannii isolates. Five AmpC β-lactamases (named ADC β-lactamases) were identified, among which those possessing the Val208Ala (inside the omega-loop) or Asn283Ser (helix H-10) substitution conferred higher levels of resistance (4- ...

Enterobacteriaceae other than Escherichia spp. and Klebsiella spp. are recognisable for their increasing resistance. Plasmid-mediated beta-lactamases, including extended-spectrum beta-lactamases (ESBLs), plasmid-mediated AmpC beta-lactamases (pAmpCs) and the newly emerged KPC, play an important role in beta-lactam resistance. In this study, we investigated the genetic characteristics of plasmid-mediated beta-lactamases amongst non-Escherichia, non-Klebsiella ...

The increased prevalence of beta-lactamases in Pseudomonas aeruginosa has begun to reduce the clinical efficacy of beta-lactams against the most common opportunistic pathogen. Of over 800 beta-lactamases identified from Gram-negative bacilli, at least 120 beta-lactamases have been detected in P. aeruginosa. IMPs and VIMs are predominantly found in P. aeruginosa ...

The aim of the present study was to investigate the mechanism of quinolone and beta-lactam resistance in an isolate of Citrobacter freundii PC2/08 collected from sewage effluent from l'Aquila, Italy. QnrB-9 and bla(TEM-116 )were co-expressed in a large plasmid identified in C. freundi PC2/08 strain. Compared to TEM-1, TEM-116 showed ...

The presence of qnr genes in 191 extended-spectrum beta-lactamase-producing Escherichia coli from 2005, with 75% of resistance to ciprofloxacin, was evaluated. An SHV-12-producing E. coli carried qnrB19; both genes were transferred by conjugation. No qnrA- or qnrS-positive strains were detected. In addition, we identified 3 new parC mutations (S80W, E84R, ...

An integrative approach combining biophysical and microbiological methods was used to characterize the antibiotic translocation through the outer membrane of Providencia stuartii. Two novel members of the General Bacterial Porin family of Enterobacteriaceae, named OmpPst1 and OmpPst2, were identified in P. stuartii. In the presence of ertapenem (ERT), cefepime (FEP), ...

Metallo-ss-lactamases (MBL) are an emerging cause of bacterial resistance to antibiotic treatment. The VIM-2 ss-lactamase is the most commonly encountered MBL in clinical isolates worldwide. Described here are potent and selective small molecule inhibitors of VIM-2 containing the arylsulfonyl-NH-1,2,3-triazole chemotype that potentiate the efficacy of the ss-lactam, imipenem, in E. ...

Extended-spectrum beta-lactamases, plasmid-mediated AmpC beta-lactamases (PABLs), and plasmid-mediated metallo-beta-lactamases confer resistance to many beta-lactams. In Japan, although several reports exist on the prevalence of extended-spectrum beta-lactamases and metallo-beta-lactamases, the prevalence and characteristics of PABLs remain unknown. To investigate the production of PABLs, a total of 22,869 strains of 4 enterobacterial ...

Synthetic riboswitch containing aptamer is constructed in E. coli to regulate the expression of β-lactamase through small molecule-aptamer interactions, which sharply reduces the antibiotic resistance of the engineered bacteria.

During January-June 2010, three Enterobacteriaceae isolates carrying a newly described resistance mechanism, the New Delhi metallo-beta-lactamase (NDM-1), were identified from three U.S. states at the CDC antimicrobial susceptibility laboratory. This is the first report of NDM-1 in the United States, and the first report of metallo-beta-lactamase carriage among Enterobacteriaceae in ...

Highly pathogenic Yersinia enterocolitica biovar 1B produces two distinct beta-lactamases, BlaA and BlaB. Mutants of a representative biovar 1B isolate were constructed and evaluated to determine the extent of limitation of susceptibility to broad-spectrum beta-lactam antibiotics by BlaA and BlaB. The results demonstrated that BlaA, a class A enzyme, plays ...

We describe a maternal death due to necrotising fasciitis caused by an extended spectrum beta-lactamase-producing Escherichia coli resistant to routinely used antimicrobial agents. Necrotising fasciitis is a rare complication of septicaemia with a high mortality. Signs of infection were insidious and masked by the use of routine analgesic agents and ...

The aim of this study was to evaluate the in vitro antibiotic susceptibility of respiratory pathogens recently isolated in Italy to commonly used antibiotics including cefditoren. Six clinical microbiological laboratories collected, between January and September 2009, a total of 2,510 respiratory pathogens from subjects with community-acquired respiratory tract infections (CARTI). ...

Probiotics must be consumed at a level of 10(7) CFU/mL for successful colonization of the gut. In yogurts containing beneficial cultures, the survival of probiotic strains can quickly decline below this critical concentration during cold storage. We hypothesized that beta-glucan would increase the viability of bifidobacteria strains in yogurt during ...

OBJECTIVES: Rahnella aquatilis is an environmental enterobacterial species with a chromosomal bla(RAHN-1) gene encoding extended-spectrum class A beta-lactamase RAHN-1. We describe the diversity of bla(RAHN) genes from two groups of strains, G1 and G2, isolated from raw fruits and vegetables, and the new class A beta-lactamase RAHN-2. METHODS: MICs were ...

During the past 15 years, emergence and dissemination of beta-lactam resistance in nosocomial Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii, became a serious problem worldwide. Especially the increasing resistance to 3rd and 4th generation cephalosporins and carbapenems is of particular concern. Gram-negative bacteria pursue various molecular strategies for development of resistance ...

The ability to produce a 2-branched (1,3)-beta-D-glucan was screened in 147 lactic acid bacteria strains recovered from cider. Among them, 32 identified as Pediococcus parvulus exhibited a ropy character and were PCR positive for the presence of the gtf gene, related to the synthesis of the beta-glucan. Half of the ...

We investigated the effects of replacing third-/fourth-generation cephalosporins with piperacillin-tazobactam on the rate of acquisition of extended spectrum beta-lactamase-producing Klebsiella pneumoniae and Escherichia coli by patients hospitalized in a Department of Respiratory Medicine. This 9-month, prospective, non-controlled, intervention study comprised two phases: a 3-month pre-intervention phase (Phase I) and a ...

To gain insight into the diversity and origins of antibiotic resistance genes, we identified resistance genes in the soil in an apple orchard using functional metagenomics, which involves inserting large fragments of foreign DNA into Escherichia coli and assaying the resulting clones for expressed functions. Among 13 antibiotic-resistant clones, we ...

Punctual mutations in the TEM-1 or TEM-2 gene may lead to inhibitor-resistant-TEM (IRT) beta-lactamases with resistance to beta-lactam-beta-lactamase inhibitor combinations and susceptibility to cephalosporins. The aim of this work was to analyze the current epidemiology of IRT beta-lactamases in contemporary clinical Escherichia coli. Isolates were prospectively collected in our hospital ...

Fourteen Enterobacteriaceae isolates with ertapenem MIC >2 mg/mL were analyzed to identify mechanisms of resistance. All isolates produced extended-spectrum beta-lactamase or AmpC beta-lactamase with variable, but decreased, expression of outer membrane proteins. One Enterobacter cloacae produced derepressed AmpC beta-lactamase, 1 Escherichia coli expressed plasmid-mediated AmpC beta-lactamase, and 1 E. cloacae ...

The occurrence of beta-lactamase-producing Escherichia coli and Staphylococcus aureus in chickens was investigated. Specimens (n = 1,300) were collected from 400 chickens and were streaked on MacConkey agar plates. From each plate, presumptive growths of organisms were picked and streaked on eosin methylene blue and Baird-Parker agars, respectively. Typical colonies ...

INTRODUCTION: Infections caused by Pseudomonas aeruginosa are difficult to treat as the majority of isolates exhibit varying degrees of beta-lactamase mediated resistance to most of the beta-lactam antibiotics. It is also not unusual to find a single isolate that expresses multiple beta-lactamase enzymes, further complicating the treatment options. Thus the ...

The beta-lactamase genes, which confer multi-drug resistance, are spreading among clinical bacterial isolates. As part of a routine surveillance program, we collected 302 bacilli isolates between June 2005 and October 2006 from four hospitals in Guangzhou, China. The isolates were screened for multidrug resistance and for the presence of beta-lactamases. ...

Aeromonas species rarely cause pulmonary infection. We report, for what is believed to be the first time, a case of severe pneumonia in a cancer patient caused by Aeromonas caviae. Detailed microbiological investigation revealed that this isolate carried three beta-lactamase-encoding genes (encoding MOX-4, CTX-M-3 and TEM-1) conferring resistance to all ...

BAL30072 is a new monocyclic beta-lactam antibiotic belonging to the sulfactams. Its spectrum of activity against significant Gram-negative pathogens with beta-lactam-resistant phenotypes was evaluated and was compared with the activities of reference drugs, including aztreonam, ceftazidime, cefepime, meropenem, imipenem, and piperacillin-tazobactam. BAL30072 showed potent activity against multidrug-resistant (MDR) Pseudomonas aeruginosa ...

A carbapenem-resistant Pseudomonas stutzeri strain isolated from a Dutch patient was analyzed in detail. This isolate produced a metallo-beta-lactamase (MBL) whose gene, with 43.5% GC content, was cloned and expressed in Escherichia coli. beta-Lactamase DIM-1 (for Dutch imipenemase) was weakly related to other Ambler class B beta-lactamases, sharing <52% amino ...

The aim of this investigation was to characterize metallo-beta-lactamases (MBLs) in Pseudomonas aeruginosa isolates from Zagreb, Croatia. One hundred P. aeruginosa isolates with reduced susceptibility to either imipenem or meropenem were tested for the production of MBLs by MBL-Etest. The susceptibility to a wide range of antibiotics was determined by ...

BACKGROUND: Carbapenems are among the few useful antibiotics against multidrug resistant gram negative bacteria particularly those with extended spectrum beta lactamase. However resistance to carbapenems occurs and is mediated by mechanisms like loss of outer membrane proteins and production of beta lactamase that is capable of hydrolyzing carbapenems. An alert ...

BACKGROUND: We determined the effects of two antibiotic policies (predominance of either beta-lactam antibiotics or fluroquinolones) on acquisition with third-generation cephalosporin-resistant Enterobacteriaceae (CRE) and fluoroquinolone-resistant CRE (FCRE) in two ICUs, with monitoring of other variables that may influence acquisition. METHODS: After an 8-month baseline period, units were randomized to a ...

We investigated the molecular epidemiology and carbapenem resistance mechanisms of 258 non-duplicate carbapenem-resistant clinical isolates of Pseudomonas aeruginosa collected from 2006 to 2007 at 28 hospitals in China. Up to 88% of the carbapenem-resistant isolates were multidrug-resistant. Pulsed-field gel electrophoresis (PFGE) revealed that levels of intrahospital and interhospital dissemination of ...

Staphylococcus lugdunensis is a coagulase-negative staphylococcus that has several similarities to Staphylococcus aureus. S. lugdunensis is increasingly being recognized as a cause of prosthetic joint infection (PJI). The goal of the present retrospective cohort study was to determine the laboratory and clinical characteristics of S. lugdunensis PJIs seen at the ...

The aim of this study is to investigate the trend of antimicrobial resistance of 696 Escherichia coli strains of chicken origin in China during 1970-2007, and to characterize the beta-lactamase determinants of these strains. Minimum inhibitory concentrations (MICs) of these strains against 11 antimicrobials were determined by the broth microdilution ...

Extended-spectrum AmpC beta-lactamase (ESAC) Escherichia coli producers were investigated over a 5-year period. Eleven isolates presenting a strong ampC promoter and different strategic AmpC mutations, including two newly described modifications (A292V and an L-A-A insertion at 295), were characterized. All the isolates belonged to phylogenetic group A and to the ...

Antimicrobials derived from plants have been receiving increasing attention in recent years. Antimicrobial activities of a number of phytochemicals have been reported. Many present day antibiotics are ineffective against several pathogenic organisms. About 90% of Staphylococcus aureus isolates from clinical specimens is reported to have resistance against beta-lactam antibiotics. In ...

Aeromonas enteropelogenes (formerly A. tructi) was described to be an ampicillin-susceptible and cephalothin-resistant Aeromonas species, which suggests the production of a cephalosporinase. Strain ATCC 49803 was susceptible to amoxicillin, cefotaxime, and imipenem but resistant to cefazolin (MICs of 2, 0.032, 0.125, and >256 microg/ml, respectively) and produced an inducible beta-lactamase. ...

Haemophilus influenzae is a frequent causative bacterial pathogen of respiratory tract infections. Resistance to beta-lactam antibiotics has been a significant clinical problem in treatment for H. influenzae respiratory infections. This study describes the serotype, antibiotic resistance and distribution of TEM-1 or ROB-1 beta-lactamase in H. influenzae isolates from local private ...

We characterized 67 Escherichia coli isolates with reduced susceptibility to cefotaxime or ceftiofur obtained from healthy broilers housed in five Italian farms. The bla(CTX-M-1), bla(CTX-M-32) and bla(SHV-12) beta-lactamase genes were identified on IncI1, IncN, or IncFIB plasmids. Considerable genetic diversity was detected among the extended-spectrum beta-lactamase (ESBL)-producing isolates, and we ...

OBJECTIVES: To establish the prevalence of the AmpC beta-lactamase phenotype in clinical isolates of Escherichia coli and characterize the genetic resistance mechanisms causing the observed phenotype. METHODS: Clinical E. coli (n = 74) with reduced susceptibility to third-generation cephalosporins and resistance to cefoxitin were collected from the Department of Clinical ...

Escherichia coli penicillin-binding protein 5 (PBP5), a dd-carboxypeptidase encoded by the dacA gene, plays a key role in the maintenance of cell shape. Although PBP5 shares one of the highest copy numbers among the PBPs, it is not essential for cell survival. To determine the effect of this redundant PBP ...

OBJECTIVES: To compare and contrast the geographic and demographic distribution of bro beta-lactamase and antibiotic MIC(50/90) for 1440 global Moraxella catarrhalis isolates obtained from children and adults between 2001 and 2002. METHODS: One thousand four hundred and forty M. catarrhalis isolates originating from seven world regions were investigated. The isolates ...

OBJECTIVES: To assess the activity of mecillinam against two groups of Escherichia coli: (i) a selection of international isolates with mechanisms of resistance caused by the presence of defined beta-lactamases; and (ii) isolates resistant to third-generation cephalosporins referred from across Wales. METHODS: Antibiotic susceptibility testing with mecillinam, meropenem, amoxicillin, co-amoxiclav, ...

Carbapenem resistance in Gram-negative bacteria is a worldwide increasing and one of the most disturbing problems, given these antibiotics are drugs of choice in the treatment of infections caused by extended-spectrum-beta-lactamase producing strains. In this study the antibiotic susceptibility of metallo-beta-lactamase-positive and negative Klebsiella pneumoniae strains isolated from intensive care ...