Rapid optical determination of ?-lactamase and antibiotic activity.
ABSTRACT: The absence of rapid tests evaluating antibiotic susceptibility results in the empirical prescription of antibiotics. This can lead to treatment failures due to escalating antibiotic resistance, and also furthers the emergence of drug-resistant bacteria. This study reports a rapid optical method to detect ?-lactamase and thereby assess activity of ?-lactam antibiotics, which could provide an approach for targeted prescription of antibiotics. The methodology is centred on a fluorescence quenching based probe (?-LEAF--?-Lactamase Enzyme Activated Fluorophore) that mimics the structure of ?-lactam antibiotics.The ?-LEAF assay was performed for rapid determination of ?-lactamase production and activity of ?-lactam antibiotic (cefazolin) on a panel of Staphylococcus aureus ATCC strains and clinical isolates. Four of the clinical isolates were determined to be lactamase producers, with the capacity to inactivate cefazolin, out of the twenty-five isolates tested. These results were compared against gold standard methods, nitrocefin disk test for ?-lactamase detection and disk diffusion for antibiotic susceptibility, showing results to be largely consistent. Furthermore, in the sub-set of ?-lactamase producers, it was demonstrated and validated that multiple antibiotics (cefazolin, cefoxitin, cefepime) could be assessed simultaneously to predict the antibiotic that would be most active for a given bacterial isolate.The study establishes the rapid ?-LEAF assay for ?-lactamase detection and prediction of antibiotic activity using S. aureus clinical isolates. Although the focus in the current study is ?-lactamase-based resistance, the overall approach represents a broad diagnostic platform. In the long-term, these studies form the basis for the development of assays utilizing a broader variety of targets, pathogens and drugs.
Project description:We conducted a survey in 2015 to evaluate the presence of extended spectrum ?-lactamase (ESBL)- and plasmid-mediated AmpC-producing Enterobacteriaceae in retail food and water of the Pearl River in Guangzhou, China, as well as their antibiotic resistance profiles. Samples (88 fresh food samples and 43 water samples) from eight different districts were analyzed by direct plating and after enrichment. Multidrug-resistant strains were found in 41.7 and 43.4% of food and water samples, respectively. ESBLs were found in 3.4 and 11.6% of food and water samples, respectively, and AmpC producers were found in 13.6 and 16.3% of food and water samples, respectively. Molecular characterization revealed the domination of blaCTX-M genes; plasmidic AmpC was of the type DHA-1 both in food and water samples. Thirteen of Fifty one ?-lactamase-producing positive isolates were detected to be transconjugants, which readily received the ?-lactamase genes conferring resistance to ?-lactam antibiotics as well as some non-?-lactam antibiotics. These findings provide evidence that retail food and the river water may be considered as reservoirs for the dissemination of ?-lactam antibiotics, and these resistance genes could readily be transmitted to humans through the food chain and water.
Project description:Kingella kingae is a human pathogen that causes pediatric osteoarticular infections and infective endocarditis in children and adults. The bacterium is usually susceptible to ?-lactam antibiotics, although ?-lactam resistance has been reported in rare isolates. This study was conducted to identify ?-lactam-resistant strains and to characterize the resistance mechanism. Screening of a set of 90 K. kingae clinical isolates obtained from different geographic locations revealed high-level resistance to penicillins among 25% of the strains isolated from Minnesota and Iceland. These strains produced TEM-1 ?-lactamase and were shown to contain additional ?50-kb plasmids. Ion Torrent sequencing of extrachromosomal DNA from a ?-lactamase-producing strain confirmed the plasmid location of the blaTEM gene. An identical plasmid pattern was demonstrated by multiplex PCR in all ?-lactamase producers. The porin gene's fragments were analyzed to investigate the relatedness of bacterial strains. Phylogenetic analysis revealed 27 single-nucleotide polymorphisms (SNPs) in the por gene fragment, resulting in two major clusters with 11 allele types forming bacterial-strain subclusters. ?-Lactamase producers were grouped together based on por genotyping. Our results suggest that the ?-lactamase-producing strains likely originate from a single plasmid-bearing K. kingae isolate that traveled from Europe to the United States, or vice versa. This study highlights the prevalence of penicillin resistance among K. kingae strains in some regions and emphasizes the importance of surveillance for antibiotic resistance of the pathogen.
Project description:First-generation cephalosporins (such as cefazolin) are recommended as antibiotic prophylaxis in groin hernia repair, but other broad-spectrum antibiotics have also been prescribed in clinical practice. This was a systematic review and network meta-analysis to compare the efficacy of different antibiotic classes for prevention of surgical-site infection (SSI) after hernia repair.RCTs were identified that compared efficacy of antibiotic prophylaxis on SSI after inguinal or femoral hernia repair from PubMed and Scopus databases up to March 2016. Data were extracted independently by two reviewers. Network meta-analysis was applied to assess treatment efficacy. The probability of being the best antibiotic prophylaxis was estimated using surface under the cumulative ranking curve (SUCRA) analysis.Fifteen RCTs (5159 patients) met the inclusion criteria. Interventions were first-generation (7 RCTs, 1237 patients) and second-generation (2 RCTs, 532) cephalosporins, ?-lactam/?-lactamase inhibitors (6 RCTs, 619) and fluoroquinolones (2 RCTs, 581), with placebo as the most common comparator (14 RCTs, 2190). A network meta-analysis showed that ?-lactam/?-lactamase inhibitors and first-generation cephalosporins were significantly superior to placebo, with a pooled risk ratio of 0·44 (95 per cent c.i. 0·25 to 0·75) and 0·62 (0·42 to 0·92) respectively. However, none of the antibiotic classes was significantly different from the others. SUCRA results indicated that ?-lactam/?-lactamase inhibitors and first-generation cephalosporins were ranked first and second respectively for best prophylaxis.?-Lactam/?-lactamase inhibitors followed by first-generation cephalosporins ranked as the most effective SSI prophylaxis for adult patients undergoing groin hernia repair.
Project description:The rapid emergence and dissemination of carbapenemase-producing Klebsiella pneumoniae strains and other members of the Enterobacteriaceae poses a considerable threat to the care of hospitalized patients and to public health. The aim of this study was to determine the frequency of metallo-β-lactamases (MBL) and VIM-1 gene in multidrug-resistant strains of K. pneumoniae.50 isolates of non - duplicated K. pneumoniae cultured from patients at intensive care units were tested for their susceptibilities to 13 different antibiotics using microbroth dilution assay. Isolates showing resistance to at least one of the carbapenems were checked for production of metallo-β-lactamase (MBLs) using imipenem-EDTA synergy tests. PCR was used to detect the gene encoding VIM-1 metallo-β-lactamase (MBL).Of 50 clinical isolates, 26 (52%) were resistant to imipenem in disk diffusion method. Using imipenem-EDTA synergy tests, production of MBL was detected in 15 (30%) isolates. PCR assay showed that 15 isolates were positive for VIM and these included 10 and 5 isolates showing positive and negative results in phenotypic method of MBL detection test respectively. Amikacin was found as the most effective antibiotic against the MBL producers in this study.The emergence of bla(VIM-1) producing K. pneumoniae in North of Iran is concerning. Microorganisms producing bla(VIM-1) constitute the prevalent multidrug-resistant population of K. pneumoniae in that region.
Project description:?-Lactam antibiotics are commonly used in outpatient parenteral antimicrobial therapy (OPAT), but data regarding outcomes of long-term therapy are limited. The purpose of this study was to compare treatment success, readmission and antibiotic switch rates in patients treated with ?-lactam antibiotics as OPAT.We carried out a retrospective review of all patients, discharged from Tufts Medical Center with cefazolin, ceftriaxone, ertapenem or oxacillin, between January 2009 and June 2013. A competing risks analysis was used to compare the cumulative incidence of first occurrence of treatment success, antibiotic switch and 30 day readmission for each drug.Four hundred patients were identified (cefazolin n?=?38, ceftriaxone n?=?104, ertapenem n?=?128 and oxacillin n?=?130). Baseline demographics were similar. Treatment success rates were higher for ceftriaxone and ertapenem (cefazolin 61%, ceftriaxone 81%, ertapenem 73% and oxacillin 58%; P?<?0.001). Thirty-day all-cause readmissions were similar (cefazolin 21%, ceftriaxone 14%, ertapenem 20% and oxacillin 15%; P?=?0.46). In 400 OPAT courses, 37 out of 50 antibiotic switches were accomplished without readmission. Adverse drug events (ADEs) were the most common reason for outpatient antibiotic switches (31/37, 84%). The ADE rate was higher for the oxacillin group (cefazolin 2.0 versus ceftriaxone 1.5 versus ertapenem 2.9 versus oxacillin 8.4 per 1000 OPAT days; P?<?0.001).OPAT with ?-lactam antibiotics is effective, but antibiotic switches for adverse events were more frequent with oxacillin use. Clinicians should be cognizant of the risk of readmissions and ADEs in OPAT patients, as the value of OPAT lies in reducing patient morbidity and readmissions by managing ADEs and preventing clinical failures.
Project description:BACKGROUND: The aim of this study was to evaluate the prevalence of beta-lactamase-producing Capnocytophaga isolates in young children hospitalized in the Pediatric Oncology Department of Hôpital Sud (Rennes, France) over a ten-year period (1993-2002). METHODS: In neutropenic children, a periodic survey of the oral cavity allows a predictive evaluation of the risk of systemic infections by Capnocytophaga spp. In 449 children with cancer, 3,053 samples were collected by oral swabbing and plated on TBBP agar. The susceptibility of Capnocytophaga isolates to five beta-lactams was determined. RESULTS: A total of 440 strains of Capnocytophaga spp. were isolated, 309 (70%) of which were beta-lactamase producers. The beta-lactamase-producing strains were all resistant to cefazolin, 86% to amoxicillin, and 63% to ceftazidime. The proportion of strains resistant to third-generation cephalosporins remained high throughout the ten-year study, while susceptibility to imipenem and amoxicillin combined with clavulanic acid was always conserved. CONCLUSION: These results highlight the risk of antibiotic failure in Capnocytophaga infections and the importance of monitoring immunosuppressed patients and testing for antibiotic susceptibility and beta-lactamase production.
Project description:A new SHV-derived extended-spectrum beta-lactamase, SHV-57, that confers high-level resistance to ceftazidime but not cefotaxime or cefazolin was identified from a national surveillance study conducted in Taiwan in 1998. An Escherichia coli isolate resistant to ampicillin, cephalothin, and ceftazidime but sensitive to cefoxitin, ceftriaxone, cefotaxime, imipenem, and a narrow-spectrum cephem (cefazolin) was isolated from the urine of a patient treated with beta-lactam antibiotics. Resistance to beta-lactams was conjugatively transferred with a plasmid of about 50 kbp. The pI of this enzyme was 8.3. The sequence of the gene was determined, and the open reading frame of the gene was found to consist of 861 bases (GenBank accession number AY223863). Kinetic parameters showed that SHV-57 had a poor affinity to cefazolin. The K(m) value toward cefazolin (5.57 x 10(3) muM) was extremely high in comparison to those toward ceftazidime (30.9 muM) and penicillin G (67 muM), indicating its low affinity to cefazolin. Although the K(m) value of the beta-lactamase inhibitor was too high for the study of catalytic activity (k(cat)), indicating the low k(cat) of SHV-57, the SHV-57 carrier was highly susceptible to a beta-lactam-beta-lactamase inhibitor combination. Comparison of the three-dimensional molecular model of SHV-57 with that of the SHV-1 beta-lactamase suggests that the substitution of arginine for leucine-169 in the Omega loop is important for the substrate specificity.
Project description:PurposePseudomonas aeruginosa causes complicated and/or nosocomial UTI. These infections are usually associated with severe and multi-drug resistant P. aeruginosa isolates. As there is no study about the activity of novel antibiotics ceftazidime-avibactam (CZA) and ceftolozane-tazobactam (C/T) against P. aeruginosa isolates in Iran, we aimed to evaluate for the first time the efficacy of these agents against P. aeruginosa isolated from patients with UTI in Iran. Then, the genetic diversity of the resistant isolates was assayed.MethodsIn this study, a total of 200 P. aeruginosa isolates were collected from patients with UTI in Tehran, Iran. Disk diffusion and Minimum Inhibitory Concentration (MIC) methods were applied to determine the resistance of the isolates to CZA, C/T, and the other antibiotics. Extended-spectrum ?-lactamases (ESBLs) and Metallo Beta Lactamase (MBL) production were assayed by Combination disk diffusion test (CDDT). Polymerase chain reaction (PCR) was carried out to detect the resistance genes, including beta-lactamases and carbapenemases genes. Finally, genomic analysis of the isolates was performed using the Pulse field gel electrophoresis (PFGE).ResultsAmong the isolates, 16 (8%) were resistant to CZA and C/T that MIC confirmed it. The resistant isolates showed high resistance to the other classes of antibiotics. Among the resistant isolates, 31.2% and 75% were ESBL and MBL producers, respectively. The prevalence of blaOXA10, blaVIM, blaOXA48, blaOXA2, and blaCTX-M was 100%, 50%, 31.2%, 25%, and 12.5%. Furthermore, two isolates (12.5%) harbored blaPER and blaNDM genes. The resistant isolates were grouped into 14 distinct pulsotypes and two shared pulsotypes were found.ConclusionCeftazidime-avibactam and ceftolozane-tazobactam showed high activity against the P. aeruginosa isolated from patients with UTI in Iran. The low rate of resistance to the antibiotics is also alarming and should be considered to avoid further spreading of the antibiotic resistance among the P. aeruginosa and the other bacteria.
Project description:Background and Objectives. The aim of this study was to determine the frequency of bla NDM, bla PER, bla VEB, bla IMP, and bla VIM type genes among A. baumannii isolates from hospitalized patients in two hospitals in Tehran, Iran. Patients and Methods. Antibiotic susceptibility tests were performed by Kirby-Bauer disc diffusion and Broth microdilution methods. The frequency of MBL (metallo-beta-lactamase) and ESBL (extended-spectrum-beta-lactamase) producers was evaluated by CDDT. The ? -lactamases genes were detected by PCR and sequencing methods. Results. The resistance of A. baumannii isolates against tested antibiotics was as follows: 103 (95.4%) to ceftazidime, 108 (100%) to cefotaxime, 105 (95.7%) to cefepime, 99 (91.7%) to imipenem, 99 (91.7%) to meropenem, 87 (80.6%) to amikacin, 105 (97.2%) to piperacillin, 100 (92.6%) to ciprofloxacin, 103 (95.4%) to piperacillin/tazobactam, 44 (40.7%) to gentamicin, 106 (98.1%) to ampicillin/sulbactam, 106 (98.1%) to co-trimoxazole, 87 (80.6%) to tetracycline, and 1 (1.8%) to colistin. Using combined disk diffusion test, 91 (84.2%) and 86 (86.86%) were ESBL and MBL producers, respectively. The prevalence of bla PER-1, bla VEB-1, bla IMP-1, and bla VIM-1 genes was 71 (78.03%), 36 (39.5%), 3 (3.48%), and 15 (17.44%), respectively. Conclusions. The prevalence of ESBLs and MBLs-producing A. baumannii strains detected in this study is a major concern and highlights the need of infection control measures.
Project description:Expression of ?-lactamase is the single most prevalent determinant of antibiotic resistance, rendering bacteria resistant to ?-lactam antibiotics. In this article, we describe the development of an antibiotic prodrug that combines ciprofloxacin with a ?-lactamase-cleavable motif. The prodrug is only bactericidal after activation by ?-lactamase. Bactericidal activity comparable to ciprofloxacin is demonstrated against clinically relevant E. coli isolates expressing diverse ?-lactamases; bactericidal activity was not observed in strains without ?-lactamase. These findings demonstrate that it is possible to exploit antibiotic resistance to selectively target ?-lactamase-producing bacteria using our prodrug approach, without adversely affecting bacteria that do not produce ?-lactamase. This paves the way for selective targeting of drug-resistant pathogens without disrupting or selecting for resistance within the microbiota, reducing the rate of secondary infections and subsequent antibiotic use.