BackgroundEnterobacteriaceae are ubiquitously present in nature and can be found in the intestinal tract of humans and animals as commensal flora. Multidrug-resistant Enterobacteriaceae are increasingly reported and are a threat to public health implicating a need for accurate identification of the isolates to species level. In developing countries, identification of bacteria basically depends on conventional methods: culture and phenotypic methods that hamper the accurate identification of bacteria. In this study, matrix-assisted desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) technique was compared to conventional identification techniques.Materials and MethodsIn total, 147 Enterobacteriaceae isolates were collected from March to May 2015 from three medical microbiology laboratories of hospitals in Edo state, Nigeria, after being tested according to the individual laboratories standard operating procedures. All isolates were stored at −20°C until tested centrally by MALDI-TOF MS.ResultsOne hundred and forty five (98.6%) isolates had a MALDI Biotyper best score > or =2.0, indicating a secure genus and probable species identification; and 2(1.36%) isolates had a best score <2.0 indicating probable genus identification. Isolates with best scores of > or =2.0 comprised nine genera and 10 species, respectively. A total of 57.2% and 33.1% of isolates identified had agreement between MALDI-TOF MS and conventional techniques for identification at genus and species level, respectively, when analyzing bacteria with MALDI Biotyper best scores > or =2.0.ConclusionThe results of our study show that the applied conventional identification techniques for Enterobacteriaceae in the investigated Nigerian hospitals are not very accurate. Use of state-of-the-art identification technologies for microorganisms is necessary to guarantee comparability of bacteriological results.
Extended Spectrum β-lactamase (ESBL)-producing Enterobacteriaceae are of major concern as they are implicated in multidrug resistant nosocomial infections. They are listed on a recently published global priority list of antibiotic-resistant bacteria by the World Health Organization which raises concern in both healthcare and community settings. This study aimed at determining the frequency of ESBL genes in multidrug resistant human clinical Enterobacteriaceae isolates from Edo state Nigeria and to characterize the resistance mechanisms using whole genome sequencing. A total of 217 consecutive clinical isolates of Enterobacteriaceae, selection based on inclusion criteria, were collected from March-May 2015 from three medical microbiology laboratories of hospitals in Edo state Nigeria. All isolates were analyzed using matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Antibiotic susceptibility testing was performed by Kirby-Bauer method and minimum inhibitory concentration (MIC) determination by E-test method. Double disc synergy test was used to screen for the production of ESBL. Whole genome sequencing (WGS) was performed for isolate characterization and identification of resistance determinants. Out of 217 consecutive clinical Enterobacteriaceae isolates, 148 (68.2%) were multi-drug resistant. Of these multi-drug resistant isolates, 60 (40.5%) were positive for the ESBL phenotypic test and carried ESBL genes. CTX-M-15 was the predominant ESBL found, among 93.3% (n = 56/60). Thirty-two plasmid incompatibility groups and 28 known and two new sequence types were identified among the ESBL isolates. The high occurrence of CTX-M-15 with associated resistant determinants in multidrug resistant Enterobacteriaceae harboring different plasmid incompatibility groups and sequence types calls for the need of continuous monitoring of this resistance threat to reduce its public health impact. To our knowledge, this study presents the first genomic characterization of ESBL production mediated by bla CTX-M-15 in human clinical isolates of Enterobacter hormaechei, Citrobacter werkmanii and Atlantibacter hermannii from Nigeria.
There is a link between antibiotic resistance in humans, livestock and the environment. This study was carried out to characterize antibiotic resistant bovine and environmental Enterobacteriaceae isolates from Edo state, Nigeria. A total of 109 consecutive isolates of Enterobacteriaceae were isolated from March–May 2015 from 150 fecal samples of healthy bovine animals from three farms at slaughter in Edo state Nigeria. Similarly, 43 Enterobacteriaceae isolates were also obtained from a total of 100 environmental samples from different sources. Isolates were recovered and identified from samples using standard microbiological techniques. Recovered isolates were pre-identified by the Microbact Gram-Negative identification system and confirmed with Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry and ribosomal multilocus sequence typing (rMLST). Antibiotic susceptibility testing was carried out by Kirby-Bauer method for 14 antibiotics. Whole genome sequencing (WGS) was carried out for isolate characterization and identification of resistance determinants. Out of 109 animal and 43 environmental Enterobacteriaceae isolates, 18 (17%) and 8 (19%) isolates based on selection criteria showed antibiotic resistance and were further investigated by whole genome sequencing (WGS). Resistance genes were detected in all (100%) of the resistant bovine and environmental Enterobacteriaceae isolates. The resistance determinants included β-lactamase genes, aminoglycoside modifying enzymes, qnr genes, sulfonamide, tetracycline and trimethoprim resistance genes, respectively. Out of the 18 and 8 resistant animal and environmental isolates 3 (17%) and 2 (25%) were multidrug resistant (MDR) and had resistance determinants which included efflux genes, regulatory systems modulating antibiotic efflux and antibiotic target alteration genes. Our study shows the dissemination of antibiotic resistance especially MDR strains among Nigerian bovine and environmental Enterobacteriaceae isolates. The presence of these resistant strains in animals and the environment constitute a serious health concern indicated by the difficult treatment options of the infections caused by these organisms. To the best of our knowledge we report the first detailed genomic characterization of antibiotic resistance in bovine and environmental Enterobacteriaceae isolates for Nigeria.
Waltheria indica has been claimed to be used in managing several diseases in traditional medicine, although substantial scientific data are not available as regards its safety despite its pronounced efficacy in management of some ailments. Therefore, methanol leaf extract of W. indica was evaluated for its effects on some toxicological parameters using experimental animals. However, acute and sub-acute toxicity were carried out using experimental animals as described by standard methods. Absence of death reported after 24 hours of single oral administration of W. indica indicated that the crude drug is safe orally and the sample also had no effect on both hematological and biochemical parameters, with mild toxicity observed with some vital enzymes and organs upon continuous oral administration of W. indica for 21 days. However, it can be concluded that prolong usage of the plant for disease management should be discouraged, which implies that usage of the pant for short time usage in disease management.
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