The rapid emergence of multiresistant microbial pathogens, dubbed superbugs, is a serious threat to human health. Extended spectrum beta lactamase (ESBL)-producing Escherichia coli is a superbug causing worldwide outbreaks, necessitating timely and accurate tracking of resistant strains. Accordingly, this study was designed to investigate the spread of ESBL-producing Escherichia coli isolates, to analyze the effect of different genotypic and phenotypic factors on in vitro resistance patterns, and to assess the diagnostic value of commonly used ESBL genetic markers. For that purpose, we cultured 250 clinical isolates and screened their susceptibility to beta-lactam antibiotics. Among 12 antibiotics screened, only imipenem seems to have remained resilient. We subsequently analyzed the ESBL phenotype of Escherichia coli isolates and examined potential associations between their resistance phenotypes and patient-related factors. ESBL genotyping of 198 multiresistant isolates indicated that 179 contained at least one blaCTX-M gene. As we statistically dissected the data, we found associations between overall resistance and body site / type of disease. Additionally, we confirmed the diagnostic value of testing both blaCTX-M-1 and blaCTX-M-15 in providing better prediction of overall resistance. Finally, on sequencing the amplification products of detected blaCTX-M genes, we discovered two novel variants, which we named blaCTX-M-14.2 and blaCTX-M-15.2.
Purpose: We aimed to optimize the factors affecting the production of the allylamine antifungal, terbinafine, by Lysinibacillus isolate MK212927, a natural producer of this broadspectrum fungicidal compound. Methods: We employed a central composite design to optimize the five most important variables influencing the production of terbinafine which were carbon source, nitrogen source, temperature, pH and agitation. Results: The optimum conditions were found to be starch 5 g/L, ammonium chloride 5 g/L, temperature 32°C, agitation 150 rpm and pH 7. The actual response (inhibition zone diameter) was highly comparable to the value predicted by the model, indicating a valid model. Using the standard calibration curve of terbinafine, the optimized conditions resulted in an increase in the antifungal metabolite production (terbinafine) by about 1.6-fold (1814.662 µg/mL compared to 1165.550 µg/mL under standardized conditions). Conclusion: This is the first report, to the best of our knowledge, on optimized production of terbinafine by Lysinibacillus species. Hence, these findings may be useful as baseline data for scaling up the production of terbinafine from a natural microbial source.
Background
Carbapenem-resistant Enterobacterales (CRE), currently listed by the World Health Organization (WHO) as top priority critical pathogens, are a major global menace to human health. In low- and middle-income countries (LMICs) the threat is mounting fueled by selective pressures caused by antibiotic abuse and inadequate diagnostic resources.
Methods
This study phenotypically and genotypically characterized carbapenem resistance among 115 Enterobacterales isolates including 76 Klebsiella (K.) pneumoniae, 19 Escherichia (E.) coli, 14 Shigella (S.) sonnei, 5 Enterobacter (E.) cloacae, and 1 Proteus (P.) mirabilis.
Results
Ninety-three isolates (80.9%) were carbapenem-resistant with an alarming 57.5% carbapenem non-susceptibility in isolates collected from the outpatient department. Molecular characterization of the carbapenemases (CPases) encoding genes showed that blaNDM (80.5%) was the most prevalent; it was detected in 62 isolates (54 K. pneumoniae, 6 E. coli and 2 S. sonnei), followed by blaVIM (36.4%) which was observed in 28 isolates (24 K. pneumoniae, 3 E. coli and 1 E. cloacae). Other CPases included blaKPC (28.6%; in 20 K. pneumoniae, 1 E. coli and 1 S. sonnei), blaOXA-48 (26%; in 17 K. pneumoniae, 1 E. coli,1 E. cloacae and 1 P. mirabilis), blaIMP (6.5%; in 5 K. pneumoniae) and blaSPM (1.3%; in K. pneumoniae). Notably more than half of the Enterobacterales isolates (54.5%) co-harboured more than one CPase-encoding gene. Co-existence of blaNDM and blaVIM genes was the most dominant (31.2%), followed by association of blaNDM and blaKPC (24.7%), then blaVIM and blaKPC (13%). Moreover, the effects of different genotypes on meropenem MIC values were assessed, and a statistically significant difference between the genotype (Ambler classes A and B) and the genotype (Ambler classes B and D) was recorded.
Conclusion
The current findings may serve for a better understanding of the context of CRE in Egypt, associated drivers and CPases.
Acinetobacter baumannii armed with multidrug resistance (MDR) and biofilm-forming ability is increasingly recognized as an alarming pathogen. A deeper comprehension of the correlation between these two armories is required in circumventing its infections. This study examined the biofilm-forming ability of the isolates by crystal violet staining and the antibiotic susceptibility by broth microdilution method. The genetic basis of the MDR and biofilm-forming phenotypes was screened by polymerase chain reaction. The antimicrobial activities of cinnamic and gallic acids against planktonic cells and biofilms of A. baumannii were investigated, and the findings were confirmed with scanning electron microscopy (SEM). Among 90 A. baumannii isolates, 69 (76.6%) were MDR, and all were biofilm formers; they were classified into weak (12.2%), moderate (53.3%), and strong (34.5%) biofilm formers. Our results underlined a significant association between MDR and enhanced biofilm formation. Genotypically, the presence of blaVIM and blaOXA–23 genes along with biofilm-related genes (ompA, bap, and csuE) was statistically associated with the biofilm-forming abilities. Impressively, both gallic and cinnamic acids could significantly reduce the MDR A. baumannii biofilms with variable degrees dependent on the phenotype–genotype characteristics of the tested isolates. The current findings may possess future therapeutic impact through augmenting antimicrobial arsenal against life-threatening infections with MDR A. baumannii biofilms.
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