International Journal of Microbiology

Surfactants are utilized to reduce surface tension in aqueous and nonaqueous systems. Currently, most synthetic surfactants are derived from petroleum. However, these surfactants are usually highly toxic and are poorly degraded by microorganisms. To overcome these problems associated with synthetic surfactants, the production of microbial surfactants (called biosurfactants) has been studied in recent years. Most studies investigating the production of biosurfactants have been associated mainly with bacteria and yeasts; however, there is emerging evidence that those derived from fungi are promising. The filamentous fungi ascomycetes have been studied for the production of biosurfactants from renewable substrates. However, the yield of biosurfactants by ascomycetes depends on several factors, such as the species, nutritional sources, and environmental conditions. In this review, we explored the production, chemical characterization, and application of biosurfactants by ascomycetes.

Endophytic bacteria isolated from medicinal plants are recognized valuable sources of novel bioactive compounds with various activities such as antimicrobial, anticancer, and antiviral. In this study, eleven bacterial endophytes were isolated from surface sterilized roots and leave tissues, of medicinal plant Dicoma anomala. The bacterial endophytes were identified by sequencing the 16S rRNA gene, and belong to five genera viz Bacillus, Staphylococcus, Stenotrophomonas, Enterobacter, and Pantoea. The dominant genera were Bacillus with five strains, Staphylococcus with two strains, and Stenotrophomonas with two strains. The crude extracts of seven selected bacterial endophytes indicated antimicrobial activity against five pathogenic strains Escherichia coli (ATCC 25922), Bacillus cereus (ATCC 10876), Staphylococcus aureus (NCTC 6571), Pseudomonas aeruginosa (ATCC 27853), and Klebsiella oxytoca (ATCC 13182), with significant inhibition concentration ranging from 0.312 mg/ml to 0.625 mg/ml. Finally, based on the data analysis of the crude extracts of the endophytes, we identified bioactive secondary metabolites with reported biological activities such as antimicrobial, anti-inflammatory, and antioxidant properties with biotechnological applications in medicine, agriculture, and other industries. This study reported for the first time bacterial endophytes associated with D. anomala, with antimicrobial activity against bacterial pathogens.

Shiga toxin-producing Escherichia coli (STEC) serogroups O157, O26, O103, O111, O121, O145, and O45 are designated as food adulterants by the U.S. Department of Agriculture-Food Safety and Inspection Service. Cattle are the primary reservoir of these human pathogens. In this study, 59 Angus crossbred heifers were tested specifically for these seven STEC serogroups using a combination of standard culture, serological, PCR, and cell cytotoxicity methods to determine if comparable results would be obtained. At the time of fecal sampling, the animals were approximately 2 years old and weighed 1000–1200 lbs. The diet comprised of 37% ground alfalfa hay, 25% ground Sudan hay, and 38% ground corn supplemented with trace minerals and rumensin with ad libitum access to water. Non-O157 STEC were isolated from 25% (15/59) of the animals tested using a combination of EC broth, CHROMagar STEC^TM, and Rainbow Agar O157. Interestingly, the O157 serogroup was not isolated from any of the animals. Non-O157 STEC isolates were confirmed to be one of the six adulterant serogroups by serology and/or colony PCR in 10/15 animals with the predominant viable, serogroup being O103. PCR using DNA extracted from feces verified most of the colony PCR results but also identified additional virulence and O-antigen genes from samples with no correlating culture results. Shiga toxin- (Stx-) related cytopathic effects on Vero cells with fecal extracts from 55/59 animals could only be associated with the Stx gene profiles obtained by fecal DNA PCR and not culture results. The differences between culture versus fecal DNA PCR and cytotoxicity assay results suggest that the latter two assays reflect the presence of nonviable STEC or infection with STEC not belonging to the seven adulterant serogroups. This study further supports the use of combinatorial culture, serology, and PCR methods to isolate viable STEC that pose a greater food safety threat.

The status of Salmonella and its antimicrobial susceptibility profile in animal origin food items from different catering establishments in Ethiopia is scarce. Hence, this study aimed to investigate the occurrence and antimicrobial susceptibility profile of Salmonella isolates from animal origin food items in the selected areas of Arsi Zone. One hundred ninety-two animal origin food samples were collected and processed for Salmonella isolation. Isolates were tested for their susceptibility to 13 antimicrobials using Kirby–Bauer disk diffusion assay. An overall prevalence of 9.4% (18/192) Salmonella spp. isolates were recovered from animal origin food samples collected from different catering establishments. Seven (21.9%) of “Dulet,” 4 (12.5%) of “Kitfo,” 3 (9.4%) of “Kurt,” 2 (6.3%) of raw milk, 1 (3.1%) of egg sandwich and 1 (3.1%) of cream cake samples were positive for Salmonella. Catering establishments, protective clothing, source of contamination, manner of hand washing, and money handling were among the putative risk factors that were significantly associated () with Salmonella spp. occurrence. Ampicillin, nitrofurans, and sulphonamide resistance were significantly associated () with Salmonella spp. occurrence in the selected food items. Three (16.7%), 5 (27.8%), 5 (27.8%), and 4 (22.2%) of the isolates were resistant to 3, 4, 5, and 6 antibiotics, respectively, whereas only a sole isolate was resistant to two antibiotics (viz. ampicillin and kanamycin). In conclusion, the general sanitary condition of the catering establishments, utensils used, and personnel hygienic practices were not to the recommended standards in the current study. Besides, detection of multidrug-resistant strains of Salmonella in animal origin food items from different catering establishments suggests the need for detailed epidemiological and molecular characterization of the pathogen so as to establish the sources of acquisition of resistant Salmonella strains. Hence, implementation of Salmonella prevention and control strategies from farm production to consumption of animal origin food items are crucial.

Background. Antimicrobial resistance especially caused by extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-PE) has become a global public health concern. Globally, these isolates have remained the most important causes of several infections and associated mortality. Their rapid spread in Ethiopia is associated with a lack of regular surveillance and antibiotic stewardship programs. Isolates of ESBL-PE from different regions of Ethiopia were searched exhaustively. However, published data regarding the pooled estimate of ESBL-PE are not conducted in Ethiopia. For this reason, we systematically reviewed laboratory-based studies to summarize the overall pooled prevalence of the isolates recovered from various human specimens. Methods. An exhaustive literature search was carried out using the major electronic databases including PubMed, Web of Science, MEDLINE, EMBASE, CINAHL, Google Scholar, Cochrane Library, Scopus, and Wiley Online Library to identify potentially relevant studies without date restriction. Original articles which address the research question were identified, screened, and included using the PRISMA follow diagram. Data extraction form was prepared in Microsoft Excel, and data quality was assessed by using 9-point Joanna Briggs Institute critical appraisal tools. Then, data were exported to STATA 16.0 software for analyses of pooled estimation of outcome measures. Estimation of outcome measures at 95% confidence interval was performed using Der-Simonian-Laird’s random-effects model. Finally, results were presented via text, figures, and tables. Results. A comprehensive electronic database literature search has yielded a total of 86 articles. Among the total, 68 original articles were excluded after the review process. A total of 18 studies with 1191 bacterial isolates recovered from 7919 various clinical samples sizes were included for systematic review and meta-analysis. In this study, the pooled prevalence of ESBL-PE was 18% (95% CI: 9–26). Nine out of the total (50%) reviewed articles were studied using the combination disk test. Likewise, E. coli and K. pneumoniae (50% both) were the predominant isolates of ESBL-PE in addition to other isolates such as Salmonella spp. and Shigella spp. Conclusion. This meta-analysis has shown a low pooled estimate of ESBL-PE in Ethiopia.

The emergence of AmpC (pAmpC) β-lactamases conferring resistance to the third-generation cephalosporins has become a major clinical concern worldwide. In this study, we aimed to evaluate the expression of AmpC β-lactamase encoding gene among the pathogenic Gram-positive and Gram-negative resistant bacteria screened from clinical samples of Egyptian patients enrolled into El-Qasr El-Ainy Tertiary Hospital in Cairo, Egypt. A total of 153 bacterial isolates of the species Pseudomonas aeruginosa, Klebsiella pneumoniae, and Enterococcus faecium were isolated from patients diagnosed with urinary tract infection (UTI), respiratory tract infection (RTI), and wound infections. The total number of E. faecium isolates was 53, comprising 29 urine isolates, 5 sputum isolates, and 19 wound swab isolates, whereas the total number of P. aeruginosa isolates was 49, comprising 27 urine isolates, 7 sputum isolates, and 15 wound swab isolates, and that of the K. pneumoniae isolates was 51, comprising 20 urine isolates, 25 sputum isolates, and 6 wound swab isolates. Our results indicated that there is no significant difference in the expression of AmpC β-lactamase gene among the tested bacterial species with respect to the type of infection and/or clinical specimen. However, the expression patterns of AmpC β-lactamase gene markedly differed according to the antibacterial resistance characteristics of the tested isolates.