International Journal of Microbiology最新文献

Objective(s): Multidrug-resistant bacteria and priority pathogens, including MRSA, are frequently found in hospital wastewaters. It is crucial to investigate the genetic diversity, biofilm formation, and virulence analysis of Staphylococcus aureus isolated from hospital wastewaters. Materials and Methods: In this cross-sectional study, 70 S. aureus isolated from hospital wastewaters were subjected to characterization through antimicrobial susceptibility tests, biofilm formation, multilocus sequence typing (MLST), and PCR analysis for detecting resistance (mecA, mecC, vanA, vanB, mupB, mupA, msr(A), msr(B), erm(A), erm(B), erm(C), tet(M), ant (4⁣')-Ia, aac (6⁣')-Ie/aph (2⁣^″), and aph (3⁣')-IIIa) and virulence genes (eta, etb, pvl, and tst). Results: Our results showed that 55.7%, 31.4%, and 12.9% of isolates were classified as strong, intermediate, and weak biofilm-forming strains, respectively. Our result revealed that about three-quarters of isolates harbored mecA (100%), ant (4⁣')-Ia (100%), tet(M) (92.9%), erm(B) (80%), and msr(A) (74.3%) resistance genes. MLST revealed that the 70 isolates belonged to five clonal complexes, including CC8 (52.9%), followed by CC30 (15.7%), CC5 (14.3%), CC1 (11.4%), and CC22 (5.7%). The vast majority of S. aureus isolates belonged to CC8/ST239-MRSA (21.5%). Among the 39 strong biofilm producers, the majority (25.6%) belonged to CC8/ST239-MRSA clone. Our result revealed that about one-third of Panton-Valentine leukocidin (PVL)-positive strains belonged to CC30/ST30. The high-level mupirocin-resistant (HLMUPR) isolates belonged to CC8/ST239-MRSA (36%), CC30/ST30-MRSA (16%), CC8/ST8-MRSA (12%), CC5/ST5-MRSA (12%), CC8/ST585-MRSA (8%), CC5/ST225-MRSA (8%), CC5/ST1637-MRSA (4%), and CC8/ST1465-MRSA (4%) lineages carrying mupA. The VRSA strain belonged to the CC8/ST239-MRSA, CC8/ST8-MRSA, and CC22/ST22-MRSA clonal lineages, carrying the vanA determinant. Conclusion: These findings highlight significant genotypic diversity and high biofilm formation among our isolates. From this study, we identified highly virulent strains of S. aureus associated with biofilm production and drug resistance; some of these strains were highly similar, highlighting the possibility of rapid spread. The high prevalence of CC8 and CC30 clones among S. aureus strains reflects the emergence of these lineages as successful clones in hospital wastewaters in Iran, which is a serious concern. The study highlights the importance of wastewater surveillance to understand genetic pattern and antimicrobial resistance profiles in surrounding communities, which can in turn support public health efforts.

The escalating threat of infectious diseases, exacerbated by antimicrobial resistance (AMR) and biofilm formation, necessitates innovative therapeutic strategies. This review presents a comprehensive exploration of the potential of nanoparticles synthesized from natural sources, including plant extracts, microbial products, and marine compounds, as antimicrobial agents. These naturally derived nanoparticles demonstrated significant antibiofilm and antivirulence effects, with specific examples revealing their capacity to reduce biofilm mass by up to 78% and inhibit bacterial quorum sensing by 65%. The integration of bioactive compounds, such as polyphenols and chitosan, facilitates nanoparticle stability and enhances antimicrobial efficacy, while green synthesis protocols reduce environmental risks. Notably, the review identifies the potential of silver nanoparticles synthesized using green tea extracts, achieving 85% inhibition of polymicrobial growth in vitro. Despite these promising results, challenges such as standardization of synthesis protocols and scalability persist. This study underscores the transformative potential of leveraging naturally sourced nanoparticles as sustainable alternatives to conventional antimicrobials, offering quantitative insights for their future application in combating mono- and polymicrobial infections.

Bacterial resistance to antibiotics is increasing globally, with the food-animal sector (FAS) playing a key role. Knowledge of the antimicrobial resistance (AMR) of microbes from the FAS is important in the development of country-specific methods to minimize the AMR burden. In Ghana, there is limited data on the susceptibility of FAS bacteria to frequently used antimicrobials. We evaluated the susceptibility of 58 Escherichia coli isolates obtained from chickens to nine antibiotics and further assessed their potential to produce extended-spectrum beta-lactamase (ESBL). The Kirby-Bauer disc diffusion and combined disc methods were used following the Clinical and Laboratory Standards Institute guidelines. Nearly all isolates showed high resistance (> 50%) to all the antibiotics except gentamicin, to which more than two-thirds (n = 48, 83%) were susceptible. Resistance to streptomycin, tetracycline, and ampicillin was observed to be 93%, 97%, and 100%, respectively. All isolates were multidrug resistant. Over one-third of the isolates (n = 22, 37.9%) were resistant to seven classes of antibiotics, and a substantial proportion (n = 12, 20.7%) exhibited resistance to all eight antimicrobial classes. None of the isolates was detected as an ESBL producer. Most farms (86%) did not have a footbath, and the majority (71%) changed the bedding material after 4 weeks. Free-range chickens were kept on 80% of the farms. The high resistance to frequently used antibiotics suggests long-term use of these antimicrobials, which may be attributed to poor biosecurity practices that may be exposing the birds to frequent infections. There is a need to educate farmers on the prudent use of antibiotics and adherence to good biosecurity practices.

The major challenge in large-scale industrial use of lipopeptide surfactin is the low yield by indigenous bacterial strains and the higher cost of its production that have been proved as a limiting factor in commercial applications. Therefore, there is an urgent demand for high-yielding strains that can be achieved through strain improvement. A first report on the use of a combination of UV and gamma-irradiation mutagenesis for the development of surfactin hyperproducing mutants of Bacillus spp. proved to be significant and resulted in a twofold enhancement in surfactin yield. The mutant was able to grow and produce surfactin on all the tested carbon and nitrogen sources, while 2% glycerol favored maximum surfactin yield (1.62 g/L) as compared to the wild-type strain that showed a maximum 0.85 g/L surfactin yield at 3% sucrose. Additionally, the mutant exhibited a good yield of pure surfactin, that is, 1.55 g/L as compared to the wild strain (0.411 g/L) by using corn steep liquor as the main component of the fermentation medium. The study concluded overall a threefold enhancement in the relative abundance of purified surfactin and its isoforms detected by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) analysis in mutant strain AF-UVγ2500.

Latent tuberculosis is characterized by the presence of dormant, nonreplicating (DNR) bacilli for years without causing clinical signs and symptoms, remaining as a major reservoir for active tuberculosis. The mechanism through which M. tuberculosis transits from DNR to active bacilli remains unclear. However, resuscitation-promoting factors (Rpfs) could participate in the reactivation. Using recombinant M. bovis BCG that expresses rpfC (M. bovis BCG-pMV261::rpfC), we evaluated the role of RpfC in the growth of bacilli and the expression of 11 hypoxia-regulated genes in comparison with M. bovis BCG-pMV261. The strains were grown in normoxic (21% O₂), hypoxic (5% O₂), and anoxic (< 0.1% O₂) conditions. In normoxic culture, M. bovis BCG-pMV261::rpfC displays a lower expression of sigB and fdxA. In anoxic culture, we did not observe drastic changes in the gene expression, except for those involved in electron transport during anaerobic respiration (pdxA, pfkB, and nark2), whose expression was significantly lower in M. bovis BCG-pMV261. When the strains were cultured in hypoxia, significantly higher culturability was observed in M. bovis BCG-pMV261::rpfC compared to M. bovis BCG-pMV261. This response was accompanied by a higher sigB and sigE expression. In both strains, we observed a higher dosT, devR, fdxA, and fpkB expression in response to hypoxia. Interestingly, except for fdxA, the expression of these genes was lower in M. bovis BCG-pMV261::rpfC. The protein profiles of M. bovis BCG-pMV261::rpfC reflected the maintenance of an active replicative state (similar to that of the strain grown in normoxic conditions). In anoxic cultures, no significant changes were observed in the expression of hypoxia-response genes. These findings suggest that rpfC may have a significant physiological role in inducing the growth of M. bovis BCG-pMV261::rpfC, which results in the delayed activation of genes related to the transition to anaerobic metabolism.

Background: Acinetobacter baumannii has become a significant problem in hospitals worldwide during the last decades. Biofilm formation is a virulence factor that may affect antibiotic resistance. This study aimed to elucidate the correlation between biofilm formation and biofilm-related and oxacillinase genes in A. baumannii clinical isolates. Methods: This study was conducted on 53 A. baumannii isolates collected from hospitals affiliated with Babol University of Medical Sciences (Babol, Iran) from April to October 2023. Kirby-Bauer disc diffusion was used to determine antibacterial resistance. Biofilm formation was examined using crystal violet staining. Polymerase chain reaction was used to detect oxacillinase (bla _OXA-23, bla _OXA-24, bla _OXA-51, and bla _OXA-58) and biofilm-encoding (bap and bla _PER-1) genes using specific primers. Results: The strains showed the highest resistance to trimethoprim/sulfamethoxazole and ciprofloxacin (98.11%) and the lowest resistance to ampicillin/sulbactam (66.03%). All isolates formed biofilms. Also, 67.92%, 18.86%, and 11.32% were strong, moderate, and weak biofilm producers, respectively. The frequencies of bla _OXA-23, bla _OXA-24, bla _OXA-51, bap, and bla _PER-1 genes were 92.45%, 71.69%, 100%, 73.58%, and 58.49%, respectively. None of the isolates harbored bla _OXA-58. Conclusions: A high prevalence of antibiotic-resistant strains was found among A. baumannii clinical isolates. There was no significant correlation between the clinical sample type and biofilm formation, but a notable link was found between antimicrobial resistance and biofilm formation, except for ciprofloxacin. Oxacillinase genes were not significantly correlated with biofilm formation, but biofilm production was associated with bap rather than bla _PER-1. Understanding the A. baumannii biofilm formation process is crucial for effective control of associated infections by targeting this mechanism.

Background: Tuberculosis (TB) is among the leading causes of morbidity and mortality in resource-limited countries. The burden of TB varies from country to country, depending on the country's condition and the effort made to prevent its transmission. The magnitude of pulmonary TB and drug resistance in eastern Ethiopia is mainly unknown due to limited information. Objective: This study aimed to determine the prevalence of pulmonary TB and rifampicin-resistant Mycobacterium tuberculosis and factors associated with pulmonary TB. Methods: A hospital-based prospective cross-sectional study was conducted among 424 presumptive TB patients who attended Adama Hospital Medical College from January 10, 2023, to November 10, 2023. Sputum (gastric lavage for children) was collected and diagnosed using the Ziehl-Neelsen (ZN) staining method and GeneXpert. A structured questionnaire was used to collect sociodemographic and clinical data. SPSS Version 20 computer software was used for data analysis. A variable with a p value less than 0.05 was considered statistically significant. Results: The prevalence of the ZN staining method and GeneXpert-confirmed TB was 160 (37.7%), 95% CI: 33-42.7 and 189 (44.6%), 95% CI: 39.8-49.5, respectively. Of the study participants, nine (2.1%) were infected with rifampicin-resistant M. tuberculosis. Out of the 189 confirmed TB cases, 4.7% were infected with rifampicin-resistant gene-positive M. tuberculosis. Gender-male (AOR = 1.47 [0.95-2.26], p=0.081), history of contact with TB patient (AOR = 7.19 [2.55-20.25], p < 0.001), previously treated TB patients (AOR = 3.11 [1.49-6.50], p=0.003), and smoking cigarette (AOR = 14.8 [1.88-117], p=0.010) were significantly associated with GeneXpert-confirmed pulmonary TB. Conclusion: The prevalence of pulmonary TB was high, with a moderate proportion of rifampicin-resistant gene-carrying M. tuberculosis in the study area. Being male, having a history of contact with TB patients, having a history of infection with TB, and smoking cigarettes were significant predictors of pulmonary TB.

Antimicrobial-resistant Escherichia coli, especially those belonging to the serotype O157, are increasingly linked to foodborne diseases with significant fatality rates worldwide. The food and medical industries have focused on E. coli O157:H7 due to its ability to produce toxins coupled with its low infectious dose. The aim of this study was to assess the virulome, resistome, and pathogenicity of E. coli O157:H7 using whole genome sequencing. Three previously isolated E. coli O157:H7 strains from cattle feces were subjected to whole genome sequencing. The genome sizes of all three E. coli O157:H7 strains were 5,117,276 bp, 5,039,443 bp, and 5,034,351 bp. The C + G contents were 50.22%, 50.53%, and 50.54%, while the number of contigs was 110, 43, and 42, respectively, for E. coli O157:H7 strains J32, J57, and J69. Several virulence determinants (hemorrhagic E. coli pilus (HCP), eaeA, hemolysin, etc.) were found in the genomes of these isolates. In addition, antibiotic resistance genes conferring resistance to aminoglycosides, tetracyclines, macrolides, fluoroquinolones, penams, carbapenems, cephalosporins, cephamycin, rifamycin, phenicols, monobactams, and nitroimidazole were found in the genomes. Interestingly, the genomes of these isolates also harbored determinants encoding resistance to disinfectants and antiseptics, indicating their concern in the food production and medical sectors. This highlights the public health concerns of these isolates, indicating the need for constant surveillance.

Introduction: Individuals with diabetes are more susceptible to urinary tract infections (UTIs) than those without the disease. This study aimed to determine the phenotypic and genotypic antibiotic resistance profiles of Escherichia coli in diabetic and nondiabetic patients. Methodology: A total of 374 clean-catch midstream urine specimens were screened for uropathogens, and antibiogram analysis was done on E. coli isolates by the Kirby-Bauer disc diffusion method, followed by phenotypic confirmation of extended spectrum beta-lactamase (ESBL) production. In addition, polymerase chain reaction (PCR) assays were carried out to determine ESBL genotypes. Result: Overall, we observed UTIs prevalence of 19.8% and 10.7% in diabetic and nondiabetic patients. Females exhibited higher UTI prevalence than males in both groups ([71.8% and 28.2%] vs. [85% and 15%]) (p < 0.0001). Among women with and without diabetes, the age groups of 55-64 and 25-34 years showed the highest prevalence of UTIs (25.6% vs. 40%). The most prevalent uropathogen was E. coli (62.2% vs. 75%); multidrug-resistant (MDR) E. coli was (61% vs. 33.3%) and ESBL-E. coli was (34.8% and 20%) in diabetic and nondiabetic patients, respectively. The most common ESBL-mediated gene was blaCTX-M (64.3%) with multiple ESBL genes in some E. coli isolates. High-level resistance was observed for ampicillin (91.2%), cefuroxime (96.7%), ciprofloxacin (44.9%), and trimethoprim (59.4%), and low-level resistance was observed for gentamicin (18.7%), ceftriaxone (20.9%), and nitrofurantoin (19.8%). There was no significant difference between antibiotic resistance in diabetic and nondiabetic patients (p > 0.05). Conclusion: We observed blaCTX-M as the most common ESBL genotype, in combination with other ESBL genes present in some E. coli isolates. Nitrofurantoin and ceftriaxone antibiotics were efficacious. Appropriate prescription of antibiotic therapy, and the prevention of transmission of resistant genes in the context of public health can be facilitated by routine monitoring of the resistance profiles and ESBL markers in patients with and without diabetes.

Staphylococcus aureus (S. aureus) is a Gram-positive bacterium capable of causing a range of infections and displaying significant antibiotic resistance. S. aureus can exhibit resistance to multi-antibiotics, particularly penicillin, methicillin, linezolid, and daptomycin. The prevalence of methicillin-resistant S. aureus (MRSA) ranges from 10%-50% in China and Russia, neighboring countries of Mongolia. This study aimed to assess S. aureus contamination in raw beef samples and surface swabs from meat-processing areas and markets, while detecting, as well as to detect virulence and resistance genes in the isolates. A total of 156 raw beef samples and 131 surface swabs were collected and analyzed using ISO 6888-1:2021 standards. The nucA gene specific to S. aureus was amplified by PCR, and antibiotic susceptibility was evaluated using the Kirby-Bauer disk diffusion method. Resistance genes (mecA, mecC, vanA, and vanB) and virulence genes (sea, sed, tsst, eta, and etb) were detected via PCR. The results showed contamination rates of 26.9% in raw beef and 15.3% in surface swabs. The isolates exhibited high resistance to oxacillin, ampicillin, and penicillin in meat samples and to oxacillin, tetracycline, azithromycin, and clindamycin in surface swabs. No resistance genes for vancomycin or methicillin (mecC, vanA, vanB) were detected. Virulence genes, including tsst (14.5%), sea and etb (9.7%), eta (3.2%), and sed (1.6%), were identified. Contamination was more prevalent in centers responsible for both transportation and sales, compared to meat-processing areas. These findings highlight the need for stricter hygiene and handling practices in meat transport and markets to reduce S. aureus contamination and limit the spread of resistant strains.