International Journal of Microbiology最新文献

Background: The rising incidence of multidrug resistance and drug toxicity has prompted the search for complementary and alternative treatments for bacterial infections.

Objective: This study aimed to screen for the phytochemical present in Psidium guajava leaves, to determine the antibacterial potential of P. guajava leaves, and to compare the effectiveness of the P. guajava leaves against current antibiotics.

Methods: Dried pulverised P. guajava leaves were macerated using different solvents and then concentrated using a rotary evaporator. The extracts were screened for phytochemicals, namely, saponins, alkaloids, tannins, flavonoids, phenols, steroids and terpenoids, according to standard testing procedures. Antibacterial discs were prepared by soaking 6-mm sterile filter paper discs in different concentrations of the various extracts. Antibacterial susceptibility testing was done using the Kirby-Bauer disc diffusion method.

Results: Phytochemical screening confirmed the presence of all tested phytochemicals in Psidium guajava leaf extracts. The ethyl acetate extract (EAE) demonstrated significant antimicrobial activity at 100 mg/mL, showing large zones of inhibition (ZOIs) against Staphylococcus aureus (22.0 ± 6.1 mm), Escherichia coli (16.3 ± 0.9 mm) and Pseudomonas aeruginosa (15.0 ± 0.0 mm). The ethanolic extract (EE) also showed strong activity, with significant ZOI against Klebsiella pneumoniae (22.0 ± 4.3 mm) and P. aeruginosa (14.0 ± 1.0 mm). ZOI for the 100 mg/mL extracts against S. aureus were significantly larger than those for ceftazidime (19 mm), while those against P. aeruginosa exceeded tetracycline (9 mm) (p = 0.001). The MIC results confirmed the strength of the EE, with the lowest values: 3.1 mg/mL against K. pneumoniae ATCC and 6.3 mg/mL against S. aureus, E. coli and P. aeruginosa, possibly due to the presence of saponins.

Conclusions: P. guajava leaves contain many phytochemicals which in turn possess great antibacterial activity and therefore have great potential as a novel complementary and alternative treatment to antibiotics.

Leprosy, one of the oldest diseases, is caused by Mycobacterium leprae and Mycobacterium lepromatosis and continues to pose a significant global public health challenge despite decades of control efforts and the widespread use of multidrug therapy. Clinical manifestations range from tuberculoid to severe lepromatous forms, often accompanied by immune-mediated inflammatory reactions. The disease exhibits a long incubation period, high infectivity, and complex immune-mediated pathology, complicating timely diagnosis and management. Although multidrug therapy comprising rifampicin, dapsone, and clofazimine remains the mainstay treatment recommended by the World Health Organization for leprosy and has proven to be highly effective in managing both multibacillary and paucibacillary forms, the treatment outcomes are hindered by drug resistance, adverse drug reactions, and poor adherence. Resistance primarily arises from genetic mutations in drug target genes such as rpoB, folP1, and gyrA, with additional contributions from efflux mechanisms and cell wall impermeability. This narrative review draws upon a comprehensive search of electronic databases to enhance understanding of the genetic mutations associated with drug resistance. It further highlights ongoing research into resistance mechanisms, novel therapeutic options, postexposure prophylaxis, and vaccine development, which are critical for sustaining the effectiveness of multidrug therapy and advancing global leprosy control efforts.

Slaughterhouses are aimed at controlling organic matter and pathogens during animal processing; however, wastewater discharge often introduces microorganisms into the environment. This investigation focused on the isolation and characterization of thermotolerant Escherichia coli strains exhibiting pathogenicity, multidrug resistance, and biofilm-forming capacity from wastewater collected at the Kaptan Bazar slaughterhouse in Dhaka, Bangladesh. Seventy E. coli isolates were identified using selective culture media (MacConkey and eosin methylene blue agar) and PCR targeting the uidA gene. Antibiotic susceptibility was assessed using the Kirby-Bauer and modified Hodge methods. Biofilm formation was evaluated through the crystal violet assay. The presence of antibiotic resistance, virulence, and biofilm-associated genes was determined by conventional PCR. The most common virotypes were EIEC (7.14%), followed by ETEC (2.86%) and EHEC (1.43%). Extended-spectrum β-lactamase (ESBL) genes blaTEM (6.94%) and blaCTX-M-15 (2.78%) were detected. Carbapenem resistance genes included blaIMP-1 (3.70%), blaIMP-4 (1.85%), blaOXA-48 (21.76%), blaOXA-47 (0.46%), and blaOXA-1 (1.39%). Eleven isolates tested positive for carbapenemase production via the modified Hodge test. Non-β-lactam resistance genes detected included dfrA17 (25.46%), tetA (13.89%), sul2 (6.48%), qnrS (6.48%), and qnrB (3.24%). Class 1 integrons were present in 16 strains (22.86%), while both Class 2 and 3 integrons were absent. Colistin MIC values ranged from ≤ 0.5 to 2 μg/mL. Plasmid analysis showed that 59 isolates (84.29%) carried plasmids ranging in size from > 500 bp to > 10 kb. The crystal violet assay indicated that 74.29% of the isolates were biofilm producers, with 68.57% forming weak biofilms. Most weak biofilm formers and all moderate biofilm formers carried multiple antibiotic resistance genes. The results underscore a significant presence of antimicrobial-resistant and biofilm-producing E. coli in slaughterhouse effluents, highlighting the potential dissemination of ARGs into the surrounding ecosystem and food chains, posing a serious public health risk. The evidence also points to the urgent necessity for enhanced hygiene and treatment protocols to mitigate environmental and public health risks.

Antibiotics are molecules produced by a microbe to inhibit the growth of another microbe. Due to prolonged improper use, the situation in which these antibiotics do not work effectively on these microbes is termed antibiotic resistance or antimicrobial resistance (AMR). Aquaculture farming is one of the major industries in the world today due to the increasing consumption of seafood. Major antibiotics used in aquaculture farms include oxytetracycline, amoxicillin, ciprofloxacin, and azithromycin. The review paper has focused on the types and modes of action of major antibiotics, the mechanism of AMR, the dissemination of AMR in the ecosystem, and their impacts on human health. Moreover, it summarized the use of various antibiotics in aquafarms in Bangladesh and in different countries of the world. Due to the extensive use of these antibiotics, AMR has become a concerning public health issue all over the world. The article also tried to provide insights into the mechanisms of AMR of various pathogenic bacteria, which will help to develop new or modified antibiotics to fight against AMR. The knowledge regarding the rate of resistance and sensitivity of different antibiotics is essential and will provide baseline information for the treatment of these pathogenic bacteria.

Intestinal microbiota plays a crucial role in host physiological adaptation, though research on the characteristics of intestinal microbiota in the endangered great bustard Otis tarda has been initiated, with prior studies focusing on gut microbial composition, diversity dynamics, and the impacts of captivity and overwintering periods. Comprehensive insights into geographical differences and short-term temporal dynamics across diverse habitats remain limited. Here, we used fecal environmental (eDNA) metabarcoding to investigate the geographical differences and temporal dynamics of the intestinal microbiota in great bustards from Hebei (HB), Inner Mongolia Autonomous Region (NMG), and Shaanxi (SX) provinces of China, with temporal sampling in two sites (the confluence area of the Yellow River and the Weihe and the Luohe rivers) of SX during December 2024-March 2025. Results revealed that the great bustard intestinal microbiota was dominated by Firmicutes, Proteobacteria, and Bacteroidota at the phylum level, with core genera including Lachnoclostridium, Subdoligranulum, and Blautia. Significant geographical divergence was observed in the NMG population (grassland habitat), which exhibited a unique enrichment of Verrucomicrobiota (especially Akkermansia), while SX (farmland) and HB populations were dominated by Firmicutes. Temporal dynamics in SX showed fluctuations in microbial diversity and composition, which may be linked to temporal dietary shifts in winter (inferred from habitat vegetation characteristics, as direct diet measurement was not conducted). Functional predictions indicated conserved metabolic functions across populations, with variations in genetic information processing and environmental adaptation-related functions. These findings highlight that the great bustard's intestinal microbiota may be shaped by habitat-specific factors (i.e., diet and environment, inferred from habitat type) and temporal changes, providing insights into putative microbial mechanisms underlying the ecological adaptation of the endangered great bustard O. tarda. This study contributes to understanding host-microbiota interactions in endangered avians and supports evidence-based conservation strategies.

Water is essential for human survival and socioeconomic development, yet its overconsumption threatens global food security and ecosystem integrity. This necessitates a 60% increase in food production, further straining water resources. Hydroponic systems represent a promising solution, utilizing up to 90% less water than traditional methods while providing optimal growing conditions for crops. This study was aimed at developing a PCR-based detection system for main human and plant pathogens in hydroponic systems using treated domestic wastewater. Metagenomic analysis of wastewater samples revealed significant microbial diversity, identifying human pathogens such as Pseudomonas aeruginosa and Yersinia enterocolitica, alongside plant pathogens including Rhodococcus fascians. Specific primer pairs for the most abundant species found in a domestic municipal wastewater sample of target pathogens (Streptococcus mutans, P. aeruginosa, Acinetobacter baumannii, Y. enterocolitica, Enterococcus faecalis, Pseudomonas viridiflava, R. fascians, Xanthomonas vesicatoria, and Pseudomonas syringae) were designed and validated, ensuring high specificity and efficiency. Future research should focus on enhancing detection methods and optimizing DNA extraction techniques to improve pathogen quantification and management in hydroponic systems. This approach is crucial for sustainable agricultural practices that minimize water usage while ensuring food safety and environmental health.

Background: Diarrheal disease remains a major cause of morbidity and mortality in children under 5 years, with the highest burden in sub-Saharan Africa. This study investigated the bacterial etiology, antimicrobial resistance (AMR), and risk factors in childhood diarrhea in Nairobi, Kenya.

Methods: A cross-sectional study was conducted among 216 children aged 0-60 months presenting with diarrhea at hospitals in Nairobi County. Stool samples were cultured and isolates tested against eight antibiotics. Caregiver questionnaires assessed risk factors. Associations were evaluated using Fisher's exact test and odds ratios (ORs) were calculated to determine effect sizes.

Results: A total of 204 bacterial isolates were recovered. Escherichia coli was the most frequent (38.2%), followed by Shigella sonnei (11.8%) and Enterobacter cloacae (9.8%). The overall prevalence of enteric bacterial infection was 94.4%. Key risk factors significantly associated with infection included the absence of consistent soap availability (OR: 7.4, 95% CI: 3.7-15.0), visible poor sanitation (OR: 4.8, 95% CI: 1.7-13.8), and lack of safe drinking water (OR: 12.9, 95% CI: 1.7-98.9). AMR was widespread, with 82.8% of isolates resistant to at least one antibiotic and 58.3% classified as multidrug-resistant (MDR). High resistance to ampicillin and amoxicillin-clavulanic acid was common, exceeding 70% in key pathogens like E. coli and E. cloacae. In contrast, meropenem, amikacin, gentamicin, and ciprofloxacin retained near-complete efficacy.

Conclusion: Childhood diarrhea in Nairobi is predominantly bacterial, driven by diverse pathogens and exacerbated by poor hygiene and alarmingly high AMR. Urgent integrated interventions are needed, including strengthening WASH infrastructure, promoting rational antibiotic use, and enhancing AMR surveillance. These findings provide a critical baseline for public health action and underscore the need to safeguard last-line antibiotics.

The associated microorganisms ("microbiome") of multicellular individuals ("host") are important for the physiology and survival of the host. Individual bacterial species vary in environmental tolerances that may limit their associations with hosts, especially when their range of survivable conditions is narrower. To elucidate the roles for different environmental niche spaces of bacteria that may compose the microbiome, we evaluated the survival and growth of individual and combinations of bacteria with and without an animal host, the sea anemone Nematostella vectensis (Cnidaria, Anthozoa). We assessed 62 environmental bacteria from seven genera (Alteromonas, Bacillus, Grimontia, Photobacterium, Pseudoalteromonas, Shewanella, and Vibrio) isolated from six estuaries and the host to determine their tolerance across a gradient of temperatures (30°-40°C) and salinities (5-30 ppt). Growth rates and plate counts revealed members of the Vibrio genus had the highest growth rate at higher salinities (15 and 30 ppt), while Bacillus and Alteromonas spp. exhibited consistent growth over a broader range of salinities and temperatures. Only 15% of isolates were capable of growth at the combination of highest temperature and lowest salinity (40°C, 5 ppt), suggesting that these environmentally relevant conditions may limit microbiome diversity. We further assessed three isolates (Bacillus velezensis, Pseudoalteromonas spiralis, and Vibrio diabolicus) for how bacterial growth changed when associated with N. vectensis. When anemones were exposed to environmentally relevant heat stress over 3 days, bacterial concentrations varied significantly. P. spiralis grew more under lower salinities and maintained stable concentrations. Conversely, V. diabolicus grew more with higher salinity and maintained these high concentrations in nearly all conditions. At sustained extreme temperatures for the anemones, the microbial composition exerted a small impact on survival. Together, these results support that environmental conditions are important drivers for the relative abundance of particular bacteria in the context of the host's microbiome.

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) was first reported in Western Australia (WA) in the 1990s. Although ST8-IVa [2B] (WA-5) was the first identified CA-MRSA in WA, ST1-IVa [2B] (WA-1) soon emerged as the dominant clone. To investigate the genomic epidemiology of clonal complex (CC) CC1 S. aureus in WA Aboriginal communities from 1995 to 2003 and assess the acquisition and diversity of the SCCmec element, whole genome sequencing was performed. Three sequence types (STs) were identified: ST1 (81.4%), ST761 (0.9%) and ST762 (17.8%). MRSA constituted 78% (n = 92) of the collection and all harboured SCCmec Type IVa [2B]. Panton-Valentine leukocidin (PVL)-encoding genes were identified in seven closely related isolates. The phylogenetic tree topology suggests the acquisition of the same SCCmec IV into the CC1 lineage occurred on two occasions. Bayesian coalescence analysis predicts the CC1 S. aureus lineage originated in WA more than 150 years ago. Dissemination of the CC1 S. aureus lineage, as well as the horizontal acquisition of SCCmec IV, may have been aided by the concurrent movement of Aboriginal inhabitants across different remote communities.

Introduction: Human parainfluenza viruses (HPIVs) are significant causes of respiratory infections, particularly in children, yet their epidemiology remains poorly understood in low- and middle-income countries. HPIVs contribute to 20%-40% of pediatric lower respiratory tract infections (LRTIs) and are a leading cause of croup and hospitalizations. This study was aimed at determining the incidence, distribution, and clinical and laboratory characteristics of HPIV in hospitalized acute febrile illness (AFI) patients.

Methods: A total of 12,409 AFI cases from 2016 to 2018 were tested for HPIVs via molecular methods. RNA was extracted from throat swab samples and tested via multiplex real-time RT-PCR for HPIV Serotypes 1-4. The demographic, clinical, and laboratory data of HPIV-positive patients were analyzed statistically.

Results: HPIVs were detected in 217 (1.75%) patients, with HPIV-3 (49.77%) being the most prevalent, followed by HPIV-4 (18.90%), HPIV-2 (17.52%), and HPIV-1 (13.83%). HPIV-3 exhibited distinct seasonal peaks, mainly affecting children (1-9 years). Significant variations in hematological and biochemical markers were observed among serotypes and age groups. Upper and lower respiratory symptoms, along with gastrointestinal issues and systemic manifestations such as chills, myalgia, and weakness, are commonly reported.

Conclusion: HPIVs contribute to respiratory illness across diverse demographics. HPIV-3 is the predominant serotype, with distinct seasonal and age-related patterns. Improved surveillance and diagnostics could aid in better management and reduce unnecessary antibiotic use.