Bacteria, Volume 5, Issue 2 (June 2026) – 9 articles

Background: Antibiotic misuse and prescribing errors are significant concerns in clinical practice, contributing to unnecessary antibiotic exposure, increased adverse effects, rising healthcare costs, and the escalation of antibiotic resistance. Understanding the prevalence, patterns, and risk factors of these prescription errors is essential for improving patient safety and healthcare efficiency in the future. Aim: Our aim was to evaluate the prevalence, patterns, and risk factors of antibiotic prescription errors in Saudi Arabia. Methods: A comprehensive search of three databases (PubMed, Scopus and ProQuest) was conducted to identify eligible cohort and cross-sectional studies in Saudi Arabia published up to January 2025. Studies that reported on error rates of antibiotic prescription errors and those that did not provide quantitative data were excluded. The primary outcome was the prevalence and patterns of inappropriate antibiotic use, while the secondary outcomes included the pooled prevalence of specific errors (i.e., selection, dose, duration, etc.). The quality of the studies was assessed using the Newcastle–Ottawa scale. This review was registered in PROSPERO (CRD42024611747). Results: Fourteen eligible cohort (n = 2) and cross-sectional (n = 12) studies conducted in Saudi Arabia were included in the review. Two studies reviewed medical records and orders of patients. Patient selection varied from emergency department to intensive care units and outpatients. The pooled prevalence of antibiotic prescription errors was 42.7% [95% CI: 37.5–47.8], with common errors including dosage (29.3%), duration (24.3%), selection (15%) and frequency (11.1%) errors. However, there was a high heterogeneity among the results. Overall, the quality assessment revealed a low risk of bias, except for one study with a high risk of bias. Conclusion: These findings highlight the high prevalence of antibiotic prescription errors. Future efforts should strengthen antibiotic stewardship, enhance clinician training, and ensure adherence to evidence-based guidelines to reduce prescription errors and combat antibiotic resistance. Full article

Enterococcus lactis is increasingly recognized as an emerging mastitis pathogen, yet the functional basis of its virulence and associated health risks remain poorly defined. This study presents an integrated genomic and phenotypic characterization of E. lactis strain EL-A150 isolated from bovine subclinical mastitis. Whole-genome sequencing revealed a 2.49 Mb circular chromosome encoding multiple genes associated with adhesion (acm, bepA, fms, sagA), biofilm formation (empB, empC) and antimicrobial resistance, including determinants related to aminoglycosides and macrolides. Phenotypic assays demonstrated rapid growth, strong biofilm-forming capacity and high adhesion to bovine mammary epithelial cells, while internalization remained low and intracellular persistence was transient. Comparative genomic analyses confirmed the taxonomic placement of the strain within the E. lactis clade (ANI up to 99.5% against reference genomes) and revealed a limited resistome composed of chromosomally encoded genes, with no detectable plasmids or major mobile genetic elements. Collectively, these findings demonstrate that E. lactis EL-A150 possesses a coordinated set of traits conducive to intramammary colonization, supporting its classification as an opportunistic pathogen. The convergence of virulence potential and clinically relevant antimicrobial resistance within a single isolate underscores a One Health concern and highlights the need for surveillance frameworks that integrate functional validation with genomic risk assessment. Full article

Leuconostoc suionicum strain JNUCC 76 (=CH10) was isolated from cherry blossom flowers (Prunus yedoensis) collected on Jeju Island, Republic of Korea, representing a flower-associated strain of L. suionicum. To clarify its taxonomic position and genomic characteristics, whole-genome sequencing was performed using a hybrid PacBio–Illumina approach. The complete genome was assembled into a single circular chromosome of 2.20 Mb with a GC content of 36.8% and high sequencing depth, indicating a high-quality, closed genome assembly. Genome annotation revealed a compact gene repertoire dominated by functions related to carbohydrate transport and metabolism, amino acid utilization, and core cellular processes, consistent with adaptation to plant-derived, sugar-rich environments. Genome-based phylogenomic analyses using average nucleotide identity (ANI), digital DNA–DNA hybridization (dDDH), and Genome BLAST Distance Phylogeny (GBDP) placed strain JNUCC 76 within the species L. suionicum. Genome-based metrics clearly exceeded the accepted species thresholds, supporting the assignment of the strain to L. suionicum. Secondary metabolite gene cluster analysis identified a limited number of low-complexity and precursor-oriented biosynthetic gene clusters, including RiPP-like, type III polyketide synthase, and terpene-precursor clusters, suggesting that the ecological fitness of the strain relies primarily on primary metabolism rather than extensive secondary metabolite production. Overall, this study expands current knowledge of flower-associated Leuconostoc lineages and provides a high-quality genomic framework for future comparative and functional studies. The genomic features of strain JNUCC 76 highlight floral environments as underexplored reservoirs of lactic acid bacteria diversity and support further evaluation of flower-derived Leuconostoc strains as potential postbiotic or fermentation-based resources for cosmetic and related biotechnological applications. Full article

Iron (Fe) and zinc (Zn) are essential micronutrients for plant metabolism; however, their bioavailability in tropical soils is often limited by low solubility and complex mineral interactions. Root-associated bacteria may enhance micronutrient availability through siderophore production and the solubilisation of insoluble mineral forms. This study aimed to functionally characterise three bacterial isolates from rice roots—Bacillus siamensis TUR07-02b, Priestia aryabhattai SMNCH17-07, and Priestia megaterium SMBH14-02—under controlled in vitro conditions. Siderophore activity was evaluated qualitatively using Chrome Azurol S (CAS) agar, where percentages represent halo-based indices relative to colony diameter, and quantitatively using the CAS–shuttle assay, expressed as percent siderophore units relative to an uninoculated reference. Zinc solubilisation was assessed in solid media as halo-based indices and in liquid media as Zn-equivalent signals (mg L⁻¹) obtained by spectrophotometry. All strains produced siderophores, with P. aryabhattai showing the highest qualitative index (167%), while P. aryabhattai and B. siamensis showed statistically similar activity in liquid medium (~23%). Zinc solubilisation was substrate-dependent: B. siamensis showed the broadest solubilisation spectrum in solid media, whereas P. aryabhattai achieved the highest Zn-equivalent signals for ZnCO₃ and Zn₃(PO₄)₂ after 20 days. These results demonstrate strain-specific functional differences and represent a preliminary screening method based on relative in vitro estimations. Full article

The aim of the study was to evaluate the biotechnological potential of thermophilic microorganisms isolated from chernozem soil during composting of poultry manure. The efficiency of the strains was determined by their effect on organic matter degradation, humification intensity, and nitrogen accumulation. The correlation between the quality indicators of the composting process was assessed with the gross values, taking into account the proportion of compost fractions. The strains were identified as: Aeribacillus pallidus KCTC 3564^T (cellulolytic), Neobacillus sedimentimangrovi FJAT-2464^T, Aeribacillus composti N.8^T, Caldifermentibacillus hisashii N-11^T (nitrogen fixers), Acinetobacter pittii CIP 70.29^T, and Pseudomonas plecoglossicida NBRC 103162^T (nitrifies). It was found that all the bacteria increase the proportion of small fractions by 19.0–19.9%. The gross content of humic acids increases under the influence of nitrifiers (15.5%) and nitrogen fixers (5.5%). The total nitrogen content increases under cellulolytics (13.8%) and nitrogen fixers (20.2%). The smallest fraction (≤0.25 mm) in nitrogen fixers and nitrifying variants has the greatest bioreclamation properties, by 16.4% (p < 0.001) and 12.9% (p < 0.001). Targeted microbial strains provide the direction of the transformation processes during biocomposting. It can also be concluded that assessing the quality of composting based on the fraction distribution can be a promising element of the biofermentation process monitoring. Full article

Acinetobacter baumannii remains a significant nosocomial infectious agent, with its ability to acquire antimicrobial resistance posing a global public health concern. Over time, substantial knowledge has been amassed regarding A. baumannii in human clinical cases. Recently, research has shifted to non-human A. baumannii. Therefore, the current work aimed to investigate the occurrence of A. baumannii carrying carbapenem resistance genes in broiler chickens via molecular detection and its public health significance. Two hundred cloacal swabs were collected from broiler chickens and grouped into 40 pools. DNA extraction was conducted on these pools, followed by molecular detection of the A. baumannii bla_OXA-51-like gene. Among the 40 pools, 31 (77.5%) tested positive for the bla_OXA-51-like gene and were further screened for additional carbapenemase genes, including bla_OXA-58, bla_OXA-23, and bla_OXA-24. The bla_OXA-58 gene was identified in eight pools (25.8%), whereas bla_OXA-23 and bla_OXA-24 were not detected. Subsequently, partial DNA sequencing was performed on two PCR amplicons of the A. baumannii bla_OXA-51-like gene derived from broiler chickens, followed by a phylogenetic analysis. The analysis revealed genetic similarity between the A. baumannii sequences obtained in this work and those retrieved from humans, birds, animals, and environmental sources. In conclusion, the occurrence of A. baumannii harboring genes coding for carbapenem resistance in broiler chickens highlights a potential new path of transmission, which may require further investigation to better understand the dynamics of transmission and to guide effective strategies for preventing and controlling A. baumannii infections. Full article

Bacteria adapted to elevated temperatures are commonly associated with geothermal environments and are recognized for their functional diversity. In this study, cultivable bacteria were isolated from a geothermal spring in northern Sinaloa, Mexico, and characterized through physicochemical analysis, molecular identification, growth kinetics, and functional screening. The isolates were identified as Bacillus licheniformis (strains J1, J3, and J8) and Brevibacillus borstelensis (strains J6 and J9). Growth analyses showed that, in nutrient broth at 45 °C, the evaluated strains exhibited specific growth rates ranging from 1.25 to 1.78 h⁻¹ and short doubling times between 23 and 33 min, with B. borstelensis J6 displaying the highest rate. At 50 °C, μmax values ranged from 0.77 to 1.08 h⁻¹, indicating sustained growth at elevated temperatures. Functional assays demonstrated extracellular proteolytic, amylolytic, and cellulolytic activities, mainly associated with B. licheniformis strains, in addition to tolerance to the pesticides fluazinam and benomyl. Antagonistic tests showed that B. licheniformis J8 inhibited the phytopathogenic fungi Sclerotinia sclerotiorum and Sclerotium rolfsii, while qualitative mineral solubilization assays indicated the ability of selected isolates to mobilize phosphate and potassium. These findings highlight geothermal ecosystems as valuable reservoirs of thermotolerant bacteria with enzymatic versatility and environmental relevance, supporting further molecular and process-optimization studies. Full article

Antimicrobial resistance [AMR] is a silent yet intensifying global threat, with particularly severe consequences in tropical and subtropical ecosystems, where high ecological connectivity, extensive antimicrobial use, and inadequate sanitation create ideal conditions for the persistence and spread of antimicrobial resistance genes [ARGs]. Within the One Health framework, migratory birds warrant special attention because they traverse tropical AMR hotspots, linking contaminated aquatic, agricultural, and peri-urban environments along established flyways. Evidence from tropical and subtropical regions indicates that migratory birds frequently carry clinically relevant AMR-associated pathogens, including extended-spectrum β-lactamase-producing Escherichia coli, multidrug-resistant Salmonella enterica, and fluoroquinolone- and macrolide-resistant Campylobacter spp. These findings suggest that migratory birds primarily function as ecological sentinels and geographic redistributors of antimicrobial resistance, reflecting environmental contamination and ecological connectivity between human-dominated and natural ecosystems, while evidence for long-term reservoir status remains context-dependent. Addressing the complex interface among AMR, migratory birds, and ARGs requires integrative surveillance strategies that explicitly incorporate wildlife into existing health systems. Genomic and metagenomic monitoring of migratory bird populations, combined with cross-sectoral data sharing, can provide early warning signals of emerging resistance patterns and inform evidence-based interventions. Understanding the ecological role of migratory birds in tropical ecosystems is therefore essential for designing effective One Health strategies to mitigate transboundary AMR risks and preserve the long-term efficacy of antimicrobial therapies. Full article

In today’s environment, rapid, reliable, and accurate bacterial detection is essential for protecting public health while preserving and ensuring the safety of food, water, and agricultural and environmental systems. Over the years, electrochemical sensors have gained widespread attention as viable candidates due to their rapid response, high sensitivity and selectivity, adaptability and portability, and low manufacturing cost. This facilitates their integration into various sectors, including healthcare and diagnostic applications, food safety and agriculture, and water and environmental monitoring. While these achievements represent tremendous progress, some of the challenges that need to be overcome include stability, batch-to-batch reproducibility, manufacturability, performance reliability, and the lack of point-of-care (POC) implementation for the utilization of these sensors for real-sample bacterial analysis. However, in the future, it is expected that with continued efforts made towards improving durability, standardization, and manufacturability, electrochemical bacterial sensors will be pivotal to the advancement of efficient bacterial diagnostics across various fields. This review presents major developments in modern electrochemical sensing technologies, which include, but are not limited to: electrochemical sensor and biosensor surface modifications, nanomaterials, the integration of artificial intelligence (AI) and machine learning (ML), and the emergence of wearable systems, for bacterial detection and monitoring. Additionally, their utilization in the aforementioned sectors is discussed. The integration and sustained use of these advanced electrochemical sensors for bacterial detection and surveillance can significantly enhance global safety and public well-being. Full article