Journal of Advances in Microbiology

Seroprevalence and Risk Factors Associated with Hepatitis B Virus Infection at the Ngoyo General Hospital, Republic of the Congo

Andrely Christ Ismael Nsadi — 2026-06-06

Hepatitis B remains one of the most widespread chronic viral infections and represents a major public health challenge worldwide. This study aimed to determine the seroprevalence of hepatitis B virus infection and to identify associated risk factors in subjects admitted to the Ngoyo General Hospital in Pointe-Noire. This was a cross-sectional analytical study conducted from January 2022 to December 2025. Sociodemographic data were collected using a questionnaire, while HBsAg detection was performed by ELISA. Statistical analyses were performed using GraphPad Prism software. A total of 1,237 patients were included, with a male predominance of 63.05% versus 36.90% females (sex ratio 1.70 ~2). The mean age was 36.72 ± 10.10 years (18 - 65 years). The most represented age group was 31 to 45 years, at 55.69%. The seroprevalence of HBV infection was 5.50%. Lack of vaccination against HBV was associated with a significant increase in the risk of infection (p = 0.033), as were a history of blood transfusion (p = 0.037) and multiple sexual partners (p = 0.038). After adjustment, a history of tattooing or scarification (p < 0.001) and drug use (p < 0.001) were independently associated with a lower probability of HBV infection. This study demonstrated the existence of risk factors related to the hepatitis B virus within the hospital population and contributes to strengthening awareness, regular clinical follow-up, and long-term management of patients infected with HBV.

Freeze-dried Starter Production and Viability Measurements with Bacillus and Lactic Acid Bacteria

Kongoza Konan Sylvestre — 2026-06-12

Freeze-drying, or lyophilization, is a preservation technique that removes water content from microbial cultures under low temperature and vacuum conditions. This process not only maintains the viability of bacillus and LAB but also retains their functional properties, making them suitable for various culinary applications. The aim of this study is produce freeze-dried starter cultures and assess their viability. Two microbial strains, previously, Bacillus proteolyticus and Lactobacillus plantarum was isoled from african locus bean were used. To the mixture of these strains, protective agents and carrier has been added at a ratio of 1 : 1. The mixtures were freeze-dried. The lyophilized starters were stored at -20 °C, 4 °C, and at room temperature (29 ± 0.67 °C). The viability rate was determined every 14 days for 3 months. The results show that cassava powder and starch allow for better viability of microbial strains. The best storage time is -20°C. For good viability of microbial strains during the production of freeze-dried starters, starch must be used as a protective agent, cassava powder as a carrier and everything must be kept at -20 °C. The viability of strains generally decreases over time, even under optimal conditions. Cumulative damage to cellular structures and nucleic acids would lead to cell death. Exposure to oxygen would cause oxidative stress, particularly for anaerobic microorganisms such as lactic acid bacteria. During the storage of the lyophilised products at −20°C, 4°C, and room temperature, the starch–cassava powder formulation used as a protective agent and carrier support demonstrated the highest viability rate for the multiple starter cultures. This finding suggests that the starch–cassava powder matrix was more effective in preserving microbial cell viability across different storage conditions, thereby enhancing the stability and survivability of the starter cultures during storage.

Sensory Evaluation of Rabri Prepared from Cow Milk as Affected by Various Sugar Levels and Storage Periods

Kuldeep — 2026-06-22

Rabri is a traditional heat-desiccated dairy product prepared by concentrating milk and incorporating successive layers of clotted cream formed during slow heating. The present investigation was conducted in the Department of Animal Husbandry and Dairying (Dairy Technology), C.S.A. University of Agriculture and Technology, Kanpur, to evaluate the influence of milk fat level, sugar level and refrigerated storage period on the sensory quality of rabri prepared from cow milk. Milk was standardised to two fat levels, 4.0% (A1) and 4.5% (A2), and rabri was prepared with four sugar levels, namely 2% (B1), 4% (B2), 6% (B3) and 8% (B4). The samples were packed in plastic cups and stored at 5 ± 1°C for 0, 5, 10, 15, 20 and 25 days. Sensory attributes, including flavour, body and texture, colour and appearance, sweetness and overall acceptability, were evaluated by a five-member panel using a 9-point hedonic scale. The experiment included 48 treatment combinations with three replications under a factorial completely randomised design, and the data were analysed using analysis of variance. Rabri prepared from milk containing 4.5% fat recorded higher mean scores than that prepared from milk containing 4.0% fat for flavour (7.513), body and texture (7.386), colour and appearance (7.409), sweetness (7.379) and overall acceptability (7.412). Among the sugar treatments, 2% sugar gave the highest mean scores for all sensory attributes. Fresh rabri obtained the highest acceptability, while all sensory scores declined progressively during storage, with the lowest overall acceptability score observed on day 25 (5.704). Overall, rabri prepared with 4.5% fat and 2% sugar showed the most acceptable sensory quality under refrigerated storage conditions.

Antibacterial Efficacy of Clove, Black Pepper, Cardamom, and Fenugreek Extracts against Gram-Positive and Gram-Negative Bacteria

Rinni Sahrawat — 2026-06-26

This study investigated the antibacterial activity of ethanolic extracts of selected spices, namely clove (Syzygium aromaticum), black pepper (Piper nigrum), cardamom (Elettaria cardamomum) and fenugreek (Trigonella foenum-graecum), against selected bacterial strains, including Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis. The antimicrobial activity was assessed using the agar well diffusion method, and the inhibitory effects of the extracts were compared with amoxicillin as the standard antibiotic control. Among the tested spice extracts, clove extract exhibited the highest antibacterial activity against the examined microorganisms. Ethanolic clove extract produced inhibition zones of 22 ± 0.97 mm against E. coli, 22 ± 1.53 mm against B. subtilis, 20 ± 1.00 mm against S. aureus and 14 ± 0.99 mm against P. aeruginosa. Black pepper extract exhibited antibacterial activity with inhibition zones of 16.67 ± 1.24 mm, 19 ± 1.00 mm, 17 ± 0.58 mm and 14.67 ± 0.47 mm against the four tested bacterial strains (E. coli, B. subtilis, S. aureus and P. aeruginosa), respectively. Cardamom extract also demonstrated activity, producing inhibition zones of 14.27 ± 1.24 mm, 16 ± 0.50 mm, 16 ± 0.58 mm and 16 ± 0.82 mm against the same organisms, respectively. Fenugreek extract exhibited comparatively lower antibacterial activity, with inhibition zones of 13 ± 0.82 mm, 14 ± 1.00 mm, 15 ± 1.00 mm and 13.67 ± 0.58 mm against the four tested bacterial strains (E. coli, B. subtilis, S. aureus and P. aeruginosa), respectively. Although amoxicillin produced larger inhibition zones, all selected spice extracts showed measurable antibacterial effects. The findings indicate that clove extract demonstrated the strongest activity among the tested spices and may be further investigated for applications in antimicrobial research, food preservation and pharmaceutical contexts.

Prevalence of Begomoviruses and their Molecular Detection in Major Solanaceous Crops of Eastern Bihar, India

Akanksha Singh — 2026-06-27

Begomovirus-induced leaf curl disease is a major constraint to the production of solanaceous crops in tropical and subtropical regions. These viruses are transmitted by whiteflies and can spread rapidly under favourable environmental conditions. During 2023-2025, systematic field surveys were conducted across ten major solanaceous crop-growing districts of eastern Bihar, namely Bhagalpur, Banka, Purnea, Katihar, Munger, Madhepura, Khagaria, Araria, Supaul and Kishanganj. The study aimed to assess leaf curl incidence, symptom variability, whitefly population and the associated begomovirus species in tomato, chilli and capsicum. At each location, approximately 18-20 symptomatic leaf samples were collected from the surveyed crops. Characteristic symptoms included leaf curling, cupping, stunting, mosaic, crinkling, puckering and blistering in interveinal areas. Disease incidence ranged from 5% to 18% across the surveyed solanaceous crops. Tomato showed the highest mean leaf curl incidence (17.28%), followed by chilli (15.89%) and capsicum (5.35%). The mean whitefly population recorded across locations and crops was 4.47 per plant. Polymerase chain reaction assays using universal and species-specific primers detected both mono- and bipartite begomoviruses in most tested DNA samples. Tomato leaf curl New Delhi virus was mainly associated with tomato crops, whereas Tomato leaf curl Joydebpur virus was commonly detected in chilli and capsicum. Other species, including Tomato leaf curl Karnataka virus, Tomato leaf curl Palampur virus, Tomato leaf curl Gujarat virus and Pepper leaf curl Bangladesh virus, were detected at low frequencies or in limited samples. The findings indicate the widespread occurrence and molecular diversity of begomoviruses infecting solanaceous crops in eastern Bihar. The results may support disease monitoring and the development of integrated management strategies, including vector management.

Isolation and Identification of Pyogenic Bacteria from Cutaneous Abscesses in Goats

Chandramani Rajoriya — 2026-06-29

Background: Cutaneous abscesses are common infections that seriously affect the quality and yield of goat breeding. The main pathogens that cause cutaneous abscesses are well understood; however, the associated microbial community remains relatively unknown.

Aim: This study showed that caprine cutaneous abscesses in the examined goats were associated with septic bacterial infection, occurring as both single and mixed infections.

Methods: To determine the different types of microorganisms present in caprine cutaneous abscesses, 30 pus samples collected from different goat farms in the Jabalpur region, India, were subjected to isolation, identification and antibiotic sensitivity testing (ABST).

Results: The microbial communities of each sample contained about 6-8 microbial species. Each sample contained different microorganisms or combinations of species, including Corynebacterium, Staphylococcus, Streptococcus, Pseudomonas, Klebsiella and E. coli. The bacteria were identified by their colony characteristics and microscopic examination, including Gram staining for bacteriological study and Giemsa staining for cytology. Out of 30 samples, 20 (66.67%) yielded single bacteria comprising three genera of Gram-positive bacteria (08 Corynebacterium spp., 05 Staphylococcus spp. and 02 Streptococcus spp.) and three genera of Gram-negative bacteria (02 Pseudomonas spp., 02 Klebsiella spp. and 01 Escherichia coli). In 10 goats (33.33%), multiple bacteria were obtained in different combinations. Based on Gram staining, the proportion of Gram-positive bacteria dominated over Gram-negative bacteria in both single and mixed isolates. The bacterial isolates were further subjected to biochemical tests (catalase, coagulase, oxidase, urease and IMViC). In antibiotic sensitivity testing, Corynebacterium spp. was sensitive to Amikacin, Ciprofloxacin, Enrofloxacin, Gentamicin, Amoxiclav, Erythromycin and Tetracycline, while Staphylococcus spp. was sensitive to Ceftriaxone, Gentamicin, Meropenem and Streptomycin.

Conclusion: The prevalence of caprine cutaneous abscesses was determined as 12.56% during the seven-month study period. All caprine cutaneous abscesses were septic, with single or multiple bacterial infections. The most prevalent bacterium was Corynebacterium spp. (26.66%), followed by Staphylococcus spp. (16.66%). Tetracycline and Gentamicin were found to be most effective against Corynebacterium spp. and Staphylococcus spp., respectively. However, Meropenem was found to be sensitive against most of the isolated bacterial spp.

Hantavirus at the Human–rodent Interface: A Global Review and Meta-analysis of Occupational Exposure

Chinwebudu M. Melford — 2026-06-11

Hantaviruses are zoonotic negative-sense RNA viruses transmitted to humans principally through inhalation of aerosolised excreta from persistently infected rodent reservoir hosts. They cause two major clinical syndromes: haemorrhagic fever with renal syndrome (HFRS), predominant across Eurasia, and hantavirus pulmonary syndrome (HPS) or hantavirus cardiopulmonary syndrome (HCPS), occurring predominantly in the Americas. Together, these syndromes account for an estimated 150,000–200,000 clinical cases annually, with case fatality rates ranging from less than 0.1% in mild Puumala virus nephropathia epidemica to greater than 50% in Araraquara virus-associated HCPS. Occupational cohorts—including agricultural and forestry workers, military personnel, and laboratory researchers—face disproportionately elevated exposure risks at the human–rodent interface, yet this occupational burden remains inadequately characterised in the global health literature. This critical narrative review, augmented by meta-analytic synthesis of published seroprevalence data, assembles and evaluates the global evidence for hantavirus epidemiology, ecology, transmission, clinical disease, diagnostics, and prevention, with particular focus on occupational risk. Structured searches of multiple biomedical and specialised databases identified peer-reviewed studies published between 2000 and 2024. Pooled seroprevalence estimates across occupational cohorts consistently exceed background population rates by 2- to 10-fold, with the highest estimates observed in Chinese and Korean farmers (8–26%) and European forestry workers (5–15%). Occupational risk is modulated by rodent population dynamics, climate variability, land-use change, and individual behavioural factors. The review critically appraises current diagnostic tools, surveillance frameworks, therapeutic options, and vaccine development, identifies key gaps in occupational health policy, and argues for a strengthened One Health approach to hantavirus surveillance and prevention, particularly in low- and middle-income countries where the burden is least well characterised.

Extraction Methods for Plant-derived Antimicrobial Phytochemicals and Their Testing Techniques: A Scoping Review

Evalsam E. Bassey — 2026-06-12

Plant-derived antimicrobials have demonstrated significant potential for therapeutic applications. However, the extraction of antimicrobial compounds from plants is a complex process involving various methods used to isolate and concentrate bioactive molecules responsible for antibacterial, antifungal, and antiviral activities. This review study aims to thoroughly investigate and evaluate the process of extracting antibacterial substances from plants and the many techniques used to assess their antimicrobial effectiveness in recent studies. This scoping review study was carried out in accordance with the PRISMA-ScR 2018 checklist guidelines. Google Scholar, PubMed, and PubMed Central were the electronic databases utilised in the search for articles. 84 articles published from January 2020 to December 2024 were included for the review. Among the conventional extraction methods, crude solvent extraction was the most prevalent extraction method, followed by maceration, Soxhlet extraction 11 (11.7%), distillation, and the conventional shaking process. The most predominantly applied advanced extraction techniques were ultrasonification-assisted extraction, followed by the microwave-assisted extraction technique. Assessing the most applied antimicrobial assay technique, Agar well diffusion was the most employed technique, followed by disc diffusion, Broth dilution, Microwell dilution, and time-kill assay. The bacterial and fungal isolates used for testing across the study are of pathological importance and readily available, including bacterial species such as Staphylococcus sp., Escherichia sp., Salmonella sp., Klebsiella sp., and Pseudomonas sp., as well as Shigella sp. Fungal isolates used across the studies included Candida sp., Aspergillus sp., Penicillium, Fusarium, and Rhizopus, among others. While conventional methods are mainly utilised for small-scale research purposes due to their less cost-intensive nature, advanced methods of extraction are gradually taking over the scene; it is important to ascertain in further studies to what extent the method of extraction affects the efficacy of the antimicrobial substances.