Microbiology Research Journal International

Aim: To determine the antibacterial activity and biofilm inhibitory activity of Nicotiana tabacum leaf extract against Streptococcus mutans isolated from oral cavity.

Place and Duration of Study: Department of Microbiology, Faculty of Science, Imo State University, Owerri, Nigeria, between April and November 2019.

Methodology: The study was carried out using the agar diffusion method for antibacterial activity and microtiter assay method for the biofilm inhibition effect.

Results: All four extracts of hot water, ethanol, acetone and methanol tested against S. mutans had no antibacterial activity as no zone of inhibition was recorded. Likewise, all the extracts did not inhibit the formation of biofilm by the organism on glass. This is seen in the increase of the optical density (OD) values from 0.572 to 0.804 for water, 0.260 to 1.420 for ethanol, 0.216 to 0.626 for acetone and 0.236 to 0.725 for methanol extracts respectively.

Conclusion: This study therefore indicates that N. tabacum does not have antibacterial and biofilm inhibitory against S. mutans. This also explains why a lot of tobacco users still suffer from dental caries and other oral infections caused by S. mutans.

Thai Pangas (Pangasiaus hypophthalmus) has been emerging as an economically very important species due their faster growth, year round production and high productivity in South-East Asian aquaculture. It has good market value as a food fish due to its good taste and deliciousness with high protein, minerals and fat content. It is also popular as a game fish.

Aims: The present study was conducted to identify bacterial pathogens in diseased P. hypophthalmus and evaluate their sensitivity to antibiotics.

Methodology: To identify the causativeagent of diseased fish pure culture of bacteria using slant and streak plate techniques and different biochemical tests such as Gram’s Staining, Motility Test, Sugar Fermentation Test, MR-VP test, Indole Test etc. were performed. To assess the sensitivity of the isolated bacteria to antibiotics five antibiotics disks i.e. Ciprofloxacin (5μg), Azithromycin (15μg), Ampicillin/Sulbactam (20μg), Tetracycline (30μg) and Erythromycin (15μg) were used.

Results: Three pathogenic bacteria i.e. Aeromonas hydrophila, Edwardsiella ictaluri and Pseudomonas sp. were identified in the studied diseased fish. Only Pseudomonas sp. were identified from Fresh fish. E. ictaluri was found only in diseased pangas which was the causative agent for thedisease, Bacillary Necrosis. The results of the antibiotic sensitivity test showed multi-resistances of the identified bacteria to the tested antibiotics. The identified bacteria were 100% sensitive to Ciprofloxacin (5μg), intermediate to Azithromycin (15μg) and Tetracycline (30μg), but resistant to Erythromycin (15μg) and Ampicilin/Sulbactam (20μg).

Conclusion: Ciprofloxacin (5µg) could be used to control bacillary necrosis disease in Thai pangas. The results of this study will be helpful to the fish farmers for the management of bacterial diseases in fish.

Aims/Objective: Methicillin-Resistant Staphylococcus aureus (MRSA) is a dominant cause of severe healthcare-associated (HA) infections but has recently emerged as Community-Associated (CA-MRSA) and Livestock-Associated MRSA (LA-MRSA). This study was carried out to detect the presence of Methicillin-Resistant S. aureus in Ready-to-Eat (RTE) Corbiculid heterodont in Bayelsa state, Nigeria.

Place of Study: This study was conducted in Yenagoa, Southern Ijaw and Sagbama Local Government Areas, Bayelsa State, Nigeria.

Methodology: Fifty-three samples (dried, fried and stewed) of the RTE C. heterodont were collected and subjected to standard microbiological procedures.

Results: Seventy Staphylococcus spp. were isolated, consisting of 65 (92.86%) S. aureus and 5 (7.14%) coagulase negative Staphylococcus (CONS). Out of the 65 S. aureus isolates, 53.8% were MRSA. Susceptibility pattern of MRSA showed a decreasing trend of resistance in the order: Amoxacillin, Ampicillin-Cloxacillin, Cefoxitin, and Oxacillin (100%) > Streptomycin (82.9%) >Ceftriaxone (40%) >Cefuroxime (31.4%), > Ciprofloxacin and Trimethoprim-Sulfamethoxazole (17.1%) > Gentamycin and Pefloxacin (8.6%) > Erythromycin (2.9%).Out of the 65 S. aureus isolates, 62 (95.4%) had Multidrug Resistance Index > 0.2 while 3 (4.6%) had 0.2 as their Multidrug Resistance Index. The MRSA isolates were 100% Multidrug Resistant (MDR) while the Methicillin-Sensitive S. aureus (MSSA) were 90% MDR. Molecular characterization of ten S. aureus isolates confirmed 80% S. aureus isolates and 20% CONS (S. sciuri and S. warneri).  Polymerase chain reaction (PCR) and Agarose gel-electrophoresis were used to detect the presence of mecA gene, a gene that confers methicillin resistance. The mecA gene with size 500bp was identified in 50% of MRSA. This study reported presence of MRSA and MDR S. aureus in C. heterodont sold in Bayelsa state, Nigeria. This could be the avenue for the spread of MRSA. Public health awareness campaigns should be advocated to enhance hygienic practices in the handling and distribution of food.

Aim: In this study, Aeromonas spp. isolated from soil of local mining sites were assessed for their tolerance to some heavy metals and their capability for its uptake.

Materials and Methods: The bacteria were isolated from soil of local mining site in Bagega District of Zamfara State in Nigeria. Maximum Tolerable Concentration (MTC) was employed to screen for metal tolerance of the bacteria to Cadmium (Cd) and Lead (Pb) via Agar Plate Method technique. DNA Extraction and 16sRNA Gene Sequence Analysis was carried out to identify the isolates and sequences were compared to those in NCBI database using Basic Local Alignment Search Tool (BLAST).

Results: Similarly, isolates identified were further characterized and validated by subjecting them to 16sRNA gene sequence analysis. Similarity search indicated a close genetic relatedness to Aeromonas spp. in NCBI database. The Aeromonas spp. Identified showed maximum tolerance to Pb at 27ppm and Cadmium at 24ppm. Bioaccumulation assay carried out revealed Aeromonas sp. BDL2 to take up Pb by as high as 70%. Biosorption capacity of their respective dried biomass assayed showed higher Pb uptake at 95.9% for Aeromonas sp. BDL2. Statistical analysis revealed a significant difference (P≤0.05) between the isolates and their respective biomass in the uptake Pb and Cd. Surface examination different bands indicated the presence of carboxyl, amine, amides, sulfates and other aromatic groups and significant shifts of surface molecules.

Conclusion: Aeromonas sp. BDL2 identified in this study exhibited higher tolerance to Pb. Surface molecules and their positional properties revealed the presence of hydroxyl, carboxyl, amine and amide group ligands with significant shifts after accumulation and biosorption experiment suggesting interaction between these surface molecules and heavy metal ions.

Research on microorganisms for the control of pests and pathogens is increasing. Such organisms display antagonistic effects on pests and pathogens, at the same time, they do not interfere with the sustainable development processes and are environmentally safe for human populations. Thus, bioprospection of fungi from restinga ecosystems is of interest as a novel source of microorganism and a yet unexplored source of chemical structures. This study selected endophytic fungi and fungi from the restinga soil samples to investigate their biological activity against insects. Fifty-three fungal isolates were used in screening bioassays against Atta sexdens rubropilosa leaf-cutting ant workers via direct contact of the insects with sporulating fungi cultures. This assay indicated that Trichoderma caused the highest mortality. Extracts from Trichoderma were then assessed for biological activity via ingestion, contact or exposure to fungal volatiles. Results showed that one Trichoderma sp. isolate (TR1) caused 50% mortality in 2, 1.5 and 4 days when ingested, sprayed onto the ants or by exposing ants to volatiles, respectively. Although this fungus is not known to be entomopathogenic, it could have potential use as an additional tool for pest control as it produces metabolites with antagonistic effects.

Aims: A great concern directed to non-O157 Shiga toxin-producing Escherichia coli (STEC) serotypes due to their public health importance. Detecting the existence, antimicrobial profiles, and virulence repertoire of different STEC serotypes from animals essential for human food are important.

Study Design: This study aimed to investigate the presence of STEC in different hosts, the distribution pattern of stx1, stx2, eaeA, and hlyA genes encoding Shiga toxins 1 and 2, intimin, and enterohemolysin, respectively, and the antimicrobial resistance of the detected serotypes.

Results: A total of 75 samples were collected, 20 fecal samples from broilers, 15 fecal samples from ducks, 20 beef samples, and 20 human urine samples. Escherichia coli was detected at a rate of 60/75 (80%) distributed as;17 (85%), 8 (53.3%), 15(75%), and 20 (100%) from broilers, ducks, human urine, and beef samples, respectively. There was a significant difference between the isolation rates of E. coli from different sources with p<0.05. The prevalent serotypes were O78, O2:H6, O15:H2, and O26: H1. The frequency of stx1 gene was 56/60 (93.3%), stx2 gene was 55/60 (91.6%), the eaeA gene was 35/60 (58.3%), and hlyA gene was 26/60 (43.3%). The most effective antimicrobials were amoxicillin/clavulanic acid and ampicillin with the efficacy of 52/60 (86.6%) for each, while the efficacy of chloramphenicol and doxycycline was 5/60 (8.3%) and 44/60 (73.3%), respectively.

Conclusion: The high frequency of non-O157 Shiga toxin-Producing Escherichia coli from different samples at Sadat City, high prevalence of virulence factors and resistance to chloramphenicol and doxycycline will help in monitoring the distribution of virulent serotypes and contribute to the establishment of control measures to reduce the spread of infection.

Microbiological quality of drinking water in market gardening sites was assessed to understand the persistence of diarrhoeal diseases and malnutrition among children under five. Households with children under five (5) were selected in Dassa, Nebia, Nariou and Tanguin-wobdo located in centre-ouest region in Burkina Faso. A total of 140 water samples were collected from storage containers in households (n=108), boreholes (n=7) and hand dug wells (n=25) during the month of February 2018. Faecal coliforms, Escherichia coli (E. coli) and faecal streptococci were isolated and enumerated according French standard methods. WHO standards guidelines for drinking water were used to assess water quality. Results showed that 100% of hand dug well water were contaminated with faecal bacteria whereas all water from boreholes were potables. 72% of hand dug well water were contaminated with E. coli, 96.3% with faecal coliforms and 96% with faecal streptococci. In households, 95.9% of drinking water from boreholes were contaminated with faecal bacteria versus 100% of water from hand dug wells. This situation is related to the lack of safe drinking water infrastructures, unimproved sanitation and lack of hygiene in households. In fact, 78.12% of water infrastructures were hand dug wells located mostly in gardens. In these areas, contaminated hand dug well water are used for both irrigation and consumption. Regarding these results, a reinforcement of safe drinking water infrastructures such as boreholes, improved hygiene and sanitation and health education are necessary to improve the quality of drinking water to reduce diarrhoeal diseases and malnutrition among market gardeners’ children.