Antibiotic resistance profiling of clinical isolates of Salmonella enterica Serovar Paratyphi A in Dhaka, Bangladesh

The study was conducted to detect the antibiotic resistance profile of the clinical isolates of Salmonella enterica Serovar Paratyphi A from 100 blood samples of patients from different age groups suspected to be suffering from enteric fever. The pure cultures of the bacterial isolates were collected from some renowned diagnostic centers of Dhaka and they were further characterized through the conventional culture, microscopy and biochemical examinations. These isolates were cross checked for the antibiogram profile by the Kirby-Bauer disc diffusion method against ten different types of antibiotics. Most of the isolates were found resistant against azithromycin (100%), nalidixic acid (100%) and ceftazidime (75%). However, isolates showed sensitivity to ciprofloxacin (95%), levofloxacin (97%), cotrimoxazole (96%) and chloramphenicol (95%). These findings highlight the need for continuous monitoring of the drug resistance pattern of S. enterica Serovar Paratyphi A for better public health management. Stamford Journal of Microbiology, Vol.11 (1) 2021: 14-16

Microbiological surveillance of air and contact surface of pubic transports with its correlation to human infection risks

Over past few years, people are giving more attention to air pollution and its effects on human health. Due to the high population density in Bangladesh, air pollution is a major issue in metropolitan areas, especially in Dhaka city. Present study aims to isolate air-borne microbes from the inside environment of public transport and different types of microbes that are frequently encountered by commuters when they touch the interior surfaces of vehicles used for public transport in Dhaka City. Atmospheric load of microorganisms was measured with petri dish which was kept open for 30 minutes in the sampling locations and swabs were taken from interior surfaces of vehicles. Air samples collected from both bus and railway stations showed a high atmospheric microbial count (total viable bacteria and total fungal count were 140 to 776 CFU/plate/30 min and 27 to 168 CFU/plate/30 min, respectively). A similar outcome was found after analysis of swab samples of the contact surfaces of the vehicles as well. A total of four bacterial pathogens were identified from the interior surfaces of the vehicle including Escherichia coli, Bacillus spp., Pseudomonas spp. and Vibrio spp. which are known to be associated with gastrointestinal tract infection. To manage and control the environmental health risks caused by air pathogens, an authorized governmental agency should do continuous monitoring of air quality to reduce the negative effects and impacts of air pathogens on human and animal health. This research has shown a great concern to health practitioners in developing countries because these are pathogens that are mostly resistant to the commonly available antibiotics used in the treatment of infection associated with these pathogens. Most importantly, we need to raise awareness among the public in order to reduce the load and spread of pathogenic bacteria in the environment. Stamford Journal of Microbiology, Vol.11 (1) 2021: 7-10

Antibaterial activity of the extracts of pineapple and pomelo against five different pathogenic bacterial isolates

To combat the infections caused by antibiotic resistant bacteria, natural candidates are being studied to find out antibacterial activity against the drug-resistant microorganisms. Among the variety of natural candidates of plant origin, many fruits have been proved to have potent antibacterial activity. In the current study, we chose pineapple (Ananas comosus), and pomelo (Citrus maxima) to determine their efficacy against some clinical isolates. Fruit samples were subjected to prepare crude, ethanol, methanol and aqueous extract to determine their antibacterial potency. Clinical isolates were used to determine the antibacterial activity of the extracts against them. The isolates were found to be multi-drug resistant. Out of twenty-eight antibiotics, Pseudomonas aeruginosa was resistant to ten antibiotics and Salmonella spp. was resistant to nine antibiotics. Rather than the crude extracts of the fruits, ethanol and methanol extracts showed antibacterial activity towards multi-drug resistant pathogenic bacteria. Aqueous extract did not show any significant antibacterial activity at all. Extracts of pomelo fruit exhibited the highest results whereas pomelo skin and pineapple peel crude extracts were the least effective compared to the other extracts. Ethanol extract of pineapple fruit (against all isolates but Staphylococcus aureus) and methanol extract of pomelo fruit (against all isolates) showed the lowest MIC (minimum inhibitory concentration) of 187.5 μg/ml. MBC (minimum bactericidal concentration) was found (within the range of 500 μg/ml to 1000 μg/ml) only with ethanol and methanol extracts of pomelo and pineapple. As the clinical isolates were found to be inhibited by the extracts, they can be used as an alternative for treating infections caused by these bacteria. Stamford Journal of Microbiology, Vol.11 (1) 2021: 1-6

Physicochemical and bacteriological screening of pathogenic microorganisms from aquarium water collected from katabon area in Dhaka city

Globally, the ornamental fish business has a high demand for its popularity as well as for its profitability. However, microbial contamination, nutrient depletion and accumulation of organic materials are the major factors in an aquafarming system which can cause death of aquatic animal and causes financial losses. This study aimed to determine the physicochemical and microbiological quality of fish aquarium water. Water of different time interval after treatment (7 days, 20 days, 30 days, 60 days, 90 days) were taken from the different aquariums. A set of physicochemical parameters such as temperature, transparency, pH, conductivity, dissolved oxygen, total dissolved solids, alkalinity, total hardness, conductivity were found within the approved standard concentration for fish. The present study also reveals the microbiological status of the aquaculture water where the total viable count ranging from 2.20×104 to 4.20×104 cfu/ml. Escherichia coli, Staphylococcus spp., and Pseudomonas spp. were present in all samples. Antimicrobial susceptibility tests were also done to determine the antibiotic resistance pattern of microbes isolated from aquarium water. Stamford Journal of Microbiology, Vol.11 (1) 2021: 20-23

Comparative study on the microbiological quality of vegetables collected from local markets and super shops of Dhaka city

Vegetables are major source of vitamins and fibers but presence of pathogens in salad vegetables can cause outbreak of diseases. Several studies have been conducted on commonly consumed vegetables so far to detect the level of microbial contamination. However, few of them compare the microbial quality of local and super shop vegetables. The present study was conducted for microbiological assessment and comparing four types of vegetables collected from two different market conditions. In this study, Green chili (Capsicum frutescens L.), Tomato (Solanum lycopersicum), Coriander (Coriandrum sativum) and Lady’s finger (Abelmoschus esculentus) were analyzed to determine Total Viable Bacterial (TVB) Counts, Total Fungal (TF) Counts, Total Coliform Counts (TCC), Total Fecal Coliform (TFC) Counts and occurrence of Staphylococcus aureus, Pseudomonas spp., Listeria spp., Bacillus spp., Salmonella spp., and Vibrio spp. Among these microorganisms, Klebsiella spp. and Pseudomonas spp. were significantly present in coriander of both local market and super shop. All pathogenic bacteria and fungi were found in huge amounts in the vegetable samples of the local market. Although some pathogenic bacteria and fungi were also found in the same samples of the super shop, relatively lower than the local market’s vegetables. In conclusion, contamination in collected vegetable samples were not acceptable but comparatively higher load in local market samples indicated that the hygienic condition in these markets is not sufficiently maintained. Stamford Journal of Microbiology, Vol.11 (1) 2021: 24-27

Determination of antimicrobial activity of traditional spices extracts against clinical isolates in Dhaka city

Spices are dried aromatic substances derived from plants and have demonstrated antimicrobial activity against pathogenic microorganisms. In the present study, a total of six spices turmeric (Curcuma longa), garlic (Allium sativum), black pepper (Piper nigrum), ginger (Zingiber officinale), clove (Syzygium aromaticum) and cinnamon (Cinnamomum verum) were evaluated for their antibacterial activity. Antibacterial activities of ethanol, propanol and water extracts were determined by agar well diffusion assay against previously isolated Klebsiella pneumoniae, Staphylococcus aureus from urine samples and Citrobacter spp. from throat swab samples. All spices examined in this study showed antibacterial activity in different types of extraction methods. Water, ethanol and propanol extracts exhibited anti-bacterial activity measured as zone of inhibition between 6 mm and 25 mm in diameter. Water extract of garlic (Allium sativum) showed the highest antibacterial activity (25mm) against clinical isolates of Staphylococcus aureus and Citrobacter spp. Water extract of other species showed the lowest antibacterial activity (6 mm) against throat swab isolates Staphylococcus aureus and Citrobacter spp. Spices which showed signifiant antimicrobial activities can be further studied for the isolation of active ingredients and development of novel drugs. Stamford Journal of Microbiology, Vol.11 (1) 2021: 17-19

Isolation and characterization of nitrogen-fixing bacteria from soil sample in Dhaka, Bangladesh

Biological nitrogen (N2) fixation is very essential for limiting the growth of plants and agricultural crops. The present study was conducted to potentially isolate N2-fixing bacteria from garden soil sample at Stamford University Bangladesh, Siddeswari, Dhaka. Here, we used culture-dependent method to perform this experiment. Firstly, we collected garden soil sample, diluted and inoculated in N2-free Jensen’s media by maintaining the aseptic procedure. We obtained 5 different colonies from soil samples. We cultured the isolates in N2-free Jensen’s media containing bromothymol blue (BMB) and also, in Yeast Extract Mannitol Agar (YEMA) media containing congo red to confirm nitrogen fixation capacity. We collected the colony characteristics of all the isolates. Only 1A isolate showed good growth after 24 h of incubation among all the isolates. We performed ammonification test with Nessler reagent to confirm N2-fixing ability for our selected isolates. The 1A isolate was positive in ammonification test. Culture, microscopy and biochemical tests were performed to identify isolate 1A. This isolate was presumptively identified as Azotobacter sp. In the present study, Azotobacter sp. that was isolated from the soil sample was found to be a potential N2-fixing bacterium. Isolate 1A can be used for N2-fixation to boost production of crops. Stamford Journal of Microbiology, Vol.11 (1) 2021: 11-13

Detection of pathogenic bacteria associated with earphones used by students of Stamford University Bangladesh

The use of earphones has increased in recent times throughout the world especially among the different level of students such as school, college or university who have a higher tendency of sharing these among them. Unlike airline headsets, headphones and stethoscope ear-pieces, ear phones are often shared by multiple users and can be a potential medium for transmission of pathogens, which can give rise to various ear related infections. The objective of this study was to detect the pathogenic bacteria from the ear-phones used by the students of Stamford University Bangladesh. A total of 16 ear-phone swabs were collected by sterile cotton swabs. The swabs were inoculated onto blood agar and incubated aerobically overnight at 37oC. Microscopic observation and standard biochemical tests were performed to confirm the identification of all the bacterial isolates. Six presumptively identified Staphylococcus spp. (38%) were tested against six different types of antibiotics following Kirby-Bauer disk diffusion method. Isolates were found to be 84% resistant against Cotrimoxazole and demonstrated 100% sensitivity to Vancomycin and Ciprorofloxacin. The findings of this study suggest the users to disinfect their respective ear phones and not to exchange them as they may act as a potential source to transfer pathogenic and antibiotic resistant bacteria among the ear phone users. Stamford Journal of Microbiology, Vol.10 (1) 2020: 1-4

Microbiological analysis of popular spreads used in restaurants inside Dhaka city, Bangladesh

Spreads are used widely for making the fast foods more amazing and tasty. Varieties and cross combinations of ingredients are used to make many flavours of fast foods. Different restaurants prepare their signature spreads for attracting people but this can cause opposite result if not prepared using high quality raw materials and proper hygienic conditions are not maintained. Current study was conducted on ten different types of spreads (pesto, cilantro, queso, tomato sauce, peanut butter, honey, mustard, cream cheese, chocolate sauce and butter) which are used by the local restaurants in Dhaka city, Bangladesh. Almost all the samples (nine out of ten) harbored total viable bacteria exceeding the standard limit. Four spread samples showed high fungal count (102 cfu/gm). Four samples showed to be positive (˃101/ml recommended acceptable count) for Escherichia coli and Klebsiella spp. which indicates that these spread cannot be recommended for public consumption. Among all the samples examined, only chocolate sauce showed acceptable result without the presence of coliforms, Staphylococcus spp. and Pseudomonas spp. This finding suggests proper maintenance of sanitation in spread preparation and selling area. A proper guidelines and monitoring can help keep up the quality of food additives. Stamford Journal of Microbiology, Vol.10 (1) 2020: 16-19

Characterization of a bacteriophage from urban sewage obtained with the bacterium Staphylococcus aureus

Bacteriophages are viruses of bacteria that have received significant attention in the last decades due to their potential as an alternative to the antibiotics, as well as their applicability in the selective control of bacterial species harmful to food. In this context, this work reports the partial results of a viral filtrate named P4CSa that was obtained with the bacterium Staphylococcus aureusand characterized by the viral host range and the restriction fragment length polymorphism technique. The results indicate that the phage P4CSa probably belongs to the order Caudovirales, it presents a polyvalent host range, and it can be preserved for the long term in the form of filtrated lysates stored at 4°C, suggesting that the phage P4CSa may have the potential for the development of a pharmaceutical product indicated for the biocontrol of pathogenic bacteria. Stamford Journal of Microbiology, Vol.10 (1) 2020: 20-24