The escalating incidence of foodborne salmonellosis poses a significant global threat to food safety and public health. As antibiotic resistance in Salmonella continues to rise, there is growing interest in bacteriophages as potential alternatives. In this study, we isolated, characterized, and evaluated the biocontrol efficacy of lytic phage L223 in chicken meat. Phage L223 demonstrated robust stability across a broad range of temperatures (20–70 °C) and pH levels (2–11) and exhibited a restricted host range targeting Salmonella spp., notably Salmonella Typhimurium and Salmonella Enteritidis. Characterization of L223 revealed a short latent period of 30 min and a substantial burst size of 515 PFU/cell. Genomic analysis classified L223 within the Caudoviricetes class, Guernseyvirinae subfamily and Jerseyvirus genus, with a dsDNA genome size of 44,321 bp and 47.9% GC content, featuring 72 coding sequences devoid of antimicrobial resistance, virulence factors, toxins, and tRNA genes. Application of L223 significantly (p < 0.005) reduced Salmonella Typhimurium ATCC 14,028 counts by 1.24, 2.17, and 1.55 log CFU/piece after 2, 4, and 6 h of incubation, respectively, in experimentally contaminated chicken breast samples. These findings highlight the potential of Salmonella phage L223 as a promising biocontrol agent for mitigating Salmonella contamination in food products, emphasizing its relevance for enhancing food safety protocols.

In the present study three mesophilic Bacillus isolates were analyzed for their α-amylase activity in shakeflask cultures. The organisms were capable to produce hydrolysis zone around their colonies on starch agar medium. The effect of various fermentation conditions on α-amylase production was investigated, and in every case it was found that B. subtilis was the best producer of the enzyme, which was followed by the newly isolated Bacillus sp. and B. amyloliquefaciens. The synthesis of extracellular α-amylase by the bacteria was repressed by the presence of readily metabolizable carbon source like glucose in the culture medium. Maximum α-amylase activity by the Bacillus isolates was obtained at 37°C with an initial medium pH 7.0 under agitation at 160-180 rpm for 72 h of growth. Keywords: Bacillus species, α-Amylase, Enzyme production, Shake-flask cultureDOI: http://dx.doi.org/10.3329/bjm.v24i2.1257 Bangladesh J Microbiol, Volume 24, Number 2, December 2007, pp 129-132

Multidrug-resistant (MDR) clones of Pseudomonas aeruginosa can cause complicated infections in human. The emergence of ST664 of MDR P. aeruginosa has been reported in Nepal, Iran and China. Here, we present the draft genome analysis of a MDR P. aeruginosa CMPL223 isolated from hospital wastewater in Bangladesh to understand antimicrobial resistance trends and pathogenicity. Cetrimide agar was used for isolation of P. aeruginosa. Polymerase chain reaction (PCR) was carried out for detection of biofilm and integron related genes. Bacterial susceptibility to antibiotics was determined by disc diffusion method. Sequencing of whole genomic DNA was performed using Illumina iSeq 100 platform. Following quality checking of raw reads, assembly and annotation of sequences, a wide array of in silico tools were used for characterization of draft genome. The isolate was a strong biofilm former, carried integron 1 in chromosomal DNA, and was predicted to be pathogenic. It belongs to sequence type ST664 and O7 serogroup. The assembled genome contained 12 acquired antimicrobial resistant (AMR) genes, 2 prophage regions, 240 virulence genes, 71 drug targets, 142 insertion sequences, and 1 CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) array. The isolate was resistant to 21 out of 23 antibiotics, except colistin and imipenem. Comprehensive Antibiotic Resistance Database and ResFinder revealed that bacteria harboured bla_OXA-50, bla_OXA-796, bla_PDC-374, fosA, tet(G), sul1, catB7, aph(3')-iib and ant(4')-IIb genes, conferring resistance to different classes of antibiotics. The results of in vitro characterization were consistent with the possible expression of detected antibiotic resistant genes through in silico analysis. Our data suggested the emergence of MDR P. aeruginosa ST664, which needs control measures for limiting its dissemination.

Objectives: Salmonellais considered one of the leading causes of foodborne illnesses worldwide. Information about the transmission of pathogens to poultry and poultry products is necessary to implement control measures for reducing both human exposure and economic loss. The aim of this study was to analyze and evaluate the transmission characteristics ofSalmonella enteritidisto laying‐type hen flocks and their laid eggs.Materials and methods: For this purpose, 15 pairs of laying hens were used in which each pair consisted of one inoculated and one contact exposed hen. The eggs and cloacal swabs from these hens were subsequently analyzed.Results: Of the 15 in‐contact hens tested, 60% were found to be positive forS. enteritidiswithin 61 days postinoculation, of which 26.7% transmission occurred within the first 31 days postinoculation. Among the collected laid eggs tested,S. enteritidiswas detected on 58% eggshells and 5.33% eggs internal contents. We also observed a 33.33% reduction in egg production fromS. enteritidis‐infected hens. In a cross‐contamination study, we demonstrated that an experimentally inoculated container can act as a potential source ofSalmonellaspp. infection.Conclusions: Our results will help establish effective monitoring programs to reduce the transmission ofSalmonellaspp. in poultry and poultry products.

Colistin is considered the last line therapy for treating multidrug-resistant (MDR) bacterial infections in humans. Therefore, the spread of colistin resistance poses a serious threat to human, and environmental health. Though Bangladesh is known as a hotspot of AMR, limited studies have been carried out regarding the status of colistin resistance. Information on the emerging bacterial resistance is inevitable for protecting public health. Nowadays, wastewater analysis has been prioritized for metagenomics-enabled AMR surveillance. Our study on the metagenomic analysis of untreated hospital effluents first detected the colistin resistance-conferring mcr-5.1 gene in the hospital environment of Bangladesh. Phylogenetic tree and in silico AMR analysis confirmed the detection of this mcr-5 variant, which is located in a plasmid contig. The plasmid was untypeable and belonged to the bacteria from the Enterobacteriaceae family. The mcr-5.1 operon was embedded in a Tn3 transposon, suggesting the mobility of the gene. Tnshfr1 transposon, chromate resistance protein ChrB, DNA invertase hin, and two MFS-type proteins were present in the genetic environment of mcr-5.1. Our findings provide evidence of the occurrence of mcr-5.1 in a hospital environment in Bangladesh, which calls for immediate attention and effective measures to contain the dissemination of colistin resistance in the environment. (c) 2024 The Author(s). Published by Elsevier Ltd on behalf of International Society for Antimicrobial Chemotherapy. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

Hospital wastewater has been identified as a hotspot for the emergence and transmission of multidrug-resistant (MDR) pathogens that present a serious threat to public health. Therefore, we investigated the current status of antibiotic resistance as well as the phenotypic and genotypic basis of biofilm formation in Pseudomonas aeruginosa from hospital wastewater in Dhaka, Bangladesh. The disc diffusion method and the crystal violet assay were performed to characterize antimicrobial resistance and biofilm formation, respectively. Biofilm and integron-associated genes were amplified by the polymerase chain reaction. Isolates exhibited varying degrees of resistance to different antibiotics, in which >80% of isolates showed sensitivity to meropenem, amikacin, and gentamicin. The results indicated that 93.82% of isolates were MDR and 71 out of 76 MDR isolates showed biofilm formation activities. We observed the high prevalence of biofilm-related genes, in which algD+pelF+pslD+ (82.7%) was found to be the prevalent biofilm genotypic pattern. Sixteen isolates (19.75%) possessed class 1 integron (int1) genes. However, statistical analysis revealed no significant association between biofilm formation and multidrug resistance (χ2 = 0.35, P = 0.55). Taken together, hospital wastewater in Dhaka city may act as a reservoir for MDR and biofilm-forming P. aeruginosa, and therefore, the adequate treatment of wastewater is recommended to reduce the occurrence of outbreaks.