Unveiling the occurrence of COVID-19 in a diverse Bangladeshi population during the pandemic.

Introduction: COVID-19 pandemic hit Bangladesh with relatively low intensity, unlike its neighbors India and European countries and USA. Methods: The present report included data of 8,480 individuals tested for COVID-19 RT-PCR of the workers and officials from readymade garments (RMG) industry in Chandra area in Gazipur. The present data looked into the clinic-demographic factors associated with the susceptibility of the condition. Result: The data elucidated the susceptibility of the individuals to SARS-CoV-2 based on age, gender, pre-existing health conditions, and the presence of symptoms. It was observed that individuals aged over 60 had the highest rate of COVID-19 positivity, and men exhibited a higher infection rate compared to women. Regardless of age, fever and cough were the most frequently reported symptoms. Two-thirds of the individuals included in this report appeared to be asymptomatic carriers. The prevalence of comorbidities among individuals who tested positive for COVID-19 was notably higher, and this exhibited a gender-specific pattern. Discussion: Although our study provides important epidemiological insights into the initial year of the pandemic among Bangladeshi populations, it can also add value for future drug and vaccine development. However, it is essential to acknowledge the limitations like - restriction of public movement, unavailability of vehicle yielding a selection bias, due to the lockdown conditions imposed owing to the pandemic and the diverse characteristics of the participants. The report emphasizes the significance of figuring out how age, gender, and underlying health conditions impact susceptibility to and transmission of COVID-19, thereby providing valuable insights for public health strategies and future research initiatives.

The majority of enteroaggregative Escherichia coli strains produce the E. coli common pilus when adhering to cultured epithelial cells.

Enteroaggregative Escherichia coli (EAEC) have emerged as a significant worldwide cause of chronic diarrhea in the pediatric population and in HIV patients. The vast majority of EAEC strains do not produce the aggregative adherence fimbriae I-III (AAFs) so far reported and thus, what adherence factors are present in these strains remains unknown. Here, we investigated the prevalence of the chromosomal E. coli common pilus (ECP) genes and ECP production amongst 130 EAEC strains of diverse origin as well as the role of ECP in EAEC adherence. Through multiplex PCR analysis we found that 96% of EAEC strains contained the ecpA structural pilin gene whereas only 3.1% and 5.4% were positive for AAF fimbrial genes aggA or aafA, respectively. Among the ecpA(+) strains, 63% produced ECP when adhering to cultured epithelial cells. An ecpA mutant derived from prototypic strain 042 (AAF/II(+)) was not altered in adherence suggesting that the AAF/II, and not ECP, plays a major role in this strain. In contrast, strain 278-1 (AAF(-)) deleted of the ecpA gene was significantly reduced in adherence to cultured epithelial cells. In all, these data indicate a potential role of ECP in adherence for EAEC strains lacking the known AAFs and that in association with other adhesive determinants, ECP may contribute to their survival and persistence within the host and in the environment.

Antibacterial activities of green tea crude extracts and synergistic effects of epigallocatechingallate (EGCG) with gentamicin against MDR pathogens.

Plant extracts and their purified compounds were examined for synergistic antimicrobial activity using selected multi-drug resistant (MDR) pathogens. The study aims to investigate the antibacterial activity of green tea (Camellia sinensis) and its purified compound epigallocatechingallate (EGCG). The synergistic relation of the compound with antibiotic was detected against selected potential Gram positive and Gram negative pathogens. Staphylococcus aureus and Escherichia coli were used as test pathogens which were resistant to different groups of antibiotics. After collection of fresh green tea leaves, samples were washed and air dried. EGCG is one of the bioactive compounds and was separated from tea plant. Antibacterial activity of EGCG and crude extracts of green tea were done by microdilution method (minimum inhibitory concentration and minimum bactericidal concentration). The synergistic effect of EGCG and gentamicin was determined. MIC value of green tea extract was found at 125 µg/mL in case of MDR E. coli, MDR S. aureus and their reference strains and MBC at 500 µg/mL against S. aureus. No MBC value was found against E. coli. EGCG showed better activity on Gram positive pathogen compared to that of Gram negative. MBC value of this compound was 1250 µg/mL for E. coli where 625 µg/mL for S. aureus. Strong synergistic relation (FICI 0.325) was found against pathogens in the combination of EGCG with gentamycin. The purified EGCG compound of green tea has great synergistic effect against MDR pathogens. More investigation is needed to know the inhibitory effect of these plant extracts and their components.

Role of outer membrane protein OprD and penicillin-binding proteins in resistance of Pseudomonas aeruginosa to imipenem and meropenem.

The main mechanism of imipenem resistance in Pseudomonas aeruginosa is via downregulation of the gene for OprD porin. In a previous study, it was shown that the level of resistance did not parallel with the degree of downregulation of the porin gene, thus arguing for the existence of other resistance mechanisms. Penicillin-binding protein (PBP) 2 and PBP3 are involved in carbapenem resistance in Escherichia coli. The genes for PBPs were sequenced in three imipenem-resistant clinical strains and these strains were conjugated with two susceptible P. aeruginosa PA0 strains, selecting for auxotrophic markers. In all the clinical and resistant isolates there was no obvious elevation of AmpC cephalosporinase. The active sites of PBP1b (ponB), PBP2 (pbpA), PBP3 (pbpB) and PBP6 (dacC) had no mutations in any of the examined strains. Production of oprD mRNA was significantly lower in clinical strains and transconjugants after selection for the proB marker (PA4565 at 5113kb). The clinical strains had alterations in OprD that were not found in transconjugants. Our findings suggest that PBPs do not play a role in imipenem resistance in the clinical strains examined here, but that a regulatory gene for oprD contributing to carbapenem resistance is located close to the proB gene.

Healthcare-associated (HA) and community-associated (CA) methicillin resistant Staphylococcus aureus (MRSA) in Bangladesh - Source, diagnosis and treatment.

Methicillin-resistant Staphylococcus aureus (MRSA) has long been a common pathogen in healthcare facilities, but now, it has emerged as a problematic pathogen in the community setting as well. This study reported source, diagnosis and treatment of HA-MRSA and CA-MRSA. A total of sixty-five clinical samples (urine, pus, wound swab) were collected from clinical origin of Dhaka city, Bangladesh. All the isolates were tested phenotypically by conventional methods and genotypically by PCR targeting nuc, pvl and mecA genes. Finally sequencing was carried out for pvl gene to know the mutagenic variation or any amino acid changes in pvl gene. Chi square test was employed for statistical analysis. Patients of age group 51-60 years are more susceptible (46.15%) to MRSA, CA-MRSA or HA-MRSA infection. Female are (32.30%) more susceptible to MRSA infection. Among 65 isolates 53 isolates identified phenotypically as S. aureus. These were positive for amplification of nuc (270 bp) gene of S. aureus. Moreover, among 53 isolates 33 phenotypically considered as MRSA and 38 (72%) showed positive amplification for mecA (162 bp) gene. Among 38 MRSA isolates 22 (57.89%) confirmed as CA-MRSA and 16 (42.10%) as HA-MRSA. Finally, sequence analysis for lukS/F-PV genes from 4 representative isolates detected a new single nucleotide polymorphism in comparison with the control sequence. However, no amino acid changes were found. Statistical analysis showed HA-MRSA isolates were more commonly found in urine sample and CA-MRSA in pus and wound swab. CA-MRSA isolates were more resistant to tested antibiotics than HA-MRSA.

Virulence-Related Genes Identified from the Genome Sequence of the Non-O1/Non-O139 Vibrio cholerae Strain VcN1, Isolated from Dhaka, Bangladesh.

We report here the first draft genome sequence of the non-O1/non-O139 Vibrio cholerae strain VcN1, isolated from Dhaka, Bangladesh. The data submitted to GenBank for this strain will contribute to advancing our understanding of this environmentally disseminated bacterium, including its virulence and its evolution as an important pathogen.

Molecular analysis of hemagglutinin, neuraminidase, matrix genes provide insight into the genetic diversity of seasonal H3N2 human influenza a viruses in Bangladesh during July-August, 2012.

Influenza A virus subtype H3 is a threat to public health and it is important to understand the evolution of the viruses for the surveillance and the selection of vaccine strains. Comparative analysis of four Bangladeshi isolates with isolates circulating other parts of the world based on three candidate genes hemagglutinin (HA), neuraminidase (NA), matrix protein (MA) showed no evidence of significant distinct subclade of viruses circulating in the country over the period of study. Despite these findings, we found N161S substitution in all four H3N2 influenza stains resulting in the gain of NSS160-162 glycosylation site. All H3N2 Influenza subtypes in the study had amino acid substitution at position 31 on the M2 protein (Aspartic acid to Asparagine) which is known to be responsible for amantadine drug resistance.

Transformation of ciprofloxacin-resistant Neisseria gonorrhoeae gyrA, parE and porB1b genes.

In several transformation experiments, we have shown that introduction of an alteration in GyrA at position 95 of a ciprofloxacin-susceptible Neisseria gonorrhoeae strain (minimum inhibitory concentration (MIC) 0.008 mg/L) increases the MIC to 0.064 mg/L. Two alterations (positions 91 and 95) increase the MIC to 0.125-0.25 mg/L. Transformants with ciprofloxacin MICs of 0.5-16 mg/L were obtained from a moderately ciprofloxacin-resistant strain (MIC 0.25 mg/L). These transformants had alterations in the gene for PorB1b and probably other genes. In one transformant, an alteration in ParE was also introduced, which probably contributed to ciprofloxacin resistance. The ciprofloxacin-resistant transformants had the donor porB1b sequence, and most of them also had altered serovars. We conclude that alterations in N. gonorrhoeae PorB1b could be involved in ciprofloxacin resistance.

Critical biophysical properties in the Pseudomonas aeruginosa efflux gene regulator MexR are targeted by mutations conferring multidrug resistance.

The self-assembling MexA-MexB-OprM efflux pump system, encoded by the mexO operon, contributes to facile resistance of Pseudomonas aeruginosa by actively extruding multiple antimicrobials. MexR negatively regulates the mexO operon, comprising two adjacent MexR binding sites, and is as such highly targeted by mutations that confer multidrug resistance (MDR). To understand how MDR mutations impair MexR function, we studied MexR-wt as well as a selected set of MDR single mutants distant from the proposed DNA-binding helix. Although DNA affinity and MexA-MexB-OprM repression were both drastically impaired in the selected MexR-MDR mutants, MexR-wt bound its two binding sites in the mexO with high affinity as a dimer. In the MexR-MDR mutants, secondary structure content and oligomerization properties were very similar to MexR-wt despite their lack of DNA binding. Despite this, the MexR-MDR mutants showed highly varying stabilities compared with MexR-wt, suggesting disturbed critical interdomain contacts, because mutations in the DNA-binding domains affected the stability of the dimer region and vice versa. Furthermore, significant ANS binding to MexR-wt in both free and DNA-bound states, together with increased ANS binding in all studied mutants, suggest that a hydrophobic cavity in the dimer region already shown to be involved in regulatory binding is enlarged by MDR mutations. Taken together, we propose that the biophysical MexR properties that are targeted by MDR mutations-stability, domain interactions, and internal hydrophobic surfaces-are also critical for the regulation of MexR DNA binding.