Shamsun Nahar

Sexually Transmitted Infections Among Brothel-based Sex Workers in Bangladesh: High Prevalence of Asymptomatic Infection

Objective and Goal: The goal of this study was to study the prevalence of sexually transmitted infections (STIs)/reproductive tract infections (RTIs) among brothel-based sex workers (SWs) in Bangladesh. Study: A cross-sectional study was conducted among SWs in 4 randomly selected brothels. A sociodemographic and behavioral survey and pelvic examination was conducted. Specimens including endocervical swab, high vaginal swab, and blood were collected and were examined for Neisseria gonorrhoeae, Chlamydia trachomatis, Trichomonas vaginalis, bacterial vaginosis candidiasis, and syphilis. Results: A total of 439 SWs were enrolled and 49.6% had genital symptoms. Among all SWs, 17.5% were positive for N. gonorrhoeae; 15.5% for C. trachomatis; 7.5% for T. vaginalis, and 6.6% had active syphilis. A total of 67.4% SWs were positive for at least 1 cervical and/or vaginal infection. Conclusion: The prevalence of STIs/RTIs among SWs in brothels in Bangladesh is high. An intervention strategy addressing both symptomatic and asymptomatic infections and periodic screening of SWs for RTIs/STIs is essential for successful HIV and STIs prevention programs.

Evidence of intra-familial transmission of Helicobacter pylori by PCR-based RAPD fingerprinting in Bangladesh

Helicobacter pylori is a genetically diverse bacterial species, which has facilitated adaptation to new hosts and persists worldwide. The main objective of this study was to explore intra-familial transmission of H. pylori in Bangladesh. We characterized H. pylori in 35 families including 138 family members using random amplified polymorphic DNA (RAPD) fingerprinting. Forty-six percent of H. pylori isolated from the mother shared a related genotype with strains isolated from their children. Twenty-nine percent of H. pylori isolates of the mother are related to the youngest children. Only 6% of the parents shared related genotype of H. pylori. These findings suggest that mother-to-child transmission occurs in early childhood and is the most probable route of transmission of H. pylori in Bangladesh.

High prevalence of cagA and vacA seropositivity in asymptomatic Bangladeshi children with Helicobacter pylori infection.

Aim: To evaluate the prevalence of antibodies against two major markers of virulence of Helicobacter pylori—cytotoxin‐associated gene A (cagA) and the vacuolating cytotoxin gene (vacA)—among children in a peri‐urban community of Bangladesh, and to evaluate Western blot (WB) assay for detection of H. pylori infection diagnosed by 13C urea breath test (UBT) in such children. Methods: One hundred and eighty‐two children aged 18–60 mo, of the peri‐urban community of Dhaka, were screened for H. pylori infection using UBT, and the serum samples were analysed for antibody against cagA and vacA by Western blot. Results: The overall prevalence of H. pylori infection by 13C‐urea breath test was 80%. The seroprevalence of cagA with or without vacA, vacA with and without cagA, and both cagA and vacA were 82%, 82% and 81%, respectively. Among children with a positive UBT, 95% were seropositive for both cagA and vacA, indicating that the products of these genes are frequently co‐expressed in H. pylori infection in this community. The sensitivity, specificity, positive and negative predictive value of the Western blot test for H. pylori infections, compared to UBT, were 94%, 68%, 92% and 76%, respectively.

Epidemiology and genetic diversity of human astrovirus infection among hospitalized patients with acute diarrhea in Bangladesh from 2010 to 2012.

BACKGROUNDnGlobally, human astroviruses (HAstVs) have emerged as another common cause of non-bacterial acute gastroenteritis. Limited data exist on the epidemiology and genetic diversity of HAstVs in Bangladesh.nnnOBJECTIVEnWe describe the epidemiology of HAstV-associated diarrhea among hospitalized patients, including HAstV genotypes, clinical symptoms and co-infecting pathogens.nnnSTUDY DESIGNnStool samples were collected from an ongoing diarrhea etiology surveillance during 2010-2012. HAstV was detected using RT-PCR and positive samples were subsequently tested for other common viral and bacterial pathogens. Phylogenetic analysis was performed and genotyped HAstV sequences were compared with previously reported Bangladeshi HAstV strains.nnnRESULTSnOf 826 fecal specimens, HAstV was detected in 26 cases (3.1%) and the majority of these cases (92%) was observed in children under 3 years of age. For 6 out of the 26 cases (23%) no other co-infecting pathogens were observed, whereas for the 20 remaining cases (77%) a variety of other known enteric viral and bacterial pathogens were observed. Based on the overlap region between ORF1b (RdRp) and ORF2 (capsid), five different genotypes (HAstV-1, -2, -3, -5 and -6) were identified circulating during the study period, with HAstV-1 being the predominant type. Genetic analysis revealed that HAstV-1 strains detected in this study were distantly related (<90% similarity of the capsid protein on the nt level) with HAstV-1 strains previously reported from Bangladesh.nnnCONCLUSIONnOur study provides an epidemiological overview and genetic diversity of HAstVs associated with acute diarrhea in Bangladesh.

RS1 Satellite Phage Promotes Diversity of Toxigenic Vibrio cholerae by Driving CTX Prophage Loss and Elimination of Lysogenic Immunity

ABSTRACT In El Tor biotype strains of toxigenic Vibrio cholerae, the CTXϕ prophage often resides adjacent to a chromosomally integrated satellite phage genome, RS1, which produces RS1ϕ particles by using CTX prophage-encoded morphogenesis proteins. RS1 encodes RstC, an antirepressor against the CTXϕ repressor RstR, which cooperates with the host-encoded LexA protein to maintain CTXϕ lysogeny. We found that superinfection of toxigenic El Tor strains with RS1ϕ, followed by inoculation of the transductants into the adult rabbit intestine, caused elimination of the resident CTX prophage-producing nontoxigenic derivatives at a high frequency. Further studies using recA deletion mutants and a cloned rstC gene showed that the excision event was recA dependent and that introduction of additional copies of the cloned rstC gene instead of infection with RS1ϕ was sufficient to enhance CTXϕ elimination. Our data suggest that once it is excised from the chromosome, the elimination of CTX prophage from host cells is driven by the inability to reestablish CTXϕ lysogeny while RstC is overexpressed. However, with eventual loss of the additional copies of rstC, the nontoxigenic derivatives can act as precursors of new toxigenic strains by acquiring the CTX prophage either through reinfection with CTXϕ or by chitin-induced transformation. These results provide new insights into the role of RS1ϕ in V. cholerae evolution and the emergence of highly pathogenic clones, such as the variant strains associated with recent devastating epidemics of cholera in Asia, sub-Saharan Africa, and Haiti.

Isolation of tetracycline-resistant clinical Helicobacter pylori without mutations in 16S rRNA gene in Bangladesh

The occurrence of 16S rRNA gene mutations associated with resistance to tetracycline in H. pylori isolated in Bangladesh was investigated. Tetracycline susceptibility was determined by the agar dilution method. The 16S rRNA genes of these isolates were sequenced and analyzed. A tetracycline accumulation assay was performed. DNA sequence and transformation tests of nine tetracycline‐resistant (MIC = 2 μg/ml) Bangladeshi H. pylori clinical isolates showed that in no case was the resistance due to mutations in the 16S rRNA gene, the only known cause of tetracycline resistance in this pathogen. Tetracycline accumulation assays implicated altered uptake or efflux.

Tumor necrosis factor-alpha -863C/A polymorphism is associated with Guillain–Barré syndrome in Bangladesh

Guillain-Barré syndrome (GBS) is a post-infectious autoimmune polyneuropathy regulated by pro- and anti-inflammatory cytokines; TNFA polymorphisms may exert immune pathogenic roles in GBS. We assessed TNFA promoter region polymorphisms (-238G/A, -308G/A, -857C/T, -863C/A) in Bangladeshi patients with GBS (n=300) and healthy controls (n=300) by PCR-RFLP and ASO-PCR. TNFA -863CA was significantly associated with GBS disease susceptibility (P=0.0154) and disease severity (P=0.0492). TNFA -238A allele was more frequent among anti-ganglioside (GM1) antibody-positive patients (P=0.0092) and -863AA associated with AMAN subtype of GBS (P=0.0398). TNFA -863C/A may contribute to GBS severity and pathogenesis in Bangladeshi patients.

CD1A and CD1E gene polymorphisms are not associated with susceptibility to Guillain-Barré syndrome in the Bangladeshi population

The post-infectious autoimmune polyradiculoneuropathy Guillain-Barré syndrome (GBS) is triggered by molecular mimicry between microbial glycolipid antigens and human peripheral nerve gangliosides. Single nucleotide polymorphisms in exon 2 of CD1A (*01/*02) and CD1E (*01/*02) were assessed using PCR-RFLP; no significant differences in genotype or allele frequency were observed between 200 patients with GBS and 200 healthy controls. CD1 gene polymorphisms cannot be recognized as a susceptibility or disease-causative factor for GBS in the Bangladeshi population. However, further studies are necessary to investigate the CD1A*01/CD1E*01 haplotype distribution and its potential causative role in the axonal form of GBS.