Ahmed S

Molecular Detection of Rickettsia felis in Humans, Cats, and Cat Fleas in Bangladesh, 2013–2014

High prevalence of Rickettsia felis in patients with fever of unknown origin was revealed in the north-central Bangladesh from 2012 to 2013. Subsequently, in this study, prevalence of R. felis in cats and cat fleas (Ctenocephalides felis), together with febrile patients, was studied by PCR detection of 17 kDa antigen gene and DNA sequencing. R. felis was detected in 28% (28/100) and 21% (14/68) of cat blood and cat flea samples, respectively, whereas 42% (21/50) of patients were positive for R. felis. R. felis-positive cat fleas were detected at significantly higher rate on R. felis-positive cats. The results suggested a potential role of cats and cat fleas for transmission of R. felis to humans in Bangladesh.

Distribution of two distinct rotavirus B (RVB) strains in the north-central Bangladesh and evidence for reassortment event among human RVB revealed by whole genomic analysis.

Human rotavirus B (RVB), a rare cause of diarrhea in several Asian countries, has been reported to be genetically highly conserved. However, 14 RVB strains with two distinct RNA electropherotypes E1 and E2 (11 and 3 strains, respectively) were detected in adult patients with diarrhea, in Mymensingh in the north-central Bangladesh in 2014. In this study, VP7 gene sequences of all the 14 strains and nearly full-length sequences of all the 11 RNA segments of four RVB (two strains each representing E1 and E2 types) were determined and analyzed phylogenetically. For all the gene segments, sequence identities among strains with the same RNA pattern were higher (99%-100%) than those between strains with different RNA patterns (94-98%). Although all the gene segments of RVB strains were grouped into Indian-Bangladeshi lineage, VP1-3, VP6, VP7, NSP1, NSP2 and NSP5 genes of strains with E1 and E2 types were assigned to distinct sublineages S1 and S2, respectively. E1-strains clustered with Bangladeshi RVB strains reported previously (e.g., Bang117), while E2-strains with those from India (e.g., NIV-1048101), Myanmar, and Nepal. In contrast, VP4, NSP3 and NSP4 genes of both E1 and E2 RVB strains were classified into sublineage S2. These findings indicated that two genetically distinct RVB strains were simultaneously circulating in Mymensingh, Bangladesh. RVB strains with E1 electropherotype were suggested to be reassortants acquiring three gene segments (VP4, NSP3 and NSP4 genes) from the foreign RVB in the genetic background of indigenous Bangladeshi RVB represented by the strain Bang117.

Whole genomic analysis of G2P[4] human Rotaviruses in Mymensingh, north-central Bangladesh

Rotavirus A (RVA) is a dominant causative agent of acute gastroenteritis in children worldwide. G2P[4] is one of the most common genotypes among human rotavirus (HRV) strains, and has been persistently prevalent in South Asia including Bangladesh. In the present study, whole genome sequences of a total of 16 G2P[4] HRV strains (8 strains each in 2010 and 2013) detected in Mymensingh, north-central Bangladesh were determined. These strains had typical DS-1-like genotype constellation. Most of gene segments from DS-1 genogroup exhibited high level sequence identities to each other (>98%), while slight diversity was observed for VP1, VP3, and NSP4 genes. By phylogenetic analysis, individual RNA segments were classified into one (V) or two-three lineages (V–VI or V–VII). In terms of lineages (sublineages) of 11 gene segments, the 16 Bangladeshi strains could be further classified into four clades (A-D) containing 8 lineage constellations, revealing the presence of three clades (A-C) with three lineage constellations in 2010, and a single clade (D) with four constellations in 2013. Therefore, co-existence of multiple G2P[4] HRV strains with different lineage constellations, and change in clades for the study period were demonstrated. Although amino acids in the antigenic regions on VP7 and VP4 were mostly identical to those of global G2P[4] strains after 2000, VP4 of clade D RVAs in 2013 had alanine and proline at positions 88 and 114, respectively, which are novel substitutions compared with recent global G2P[4] strains. Replacement of lineage constellations associated with unique amino acid changes in the antigenic region in VP4 suggested continuous genetic evolutionary state for emerging new G2P[4] rotavirus strains in Bangladesh.

Nationwide prevalence of Rickettsia felis infections in patients with febrile illness in Bangladesh

From July 2015 to December 2016, the presence of rickettsial pathogens was investigated for 414 patients with unknown fever in eight places in all the divisions of Bangladesh. Rickettsia felis was identified in blood samples from all the regions (overall detection rate, 19.6%), suggesting nationwide prevalence of R. felis infections.

Collaborative Research on Puerperal Infections in Bangladesh

Bangladesh is considered as a high-risk country for emerging infectious diseases because of its high population density, poverty, and unhygienic conditions. Although control efforts have primarily been focused on major infectious diseases such as diarrheal diseases, tuberculosis, malaria, and HIV infection, the prevalence and impact of many local or minor infectious diseases are still unclarified in this country. In this review, we present our recent experience and outcomes of collaborative research on puerperal infection (PI), which is a poorly defined infectious disease in Bangladesh. PI is the most common complication during the perinatal period in developing countries. We investigated the incidence of individual species of aerobic bacteria causing PIs and their drug resistance, and the genetic traits of isolates during the two-year period (2010-2012). The common species of isolates from patients with PIs were Escherichia coli, Enterococcus faecalis, Staphylococcus haemolyticus, Proteus mirabilis, Staphylococcus aureus, and Klebsiella pneumoniae. A remarkable finding was the high rates of resistance to cephalosporins among Gram-negative bacteria harboring extended-spectrum beta-lactamase genes, which were associated with carbapenem resistance in a few isolates. This study defined the importance of control of antimicrobial resistance in Bangladesh, and provided suggestions for the future direction of collaborative research on infectious diseases in Bangladesh.

Antimicrobial susceptibility pattern of enterococci isolated from clinical specimens at mymensingh medical college hospital, Mymensingh, Bangladesh

Enterococci are part of the normal intestinal flora of humans and animals but have also emerged as important pathogens responsible for serious infections in hospital and community acquired infections. The aim of this study was to investigate the prevalence of Enterococcus with their antimicrobialsusceptibility pattern from patients ofMymensingh Medical College Hospital, Bangladesh during the period from July 2015 to June 2016.Samples were collected and identification of enterococcus was done by standard microbiological procedure and biochemical tests.Multiplex PCR was performed by using species specific primers for Enterococcus faecalis (E. faecalis) and Enterococcus faecium (E. faecium),vanA, vanB, vanC1, vanC2/C3 genes for vancomycin resistance.A total of 105 enterococci were isolated from 1201 different clinical specimens (from urine (931), pus (175) and wound swab (95) respectively) from July, 2015 to June, 2016.The prevalence of enterococci was 12.34% in urine, 17.17% in pus and 1.58% in wound samples. Out of 105 enterococci,80 (77.14%) were Enterococcus faecalis,1 (0.95%) was E. gallinaramand 24 (22.86%) were other species. All the species were highly resistant to aminoglycosides (Gentamicin) (75.24%) and ciprofloxacin (73.33%). Regarding antibiotic sensitivity, all the enterococci were (100%) sensitive to linezolidand vancomycin followed by nitrofurantoin 93 (88.57%) and imipenem 89 (84.76%). No vancomycin resistant enterococci were identified by disk-diffusion method. But by PCR, vanB was found in 1/80 (1.25%) of the E. faecalis isolates and 01 (100%) of the E. gallinarum.vanC1 was detected in 1 (100%) ofE. gallinarum isolates. The vanA and vanC2/C3 gene was not found in any isolates. For the first time, one isolate of E. gallinarum has been found harboringthe vanB gene in our hospital.The presence of multidrug resistant enterococci should be considered as danger alarm for serious enterococcal infections and further study in large scale is needed.