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Fourteen multi drug resistant Staphylococcus aureus isolates from surgical site infection were analyzed for their antibiotic sensitivity and the presence of nine virulence genes. The isolates showed a high resistance pattern, all being resistant to methicillin, oxacillin, azithromycin, ceftazidime and amoxyclav. Seven of the isolates were sensitive to linezolid; three were sensitive to trimethoprim: sulfamethoxazol and another three were sensitive to ciprofloxacin. Ceftriaxone, gentamicin and amikacin were the drugs of choice as nine (64.3%) isolates were sensitive to ceftriaxone, eleven (78.6%) were sensitive to gentamicin and another eleven (78.6%) to amikacin. The present study focused to identify nine important virulence genes including intrinsic methicillin resistance gene mecA, methicillin resistance assisting gene femA, toxic shock syndrome toxin gene tst, exfoliative toxin A and B genes, eta and etb, Panton Valentine leukocidin gene LukS/F-PVL, along with three enterotoxin genes sec, sed and see. According to the presence of mecA gene and antibiotic resistance profile, two isolates were identified as methicillin resistant Staphylococcus aureus. However, another isolate, despite harbouring both mecA and femA genes, was sensitive to ceftriaxone which excluded it from being considered as an MRSA. Thus, the ratio of MRSA can be considered to be quite high (2/14) among the strains. Interestingly, most of the isolates (10/14) harboured femA gene, the majority of which were mecA negative with an MSSA type antibiotic profile. Although considered as a marker for community acquired MRSA, LukS/F-PV was found in half of these nosocomial isolates. Five, four and two of the isolates harboured etb, tst and sec gene, respectively. However, all the isolates were negative for eta, sed and see genes. Two isolates showed the co-existance of “femA, LukS/F-PV, etb, and tst” genes. Another two virulence gene patterns observed were “femA, mecA, tst, sec” and “femA, LukS/F-PV, etb”. The presence of several virulence genes can be correlated to the highly pathogenic nature of the isolates. Bangladesh J Microbiol, Volume 38, Number 1, June 2021, pp 21-26

This study describes the development and validation of a simple, specific, accurate, and precise method for quantitative determination of Esomeprazole in human serum using Pantoprazole as internal standard (IS). After the addition of internal standard, Esomeprazole from serum samples was extracted simply by protein precipitation method followed by centrifugation and the supernatants were directly injected into the high performance liquid chromatography (HPLC). The chromatographic separation of the compounds was obtained on Hitachi Lachrom C8 column (5 µm, 250 × 4.6 mm) with a mobile phase consisting of 5 mM potassium dihydrogen phosphate pH 7.4 and acetonitrile in a ratio of 70:30 with UV detection at 302 nm with a flow rate of 1 mL/min. The method was sensitive and specific, and validated over a concentration range of 0.06–6.0 µg/mL. The limit of detection (LOD) and lower limit of quantification (LOQ) was 0.03 µg/mL and 0.06 µg/mL, respectively. The precision and accuracy expressed as relative standard deviation were less than 15%. The average recovery of Esomeprazole from serum was 97.08%.

In recent years, our group isolated the Escherichia albertii strain DM104 and characterized it as a vaccine strain against Shigella dysenteriae type 4 in the guinea pig eye model. Protective efficacy of different routes of immunization such as intranasal, oral, and intrarectal routes were also determined and compared by challenging immunized guinea pigs against live S. dysenteriae. In the current study, we compared the intranasal and intraperitoneal routes of immunizations with the DM104 vaccine strain in mice to understand the better route of administration of the DM104 vaccine and its immunogenicity as well as protective efficacy in mouse model. The results indicate that the immune response elicited by the DM104 strain is strongly dependent on the immunization route, with the intranasal route being more effective than the intraperitoneal route following intraperitoneal live S. dysenteriae challenge. Intranasal immunization yielded 80% protective efficacy in immunized mice whereas, intraperitoneal immunization could not provide any protection. Protection generated by intranasal immunization was accompanied by high titre of anti-whole cell lysate IgG and IgA in DM104 immunized sera compared to sera collected from mice of control group. All these data demonstrate the intranasal route of the vaccine DM104 strain in mouse model to be a better immunization route to protect the animals against live S. dysenteriae challenge. Bangladesh J Microbiol, Volume 37 Number 2 December 2020, pp 38-41

Present work describes the isolation and morphological identification of endophytic fungi from Phyllanthus niruri L. including their chemical and bioactivity screening. Two isolated and purified endophytic fungi with the internal strain numbers PNRE and PNLE were taxonomically identified as Colletotrichum sp. and Fusarium sp., respectively. Preliminary chemical screening of the fungal extracts through thin layer chromatography (TLC) revealed the presence of various components. PNLE showed significant antifungal activity against the fungi Aspergillus niger (24 mm) and Aspergillus flavus (20 mm). Extracts of PNRE and PNLE gave significant cytotoxic activity with LC50 values of 1.08 μg mL-1 and 1.05 μg mL-1, respectively in the brine shrimp lethality bioassay. PNRE extract showed mild scavenging of DPPH with IC50 value of 96.06 μg mL-1 during antioxidant activity screening. Crystal formation was observed in the crude PNRE fungal extract which was purified using methanol/dichloromethane (0-20%) to obtain pure white crystal and the structure was elucidated by NMR (1H NMR and 13C NMR) spectroscopic analysis to be confirmed as ergosterol. Since isolated fungi showed promising antifungal and cytotoxic activities, the crude extract of endophytic fungi of P. niruri could be considered as a promising source for isolation of potential bioactive compounds. Bangladesh J. Sci. Ind. Res.55(4), 311-318, 2020

Endophytic fungi are a group of fungi that reside in the living plant without causing any disease symptoms. It shows symbiotic/mutualistic characteristics with host plants. Endophytic fungi may increase the host defense system against various pathogenic microorganisms and may encompass secondary metabolites of respective host plants. Isolation of endophytic fungi and its metabolites from Justicia gendarussa plant grown in Bangladesh is a recent and new approach. A total of seven endophytic fungi were isolated and purified from the leaf and bark part of the plant. All of the isolated endophytic fungi were identified up to genus level on the basis of macroscopic and microscopic characteristics and up to species level on the basis of molecular characteristics as Colletotrichum gloeosporioides, Diaporthe pseudomangiferae, Pseudopestalotiopsis camelliae-sinensis, Colletotrichum gloeosporioides, Fusarium solani, Colletotrichum tropicale and Colletotrichum siamense. Preliminary chemical screening of the fungal extracts by thin-layer chromatographic technique revealed the presence of various compounds such as flavonoids, anthraquinones, couramins, isocoumarins etc. Fungal strain Pseudopestalotiopsis camelliae-sinensis exhibited significant antiradical activity through DPPH scavenging method and moderate antimicrobial activity against a wide range of human pathogenic microbes. Using brine shrimp lethality bioassay, all the isolates showed strong cytotoxic activity, therefore suggested that all the extracts may have bioactive metabolites. Overall, these findings indicate that Justicia gendarussa and its associated endophytic fungi could be an important source for exploring potentially bioactive compounds or leads for the new drug candidates.

The recent rise of antibiotic resistance and lack of an effective vaccine make the scenario of shigellosis alarming in developing countries like Bangladesh. In recent years, our group reported the vaccine efficacy of a non-pathogenic Escherichia albertii strain DM104 in different animal models, where an ocularly administered vaccine in the guinea pig eye model against Shigella dysenteriae type 4 challenge showed high protective efficacy and also induced a high titer of serum IgG against S. dysenteriae type 4 whole cell lysate (WCL) and LPS. In this study, we report further evaluation of the non-invasive and non-toxic environmental strain DM104 as a vaccine candidate against S. dysenteriae type 4 in mice model. Oral immunization of live DM104 bacterial strain demonstrated better protective immunity in mice model by showing 90% protection in mice against live S. dysenteriae type 4 lethal dose challenge and by inducing effective humoral and mucosal immune responses.

Surface proteins of Escherichia coli O157:H7, those that are prominent in antigen-antibody reactions among different strains, were found to provide protection against E. coli O157 challenge in mice. Three strains such as E. coli O157:H7 NCTC reference strain and two other environmentally isolated strains have been used in this study. New Zealand rabbits were immunized with surface proteins of NCTC reference strain and immunoblot analysis was performed against the surface proteins of all three strains. Immunoblot analysis revealed that a 94 kDa surface protein of E. coli O157:H7 could be the possible candidate for the protective activity experiment. Group of mice receiving the 94 kDa surface protein through both intraperitoneal and intranasal routes survived the challenge experiment. Whereas, all the control mice died within a couple of days. Mice challenge experiment clearly demonstrated the strong potential of the 94 kDa protein in the immunized mice. The data of this study provide us with a basis for further characterization of 94 kDa surface protein of E. coli O157:H7 as a protective antigen. Bangladesh J Microbiol, Volume 36 Number 1 June 2019, pp 11-15

Environmental Escherichia albertii strain DM104 has been found to induce protective immunity against Shigella dysenteriae in guinea pig model and intranasal immunization showed promising results in terms of antibody response and protective efficacy. For selecting a proper immunodiagnostics marker against shigellosis, the current study investigated the antigenic cross-reactivity between DM104 and four different Shigella spp (S. dysenteriae type 4, S. flexneri type 2a, S. boydii type 15 and S. sonnei). At least six antigenic protein bands (85, 72, 34, 30, 23 and 20 k Da) of the surface components from all these species reacted strongly with both homologous and heterologous antisera, suggesting common distribution of antigenic determinants/epitopes in these bacterial species. This experiment, thus gave a clear idea of the level of antigenic determinants/epitopes sharing and variations between the DM104 and four Shigella spp. Results from this study suggest that the 34, 23 and 20 k Da antigenic proteins may be incorporated as immunodiagnostic marker for the detection of different Shigella spp. Bangladesh J Microbiol, Volume 35 Number 1 June 2018, pp 17-21

A reverse phase liquid chromatographic method for estimation of Aceclofenac in bulk drug and tablet dosage form was developed and validated. The chromatographic conditions to achieve the highest performance parameters using octylsilyl column with guard filter were optimized. The separation was carried out using a mobile phase containing 10 mM Phosphate Buffer, pH 2.1 and methanol (30:70% v/v) pumped at a flow rate of 1.0 mL/min with detection at 272 nm. The method was shown to be linear in 19.8–148.5 μg/mL concentration range (regression coefficient of 0.999). The limit of detection (LOD) and limit of quantification (LOQ) was found to be 0.0692 μg/mL and 0.2076 μg/mL, respectively. The accuracy of the method was assessed by adding fixed amount of pre-analyzed sample to different standard solutions (80%, 100%, and 120% of the tested concentration) in triplicate. The percentage mean recoveries were 97.91% to 100.39% with %RSD values of 0.64–0.79. The method was found to be precise with %RSD value of 1.13 and 1.60 for intraday and interday precision study, respectively. The method specificity and robustness were also established. New and sensitive HPLC method for estimation of Aceclofenac has been developed, in respect to the reviewed analytical methods.

Graphical abstract, Highlights • Endophytric fungi are natural reservoir for bioactive secondary metabolites. • Fusarium solani, an endophytic fungus, is a rich source for secondary metabolites specially for quinone groups. • Napthaquinone and aza-anthraquinone derivatives have significant antimicrobial, antioxidant and cytotoxic effect. • Napthaquinone and aza-anthraquinone derivatives have the potentiality to be lead for anticancer and antimicrobial agent. • Aza-anthraquinone derivatives are more bioactive than napthaquinone group due to the presence of nitrogen group., This study reports the chemical investigation and bioactivity of the secondary metabolites produced by the endophytic fungus Fusarium solani isolated from Cassia alata Linn. growing in Bangladesh. This plant was collected from conservation forest in Bangladesh and belongs to the Caesalpiniaceae family. The endophytic fungus Fusarium solani was isolated from the tissue of root of this plant. The fungal strain was identified by morphological characters and DNA sequencing. The crude organic extract of the fungal strain was proven to be active when tested for cytotoxicity against Brine Shrimp Lethality Bioassay, antimicrobial and antioxidant activity. The bioactivity guided fractionation of the ethyl acetate extract leads to the isolation of seven secondary metabolites in pure form. The structures of the isolated compounds were determined by the analysis of NMR and mass spectroscopic data. Bioassay investigation of the isolated secondary metabolites suggested aza-anthraquinones are more potent bioactive compounds as anticancer and antimicrobial agent.

In the pharmaceutical world the majority of the active pharmaceutical ingredients (API) have been obtained from the natural products. Piperine is such naturally occurring alkaloid which can be considered as major bioactive phytochemical having broad spectrum of pharmacological activities. It is obtained from the most valuable ethnomedicinal spices peppercorns i.e. black pepper and white pepper, which are the fruits of the Asian vine Piper nigrum L. Because of the widespread traditional uses of this medicinal compound, present article reveals a simple and effective isolation method of bulk piperine. The novelty of this investigation is to provide an idea for utilizing such natural method of large scale commercial piperine production as API drug in spite of chemical synthesis. Piperine was isolated in a pure crystal form and characterized by its melting point, X-Ray diffraction (XRD) studies and spectral data, including two-dimensional nuclear magnetic resonance (2D-NMR) spectroscopy. Chromatographic techniques like Thin Layer Chromatography (TLC) and High Performance Liquid Chromatography (HPLC) were applied to determine the purity of the yielded piperine. It was found that piperine yield from black pepper was within 2.5% - 3.0% and from white pepper within 4.0% - 4.5% and the purity of the yielded piperine was found to be up to 98.5% for black pepper and 98.2% for white pepper. Considering this yield value and purity it is indicated that, such effective isolation method can be successfully utilized for industrial large-scale production commercially. According to the result, it can be claimed that, as a natural product the isolated piperine can also be utilized as API drug like other expensive chemically synthesized piperine in different drug formulation.

Recently, we reported the induction of protective immunity by environmental Escherichia albertii strain DM104 against Shigella dysenteriae in guinea pig model. In this study, we assessed three different immunization routes, such as intranasal, oral, and intrarectal routes, and revealed differences in immune responses by measuring both the serum IgG and mucosal IgA antibody titers. Protective efficacy of different routes of immunization was also determined by challenging immunized guinea pigs against live S. dysenteriae. It was found that intranasal immunization showed promising results in terms of antibody response and protective efficacy. All these results reconfirm our previous findings and additionally point out that the intranasal immunization of the environmental E. albertii strain DM104 in guinea pig model can be a better live vaccine candidate against shigellosis.

Escherichia coli O157:H7 is a predominant serotype of Shiga toxin producing E. coli (STEC) and is responsible for many outbreaks worldwide. Until recently, there is no comparative study on the bovine and clinical isolates as no STEC O157:H7 has been isolated from patients in Bangladesh. In the present study, the local bovine isolates were compared with a reference clinical strain to investigate whether the bovine isolates are capable of producing same degree of illness as the clinical strain. Two local isolates (CD-11 and CD-17) of bovine origin and a reference clinical strain (E. coli O157:H7 NCTC 12079) were investigated for the presence of virulence genes by polymerase chain reaction (PCR), Shiga toxin production by VTEC-RPLA, invasive property by Congo red binding and Sereny’s keratoconjunctivitis, and other enterotoxic, cytotoxic and mouse lethal activities. Both the local isolates and the reference clinical strain showed the presence of eae and stx2 genes and were found to be non-invasive. The isolates also produced enterotoxin, cytotoxin and mouse lethality similar to that found with the reference strain. All these results strongly suggest that the local bovine STEC O157:H7 isolates have potential to cause diseases similar to clinical STEC O157:H7 strain, which might lead to any outbreak in Bangladesh. Key words: Bovine, Escherichia coli, STEC O157:H7, Bangladesh.

Background Thysanolaena maxima (Roxb.) Kuntze, a perennial grass plant, is usually distributed in hilly regions of the Indian Subcontinent. Different parts of T. maxima have been used as herbal medicine by traditional healers of this region. In this present study, T. maxima plant extract has been screened for examination of its secondary metabolite content with their probable cytotoxic activity. Methods Secondary metabolites of the crude T. maxima plant extract were isolated by different chromatographic methods. The structures were elucidated by spectroscopic data (1H NMR, 13C NMR) as well as comparison with available literature sources. Antiradical activity by DPPH radical scavenging assay and antimicrobial activity by disc diffusion method of the fractions and cytotoxic activity by trypan blue exclusion method of the isolated compounds were also evaluated. Results Three phenolic compounds 4-hydroxybenzaldehyde (1), 4-hydroxycinnamic acid (2), 4-hydroxybenzoic acid (3) and two steroids stigmast-4-en-3-one (4) and β-stigmasterol (5) were isolated from the aerial part of T. maxima. Among the compounds 4-hydroxycinnamic acid, 4-hydroxybenzoic acid and stigmast-4-en-3-one exhibited notable cytotoxic activity against African Green Monkey Kidney Cell line (Vero cell). Conclusion Bioassay investigation of the isolated compounds and fractions suggested that T. maxima could be a potential source of bioactive secondary metabolites. Graphical abstract