Occurrence and characterization of β-lactamase-producing bacteria in biomedical wastewater and in silico enhancement of antibiotic efficacy

Wastewater discharged from hospitals is a recognized contributor to the dissemination of antibiotic-resistant bacteria and their associated genetic traits into the environment. This study focused on the analysis of β-lactamase-producing pathogenic bacteria within untreated biomedical wastewater originating from various hospitals in Dhaka City, Bangladesh, as well as in silico evaluation and structural activity relationship mentioned antibiotics were evaluated. In silico drug design techniques were applied to identify the relationship with how the functional group impacts the binding energy. Out of the 184 isolates obtained from well-established hospital sewage discharge points in Dhaka, 89 were identified as β-lactamase positive. These bacteria were subjected to antimicrobial susceptibility testing using the VITEK-2 assay, and their profiles of extended-spectrum beta-lactamase (ESBL) production were determined through molecular methodologies. Among the β-lactamase-positive isolates, considerable resistance was observed, particularly against ampicillin, Ceftriaxone, Cefuroxime, and Meropenem. The predominant resistant species included Escherichia coli, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter cloacae. The study identified the prevalence of ESBL-producing genes, with blaNDM-1 being the most prevalent, followed by blaOXA-1, blaSHV, blaCTX-M, and blaKPC. None of the isolates carried the blaTEM gene. In addition to characterizing these bacteria, the research explored ways to enhance the binding energy of four existing antibiotics as new inhibitors through computational studies. The findings revealed significant improvements in binding energy. Specifically, Meropenem initially exhibited a binding energy of -7.5 kcal/mol, notably increasing to -8.3 kcal/mol after modification. With an initial binding energy was only -7.9 kcal/mol, Ampicillin experienced an enhancement, reaching -8.0 kcal/mol post-modification. Similarly, Ceftriaxone, with an initial binding energy of -8.2 kcal/mol, increased to -8.5 kcal/mol following structural adjustments. Finally, Cefuroxime, initially registering a binding energy of -7.1 kcal/mol, substantially increased to -8.9 kcal/mol after modification. This finding establishes a foundation for future investigations in the development of modified antibiotics to address the issue of antibiotic resistance. It presents prospective remedies for the persistent problem of antibiotic-resistant bacteria in healthcare and the environment.

Phylogeographic characterization of Burkholderia pseudomallei isolated from Bangladesh

BACKGROUND

Burkholderia pseudomallei possesses a diverse set of genes which encode a vast array of biological functions reflecting its clinical, ecological and phenotypic diversity. Strain variation is linked to geographic location as well as pattern of land uses. This soil-dwelling Gram-negative pathogen causes melioidosis, a tropical disease endemic in northern Australia and Southeast Asian regions including Bangladesh. Phylogeographic analyses of B. pseudomallei isolates by molecular typing techniques could be used to examine the diversity of this organism as well as to track melioidosis epidemics.

METHODS

In this study, 22 B. pseudomallei isolates, of which 20 clinical and two soil isolates were analyzed, utilizing Real-time PCR assay and multilocus sequence typing (MLST). The sequences were then submitted to PubMLST database for analysis and construction of phylogenetic tree.

FINDINGS

A total of 12 different sequence types (STs) that includes four novel STs were identified for the first time. Strains having STs 1005, 1007 and 56 were the most widespread STs frequently isolated in Bangladesh. ST 1005, ST 56, ST 1007 and ST 211 have been detected not only in Bangladesh but are also present in many Southeast Asian countries.

SIGNIFICANCE

ST 1005 was detected in both soil and clinical samples of Gazipur. Most prevalent, ST 56 has been previously reported from Myanmar, Thailand, Cambodia and Vietnam, confirming the persistence of the genotype over the entire continent. Further large-scale study is necessary to find out the magnitude of the infection and its different reservoirs in the environment along with phylogeographic association.

M gene targeted qRT-PCR approach for SARS-CoV-2 virus detection

Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) is the gold standard method for SARS-CoV-2 detection, and several qRT-PCR kits have been established targeting different genes of the virus. Due to the high mutation rate of these genes, false negative results arise thus complicating the interpretation of the diagnosis and increasing the need of alternative targets. In this study, an alternative approach for the detection of SARS-CoV-2 viral RNA targeting the membrane (M) gene of the virus using qRT-PCR was described. Performance evaluation of this newly developed in-house assay against commercial qRT-PCR kits was done using clinical oropharyngeal specimens of COVID-19 positive patients. The limit of detection was determined using successive dilutions of known copies of SARS-CoV-2 pseudovirus. The M gene based assay was able to detect a minimum of 100 copies of virus/mL indicating its capacity to detect low viral load. The assay showed comparable accuracy, sensitivity and specificity with commercially available kits while detecting all the variants efficiently. The study concluded that the in-house M gene based assay might be an effective alternative for the currently available commercial qRT-PCR kits.

Genomic landscape of prominent XDR Acinetobacter clonal complexes from Dhaka, Bangladesh

BACKGROUND

Acinetobacter calcoaceticus-A. baumannii (ACB) complex pathogens are known for their prevalence in nosocomial infections and extensive antimicrobial resistance (AMR) capabilities. While genomic studies worldwide have elucidated the genetic context of antibiotic resistance in major international clones (ICs) of clinical Acinetobacter spp., not much information is available from Bangladesh. In this study, we analysed the AMR profiles of 63 ACB complex strains collected from Dhaka, Bangladesh. Following this, we generated draft genomes of 15 of these strains to understand the prevalence and genomic environments of AMR, virulence and mobilization associated genes in different Acinetobacter clones.

RESULTS

Around 84% (n = 53) of the strains were extensively drug resistant (XDR) with two showing pan-drug resistance. Draft genomes generated for 15 strains confirmed 14 to be A. baumannii while one was A. nosocomialis. Most A. baumannii genomes fell under three clonal complexes (CCs): the globally dominant CC1 and CC2, and CC10; one strain had a novel sequence type (ST). AMR phenotype-genotype agreement was observed and the genomes contained various beta-lactamase genes including bla_OXA-23 (n = 12), bla_OXA-66 (n = 6), and bla_NDM-1 (n = 3). All genomes displayed roughly similar virulomes, however some virulence genes such as the Acinetobactin bauA and the type IV pilus gene pilA displayed high genetic variability. CC2 strains carried highest levels of plasmidic gene content and possessed conjugative elements carrying AMR genes, virulence factors and insertion sequences.

CONCLUSION

This study presents the first comparative genomic analysis of XDR clinical Acinetobacter spp. from Bangladesh. It highlights the prevalence of different classes of beta-lactamases, mobilome-derived heterogeneity in genetic architecture and virulence gene variability in prominent Acinetobacter clonal complexes in the country. The findings of this study would be valuable in understanding the genomic epidemiology of A. baumannii clones and their association with closely related pathogenic species like A. nosocomialis in Bangladesh.

Salmonellacidal antibody response to Salmonella enterica serovar Typhi in enteric fever and after vaccination with Vi capsular polysaccharide

OBJECTIVES

Serum salmonellacidal (bactericidal) antibody could be used to detect functional capacity of antibody in patients with enteric fever and after typhoid vaccination.

METHODS

Salmonellacidal antibody response was measured by colorimetric serum salmonellacidal assay from 70 acute and 11 convalescence sera of patients infected with Salmonella Typhi and Paratyphi A and also from 15 control and 6 Vi capsular polysaccharide vaccinated volunteer's sera.

RESULTS

Sera from patients with typhoid and paratyphoid A showed significant (p < 0.05) levels of salmonellacidal antibody titer (549.9 ± 108.5 and 528.7 ± 187.3) compared with control (0.133 ± 0.1). Moreover, this titer increased significantly (p <0.05) in sera collected between 7 and 10 days and between 11 and 25 days of fever (titer 535.7 ± 119.2 and 794.6 ± 235.6) compared with sera collected from patients with fever for less than 7 days (136.4 ± 52.7). The mean titer significantly (p < 0.05) decreased to 5.5 ± 2.1 after 6-8 weeks onset of illness. Although, very low salmonellacidal titers (2.5 ± 1.5 and 2.3 ± 1.5) were detected after Vi CPS vaccine among the human volunteers, but mean titer was raised 15-fold from pre- to postvaccinated sera (0.166-2.5).

CONCLUSION

The serum salmonellacidal antibody by colorimetric salmonellacidal assay could be used to detect acute typhoidal cases and also to monitor immune response of typhoid vaccine.

Draft-genome analysis provides insights into the virulence properties and genome plasticity of Vibrio fluvialis organisms isolated from shrimp farms and Turag river in Bangladesh

Vibrio fluvialis is an opportunistic waterborne and seafood-borne enteric pathogen capable of causing severe diarrhea leading to death. This pathogen is endemic to Bangladesh, a country which is a major producer of cultured shrimp and wild-caught prawns. In this study, we carried out whole-genome sequencing of three V. fluvialis organisms isolated from shrimp farm and river sediment showing strong pathogenic characteristics in vivo and in vitro and compared their genomes against other V. fluvialis and related pathogenic species to glean insights into their potential as pathogens. Numerous virulence-associated genes including hemolysins, cytolysins, three separate Type IV pili, Types II and VI secretion systems, biofilm, and the V. cholerae pathogenesis regulating gene, toxR, were identified. Moreover, we found strain S-10 to have the propensity to acquire antibiotic resistance genes through horizontal gene transfer. These findings indicate that shrimp farms and rivers could be potential sources of V. fluvialis organisms which are an infection threat of public health concern.

Invasive Fungal Infections in Under-Five Diarrheal Children: Experience from an Urban Diarrheal Disease Hospital

Invasive fungal infections (IFIs) are opportunistic, especially in immunocompromised and hospitalized patients. Children with IFIs are more vulnerable to a fatal outcome. For early diagnosis and treatment, knowledge of the spectrum and frequency of IFIs among children is prerequisite. In this prospective observational study, we enrolled 168 children of 2–59 months old of either sex from March 2018 to December 2019 admitted to the Dhaka hospital, icddr,b. Study participants with suspected IFIs were with or without severe acute malnutrition (SAM) along with sepsis/pneumonia and fulfilled any of the following criteria: (i) failure to respond to injectable antibiotics, (ii) development of a late-onset hospital-acquired infection, (iii) needed ICU care for >7 days, (iv) took steroids/antibiotics for >2 weeks before hospitalization, and (v) developed thrush after taking injectable antibiotics. The comparison group included non-SAM (weight-for-length Z score ≥ −2) children with diarrhea and fever <3 days in the absence of co-morbidity. We performed real-time PCR, ELISA, and blood culture for the detection of fungal pathogen. Study group children with SAM, positive ELISA and PCR considered to have a IFIs. In the study group, 15/138 (10.87%) children had IFIs. Among IFIs, invasive candidiasis, aspergillosis, histoplasmosis detected in 6 (4.53%), 11 (7.97%), and 1 (0.72%) children, respectively, and (3/15 [2.17%]) children had both candidiasis and aspergillosis. Children with IFIs more often encountered septic shock (26.7% vs. 4.9%; p = 0.013) and had a higher death rate (46.7% vs. 8.9%; p < 0.001) than those without IFIs. IFIs were independently associated with female sex (OR = 3.48; 95% CI = 1.05, 11.55; p = 0.042) after adjusting for potential confounders. Our findings thus implicate that, malnourished children with septic shock require targeted screening for the early diagnosis and prompt management of IFIs that may help to reduce IFIs related deaths.

Genotypic distribution and prevalence of human papillomavirus infection in an apparently healthy female population in Bangladesh

Objective

Human papillomavirus (HPV) comprises around 120 genotypically related viruses, classified into low- and high-risk HPVs, which are capable of replicating inside the keratinocytes of skin or mucous membranes. Studies suggest that infections with HPV-16 or HPV-18 have a higher rate of developing cancer. The aim of our study was to detect HPV early, and to estimate the genotype-specific prevalence of HPV in apparently healthy and asymptomatic females in Bangladesh.

Method

After cervical swab specimen collection, a VIA test was performed to identify any type of abnormality in the cervix. A multiplex PCR amplification of HPV DNA, using L1 consensus primer systems, was performed with type-specific primers, followed by sequencing to detect HPV genotypes.

Result

Of the 417 females, 121 were found to be HPV positive. The most prevalent high-risk HPV genotypes were found to be HPV-16 and HPV-18. Different patient demographic parameters, such as age, socioeconomic status, education, and history of first intercourse, were also studied to establish correlations with HPV infection.

Conclusion

Our results might provide some insights into factors that influence the development of cervical cancer. They might also help in guiding better patient management, increased public health awareness, further testing, and the implementation of existing vaccines.

Evaluation of plasma Epstein-Barr virus DNA as a biomarker for Epstein-Barr virus-associated Hodgkin lymphoma

Objectives:

Epstein–Barr virus is a tumorigenic virus and has been extensively studied as a causative agent for Hodgkin lymphoma. Although immunostaining of the tumor biopsy is the standard method for diagnosis of Epstein–Barr virus-driven Hodgkin lymphoma, the invasiveness of the procedure renders it difficult and less desirable for the patients. Therefore, we designed this study to evaluate the efficiency of plasma Epstein–Barr virus DNA detection as an alternative diagnostic and prognostic method for Epstein–Barr virus–associated Hodgkin lymphoma.

Methods:

This analytical cross-sectional study was conducted during March 2017 to December 2018 including 43 Hodgkin lymphoma patients diagnosed histopathologically followed by the latent membrane protein-1 immunohistochemistry to determine their Epstein–Barr virus association. Plasma Epstein–Barr virus DNA in these samples was measured using quantitative polymerase chain reaction (qPCR).

Results:

Of total, 29 (67.44%) patients tested positive for plasma Epstein–Barr virus DNA. On comparing results of latent membrane protein-1 immunohistochemistry (IHC) with plasma Epstein–Barr virus DNA, plasma Epstein–Barr virus DNA was found in 25 of 30 patients with latent membrane protein-1 expression and 4 of 13 patients without latent membrane protein-1 expression. The sensitivity and the specificity of plasma Epstein–Barr virus DNA detection with respect to latent membrane protein-1 IHC were found to be 83.33% and 69.23%, respectively (p = 0.0014).

Conclusion:

Determination of plasma Epstein–Barr virus DNA was found to be highly sensitive and specific in characterizing Epstein–Barr virus–associated Hodgkin lymphoma, suggesting that this diagnostic method holds promise as an alternative and more convenient method of diagnosis compared with tissue biopsy.

Evaluation of the Anti-Inflammatory Activities of Diclofenac Sodium, Prednisolone and Atorvastatin in Combination with Ascorbic Acid

Objectives: Inflammation is our body’s normal defense mechanism, but in some cases, it may be responsible for causing different kinds of disorders. Several anti-inflammatory drugs are present for the treatment of these disorders; however, the conventional anti-inflammatory drugs cause side effects when used in the long term and therefore, it is better to use them in a low dose for a shorter duration of time. This study was designed to find out whether there is an augmentation of the therapeutic effectiveness of the anti-inflammatory drugs like diclofenac sodium (NSAID), prednisolone (steroid) and atorvastatin (statin) when used in combination with ascorbic acid (antioxidant).

Methods: Wistar Rats (n=144) were selected and divided into 24 groups of 6 rats in each. Carrageenan and formalin were used to induce local inflammation and neuropsychiatric effects, respectively. The inhibitions of such responses were measured after administering a drug alone and in combination with ascorbic acid.

Results: In case of carrageenan mediated inflammation, the combination of 5 mg/kg diclofenac and 200 mg/kg ascorbic acid gave the highest inhibition of 74.19% compared to other groups of drugs. The combination of 5 mg/kg diclofenac and 200 mg/kg ascorbic acid gave 97.25% inhibition for formalin-mediated inflammation group. In both cases, combination therapy showed statistically significant anti-inflammatory activities compared to monotherapy (p values <0.05).

Conclusion: All the data clearly indicate new combinations of drug therapy comprising diclofenac sodium, prednisolone, atorvastatin with ascorbic acid, which may be more effective against both local edema and the neuropsychiatric effect caused due to inflammation.

Oral immunization of Escherichia albertii strain DM104 induces protective immunity against Shigella dysenteriae type 4 in mouse model

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.

Mutational profiles of marker genes of cervical carcinoma in Bangladeshi patients

Background

Cervical cancer is a gynecologic cancer type that develops in the cervix, accounting for 8% mortality of all female cancer patients. Infection with specific human papillomavirus (HPV) types is considered the most severe risk factor for cervical cancer. In the context of our socioeconomic conditions, an increasing burden of this disease and high mortality rate prevail in Bangladesh. Although several researches related to the epidemiology, HPV vaccination, and treatment modalities were conducted, researches on the mutation profiles of marker genes in cervical cancer in Bangladesh remain unexplored.

Methods

In this study, five different genomic regions within the top three most frequently mutated genes (EGFR, KRAS and PIK3CA) in COSMIC database with a key role in the development of cervical cancers were selected to study the mutation frequency in Bangladeshi patients. In silico analysis was done in two steps: nucleotide sequence analysis and its corresponding amino acid analysis.

Results

DNA from 46 cervical cancer tissue samples were extracted and amplified by PCR, using 1 set of primers designed for EGFR and 2 sets of primers designed for two different regions of both PIK3CA and KRAS gene. In total, 39 mutations were found in 26 patient samples. Eleven different mutations (23.91%), twenty-four different mutations (52.17%) and four mutations (8.7%) were found in amplified EGFR, PIK3CA and KRAS gene fragments, respectively; among which 1 (EGFR) was common in seven patient samples and 2 (PIKCA) were found in more than 1 patient. Our study shows that except for KRAS, the frequency of observed mutations in our patients is higher than those reported earlier in other parts of the world. Most of the exonic mutations were found only in the PIK3CA and EGFR genes.

Conclusions

The study can be used as a basis to build a mutation database for cervical cancer in Bangladesh with the possibility of targetable oncogenic mutations. Further explorations are needed to establish future diagnostics, personalized medicine decisions, and other pharmaceutical applications for specific cancer subtypes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-07906-5.

Detection of antibodies to recombinant truncated flagellin and sonicated whole cell antigen of Burkholderia pseudomallei in acute melioidosis and in healthy Bangladeshi individuals

Background and objectives: Several types of Burkholderia pseudomallei antigens have been used to determine the antibody response in acute and asymptomatic cases. In the present study, we have detected immunoglobulin G (IgG) antibody to recombinant truncated flagellin antigen (RTFA) of B. pseudomallei in the sera of acute melioidosis cases and healthy individuals from melioidosis endemic areas of Bangladesh by indirect enzyme-linked immunosorbent assay (ELISA). In parallel, IgG antibody to sonicated whole cell antigen (SWCA) of B. pseudomallei was determined to compare with anti-RTFA antibody. Methodology: Serum samples from culture confirmed melioidosis cases and from healthy individuals aged 21 years and above residing in melioidosis endemic rural areas were included in the study. Serum IgG antibody to RTFA and SWCA of B. pseudomallei was determined by indirect ELISA. Results: Out of 8 culture confirmed acute melioidosis cases, 7 (87.5%) and 8 (100%) were positive for anti-B. pseudomallei IgG antibodies by RTFA and SWCA methods respectively. Among 361 healthy individuals, the rate of seropositivity by RTFA-ELISA was significantly less than that of SWCA-ELISA (16.1% versus 26.8%; p = 0.001). The mean optical density (OD) of RTFA-ELISA of positive cases was significantly less than that of SWCA-ELISA in both melioidosis and healthy individuals (0.79±0.11 versus 2.4±0.08, p = 0.0001; 0.67±0.01 versus 1.27±0.02, p = 0.0001). The sensitivity and specificity of RTFA-ELISA were 88.9% and 100% respectively. Conclusion: Findings of the study suggest that multiple or combination of antigens should be used to study the seroprevalence of B. pseudomallei infection in a community. Also, prospective study is necessary to find out the duration of persistence of antibodies to different antigenic components of B. pseudomallei after exposure. Ibrahim Med. Coll. J. 2020; 14(1): 47-52

Presence of blaCTX-M antibiotic resistance gene in Lactobacillus spp. isolated from Hirschsprung diseased infants with stoma

INTRODUCTION

Although antibiotics have revolutionized health care by saving lives, the evolution of both pathogenic and commensal antibiotic-resistant bacteria are emerging as a threat in the health sector. As for Lactobacillus spp., it is usually a non-pathogenic bacteria. However, it can cause infection in immunocompromised condition. In this study, Lactobacillus spp. has been isolated from the faeces of infants with Hirschsprung disease (HD), which is congenital aganglionosis of intestine, where surgical approach and antibiotics are frequently used as medical intervention. The aim of this study is to assess the antibiotic resistance pattern and determine the presence of resistance genes, if any, in Lactobacillus spp. isolated from HD infants with ileostomy.

METHODOLOGY

Six Lactobacillus spp. were isolated from faeces of six HD infants and confirmed using both conventional and molecular methods. Antibiotic resistance pattern was checked through disc diffusion method and was further investigated for the presence of antibiotic resistance genes (blaTEM, blaCTX-M, blaOXA-2, blaIMP, blaVIM-2, blaNDM-1 and mcr-1).

RESULTS

Antibiotic susceptibility of the isolates showed high level of resistance towards cephalosporins, oxacillin, aztreonam, meropenem and polymyxin group. However, four of the isolates showed the presence of blaCTX-M gene after PCR amplification.

CONCLUSIONS

To our knowledge, this is the first report on the presence of antibiotic resistance gene blaCTX-M in Lactobacillus spp. and this presence may pose a serious threat in treatment regimen. As not much is known regarding the presence of blaCTX-M in Lactobacillus spp., this finding may provide new light to research on antibiotic resistance in gut microflora.

Prevalence of Metallo-β-lactamase Producing Non-fermentative Pseudomonas Species from Clinical Isolates in Dhaka, Bangladesh

Antimicrobial drug resistance, a global concern, has been increasing unpredictably in microorganism causing human infections specially among Gram negative non-fermenting Pseudomonas spp. Carbapenems, a beta lactam antibiotics, are the most potent and effective drug usually kept reserved for treating the multi-drug resistant Psedomonas spp and other infections caused by organisms producing Extended Spectrum Beta Lactamase (ESBL) and AmpC. Clinical utility of carbapenem will reduce when resistant bacteria evolve due to production of carbapenem hydrolyzing Metallo-β-lactamase (MBL) which confers high-level resistance to all beta-lactam antibiotics except aztreonam. The various reports on the prevalence of MBLs are available from many countries but few from Bangladesh. We investigated the prevalence of MBL production in these Pseudomonads obtained from clinical sources in an uraban setting in Dhaka, Bangladesh. A total of 29,136 specimens were processed for culture from January 2011 and December 2015 from non duplicated patients attending diagnostic unit of icddr,b from different settings of Bangladesh. The specimens included urine 14,323; blood 11,378; other body fluid 2,487; sputum 535 and tracheal aspirate 413. All specimens were processed for culture following standard bacteriological methods and the Pseudomonas spp were identified following defined standard biochemical procedures. Metallo-β-lactamase (MBL) was determined by EDTA disk synergy (EDS) test. Antimicrobial susceptibility test was performed by disk diffusion method and susceptibility pattern was interpreted and reported following Clinical Laboratory Standard Institute (CLSI) guideline. From 29,136 specimens a total of 2,340(8%) were isolated and identified as Pseudomonas spp. Of the identified Pseudomonas spp, 238(57.6%) were from tracheal aspirate, 216(40.4%) from sputum, 902(36.7%) from other body fluids, 463(4.1%) from blood and 521(3.6%) from urine samples. From 2,340 Pseudomonas spp, by selective sampling, imipenem-meropenem resistant and intermediate susceptible 100 strains were tested for MBL production and 92 were found positive. Tracheal aspirate showed 38%, other body fluids 30%, Urine 17%, sputum 4% and blood 3% MBL production respectively. Irrespective of the sources of specimens, Pseudomonas spp showed 71% resistance to cefixime, 70% to ceftriaxone, 64% to gentamicin, 56% to piperecillin+tazobactam, 50% to ciprofloxacin, 49% to amikacin, 46% to netilmicin, 45% to ceftazidime, 30% to meropenem, 26% to imipenem and 19% to polymyxin B. As multi-drug resistant Pseudomonas showed high level of (92%) MBL production, so MBL detection testing facility may be a useful battery to determine MDR producing Pseudomonas from clinical isolates.

Protection against shigellosis caused by Shigella dysenteriae serotype 4 in guinea pigs using Escherichia albertii DM104 as a live vaccine candidate strain

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.

Unexpected genomic relationships between Bacillus anthracis strains from Bangladesh and Central Europe

The zoonosis anthrax caused by the bacterium Bacillus anthracis has a broad geographical distribution. Active enzootic areas are typically located away from central and northern Europe where cases of the disease occur only sporadically and in limited numbers. In contrast, a few out of the 64 districts of Bangladesh are hyper-endemic for anthrax and there the disease causes major losses in live-stock. In this study we genotyped eight strains of B. anthracis collected from the districts of Sirajganj and Tangail in 2013. All these strains belonged to canSNP group A.Br.001/002 Sterne differing only in a few of 31 tandem-repeat (MLVA)-markers. Whole genome sequences were obtained from five of these strains and compared with genomic information of B. anthracis strains originating from various geographical locations. Characteristic signatures were detected defining two "Bangladesh" clusters potentially useful for rapid molecular epidemiology. From this data high-resolution PCR assays were developed and subsequently tested on additional isolates from Bangladesh and Central Europe. Remarkably, this comparative genomic analysis focusing on SNP-discovery revealed a close genetic relationship between these strains from Bangladesh and historic strains collected between 1991 and 2008 in The Netherlands and Germany, respectively. Possible explanations for these phylogenetic relationships are discussed.

Genotype Analysis of Bacillus anthracis Strains Circulating in Bangladesh

In Bangladesh, anthrax, caused by the bacterium Bacillus anthracis, is considered an endemic disease affecting ruminants with sporadic zoonotic occurrences in humans. Due to the lack of knowledge about risks from an incorrect removal of infected carcasses, the disease is not properly monitored, and because of the socio-economic conditions, the situation is under-reported and under-diagnosed. For sensitive species, anthrax represents a fatal outcome with sudden death and sometimes bleeding from natural orifices. The most common source of infection for ruminants is ingestion of spores during grazing in contaminated pastures or through grass and water contaminated with anthrax spores. Domestic cattle, sheep and goats can also become infected through contaminated bone meal (used as feed) originating from anthrax-infected carcasses. The present investigation was conducted to isolate B. anthracis organisms from 169 samples (73 soil, 1 tissue, 4 bone and 91 bone meal samples) collected from 12 different districts of Bangladesh. The sampling was carried out from 2012 to 2015. Twelve samples resulted positive for B. anthracis. Biomolecular analyses were conducted starting from the Canonical Single Nucleotide Polymorphism (CanSNP) to analyze the phylogenetic origin of strains. The analysis of genotype, obtained through the Multiple Locus Variable Number Tandem Repeat Analysis (MLVA) with the analysis of 15 Variable Number Tandem Repeats (VNTR), demonstrated four different genotypes: two of them were previously identified in the district of Sirajganj. The sub-genotyping, conducted with Single Nucleotide Repeats analysis, revealed the presence of eight subgenotypes. The data of the present study concluded that there was no observed correlation between imported cattle feed and anthrax occurrence in Bangladesh and that the remarkable genetic variations of B. anthracis were found in the soil of numerous outbreaks in this country.

Evaluation of efficiency of nested multiplex allele-specific PCR assay for detection of multidrug resistant tuberculosis directly from sputum samples

For an effective control of tuberculosis, rapid detection of multidrug resistant tuberculosis (MDR-TB) is necessary. Therefore, we developed a modified nested multiplex allele-specific polymerase chain reaction (MAS-PCR) method that enables rapid MDR-TB detection directly from sputum samples. The efficacy of this method was evaluated using 79 sputum samples collected from suspected tuberculosis patients. The performance of nested MAS-PCR method was compared with other MDR-TB detection methods like drug susceptibility testing (DST) and DNA sequencing. As rifampicin (RIF) resistance conforms to MDR-TB in greater than 90% cases, only the presence of RIF-associated mutations in rpoB gene was determined by DNA sequencing and nested MAS-PCR to detect MDR-TB. The concordance between nested MAS-PCR and DNA sequencing results was found to be 96·3%. When compared with DST, the sensitivity and specificity of nested MAS-PCR for RIF-resistance detection were determined to be 92·9 and 100% respectively.

SIGNIFICANCE AND IMPACT OF THE STUDY

For developing- and high-TB burden countries, molecular-based tests have been recommended by the World Health Organization for rapid detection of MDR-TB. The results of this study indicate that, nested MAS-PCR assay might be a practical and relatively cost effective molecular method for rapid detection of MDR-TB from suspected sputum samples in developing countries with resource poor settings.

Prevalence of genotypes and subtypes of hepatitis B viruses in Bangladeshi population

The genetic variability of hepatitis B virus (HBV) represents a challenge for the sensitivity of immunologic and molecular based assays. Based on sequence divergences in the entire genome of >8 %, HBV genomes have been classified into ten genotypes designated as A to J. The aim of this study was to determine HBV genotypes and subtype in samples of HBV infected patients in Bangladesh. The sera samples were collected from chronically infected HBV patients. At first the DNA positive HBV samples were screened by EIA in our laboratory and the 1063 bp region of surface gene was amplified, sequenced and genotyped by sequence analysis. The same sequences were also used for subtypes and mutational analyses. After that, genotyping was also carried out by nested PCR using genotype specific primers in the same region of HBV surface gene. A total of 39 samples were sequencing to find out the genotypes and subtypes. It was found that the prevalent genotype was genotype C (subgenotype C1) which accounted for 48.7 %. The other genotypes found were genotype A (23.1 %) and genotype D (28.2 %). Predominant subtypes in Bangladesh were adr (41 %) followed by subtype adw2 (28.2 %), ayw3 (25.6 %), and others. Additionally, genotyping was also done by nested PCR using type-specific primers. In this method, out of 17 samples 6 were found to be genotype C, followed by genotype D (4 of 17) and genotype A (3 of 17). In PCR-based genotyping system we also observed the mix genotypes; 3 samples contained both genotype A and D, and 2 samples contained both C and D. The genetic diversity of HBV and distribution of its genotypes and subtypes amongst Bangladeshi population were done in this study, which will help us to provide information regarding circulating genotypes in this region and also help physicians to prescribe proper antiviral/interferon therapy.

Burkholderia pseudomallei: Its Detection in Soil and Seroprevalence in Bangladesh

Background

Melioidosis, caused by Burkholderia pseudomallei, is an endemic disease in Bangladesh. No systematic study has yet been done to detect the environmental source of the organism and its true extent in Bangladesh. The present study attempted to isolate B. pseudomallei in soil samples and to determine its seroprevalence in several districts in Bangladesh.

Methodology and Results

Soil samples were collected from rural areas of four districts of Bangladesh from where culture confirmed melioidosis cases were detected earlier. Multiple soil samples, collected from 5–7 sampling points of 3–5 sites of each district, were cultured in Ashdown selective media. Suspected colonies of B. pseudomallei were identified by biochemical and serological test, and by polymerase chain reaction (PCR) using 16s rRNA specific primers. Blood samples were collected from 940 healthy individuals of four districts to determine anti- B. pseudomallei IgG antibody levels by indirect enzyme linked immunosorbent assay (ELISA) using sonicated crude antigen. Out of 179 soil samples, B. pseudomallei was isolated from two samples of Gazipur district which is located 58 km north of capital Dhaka city. Both the isolates were phenotypically identical, arabinose negative and showed specific 550bp band in PCR. Out of 940 blood samples, anti- B. pseudomallei IgG antibody, higher than the cut-off value (>0.8), was detected in 21.5% individuals. Seropositivity rate was 22.6%-30.8% in three districts from where melioidosis cases were detected earlier, compared to 9.8% in a district where no melioidosis case was either detected or reported (p<0.01). Seropositivity increased with the advancement of age from 5.3% to 30.4% among individuals aged 1–10 years and > 50 years respectively. The seropositivity rates were 26.0% and 20.6% in male and female respectively, while it was 20–27% among different occupational groups. No significant association was observed with gender (χ2 = 3.441, p = 0.064) or any occupational group (χ² = 3.835, p = 0.280).

Conclusion

This is the first study demonstrating the presence of B. pseudomallei in the environmental (soil) samples of Bangladesh. It also suggested that a large proportion of people, residing in these districts, were exposed to the organism.

Melioidosis, caused by B. pseudomallei, can be a fatal disease if not treated with appropriate antibiotics. The organism is mainly present in soil and water in endemic areas, and people become infected through skin inoculation, inhalation or ingestion. The disease has been sporadically detected in Bangladesh over last several decades. However, its actual prevalence in Bangladesh is largely unknown due to the lack of systematic study and awareness of the medical community about the disease and the organism. In order to address the issue, we have undertaken this study to assess the presence of the organism in the soil as well as its magnitude of exposure among the people of selected areas of the country. The study revealed the presence of B. pseudomallei in the soil and its exposure among the people of different areas. The information would increase the awareness of the medical community for prevention and correct diagnosis of the disease.

An environmental Escherichia albertii strain, DM104, induces protective immunity to Shigella dysenteriae in guinea pig eye model

The environmental Escherichia albertii strain DM104, which cross-reacts serologically with Shigella dysenteriae was assessed for pathogenic properties, immunogenicity, and protective efficacy in different animal models to evaluate it as a vaccine candidate against S. dysenteriae, which causes the severe disease, shigellosis. The DM104 isolate was found to be non-invasive and did not produce any entero- or cyto-toxins. The strain also showed negative results in the mouse lethal activity assay. The non-pathogenic DM104 strain gave, however, a high protective efficacy as an ocularly administered vaccine in the guinea pig eye model against S. dysenteriae type 4 challenge. It also induced a high titer of serum IgG against S. dysenteriae type 4 whole cell lysate and lipopolysaccharide. Taken together, all these results indicate a good potential for the use of the DM104 as a live vaccine candidate against shigellosis.

Analysis of Different Prognostic Indicators for Malnutrition and Shigella flexneri Infection Among the Children in Bangladesh

The present study investigates into some socio-economic, demographic, and nutritional features that can predispose Bangladeshi children to malnutrition and Shigella flexneri infection. Significant prognostic indicators associated with malnutrition were mother's illiteracy (unadjusted odds ratio, OR = 2.580; 95% confidence interval, CI = 1.134-5.867 and adjusted odds ratio, ORa, 3.814; 95% CI = 1.124-12.943), low birth weight (OR = 3.143; 95% CI = 1.2-8.232 and ORa = 2.404; 95% CI = 0.870-6.644) and poor socioeconomic status (OR = 2.549; 95% CI = 1.382-4.701 and ORa = 1.808; 95% CI = 0.852-3.838). Age was the strongest predictor for the acquisition of S. flexneri infection in the studied population (OR = 5.472; 95% CI = 2.583-11.592 and ORa = 5.808; 95% CI = 2.420-13.942). The severity of malnutrition was significantly (P = 0.033) related to seroprevalence of S. flexneri infection. To reduce malnutrition emphasis should be given on controlling the incidence of low birth weight, improving the literacy status especially of mothers and narrowing the gap between different socio-economic levels. Malnourished children should be examined for severity and direct intervention therapy should be given when necessary.

Reduction of Sodium Arsenite-Mediated Adverse Effects in Mice using Dietary Supplementation of Water Hyacinth (Eichornia crassipes) Root Powder

BACKGROUND

In this study, we evaluated the protective effects of water Hyacinth Root Powder (HRP) on arsenic-mediated toxic effects in mice.

METHODS

Swiss albino mice, used in this study, were divided into four different groups (for each group n=5). The control group was supplied with normal feed and water, Arsenic group (As-group) was supplied with normal feed plus arsenic (sodium arsenite)-containing water, and arsenic+hyacinth group (As+Hy group) was supplied with feed supplemented with HRP plus arsenic water. The remaining Hy-group was supplied with feed supplemented with HRP plus normal water.

RESULTS

Oral administration of arsenic reduced the normal growth of the mice as evidenced by weight loss. Interestingly, tip of the tails of these mice developed wound that caused gradual reduction of the tail length. Supplementation of HRP in feed significantly prevented mice growth retardation and tail wounding in As+Hy group mice. However, the growth pattern in Hy-group mice was observed to be almost similar to that of the control group indicating that HRP itself has no toxic or negative effect in mice. Ingested arsenic also distorted the shape of the blood cells and elevated the serum enzymes such as lactate dehydrogenase (LDH), alkaline phosphatase (ALP) and serum glutamic pyruvic transaminase (SGPT). Importantly, elevation of these enzymes and distortion of blood cell shape were partially reduced in mice belong to As+Hy group, indicating HRP-mediated reduction of arsenic toxicity.

CONCLUSION

Therefore, the preventive effect of hyacinth root on arsenic-poisoned mice suggested the future application of hyacinth to reduce arsenic toxicity in animal and human.

Distribution of coliphages against four e. Coli virotypes in hospital originated sewage sample and a sewage treatment plant in bangladesh

The distribution of coliphages infecting different Escherichia coli virotypes (EHEC, EIEC, EPEC, ETEC) and an avirulent strain (K-12) in sewage system of a hospital and a sewage treatment plant (STP) was investigated by culture-based agar overlay methods. Coliphages were found in all the samples except stool dumping site in the sewage system of the hospital and lagoon of the STP. Bacteriophage count (pfu/ml) infecting E. coli strains showed the following ascending pattern (EHEC < EIEC < EPEC < ETEC < E coli K-12) in all the collected samples except one. Phages capable of infecting avirulent E. coli K-12 strains were present in the highest number among all the examined locations. Phages specific for E. coli K-12 presented high diversity in plaque size on the bacterial lawn. Virulent E. coli specific coliphages rarely produced plaques with diameter of 1-2 mm or over. Conventional agar overlay method was found to be not satisfactory for phage community analysis from primary stool dumping site of the hospital, probably due to the presence of high concentration of antimicrobial substances. The gradual decrease seen in the five groups of coliphage quantity with the ongoing treatment process and then the absolute absence of coliphages in the outlet of the examined treatment plant is indicative of the usefulness of the treatment processes practiced there.

Local bacteriophage isolates showed anti- Escherichia coli O157:H7 potency in an experimental ligated rabbit ileal loop model

Escherichia coli O157:H7 is considered among the most important recently emerged food-borne bacteria causing severe hemorrhagic diarrhea. Antibiotic treatment is not recommended as a prospective curative agent against this pathogen. Therefore, potency assessment of the local lytic phage isolates infecting E. coli O157:H7 as an alternate remedy to antibiotics was the principal concern of this study. Phage isolates against E. coli O157:H7 were checked by polymerase chain reaction for the presence of the virulence genes stx1 and stx2, and the safe phages were further screened in vitro for their capacity as biocontrol agents. Two bacteriophage strains, namely PAH6 and P2BH2, that had expressed potential antibacterial activity (P < 0.05) in vitro were selected for in vivo testing in ligated rabbit ileal loop models. Both phage isolates were capable of decreasing fluid accumulation in rabbit ileal loops along with reducing bacterial growth (r = 0.992). Combined application of the phages was found most satisfactory, reducing seven log cycles of bacterial growth. Consistent results in both in vivo and in vitro experiments demonstrate the applicability of bacteriophages as a rapid response tool against E. coli O157:H7. To our knowledge, this is the first successful application of the rabbit ileal loop test for therapeutic evaluation of bacteriophages.

Molecular versus conventional methods: clinical evaluation of different methods for the diagnosis of tuberculosis in Bangladesh

BACKGROUND

The diagnosis of tuberculosis (TB) in developing countries, such as Bangladesh, is based mainly on microscopic detection of acid-fast bacilli in smears from clinical specimens. On the other hand, the detection of TB by polymerase chain reaction (PCR) is quite new in Bangladesh. In this study, we compared the molecular method with the conventional diagnosis procedures, where Lowenstein-Jensen medium culture results have been used as the "gold standard."

METHODS

A total of 135 sputum samples were collected from clinically suspected patients with pulmonary TB. A direct smear was made from each sputum specimen and stained by the Ziehl-Neelsen (Z-N) method. The sputum samples were then processed, and the pellet was used for both Z-N (concentration) and auramine O fluorescence staining or resuspended in phosphate buffered saline to inoculate Lowenstein-Jensen medium or processed for PCR detection of Mycobacterium tuberculosis.

RESULTS

The direct smear staining yielded 44 (32.6%) sputum samples that were acid-fast positive, which increased after concentration, yielding 60 (44.4%) acid-fast-positive samples. Fluorescence microscopy using auramine O staining further increased the number of positive samples to 67 (49.6%). The biochemical tests showed 75 (55.6%) sputum samples to be culture positive, and the MB/BacT system increased the recovery up to 90 (66.7%) culture positives. On the other hand, PCR yielded 93 (68.9%) positive results, 20 (21.5%) of which were culture-negative sputum specimens.

CONCLUSION

It is suggested that the Z-N direct microscopy on its own is the best method (with high specificity) for confirming the diagnosis of acid-fast bacilli. Although the PCR diagnosis of TB appears to be a rapid and sensitive method, the results should be interpreted with care in the clinical settings.

Analysis of immune responses against H pylori in rabbits

AIM: To investigate the immunogenicity of H pylori proteins, to evaluate the production rate of anti H pylori IgG antibodies in relation to time and to demonstrate the fidelity of newly optimized in-house enzyme-linked immunosorbent assay (ELISA) technique as an alternative for H pylori infection assay.

METHODS: In the present study, 100 μg of formalin-fixed H pylori whole cell antigens was injected into an experimental animal (New Zealand white female rabbit) intramuscularly on d 0, 16, 27 and 36. The first two doses were injected with adjuvants. On d 0, a serum sample was collected from the rabbit before immunization and this pre-immunized serum was used as a negative control for the whole study. To evaluate the immunogenic responses of the injected antigen, serum samples were collected from the rabbit at regular intervals up to d 42. The sera were analyzed using in-house ELISA and Western blot techniques.

RESULTS: The production of anti H pylori IgG antibodies in the rabbit in response to the injected antigen increased almost exponentially up to d 14 and after that it was maintained at the same level until the last day (d 42). By analyzing the immune profiles of immunized sera, 11 proteins were identified to be immunogenic, among them 2 (approximately 100 kDa and 85 kDa) were most prominent.

CONCLUSION: Analysis of the immune responses against pathogenic microorganisms like H pylori is necessary for the development of various diagnostic and preventive approaches. The results of this experiment reveal that the formalin-fixed H pylori whole cell antigens injected into the rabbit are highly immunogenic. These prominent proteins (approximately 100 kDa and 85 kDa) might have higher immunogenic effects among humans infected with H pylori and some of these immunogenic proteins can be included in diagnostic approaches based on serology and also for vaccine formulation. The in-house ELISA is a promising alternative compared to invasive techniques.

The Mycobacterium bovis BCG 64-kDa surface protein is antigenically shared with different mouse tumor cells and has anti-tumor activity in immunized mice

The Mycobacterium bovis BCG 64-kDa surface protein, which was found to share antigenic determinants with line 10 hepatoma cells and showed anti-line 10 tumor activity in immunized guinea pigs, has also been found to share common antigenic determinants with Meth A, CT-26 and RL female 1 mouse tumor cells. The 64-kDa protein also demonstrated anti-tumor activity in immunized mice and 37% of the animals challenged with Meth A tumor cells and 50% of those challenged with CT-26 tumor cells completely rejected further tumor growth in the immunized mice. All these data clearly suggest that BCG 64 kDa protein is probably identical with the tumor specific antigen.

Crossed immunoelectrophoretic analysis of antigenic composition of B-subunit/whole-cell and whole-cell only killed oral cholera vaccines

Crossed immunoelectrophoresis was used to identify antigens preserved in the whole-cell component of oral cholera vaccines tested in the field trial in Bangladesh. The composition and immunogenicity of the vaccine antigens were compared with those of antigens obtained from live cells of Vibrio cholerae 01 of both biovars and serovars. The whole-cell component of the vaccine contained ten antigens in comparison with the live Vibrio cells which revealed the presence of 30 antigens. The whole-cell component contained lipopolysaccharide, flagellar antigen, one cell-bound haemagglutinin and at least six outer membrane protein antigens.

A 64 kDa protein from Mycobacterium bovis BCG shares the same antigenic determinants with line 10 hepatoma cells and has anti-line 10 tumor activity

A 64 kilodalton (kDa) surface protein was isolated from the water-extracted materials from Mycobacterium bovis strain BCG, the determinants of which are antigenically shared by a 64 kDa major surface antigenic component of line 10 hepatoma cells. The 64 kDa protein showed anti-line 10 tumor activity in pre-immunized guinea pigs, and this suggest that the BCG 64 kDa protein is probably identical with the tumor specific antigen.

Idiotype vaccine for tumor by anti-idiotypic antibody prepared against anti-(bacillus Calmette Guèrin)BCG monoclonal antibody

The anti-idiotypic antibody (Ab2) prepared against the anti-BCG monoclonal antibody (mAb) (Ab1) exhibited potential vaccine activity against Meth A fibrosarcoma that shared a common antigen(s) with Mycobacterium bovis strain bacillus Calmette Guèrin (BCG). Mice vaccinated with the anti-idiotypic antibody (Ab2) were protected significantly against growth of the transplanted Meth A tumor (66%), and the presence of anti-(anti-idiotypic antibody) (Ab3) was proved in the Ab2-vaccinated mice by enzyme-linked immunosorbent assay and indirect immunofluorescence analyses using unabsorbed or absorbed sera against the BCG antigen(s) and Meth A tumor cells. This indicated that the anti-idiotypic antibody (Ab2) mimicked the structures of the BCG antigen(s) and behaved as the BCG antigen(s) to induce the Ab1-like antibody (Ab3) in vivo. Presumably the Ab2-induced Ab3 plays a significant role in preventing growth of the transplanted tumor in animals. By contrast, the control mice treated with normal mouse serum failed to inhibit the tumor growth. These results suggest the possible development of a tumor vaccine from the anti-idiotypic antibody (Ab2) prepared against the anti-BCG monoclonal antibody, for tumors sharing a common antigen(s) with Mycobacterium bovis strain BCG.

Antigenic analysis between BCG and tumor cells by BCG-monoclonal antibodies

Antigenic relation between Mycobacterium bovis strain BCG and experimental animal tumor cells was analyzed with BCG monoclonal antibodies (BCG-MoAbs). Four BCG-MoAbs of 602, 603, 609, and 612 were successfully established and applied for the antigenic analysis of Meth A, RL male 1, colon tumor 26 of mouse, and line 10 of guinea pig tumor. MoAb 602 showed broad reactivity against all types of tumor cells. BCG antigen(s) was clearly recognized as small granules on the tumor cell surface under the fluorescence microscope, indicating that the animal tumor cells shared the common antigen(s) with BCG.

Oral cholera vaccines containing B-subunit-killed whole cells and killed whole cells only. I. Cross-reacting antigens of members of family Vibrionaceae and the vaccines

Antigenic similarity between the oral cholera B subunit-whole cell (BS-WC) and whole-cell only (WC) vaccines and strains of the family Vibrionaceae was studied by crossed immunoelectrophoresis. A reference system consisting of Vibrio cholerae Inaba E1 Tor antigenic extract and homologous rabbit antiserum was applied in the study. The system was represented by 30 anodically migrating antigens forming distinct precipitation bands. Antigenic extracts of other members of the family Vibrionaceae showed the following numbers of cellular antigens shared in common with the reference system: Vibrio cholerae non-01-30, V. mimicus-23, V. fluvialis-15, V. parahaemolyticus-10, Aeromonas hydrophila-7, A. sobria-5, A. caviae-4 and Plesiomonas shigelloides-5 antigens. Homologous rabbit antiserum reacted with 11 antigens of BS-WC vaccine and 10 antigens of WC vaccine. The number of antigens which members of the family Vibrionaceae shared in common with those preserved in the WC component of the vaccines were as follows: Vibrio cholerae non-01, 7; V. mimicus, 5; V. fluvialis, 3; V. parahaemolyticus, 3; Aeromonas hydrophila, 2; A. sobria, 2; and A. caviae, 2; Plesiomonas shigelloides, 1. None of the strains produced an antigen reacting with anti-cholera toxin antibodies. The presence of common antigens in the vaccine and among members of family Vibrionaceae indicates that the oral cholera vaccine could stimulate immunity effectively against other members of the family.

Isolation of line 10 hepatoma-cell membrane by the water extraction method and immunochemical analysis

Water extraction method was applied to isolate the cell membrane from line 10 hepatoma cells and normal liver cells in strain 2 guinea pig. The materials isolated by this method were further analyzed by different immunochemical techniques including SDS-PAGE, crossed immunoelectrophoresis and crossed affino immunoelectrophoresis to demonstrate the major components and their antigenicities. Five major glycoproteins of apparent molecular weights of 44, 46, 62, 64, and 68 kDa were prominent in line 10 tumor cell materials, whereas one band of molecular weight of 82 kDa was prominent in the materials from normal liver cells. Also four minor components from line 10 tumor cells were found to be glycoprotein in nature.

[Rapid diagnosis of experimental tumor by FITC-Con A lectin--a comparative study of smear and section specimens]

FITC-Con A staining as a rapid diagnostic method for tumor cells was applied to the tumors smeared on glass slide and section specimens to evaluate the reactivity with FITC-Con A. Good staining results were obtained in smear specimens with clear fluorescence on the membrane of tumor cells. Con A and LCH lectins bound well with tumor cells to produce strong fluorescence in comparison with PEA and DBA. It indicates that tumor cells expressed dominantly the receptors of alpha-D-glucose and alpha-D-mannose sugar chain on the membrane of tumor cells. From these results it was concluded that FITC-Con A staining method applied to smear specimens is more advantageous in the rapidity and the simplicity for tumor cell diagnosis than section specimen method.

Immunobiological relationships between Vibrio fluvialis and Vibrio cholerae enterotoxins

A total of 26 strains of Vibrio fluvialis was included in this study, which were isolated from patients with diarrhoea and other sources. The GM1 enzyme linked immunosorbent assays performed with the culture filtrates of V. fluvialis yielded negative results, indicating that their receptor site is different from that of the known labile toxin. The cholera antitoxin failed to neutralize the skin permeability factor activities of all the V. fluvialis culture filtrates and none of the concentrated culture filtrates gave any precipitin band, when tested against the cholera antitoxin in Ouchterlony's gel diffusion test. These observations suggest that the toxin of V. fluvialis differs from the known cholera toxin in receptor site, mode of action and antigenicity.