NIR spectroscopy-CNN-enabled chemometrics for multianalyte monitoring in microbial fermentation.

As the biopharmaceutical industry looks to implement Industry 4.0, the need for rapid and robust analytical characterization of analytes has become a pressing priority. Spectroscopic tools, like near-infrared (NIR) spectroscopy, are finding increasing use for real-time quantitative analysis. Yet detection of multiple low-concentration analytes in microbial and mammalian cell cultures remains an ongoing challenge, requiring the selection of carefully calibrated, resilient chemometrics for each analyte. The convolutional neural network (CNN) is a puissant tool for processing complex data and making it a potential approach for automatic multivariate spectral processing. This work proposes an inception module-based two-dimensional (2D) CNN approach (I-CNN) for calibrating multiple analytes using NIR spectral data. The I-CNN model, coupled with orthogonal partial least squares (PLS) preprocessing, converts the NIR spectral data into a 2D data matrix, after which the critical features are extracted, leading to model development for multiple analytes. Escherichia coli fermentation broth was taken as a case study, where calibration models were developed for 23 analytes, including 20 amino acids, glucose, lactose, and acetate. The I-CNN model result statistics depicted an average R2 values of prediction 0.90, external validation data set 0.86 and significantly lower root mean square error of prediction values ∼0.52 compared to conventional regression models like PLS. Preprocessing steps were applied to I-CNN models to evaluate any augmentation in prediction performance. Finally, the model reliability was assessed via real-time process monitoring and comparison with offline analytics. The proposed I-CNN method is systematic and novel in extracting distinctive spectral features from a multianalyte bioprocess data set and could be adapted to other complex cell culture systems requiring rapid quantification using spectroscopy.

Spatiotemporal genome diversity of SARS-CoV-2 in wastewater: a two-year global epidemiological study.

Wastewater surveillance locally and globally is important for the investigation of the molecular epidemiological features of SARS-CoV-2 in the environment. The current study investigated the genomic diversity and mutation profile of SARS-CoV-2 variants in wastewater for the period spanning COVID-19 pandemic up to December, 2022. A total of 3618 complete SARS-CoV-2 genome sequences from waste water samples submitted to the GISAID database were retrieved. The SARS-CoV-2 sequences were subjected to pairwise alignment against reference, followed by clade and lineage assignment (based on Nextstrain, GISAID and Pango), distance metric phylogenetic analysis, and detection of substitution mutations. Following GISAID, Nextstrain, and Pango nomenclatures, an overall agreement in clade and lineage determination in wastewater samples was observed. There was successive appearance, dissemination, and disappearance of SARS-CoV-2 lineages along time in wastewater. The SARS-CoV-2 genomes from wastewater were clustered into the variants of concern (VOC) as Alpha GRY (B.1.1.7 + Q.7), Delta GK (B.1.617.2 + AY.*), and Omicron GRA (BA.1*, BA.2* + B.1.1.529, BA.5*). The evolutionary rate was 9.63e-04 substitutions/site/year for SARS-CoV-2 in wastewater. B.1.1.7 was less prevalent than B.1.617.2 in 2021, appeared in succession, and BA.1, BA.2, BA.5 were serially detected in 2022, the latter strain continued to persist in wastewater. The N501Y, E484K/Q, K417N/T, L452R, T478K spike substitutions remained dominant attribute of SARS-CoV-2 VOCs. The study underlines the importance of wastewater surveillance for enumerating spatiotemporal diversity of SARS-CoV-2 variants and mutations, which might pave the way for novel antiviral and vaccine designing towards management and prevention of SARS-CoV-2 infection.

Rapid Estimation of Size-Based Heterogeneity in Monoclonal Antibodies by Machine Learning-Enhanced Dynamic Light Scattering.

Aggregation of monoclonal antibody therapeutics is a serious concern that is believed to impact product safety and efficacy. There is a need for analytical approaches that enable rapid estimation of mAb aggregates. Dynamic light scattering (DLS) is a well-established technique for estimating the average size of protein aggregates or for evaluating sample stability. It is usually used to measure the size and size distribution over a wide range of nano- to micro-sized particles using time-dependent fluctuations in the intensity of scattered light arising from the Brownian motion of particles. In this study, we present a novel DLS-based approach that allows us to quantify the relative percentage of multimers (monomer, dimer, trimer, and tetramer) in a monoclonal antibody (mAb) therapeutic product. The proposed approach uses a machine learning (ML) algorithm and regression to model the system and predict the amount of relevant species such as monomer, dimer, trimer, and tetramer of a mAb in the size range of 10-100 nm. The proposed DLS-ML technique compares favorably to all potential alternatives with respect to the key method attributes, including per sample cost of analysis, per sample time of data acquisition along with ML-based aggregate prediction (<2 min), sample requirements (<3 µg), and user-friendliness of analysis. The proposed rapid method can serve as an orthogonal tool to size exclusion chromatography, which is the current industry workhorse for aggregate assessment.

Novel semi-automated fluorescence microscope imaging algorithm for monitoring IgG aggregates in serum.

Analysis of therapeutic IgG aggregates in serum is a potential area of investigation as it can give deeper insights about the function, immunogenic issues and protein interaction associated with the aggregates. To overcome various complexities associated with the existing analytical techniques for analyzing aggregates in serum, a novel florescence microscopy-based image processing approach was developed. The monoclonal antibody (mAb) was tagged with a fluorescent dye, fluorescein isothiocyanate (FITC). Aggregates, generated by stirring, were spiked into serum and images were captured at various time points. After denoising, thresholding by weighted median, 1D Otsu, and 2D Otsu was attempted and a modified 2D Otsu, a new mode of thresholding, was developed. This thresholding method was found to be highly effective in removing noises and retaining analyte sizes. Out of 0-255, the optimized threshold value obtained for the images discussed in modified 2D Otsu was 9 while 2D Otsu's overestimated values were 38 and 48. Other morphological operations were applied after thresholding and the area, perimeter, circularity, and radii of the aggregates in these images were calculated. The proposed algorithm offers an approach for analysis of aggregates in serum that is simpler to implement and is complementary to existing approaches.

Principal component analysis exploring the association between antibiotic resistance and heavy metal tolerance of plasmid-bearing sewage wastewater bacteria of clinical relevance.

This paper unravels the occurrence of plasmid-mediated antibiotic resistance in association with tolerance to heavy metals among clinically relevant bacteria isolated from sewage wastewater. The bacteria isolated were identified following conventional phenotypic and/or molecular methods, and were subjected to multiple-antibiotic resistance (MAR) profiling. The isolates were tested against the heavy metals Hg2+, Cd2+, Cr2+ and Cu2+. SDS-PAGE and agarose gel electrophoretic analyses were performed, respectively, for the characterization of heavy metal stress protein and R-plasmid among the isolated bacteria. Principal component analysis was applied in determining bacterial resistance to antibiotics and heavy metals. Both lactose-fermenting ( Escherichia coli ) and non-fermenting ( Acinetobacter baumannii and Pseudomonas putida ) Gram-negative bacterial strains were procured, and showed MAR phenotypes with respect to three or more antibiotics, along with resistance to the heavy metals Hg2+, Cd2+, Cr2+ and Cu2+. The Gram-positive bacteria, Enterococcus faecalis , isolated had 'ampicillin-kanamycin-nalidixic acid' resistance. The bacterial isolates had MAR indices of 0.3-0.9, indicating their ( E. faecalis , E. coli , A. baumannii and P. putida ) origin from niches with high antibiotic pollution and human faecal contamination. The Gram-negative bacteria isolated contained a single plasmid (≈54 kb) conferring multiple antibiotic resistance, which was linked to heavy metal tolerance; the SDS-PAGE analysis demonstrated the expression of heavy metal stress proteins (≈59 and ≈10 kDa) in wastewater bacteria with a Cd2+ stressor. The study results grant an insight into the co-occurrence of antibiotic resistance and heavy metal tolerance among clinically relevant bacteria in sewage wastewater, prompting an intense health impact over antibiotic usage.

Indigenous Probiotic Lactobacillus Isolates Presenting Antibiotic like Activity against Human Pathogenic Bacteria.

BACKGROUND: Indigenous lactic acid bacteria are well known probiotics having antibacterial activity against potentially pathogenic bacteria. This study aims to characterize the curd lactobacilli for their probiotic potentiality and antagonistic activity against clinical bacteria. METHODS: Four curd samples were processed microbiologically for the isolation of lactic acid bacteria (LAB). The LAB strains obtained were identified by conventional methods: cultural aspect, gram-staining, biochemical and sugar fermentation tests. The probiotic properties were justified with tolerance to low-pH, bile salt and sodium chloride, and the antagonistic activity of the lactobacilli against human pathogenic bacteria (Escherichia coli, Proteus vulgaris, Acinetobacter baumannii and Salmonella enterica serovar Typhi) was assessed. Hemolytic activity and antibiotic susceptibility were determined for the lactobacilli isolates, and the cumulative probiotic potential (CPP) values were recorded. RESULT: Four lactobacilli isolates, L. animalis LMEM6, L. plantarum LMEM7, L. acidophilus LMEM8 and L. rhamnosus LMEM9, procured from the curd samples, survived in low-pH and high bile salt conditions, and showed growth inhibitory activity against the indicator bacteria by agar-well (zone diameter of inhibition; ZDIs: 13.67 ± 0.58-29.50 ± 2.10 mm) and agar overlay (ZDIs: 11.33 ± 0.58-35.67 ± 2.52 mm) methods; the average growth inhibitory activity of lactobacilli ranged 233.34 ± 45.54-280.56 ± 83.67 AU/mL, against the test bacterial pathogens. All the lactobacilli were non-hemolytic and sensitive to most of the test antibiotics. The CPP values of the isolated LAB were recorded as 80-100%. CONCLUSION: The curd lactobacilli procured might be used as the valid candidates of probiotics, and bio-therapeutics against bacterial infection to humans.

Assessment of oral health status of Santal (tribal) children of West Bengal.

CONTEXT: Santal is the third largest tribal community of India leading a very poor standard of education and life style. There are, however, few population-based studies evaluating the oral health status among Santal children in West Bengal. AIMS: The aim of the study was to evaluate the oral health status of Santal children of West Bengal by assessing prevalence of dental caries and inflammatory condition of gingival. SETTINGS AND DESIGN: Santal children aged between 2-14 years (N = 1205) were randomly selected from different Santal communities of West Bengal for this study. The children were divided into three different groups according to dentition. MATERIALS AND METHODS: Caries for permanent dentition Decayed Missing Filled Tooth (DMFT), for deciduous dentition decayed extracted filled (def index was used. For mixed dentition DMF and def was measured respectively and then added together. Inflammatory condition of gingival was assessed by papillary marginal attachment (PMA) index. STATISTICAL ANALYSIS USED: the data was analyzed statistically by SPSS software version 11. RESULTS: The study showed there was no significant difference (P > 0.05) between the average decayed extracted filled teeth (deft)/DMFT for boys and girls in deciduous and permanent dentition. But in mixed dentition this value for the boys was significantly higher (P < 0.001) than girls. 'Z' values were found to be non significant when compared mild, moderate and severe gingivitis between boys and girls in each dentition group, but mild gingivitis significantly increases from deciduous dentition to mixed to permanent dentition (P <0.001).

Antibiotic resistance of Salmonella enterica serovar Typhi in Kolkata, India, and in vitro experiments on effect of combined chemotherapy.

This communication states the changing patterns of Salmonella enterica serovar Typhi (S. Typhi) isolates causing enteric fever in and around Kolkata, India. Among the isolates resistance to ampicillin (A), chloramphenicol (C), cotrimoxazole (Co) and tetracycline (T) were plasmid mediated; the plasmid was unstable in S. Typhi, and the other enteric bacteria like Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris were found to be the potential source of dissemination of such plasmids into S. Typhi. The infection with such S. Typhi strains were successfully treated with ciprofloxacin (Cp: MICs 0.0075-0.075 µg mL⁻¹) and/or ofloxacin (Ofx: MICs 0.0125-0.075 µg mL⁻¹), but in the later course, the S. Typhi strains, showing resistance to nalidixic acid, developed low level of resistance to Cp and Ofx, causing the treatment failure. Thus, the treatment regimen was shifted to the third generation cephalosporins like ceftriaxone (Ct) and cefotaxime (Cf). Keeping in mind the anticipation of development of resistance to Ct/Cf, we prepared the treatment regimen for MDR enteric fever, based on the double-drug synergy tests in vitro; Cp-gentamycin (FICI 0.121-0.216) and Cp-trimethoprim (FICI 0.14-0.483) combinations were found effective against S. Typhi isolates having decreased sensitivity to cp (MICs: 0.5-1.25 µg mL⁻¹).

Human cystic echinococcosis: epidemiologic, zoonotic, clinical, diagnostic and therapeutic aspects.

This review represents an updated scenario on the transmission cycle, epidemiology, clinical features and pathogenicity, diagnosis and treatment, and prevention and control measures of a cestode parasite Echincoccus granulosus (E. granulosus) infection causing cystic echinococcosis (CE) in humans. Human CE is a serious life-threatening neglected zoonotic disease that occurs in both developing and developed countries, and is recognized as a major public health problem. The life cycle of E. granulosus involves a definitive host (dogs and other canids) for the adult E. granulosus that resides in the intestine, and an intermediate host (sheep and other herbivores) for the tissue-invading metacestode (larval) stage. Humans are only incidentally infected; since the completion of the life cycle of E. granulosus depends on carnivores feeding on herbivores bearing hydatid cysts with viable protoscoleces, humans represent usually the dead end for the parasite. On ingestion of E. granulosus eggs, hydatid cysts are formed mostly in liver and lungs, and occasionally in other organs of human body, which are considered as uncommon sites of localization of hydatid cysts. The diagnosis of extrahepatic echinococcal disease is more accurate today because of the availability of new imaging techniques, and the current treatments include surgery and percutaneous drainage, and chemotherapy (albendazole and mebendazole). But, the wild animals that involve in sylvatic cycle may overlap and interact with the domestic sheep-dog cycle, and thus complicating the control efforts. The updated facts and phenomena regarding human and animal CE presented herein are due to the web search of SCI and non-SCI journals.

Enhancing chloramphenicol and trimethoprim in vitro activity by Ocimum sanctum Linn. (Lamiaceae) leaf extract against Salmonella enterica serovar Typhi.

OBJECTIVE: To evaluate the antibacterial activity of Ocimum sanctum (O. sanctum) leaf extract, alone, and in combination with chloramphenicol (C) and trimethoprim (Tm) against Salmonella enterica serovar Typhi (S. typhi). METHODS: The antibacterial activity of ethanolic extract of tulsi, O. sanctum, leaf (TLE; 500 µg) for 23 S. typhi isolates was determined following agar diffusion. The C (30 µg) and Tm (5 µg) activity alone and in combination with TLE (250 µg) was determined by disk diffusion. The zone diameter of inhibition (ZDI) for the agents was recorded, and growth inhibitory indices (GIIs) were calculated. RESULTS: The S. typhi isolates (n=23), which were resistant to both C (ZDI 6 mm) and Tm (ZDI 6 mm), had TLE (500 µg) ZDIs 16-24 mm. The ZDIs of C and Tm were increased up to 15-21 mm and 17-23 mm, respectively, when TLE (250 µg) was added to the C and Tm discs. The GIIs ranged 0.789-1.235 and 0.894-1.352, due to combined activity against S. typhi isolates, of C and TLE and Tm and TLE, respectively. CONCLUSIONS: The data suggest that TLE, in combination with C and Tm, had synergistic activity for S. typhi isolates, and hence O. sanctum is potential in combating S. typhi drug resistance, as well promising in the development of non-antibiotic drug for S. typhi infection.

Serologic evidence of human leptospirosis in and around Kolkata, India: a clinico-epidemiological study.

OBJECTIVE: To investigate the prevalence of leptospirosis among patients from within and outside Kolkata, India, attending the Calcutta School of Tropical Medicine, for treatment during August 2002 to August 2008. METHODS: The leptospirosis cases were determined on the basis of clinical, epidemiological, and biochemical factors, and were tested for leptospiral antibodies using IgM ELISA. Serum samples with absorbance ratio ≥ 1.21 were interpreted as reactive. RESULTS: The commonest presentation involved fever, headache and jaundice. The male-female ratio was 61:46. A total of 65(64.20%) cases had abnormal liver and renal functions respectively, and 57.1% had both the abnormalities. The highest incidence (75, 35.04%) was recorded in September-October followed by July-August (53, 24.77%). The reactive cases had absorbance ratios between 1.21 and 8.21, and 53 showed equivocal result, while IgM non reactivity were seen in 90 patients (absorbance ratios 0.10-0.90). The patients responded to treatment with parenteral antibiotics, penicillin, ceftriaxone and cefotaxime; follow up did not reveal case fatality. CONCLUSIONS: The cardinal signs of leptospirosis help in making clinical diagnosis, but in any hyper-endemic situation any patient reporting with acute fever and signs of pulmonary, hepatic or renal involvement should be suspected to have leptospirosis and investigated accordingly. Increased awareness, and early diagnosis and treatment, can reduce mortality due to leptospirosis.

Cholera: a great global concern.

Cholera, caused by the infection of toxigenic Vibrio cholerae (V. cholerae) to humans, is a life threatening diarrheal disease with epidemic and pandemic potential. The V. cholerae, both O1 and O139 serogroups, produce a potent enterotoxin (cholera toxin) responsible for the lethal symptoms of the disease. The O1 serogroup has two biotypes (phenotypes), classical and El Tor; each of which has two major serotypes (based on antigenic responses), Ogawa and Inaba and the extremely rare Hikojima. V. cholerae O1 strains interconvert and switch between the Ogawa and Inaba serotypes. Fluid and electrolyte replacement is the mainstay of treatment of cholera patients; the severe cases require antibiotic treatment to reduce the duration of illness and replacement of fluid intake. The antibiotic therapy currently has faced difficulties due to the rapid emergence and spread of multidrug resistant V. cholerae causing several outbreaks in the globe. Currently, cholera has been becoming endemic in an increasing number of geographical areas, reflecting a failure in implementation of control measures. However, the current safe oral vaccines lower the number of resistant infections and could thus represent an effective intervention measure to control antibiotic resistance in cholera. Overall, the priorities for cholera control remain public health interventions through improved drinking water, sanitation, surveillance and access to health care facilities, and further development of safe, effective and appropriate vaccines. Thus, this review describes the facts and phenomena related to the disease cholera, which is still a great threat mainly to the developing countries, and hence a grave global concern too.

Coconut (Cocos nucifera L.: Arecaceae): in health promotion and disease prevention.

Coconut, Cocos nucifera L., is a tree that is cultivated for its multiple utilities, mainly for its nutritional and medicinal values. The various products of coconut include tender coconut water, copra, coconut oil, raw kernel, coconut cake, coconut toddy, coconut shell and wood based products, coconut leaves, coir pith etc. Its all parts are used in someway or another in the daily life of the people in the traditional coconut growing areas. It is the unique source of various natural products for the development of medicines against various diseases and also for the development of industrial products. The parts of its fruit like coconut kernel and tender coconut water have numerous medicinal properties such as antibacterial, antifungal, antiviral, antiparasitic, antidermatophytic, antioxidant, hypoglycemic, hepatoprotective, immunostimulant. Coconut water and coconut kernel contain microminerals and nutrients, which are essential to human health, and hence coconut is used as food by the peoples in the globe, mainly in the tropical countries. The coconut palm is, therefore, eulogised as 'Kalpavriksha' (the all giving tree) in Indian classics, and thus the current review describes the facts and phenomena related to its use in health and disease prevention.

Honey: its medicinal property and antibacterial activity.

Indeed, medicinal importance of honey has been documented in the world's oldest medical literatures, and since the ancient times, it has been known to possess antimicrobial property as well as wound-healing activity. The healing property of honey is due to the fact that it offers antibacterial activity, maintains a moist wound condition, and its high viscosity helps to provide a protective barrier to prevent infection. Its immunomodulatory property is relevant to wound repair too. The antimicrobial activity in most honeys is due to the enzymatic production of hydrogen peroxide. However, another kind of honey, called non-peroxide honey (viz., manuka honey), displays significant antibacterial effects even when the hydrogen peroxide activity is blocked. Its mechanism may be related to the low pH level of honey and its high sugar content (high osmolarity) that is enough to hinder the growth of microbes. The medical grade honeys have potent in vitro bactericidal activity against antibiotic-resistant bacteria causing several life-threatening infections to humans. But, there is a large variation in the antimicrobial activity of some natural honeys, which is due to spatial and temporal variation in sources of nectar. Thus, identification and characterization of the active principle(s) may provide valuable information on the quality and possible therapeutic potential of honeys (against several health disorders of humans), and hence we discussed the medicinal property of honeys with emphasis on their antibacterial activities.

Honey：its medicinal property and antibacterial activity

Indeed, medicinal importance of honey has been documented in the world's oldest medical literatures, and since the ancient times, it has been known to possess antimicrobial property as well as wound-healing activity. The healing property of honey is due to the fact that it offers antibacterial activity, maintains a moist wound condition, and its high viscosity helps to provide a protective barrier to prevent infection. Its immunomodulatory property is relevant to wound repair too. The antimicrobial activity in most honeys is due to the enzymatic production of hydrogen peroxide. However, another kind of honey, called non-peroxide honey (viz., manuka honey), displays significant antibacterial effects even when the hydrogen peroxide activity is blocked. Its mechanism may be related to the low pH level of honey and its high sugar content (high osmolarity) that is enough to hinder the growth of microbes. The medical grade honeys have potentin vitrobactericidal activity against antibiotic-resistant bacteria causing several life-threatening infections to humans. But, there is a large variation in the antimicrobial activity of some natural honeys, which is due to spatial and temporal variation in sources of nectar. Thus, identification and characterization of the active principle(s) may provide valuable information on the quality and possible therapeutic potential of honeys (against several health disorders of humans), and hence we discussed the medicinal property of honeys with emphasis on their antibacterial activities.

Antibacterial activity of ciprofloxacin and trimethoprim, alone and in combinittion, against Vibrio cholerae O1 biotype El Tor serotype Ogawa isolates.

In this communication, the ciprofloxacin-trimethoprim (Cp-Tm) combination showed synergistic (Fractional Inhibitory Concentration, FIC index 0.399) and additive (FIC index 0.665-0.83) effects against Vibrio cholerae O1 biotype El Tor serotype Ogawa isolates having Cp MICs 10 microg/ml and Cp 0.66 microg/ml, respectively, following agar dilution checkerboard method. The time-kill study results demonstrated synergy between Cp and Tm against both groups of isolates providing 2.04 log10 (for strain with Cp MIC 0.66 microg/ml) and 3.12 log10 (for strain with Cp MIC 10 microg/ml) decreases in CFU/ml between the combination and its most active compound. Thus, the findings of the present study suggest an introduction of Cp-Tm combination treatment regimen against drug resistant cholera and this in turn will help in combating the drug resistance of V. cholerae O1 biotype El Tor serotype Ogawa.

Antibiotic resistance of Salmonella enterica serovar Paratyphi A in India: emerging and reemerging problem.

BACKGROUND: Antibiotic resistance pattern and R-plasmid of Salmonella enterica serovar Paratyphi A isolates from Kolkata, India are not well documented. AIMS: To determine the trend of antibiotic resistance of S. paratyphi A isolates. SETTINGS AND DESIGN: A retrospective study was carried out using blood culture isolates of S. paratyphi A (1991 to 2005) obtained from patients of enteric fever from Asansol and Kolkata and its suburbs (India). MATERIALS AND METHODS: Antibiotic susceptibility pattern, using seven antibiotics, for the isolates was determined following agar dilution and disk diffusion methods. Transferability of multidrug resistance to ampicillin (Am), chloramphenicol (Chl), cotrimoxazole (Cot) and tetracycline (Tet) among the isolates was determined by in vitro conjugation. The multi-drug resistant (MDR) and antibiotic susceptible S. paratyphi A strains and the trans-conjugants were screened for the presence of plasmid. STATISTICAL ANALYSIS USED: The t test was used to compare the difference between mean minimum inhibitory concentration values of ciprofloxacin (Cp) for nalidixic acid (Nx)-resistant and Nalidixic acid (Nx)-susceptible isolates. RESULTS: Among 13 outbreak causing isolates in 1991, 9 (69.23%) showed AmChlCotTet-resistance, while 4 (30.77%) Cot-resistance only. During 1992-1994, all 13 isolates were susceptible to Am, Chl, Cot and Tet. During 1995-2005, isolates demonstrated different resistance patterns and emergence of nalidixic acid (Nx)-resistance. A transferable plasmid conferring AmChlCotTet-resistance was detected among MDR isolates. All the isolates were susceptible to ceftriaxone (Ctx) and ciprofloxacin (Cp). Association between Nalidixic acid (Nx)-resistance and reduced susceptibility to ciprofloxacin (Cp) among 59 S. paratyphi A isolates was noticed (P < 0.001). CONCLUSION: Vigilance for R-plasmid and surveillance of antibiotic susceptibility among S. paratyphi A isolates in and around Kolkata, India, are mandatory in order to combat antibiotic resistance of the isolates in this part of the world.

Plasmid-mediated dimethoate degradation by Bacillus licheniformis isolated from a fresh water fish Labeo rohita.

The Bacillus licheniformis strain isolated from the intestine of Labeo rohita by an enrichment technique showed capability of utilizing dimethoate as the sole source of carbon. The bacterium rapidly utilized dimethoate beyond 0.6 mg/mL and showed prolific growth in a mineral salts medium containing 0.45 mg/mL dimethoate. The isolated B licheniformis exhibited high level of tolerance of dimethoate (3.5 mg/mL) in nutrient broth, while its cured mutant did not tolerate dimethoate beyond 0.45 mg/mL and it was unable to utilize dimethoate. The wild B licheniformis strain transferred dimethoate degradation property to E coli C600 (Nar, F-) strain. The transconjugant harbored a plasmid of the same molecular size (approximately 54 kb) as that of the donor plasmid; the cured strain was plasmid less. Thus a single plasmid of approximately 54 kb was involved in dimethoate degradation. Genes encoding resistance to antibiotic and heavy metal were also located on the plasmid.