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Biomedical subjects

A N Chakrabarty

Publications and source records attributed to A N Chakrabarty.

At least 37 records · Page 2Linked to original sources
PubMed1997

Studies on antimicrobial effect of the antihistaminic phenothiazine trimeprazine tartrate.

The antibacterial and bactericidal activities of the antihistamine trimeprazine were studied against 243 strains of bacteria which included both Gram positive and Gram negative types. The susceptibility of these bacterial strains to trimeprazine was assessed by determining their minimum inhibitory concentration (MIC) which was found to be between 10 and 100 micrograms/ml. Nineteen strains of Staphylococcus spp. and Salmonella spp. were trimeprazine. Most of the strains belonging to Bacillus spp. and Salmonella spp. were inhibited by less than 100 micrograms/ml. Trimeprazine could also inhibit strains of Shigella spp. Vibrio cholerae and V. parahaemolyticus at 10-100 micrograms/ml. Strains of klebsiella, proteus, pseudomonas and citrobacter were moderately sensitive to trimeprazine. In in vivo studies it was seen that when trimeprazine was used at a concentration of 0.75 and 0.4 micrograms/gm body weight of the mouse both levels offered significant protection to Swiss mice challenged with 50LD50 of virulent strain of S. typhimurium 74. Statistical analysis of the data was found to be significant, p < 0.001 according to chi 2 test.

Animals↗
PubMed1996

Electron microscopic characteristics of actinomycetic agents having aetiological association with human leprosy and epizootic ulcerative syndrome of fish.

The transmission electron microscopic (TEM) studies of the human leprosy derived chemoautotrophic nocardio-form (CAN) bacteria and EUS derived CAN bacteria showed presence of double contoured cell-walls consisting of an electron transparent and a dense layer. The fibrillar structures on the surface of these CAN bacterial cells also suggested their similarity to the human tissue derived Mycobacterium leprae cells. These EM studies further revealed mycelial and coccoid bodies in all these bacteria as was observed originally.

Actinomycetales↗
PubMed1996

In vitro & in vivo experimental susceptibility of Mycobacterium marinum to augmentin.

The effect of augmentin alone and in combination with various beta-lactam antibiotics was studied against a pathogenic Mycobacterium, M. marinum. The in vitro studies did not reveal any additional advantage over that found with augmentin alone and this antibiotic seemed considerably inhibitory to M. marinum at < 1 microgram/ml concentration. In vivo, the effects of augmentin on experimentally produced lesions in the mouse foot pads (MFPs) showed a significant regression of the lesions, which was compatible with an early disappearance of M. marinum from the MFP, in contrast with those of the untreated, control animals.

Amoxicillin↗
PubMed1995

In vitro and in vivo antimicrobial action of fluphenazine.

The antipsychotic drug fluphenazine was obtained in a dry powder form and was screened with respect to 482 strains of bacteria, which included 170 Gram-positive and 326 Gram-negative strains. Nutrient agar plates containing increasing concentrations of fluphenazine (0-200 micrograms/ml) were used for the determination of the minimum inhibitory concentration (MIC) which was demonstrated by inoculating a loopful of an overnight peptone water culture of the organism on nutrient agar plates and determining the MIC against a control. Fluphenazine was detected to possess pronounced action against both Gram-positive and Gram-negative bacteria at 20-100 micrograms/ml. In the in vivo studies it was seen that when fluphenazine was used at a concentration of 1.5 micrograms/g and 3 micrograms/g mouse body weight both the levels offered significant protection to Swiss strain of white mice when challenged with 50 minimum lethal dose (MLD) of a virulent strain of Salmonella typhimurium 74. The in vivo data with fluphenazine were highly significant (p < 0.001) according to the chi-square test.

Animals↗
PubMed1995

Phage-mediated conjugation in staphylococci as a means of transfer of drug-resistance.

Penicillin resistance plasmid was transferred from Staphylococcus aureus B4 (PcrKms, donor) to S. aureus ML351 (PcsKmr, recipient) by co-cultivation of the donor with the recipient in nutrient broth with or without the modifying effects of CaCl2 or sodium dodecyl sulfate. It was found that the transfer of drug-resistance occurred maximally between 6 and 18 hr postinoculation; however, addition of DNase (200 micrograms/ml) could totally prevent such a transfer up to 6 hr and significantly reduce it thereafter. Cell-free filtrate of the donor culture when mixed with the recipient was ineffective in bringing about the transfer of Pcr.

Conjugation, Genetic↗
PubMed1995

A pathogenicity model for the agents of epizootic ulcerative syndrome (EUS) in fish.

Chemoautotrophic nocardioform (CAN) bacteria had been repeatedly isolated from fish with ulcerative disease syndromes (EUS) from the massive epizootics that had repeatedly occurred since 1988 in eastern India as the major or only pathogenic agent in the background of distinctive environmental and epizootic data. Since these isolates bear significant similarity to the human and rat leprosy bacilli, attempts had been made to demonstrate the pathogenicity of this fish pathogen in the "Swiss" strain of mice as a convenient model. The studies reveal that the fish CAN bacteria could produce pathogenic effects in mice similar to that of the rat leprosy bacillus.

Animals↗
PubMed1995

Propagation of Mycobacterium lepraemurium on supplemented minimal medium and its experimental pathogenesis.

The splenic tissue of a mouse experimentally infected with M. lepraemurium (Hawaiian strain, M-65) and developing 'rat leprosy', yielded a pure culture of an acid - fast bacterium having all the characteristics of M. lepraemurium on mineral salt minimal medium supplemented with simple sources of C and N, e.g., NH4 -salts, liquid paraffin, urea, gelatin etc. This could be maintained, by serial passages in vitro with good growth. Its indefinite propagation with tissue - free washed, small inoculum on complex media including Ogawa medium was difficult, and its serial sub-culture was practically impossible. The in vitro isolate from supplemented minimal medium could produce pathological lesions in mice typical of rat leprosy.

Animals↗
PubMed1994

Plasmid-determined degradative metabolism and halophilism of Vibrio parahaemolyticus.

A set of 25 Kanagawa(+) and Kanagawa(-) strains of V. parahaemolyticus was studied for their ability to degrade hydrocarbons in minimal media. All strains gave positive results with respect to crystal violet (CV), methyl violet, liquid paraffin, benzene, naphthalene and phenol. The CV double ring (CVDR) response had earlier appeared to be a significant pathogenic marker [Chakrabarti et al, Indian J Med Res, 85 (1987) 508]. The CVDR response was found also to be a biodegradative marker, and correlates perfectly well with polymyxin resistance and low level of halophilism (4% NaCl). All these markers (characters) were found to be controlled by a single plasmid in the wild type. Elimination of the plasmid, as confirmed by gel electrophoresis studies, resulted in loss of CVDR response, polymyxin resistance, and acquisition of halophilism at a higher level (> 7%). The massive drainage of industrial effluents, rich in hydrocarbons, in the estuarine areas in many countries might have altered the ecosystem in favour of V. parahaemolyticus and its emergence as a new biodegradative and enterotoxigenic pathogen, contaminating fauna and flora in the littoral sea regions, with increased changes of communicability to humans.

Plasmids↗
PubMed1994

Studies on the existence of synergism between different antibiotics and a phenothiazine tranquilizer, promazine, possessing antimicrobial property.

Different antibiotics were tested for their capacity to exhibit synergism when used in combination with promazine (Pr), a tranquilizer endowed with powerful antimicrobial property. For this purpose the minimum inhibitory concentration (MIC) of different antibiotics and Pr was first determined by spot inoculation technique on nutrient agar plates to select the concentrations of the antibiotics and Pr to be used as well as the sensitive strains. It was observed that Pr in combination with tetracycline (Tc) demonstrated a marked enhancement of the inhibitory capacity of each drug, both against the Gram-positive and Gram-negative bacteria, following disc diffusion technique. The in vitro findings were further substantiated with the in vivo effects of Pr along with Tc using Salmonella typhimurium NCTC 74 as the challenge strain in mice. The synergism obtained was further corroborated in terms of the increase in the size of their inhibition zones compared with their unaltered individual zones to determine the level of significance. This result was also confirmed by the checkerboard test using doubling dilutions of both the agents.

Animals↗
PubMed1992

Viability of acid-fast bacilli from gamma-& UV-irradiated lepromatous armadillo tissues infected with Mycobacterium leprae.

Gamma-irradiated splenic homogenates of armadillos infected with M. leprae proved sterile by conventional tests and media. However, on media for chemoautotrophy, these could repeatedly grow as a single type of acid-fast nocardioform bacterium like the unirradiated specimens, although with a much reduced count. In the slide culture, transition from the initial AFB/coccoid bodies, to sporulating mycelia and granules in the final stage, could be observed sequentially. The gamma-irradiated tissue specimens failed to yield any other mycobacterium/corynebacterium tested according to standard protocols.

Animals↗
PubMed1992

Metabolism of silicon as a probable pathogenicity factor for Mycobacterium & Nocardia spp.

The role of silicon (Si) in metabolism and growth of 22 strains of mycobacteria and 3 strains of nocardiae, which were mostly pathogenic, was studied on Kirchner's medium solidified with sodium metasilicate (KSM) and the C-free solidified metasilicate minimal medium (SMM) consisting of mineral salts only. On KSM, initial growth of mycobacteria appeared to be better, compared with that on Lowenstein-Jensen medium (LJM), although subsequent growth on the former was slower. On SMM lacking C, growth of mycobacteria and nocardiae could be achieved, only after repeated passages. These findings indicate that the mycobacteria and nocardiae are able to utilise Si at least to a limited extent, possibly as an alternative to C, with greater chances of survival.

Culture Media↗
PubMed1991

Possible human health hazards from outbreak of epizootic ulcerative syndrome (EUS) in fish in the Asia-Pacific region.

Acid fast rods, constituting chemoautotrophic nocardioform bacteria, could be repeatedly cultivated and isolated and propagated indefinitely in vitro from fish actinomycotic macrophage granuloma from the massive epizootics of ulcerative disease syndrome of fish in eastern India during 1988-90. The possible human hazards of zoonotic actinomycotic infections as a result of handling and consumption of such fish are assessed.

Actinomycetales↗
PubMed1991

Repeated isolation of chemoautotrophic nocardioform bacteria from fish epizootic ulcerative syndrome.

Nocardioform actinomycetic organisms were present regularly in, and isolated repeatedly from, different varieties of fish affected with epizootic ulcerative syndrome lesions of dermis, muscle, subcutaneous tissues and internal organs. These acid-fast bacilli, resembling human and rat leprosy bacilli, together with other actinomycotic bodies, appeared to explain the characteristic macrophage granuloma observed in such lesions, similar to those of humans. These isolates possessed fundamental similarities to the human isolates of chemoautotrophic nocardioform bacteria reported earlier.

Actinomycetales↗
PubMed1990

Studies on synergism between penicillins and ambodryl (bromodiphenhydramine HCl), an antihistamine with antimicrobial property.

With respect to 31 different selected test bacteria, all sensitive to benzyl penicillin (Pc), ampicillin (Ap), methicillin (Me), ceporan (Ce), cloxacillin (Cx), streptomycin (Sm), kanamycin (Km), gentamicin (Gm), chloramphenicol (Cm), tetracycline (Tc), polymyxin (Pm) as well as ambodryl [Am; an antihistamine (bromodiphenhydramine HCl) with distinct antimicrobial properties], it was found that Am in combination either with Pc, Ap, Ce or Me consistently showed enhancement of antimicrobial effects resulting from synergism. A combination of Am with either Sm, Km, Gm or Tc, on the other hand, showed only additive effects. An interaction of the activities of Am with Pm also resulted in indifference effects. Determination of the area of inhibition zone, calculated from its diameter for the degree of synergism in case of Am and Pc, showed these synergistic effects to be significant (P less than 0.05) in comparison with their individual effects: this was corroborated by the determination of the fractional inhibitory concentration (FIC) index which was found to be less than 0.5. The synergism of Am-Pc combination was confirmed by in vivo studies by challenging mice with a virulent strain of S. typhimurium and looking for protection.

Bacteria↗
PubMed1990

Cultivation of a nocardioform acid-fast chemoautotrophic bacterium from armadillo tissues infected with Mycobacterium leprae.

A nocardioform bacterium was isolated from the spleen tissue of an armadillo infected with M. leprae and easily propagated in pure culture in mineral salt medium supplemented with only simple C and N sources (e.g., liquid paraffin, tetradecane, ammonium salts, urea, asparagine, gelatin, xanthin, hypoxanthin etc.). Complex organic substances, e.g., tyrosin, casein, peptone, meat extract, egg proteins, serum, blood, yeast extract as well as medium 199, did not support the growth of this organism. Microscopically, the organism consisted of acid-fast, long, slender rods which originated from long, fragmented hyphae, or sporulating mycelial tufts; it was acid-fast (at less than 4.0% H2SO4) which was pyridine-susceptible. It produced DOPA-oxidase and Catalase and was lysozyme resistant; this grew best under reduced O2 tension, at pH 7.0 to 8.0 and 28 degrees C. Serologically, it appeared to be only weakly related to the prototype human multibacillary leprosy-derived (reference) nocardioform strain, Nocardia brasiliensis and N. caviae, but was variably related to several mycobacteria strains.

Animals↗
PubMed1990

Physical demonstration of a high molecular weight bacteriocin plasmid in Vibrio cholerae by genetic transformation process.

Bacteriocinogeny was transferred at high frequencies from bacteriocinogenic (Bac+) V. cholerae strains to non-bacteriocinogenic (Bac-) recipients in the in situ genetic transformation system on agar surface. DNA extracted from samples of growth of bacteria transformed to Bac+ were obtained at 2 h intervals following contact with the sterile agar surface where the donor had grown previously. This showed acquisition of a high molecular weight plasmid which could be physically demonstrated best in the 6 h sample of the Bac+ transformants; their 4 h samples failed to show this specific plasmid, while it was demonstrable only as a faint band in the 8 h samples.

Bacteriocins↗
PubMed1990

'DNA' as contaminants in antibiotics and its capacity to transform bacteria to drug resistance.

DNA/and deoxyribose sugars were detected in streptomycin (Sm), kanamycin, polymyxin, penicillin G, ampicillin, methicillin, cloxacillin and mitomycin C in small amounts/traces. Stained DNA could be feebly visualized directly in Sm run in agarose gel, which improved after its separation and concentration. These DNA materials were DNase sensitive, RNase and pronase resistant, and appeared to consist of fragments, c. less than or equal to 6 Mdal; this could repeatedly transform to SmR several recipient enterobacteria and vibrios; E. coli C600 and S. typhi 57, after such transformation revealed similar plasmid DNA bands that were absent in their wild-types. G + C mole% of plasmid and chromosomal DNA of recipient (57) along with that of Streptomyces griseus reference strain, suggested an extraneous origin for the plasmid DNA.

Anti-Bacterial Agents↗