Plasmid-Encoded Multidrug Resistance of Salmonella typhi and some Enteric Bacteria in and around Kolkata, India: A Preliminary Study

The present study investigates the occurrence of R-plasmid in Salmonella typhi isolates from enteric fever cases in and around Kolkata (1991-2001), India following in vitro conjugation experiments, isolation of plasmid DNAs and agarose gel electrophoretic analysis. The multidrug resistant (MDR) S. typhi strains contained a transferable plasmid conferring resistance to ampicillin, chloramphenicol, cotrimoxazole and tetracycline. The plasmid encoding ACCoT-resistance of Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris were conjugative and co-migrated with the plasmid of MDR S. typhi isolates. The antibiotic sensitive S. typhi isolates did not contain any plasmid. Thus the findings of the present study confirmed the instability of the R-plasmid in S. typhi, and that the antibiotic sensitive S. typhi strains acquired the R-plasmid from other enteric bacteria such as E. coli, K. pneumoniae and P.vulgaris to undergo a suitable adaptation for survival in the changing antibiotic environment

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)

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

AbstractObjectiveTo 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).MethodsThe 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.ResultsThe 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.ConclusionsThe 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

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 (Na(r), 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

ASSOCIATION OF GENERATION TIME WITH ANTI-TUBERCULAR DRUG(S) RESISTANCE PATTERN OF MYCOBACTERIUM TUBERCULOSIS ISOLATES AMONG TREATMENT FAILURE PULMONARY TUBERCULOSIS PATIENTS

ABSTRACTObjective: The emergence of drug resistance has complicated tuberculosis (TB) scenario and is associated to treatment failure. The causative agent,Mycobacterium tuberculosis is usually slow growing and has been implicated as a contributing factor for drug tolerance and development of resistantstrains. On the other hand, if rapidly growing bacilli, with shorter generation time emerge, mutations may lead to the development of drug resistance.From the hypothesis, this study was aimed to explore the whether there is any association between the generation time of Mycobacteria with theirdistinct drug resistant pattern.Methods: In-vitro generation time was determined from 77 mycobacterial isolates with varied drug resistance pattern, i.e. rifampicin resistant (RIFR),isoniazid resistant, multi-drug resistant (MDR), the sensitive clinical strains along with reference strains. The minimal inhibitory concentration wasalso determined for the respective resistant groups.Results: Among the individual group of clinical isolates, there was a significant negative association between generation time and drug resistancepattern of RIFR isolates.Conclusion: Keeping the current upsurge of the MDR-TB epidemic in India and the influence of generation time on dosing schedule and treatmentstrategy, necessary customization of dosing and therapeutic planning seemed urgent to minimize the operational and clinical potential for developmentof drug resistance among treatment failure pulmonary TB patients in this country.Keywords: Mycobacterium tuberculosis, Generation time, Multi-drug resistant, Treatment failure

Immunomodulatory Effects of the Neuropeptide Pituitary Adenylate Cyclase-Activating Polypeptide in Acute Toxoplasmosis

Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) is an endogenous neuropeptide with distinct functions including the regulation of inflammatory processes. PACAP is able to modify the immune response by directly regulating macrophages and monocytes inhibiting the production of inflammatory cytokines, chemokines and free radicals. Here, we analyzed the effect of exogenous PACAP on peripheral immune cell subsets upon acute infection with the parasite Toxoplasma gondii (T. gondii). PACAP administration was followed by diminished innate immune cell recruitment to the peritoneal cavity of T. gondii-infected mice. PACAP did not directly interfere with parasite replication, instead, indirectly reduced parasite burden in mononuclear cell populations by enhancing their phagocytic capacity. Although proinflammatory cytokine levels were attenuated in the periphery upon PACAP treatment, interleukin (IL)-10 and Transforming growth factor beta (TGF-β) remained stable. While PACAP modulated VPAC1 and VPAC2 receptors in immune cells upon binding, it also increased their expression of brain-derived neurotrophic factor (BDNF). In addition, the expression of p75 neurotrophin receptor (p75NTR) on Ly6Chi inflammatory monocytes was diminished upon PACAP administration. Our findings highlight the immunomodulatory effect of PACAP on peripheral immune cell subsets during acute Toxoplasmosis, providing new insights about host-pathogen interaction and the effects of neuropeptides during inflammation

A typhoid fever outbreak in a slum of South Dumdum municipality, West Bengal, India, 2007: Evidence for foodborne and waterborne transmission

<p>Abstract</p> <p>Background</p> <p>In April 2007, a slum of South Dumdum municipality, West Bengal reported an increase in fever cases. We investigated to identify the agent, the source and to propose recommendations.</p> <p>Methods</p> <p>We defined a suspected case of typhoid fever as occurrence of fever for ≥ one week among residents of ward 1 of South Dumdum during February – May 2007. We searched for suspected cases in health care facilities and collected blood specimens. We described the outbreak by time, place and person. We compared probable cases (Widal positive >= 1:80) with neighbourhood-matched controls. We assessed the environment and collected water specimens.</p> <p>Results</p> <p>We identified 103 suspected cases (Attack rate: 74/10,000, highest among 5–14 years old group, no deaths). Salmonella (enterica) Typhi was isolated from one of four blood specimens and 65 of 103 sera were >= 1:80 Widal positive. The outbreak started on 13 February, peaked twice during the last week of March and second week of April and lasted till 27 April. Suspected cases clustered around three public taps. Among 65 probable cases and 65 controls, eating milk products from a sweet shop (Matched odds ratio [MOR]: 6.2, 95% confidence interval [CI]: 2.4–16, population attributable fraction [PAF]: 53%) and drinking piped water (MOR: 7.3, 95% CI: 2.5–21, PAF-52%) were associated with illness. The sweet shop food handler suffered from typhoid in January. The pipelines of intermittent non-chlorinated water supply ran next to an open drain connected with sewerage system and water specimens showed faecal contamination.</p> <p>Conclusion</p> <p>The investigation suggested that an initial foodborne outbreak of typhoid led to the contamination of the water supply resulting in a secondary, waterborne wave. We educated the food handler, repaired the pipelines and ensured chlorination of the water.</p

Kinetics of Dimethoate Biodegradation in Bacterial System

The present study is an investigation on the kinetics of dimethoate biodegradation and an estimation of residual dimethoate in bacterial culture by spectrophotometry. The methylene chloride extract of the culture medium was used for determination of dimethoate through its reaction with 1 chloro-2, 4 dinitrobenzene to produce methylamine whose absorbance at 505 nm gave an estimation of dimethoate content. The dimethoate standard curve follows Beer’s law at 505 nm with a slope of 0.0129 absorbance units per µg/mL. The regression equation relating concentration of dimethoate (x) with the absorbance is (y): y = 0.037 + 0.0129x. The amount of residual dimethoate after 7 days were 0, 4, 17, 28 and 29 µg/mL; the rate constants were 0.775, 0.305, 0.225, 0.167 and 0.127 each per day, and the efficiency of dimethoate degradation were 100%, 96%, 83%, 72% and 71%, for Bacillus licheniformis, Pseudomonas aeruginosa, Aeromonas hydrophila, Proteus mirabilis and Bacillus pumilus respectively. Dimethoate remediation could be attained through bacterial metabolism of the pesticide and colorimetric analysis might be useful in the estimation of dimethoate within a detection limit of 5–100 µg/mL

SYNERGISM BETWEEN MIMUSOPS ELENGI AND BAUHINIA VARIEGATA SEED EXTRACTS AGAINST SALMONELLA ENTERICA SEROVAR TYPHI AND VIBRIO CHOLERAE O1 BIOTYPE EL TOR SEROTYPE OGAWA ISOLATES

ABSTRACT The current communication evaluates the antibacterial activity of Mimusops elengi (M. elengi) and Bauhinia variegata (B. variegata) seed extracts, alone and in combination, against Salmonella enterica serovar Typhi (S. typhi) and Vibrio cholerae O1 biotype El Tor serotype Ogawa (V. cholerae) isolates. The antibacterial activity of ethanolic extracts of bakul, M. elengi, seed (MSE; 500 µg) and kanchan, B. variegata, seed (BSE; 500 µg), alone and in combination, was determined following agar diffusion method, for a total of 16 S. typhi and V. cholerae isolates. The zone diameter of inhibition (ZDI) for the agents was recorded, and growth inhibitory indices (GIIs) were calculated. The V. cholerae and S. Typhi isolates had BSE (500 µg) and MSE (500 µg) ZDIs 12-17 mm and 13-15 mm, respectively. The GIIs of the BSE-MSE combination ranged 0.654 -0.788 and 0.538 -0.759 for the isolates of S. typhi and V. cholerae, respectively. The combined activity of BSE and MSE was synergistic against the test bacterial isolates, and the test plant extracts are potential in combating S. typhi and V. cholerae drug resistance and hence are important sources for the development of non-antibiotic drug(s) against S. typhi and V. cholerae infection

In Vitro Antibacterial Activity of three Indian Spices Against Methicillin-Resistant Staphylococcus aureus

 Objective: To explore the in vitro antibacterial activity of ethanolic extracts of cinnamon (Cinnamomum zeylanicum; CIN), clove (Syzygium aromaticum, CLV) and cumin (Cuminum cyminum, CMN) against clinical isolates of methicillin resistant Staphylococcus aureus (MRSA), from Kolkata, India.Methods: The CIN, CLV and CMN were tested for their antibacterial activity against MRSA by in vitro methods. Minimum inhibitory concentration (MIC) values of the three extracts were determined, and time-kill studies were performed in order to investigate the bactericidal activity of the extracts (at the MIC level) for the isolates. The killing efficacy of the extracts was determined at various concentrations.Results: The zone diameter of inhibition (ZDI) obtained due to CIN, CLV and CMN ranged between 22-27 mm, 19-23 mm and 9-15 mm, respectively; while the MICs, for the isolates, were in the range of 64-256, 64-512 and 128-512 µg/ml, respectively. When tested for their MIC levels; the CIN and CLV were found to be bactericidal after 6 hrs of incubation, while CMN showed bactericidal activity after 24 hrs. However, when tested at various concentrations; CIN, CLV and CMN displayed bactericidal activity against S. aureus, after 24 hrs of incubation, at 200, 200 and 300 µg/ml, respectively.Conclusion: The C. zeylanicum and S. aromaticum showed the strongest in vitro antibacterial activity followed by C. cyminum against MRSA, and such findings could be considered a valuable support in the treatment of infection and may contribute to the development of potential antimicrobial agents for inclusion in anti- S. aureus regimens