Dharmendra K Sinha

Spatial molecular epidemiology of carbapenem‐resistant and New Delhi metallo beta‐lactamase (blaNDM)‐producing Escherichia coli in the piglets of organized farms in India

A cross‐sectional study was conducted in 10 government‐organized pig farms between 2014 and 2016 representing seven states of India to understand the epidemiology of carbapenem resistance in the Escherichia coli.

Antimicrobial Activity of Methanolic Extract and Ether Extract ofAgeratum conyzoides

Ageratum conyzoides, a weed prevalent in India, is known for its several therapeutic uses to control infections. In the present study we compared the antimicrobial potential of its ether extract and methanolic extract with ciprofloxacin on 294 strains of Gram positive bacteria (GPBs), 575 strains of Gram negative bacteria (GNBs), 15 yeast and 5 mould strains of clinical and nonclinical origin belonging to 49 genera and more than 155 species using disc diffusion assay. The microbial strains in the study were isolated from samples of abiotic (41) and biotic (101) environment, foods (81), clinically sick (441), dead (108) and healthy (75) animals and human beings, and 42 were reference strains. The study revealed that there was no appreciable difference in antimicrobial activity of ether extract (ACEE) or methanolic extract (ACME) of A. conyzoides. A total of 214 (24.1%) strains were sensitive to ACME while of the 697 strains tested for ciprofloxacin 551 (79.1%) were sensitive. Sensitivity to ACME among 294 GPBs (44.9%) was significantly (p<0.0001) higher than among 575 strains of GNBs (12.4%). There was no significant difference among GPBs and GNBs for ciprofloxacin (one of the most commonly used antibiotics in India) sensitivity, but oxidase negative GNBs (385) as well as GPBs (238) were about two times more commonly sensitive to ciprofloxacin than 190 oxidase positive GNBs (p = 0.001) and 56 oxidase positive GPBs (p, 0.03), respectively. For ACME oxidase positive strains had 2.4 times more odds (p < 0.0001) in their favour of being sensitive to ACME (53.4%) than oxidase negative strains (18.6%). The most sensitive strains to ACME belonged to oxidase positive GPBs (62.5%) followed by oxidase negative GPBs (40.8%), oxidase positive GNBs (27.4%) and oxidase negative GNBs (4.9%). All Aeromonas, Alcaligenes, Klebsiella, and Proteus species strains were resistant to ACME irrespective of source of isolation or association with illness. In contrast, majority of the strains of Burkholderia (76.9%), Bacillus (66.7%) and Brucella (53.8%) species were sensitive to ACME. The study revealed that A. conyzoides might be containing useful antimicrobial component(s) more active against oxidase positive potentially pathogenic strains often associated with systemic and deadly infections in animals as well as in humans.

Gallibacterium anatis: An Emerging Pathogen of Poultry Birds and Domiciled Birds

Gallibacterium anatis though known since long as opportunistic pathogen of intensively reared poultry birds has emerged in last few years as multiple drug resistance pathogen causing heavy mortality outbreaks not only in poultry birds but also in other domiciled or domestic birds. Due to its fastidious nature, commensal status and with no pathgnomonic lesions in diseased birds G. anatis infection often remains obscure for diagnosis. Poor understanding of its epidemiology, virulence factors and pathogenesis work on development of effective vaccine obscured its importance; however, it is difficult to get rid of G. anatis infection on affected poultry farms. The present review summarises the current knowledge on G. anatis and its infections.

Molecular characterisation of bla OXA48 carbapenemase, extended spectrum beta −lactamase (ESBL) and Shiga toxin producing Escherichia coli isolated from farm piglets of India

OBJECTIVES The aim of this study was to characterise carbapenemase-, extended-spectrum β-lactamase (ESBL)- and Shiga toxin-producing Escherichia coli isolated from farm piglets in India. METHODS Faecal samples (n=741) from 10 organised pig farms, including non-diarrhoeic (n=546) and diarrhoeic (n=195) piglets, were processed for isolation of carbapenem-resistant and ESBL-producing E. coli. RESULTS A total of 27 and 243 isolates were phenotypically confirmed as carbapenem-resistant and ESBL-producers, respectively. The meropenem minimum inhibitory concentration (MIC) of carbapenem-resistant isolates ranged from 8-128μg/mL. On genotypic screening of the 27 carbapenem-resistant isolates, 3 isolates were positive for the blaOXA-48 carbapenemase gene; no other carbapenemase genes were detected. The 243 ESBL-producing isolates were positive for blaCTX-M-1 (n=135), qnrA (n=92), qnrB (n=112), qnrS (n=49), tetA (n=42), tetB (n=45) and sul1 (n=43). The Shiga toxin virulence markers stx1 and stx2 were detected in 41 and 38 of the 243 phenotypic ESBL-producing isolates, respectively. Multilocus sequence typing (MLST) of blaOXA-48-positive E. coli isolates showed ST10- and ST5053-like sequence types. CONCLUSION This is the first report on the presence of blaOXA-48-carrying E. coli in piglets in India, which pose a potential risk to public health.

Comparative Antimicrobial Activity of Tea Tree Oil (Melaleuca Oil) andCommon Topical Antimicrobials against Bacteria Associated With Woundand Topical Infections

Tea Tree Oil (TTO) is a popular herbal antimicrobial for topical application against many microbes. This study was conducted to determine a spectrum of antimicrobial activity of TTO against bacteria often associated with topical infections and wound infection in human and animals. A total of 550 strains of bacteria and one strain of Candida albicans were tested for their sensitivity to TTO and eight antibiotics including polymyxin B sulfate, gentamicin, nitrofurantoin, tetracycline, chloramphenicol, co-trimoxazole, ciprofloxacin, and novobiocin. Gentamicin was the most effective antibiotic followed by chloramphenicol, ciprofloxacin, nitrofurantoin and polymyxin B inhibiting 87.1%, 84.8%, 76.8%, 75% and 72.8% strains, respectively. Tea tree oil (at 1 μL/ mL) could inhibit the growth of 20.5% strains. Except all strains of Streptobacillus, Sphingomonas, Cytophaga and Brahmnella, 71.4% Brucella, 60% Bordetella and 53.1% Aeromonas species (46.9%), only a few strains of other genera were sensitive to TTO. Only 20.5% strains were sensitive to TTO and multiple drug resistance (MDR) was positively correlated to their resistance to TTO, as 50%, 25%, 12%, 6% and 5% of the strains resistant to 0, 1-2, 3-4, 5-6 and 7-8 antimicrobial drugs, respectively were sensitive to TTO. Sensitivity of bacteria to TTO was positively correlated (p, ≤0.05) with their sensitivity to novobiocin (r, 0.24), tetracycline (r, 0.22), gentamicin (r, 0.21), ciprofloxacin (r, 0.17), nitrofurantoin (r, 0.16), and chloramphenicol (r, 0.14) while correlation was insignificant (p, >0.05) with sensitivity to co-trimoxazole (r, 0.10) and polymyxin B (r, 0.12). Minimum inhibitory concentration (MIC) of TTO varied from 0.001% to >0.512% (v/v) for different strains. The study revealed that TTO is a broad-spectrum antimicrobial active on 26 out of 44 genera of bacteria is a less promising antimicrobial than antibiotics on MDR strains. The study concluded that resistance to TTO, antibiotics and other antimicrobials in bacteria of clinical origin go hand in hand.