Ashok J. Tamhankar

Dr. Ashok J. Tamhankar

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Research Focus & Metrics

Academic Career Length

32Years (1995-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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13 July 2010 in BMC Public Health
Verified
Journal Article
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VDVishal Diwan
Vishal Diwan
ATAshok J. Tamhankar
Ashok J. Tamhankar
RKRakesh K Khandal
Rakesh K Khandal
SSShanta Sen
Shanta Sen
MAManjeet Aggarwal
Manjeet Aggarwal
CLCecilia Stålsby Lundborg
Cecilia Stålsby Lundborg
Concerns have been raised about the public health implications of the presence of antibiotic residues in the aquatic environment and their effect on the development of bacterial resistance. While there is information on antibiotic residue levels in hospital effluent from some other countries, information on antibiotic residue levels in effluent from Indian hospitals is not available. Also, concurrent studies on antibiotic prescription quantity in a hospital and antibiotic residue levels and resistant bacteria in the effluent of the same hospital are few. Therefore, we quantified antibiotic residues in waters associated with a hospital in India and assessed their association, if any, with quantities of antibiotic prescribed in the hospital and the susceptibility of Escherichia coli found in the hospital effluent.

LQLien La Thi Quynh
Lien La Thi Quynh
NHNguyen Quynh Hoa
Nguyen Quynh Hoa
NCNguyen Thi Kim Chuc
Nguyen Thi Kim Chuc
NTNguyen Thi Minh Thoa
Nguyen Thi Minh Thoa
HPHo Dang Phuc
Ho Dang Phuc
CLCecilia Stålsby Lundborg
Cecilia Stålsby Lundborg
Hospital effluents represent an important source for the release of antibiotics and antibiotic resistant bacteria into the environment. This study aims to determine concentrations of various antibiotics in wastewater before and after wastewater treatment in a rural hospital (60 km from the center of Hanoi) and in an urban hospital (in the center of Hanoi) in Vietnam, and it aims to explore the relationship between antibiotic concentrations in wastewater before wastewater treatment and quantities of antibiotics used in the rural hospital, over a period of one year in 2013. Water samples were collected using continuous sampling for 24 h in the last week of every month. The data on quantities of antibiotics delivered to all inpatient wards were collected from the Pharmacy department in the rural hospital. Solid-phase extraction and high performance liquid chromatography-tandem mass spectrometry were used for chemical analysis. Significant concentrations of antibiotics were present in the wastewater both before and after wastewater treatment of both the rural and the urban hospital. Ciprofloxacin was detected at the highest concentrations in the rural hospital’s wastewater (before treatment: mean = 42.8 µg/L; after treatment: mean = 21.5 µg/L). Metronidazole was detected at the highest concentrations in the urban hospital’s wastewater (before treatment: mean = 36.5 µg/L; after treatment: mean = 14.8 µg/L). A significant correlation between antibiotic concentrations in wastewater before treatment and quantities of antibiotics used in the rural hospital was found for ciprofloxacin (r = 0.78; p = 0.01) and metronidazole (r = 0.99; p < 0.001).

21 March 2019 in Frontiers in Microbiology
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Journal Article
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Prasanth ManoharPrasanth Manohar
Prasanth Manohar
ATAshok J. Tamhankar
Ashok J. Tamhankar
CLCecilia Stålsby Lundborg
Cecilia Stålsby Lundborg
Ramesh NachimuthuRamesh Nachimuthu
Ramesh Nachimuthu
Infections due to antibiotic resistant bacteria are increasing globally and this needs immediate attention. Bacteriophages are considered an effective alternative for the treatment of bacterial infections. The aim of this study was to isolate and characterize the bacteriophages that infect Escherichia coli, Klebsiella pneumoniae, and Enterobacter species. For this, clinical bacterial isolates of the mentioned species were obtained from diagnostic centers located in Chennai, Tamil Nadu, India. The bacteriophages were isolated from sewage water samples collected from Tamil Nadu, India. Phage isolation was performed using enrichment method and agar overlay method was used to confirm the presence of bacteriophages. All the phages were characterized for their life cycle parameters, genome analysis, and in vitro phage cocktail activity. The three bacteriophages exhibited broad host range activity: Escherichia virus myPSH2311 infecting E. coli belonging to six different pathotypes, Klebsiella virus myPSH1235 infecting K. pneumoniae belonging to four different serotypes and Enterobacter virus myPSH1140 infecting four different species of Enterobacter. Morphological observations suggested that the bacteriophages belonged to, Phieco32virus (Escherichia virus myPSH2311), Podoviridae (Klebsiella virus myPSH1235), and Myoviridae (Enterobacter virus myPSH1140). The life cycles (adsorption, latent period, and cell burst) of Escherichia virus myPSH2311, Klebsiella virus myPSH1235 and Enterobacter virus myPSH1140 were found to be 26, 40, and 11 min, respectively. Genomic analysis revealed that Escherichia virus myPSH2311 is closely related to Escherichia phage vB_EcoP_SU10, Klebsiella virus myPSH1235 is closely related to Klebsiella phage vB_KpnP_KpV48 and Enterobacter virus myPSH1140 is closely related to Enterobacter phage PG7 and Enterobacter phage CC31. When phage cocktail was used against multiple bacterial mixtures, there was a reduction in bacterial load from 106 to 103 CFU/mL within 2 h. All the three characterized phages were found to have a broad host range activity and the prepared phage cocktails were effective against mixed bacterial population that are resistant to meropenem and colistin, two last resort antibiotics. Infections caused by drug resistant bacteria will be a serious threat in the future and the use of virulent bacteriophages in therapy may offer an effective solution.

SDSourav Das
Sourav Das
SGSoumen Ghosh
Soumen Ghosh
AMAnanyo Jyoti Misra
Ananyo Jyoti Misra
ATAshok J. Tamhankar
Ashok J. Tamhankar
AMAmrita Mishra
Amrita Mishra
STSuraj K Tripathy
Suraj K Tripathy
Antibiotic residues in the aquatic environment have the potential to induce resistance in environmental bacteria, which ultimately might get transferred to pathogens making treatment of diseases difficult and poses a serious threat to public health. If antibiotic residues in the environment could be eliminated or reduced, it could contribute to minimizing antibiotic resistance. Towards this objective, water containing ciprofloxacin was treated by sunlight-assisted photocatalysis using Fe- doped ZnO nanoparticles for assessing the degradation potential of this system. Parameters like pH, temperature, catalytic dosage were assessed for the optimum performance of the system. To evaluate degradation of ciprofloxacin, both spectrophotometric as well as microbiological (loss of antibiotic activity) methods were employed. 100 mg/L Fe-doped ZnO nanoparticle catalyst and sunlight intensity of 120,000–135,000 lux system gave optimum performance at pH 9 at 30 °C and 40 °C. Under these conditions spectrophotometric analysis showed complete degradation of ciprofloxacin (10 mg/L) at 210 min. Microbiological studies showed loss of antibacterial activity of the photocatalytically treated ciprofloxacin-containing water against Staphylococcus aureus (108 CFU) in 60 min and for Escherichia coli (108 CFU) in 75 min. The developed system, thus possess a potential for treatment of antibiotic contaminated waters for eliminating/reducing antibiotic residues from environment.

21 October 2010 in BMC Public Health
Verified
Journal Article
Open access
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KSKrushna Chandra Sahoo
Krushna Chandra Sahoo
ATAshok J. Tamhankar
Ashok J. Tamhankar
EJEva Johansson
Eva Johansson
CLCecilia Stålsby Lundborg
Cecilia Stålsby Lundborg
Background: Antibiotic resistance is a major public health problem affecting both current and future generations. The influence of environmental factors on antibiotic use and resistance development in bacteria is largely unknown. This study explored the perceptions of healthcare providers on antibiotic use and resistance development in relation to environmental factors i.e. physical, natural, social and behavioural factors. Methods: A qualitative interview study was conducted using face-to-face, semi-structured interviews among registered allopathic doctors, veterinarians and drug dispensers in Orissa, India. The interview transcripts were analyzed using latent content analysis. Results: The main findings of this study relate to two themes: 'Interrelationship between antibiotic use, resistance development and environment' and 'Antibiotic management contributing to the development and spread of resistance'. The interviewees viewed the following as possible contributors to antibiotic use/misuse and resistance development: changes in the natural and physical environment i.e. climate variability, pollution, physiography and population growth; the socioeconomic environment affecting health-seeking behaviour and noncompliance with medication; a lack of healthcare facilities and poor professional attitudes; and ineffective law enforcement regarding medicine dispensing and disposal. Conclusions: Generally, the interviewees perceived that although behavioural and social environmental factors are major contributors to resistance development, changes in the physical and natural environment also influence development of antibiotic resistance. The respondents also perceived that there is a lack of information about, and poor awareness of, what constitutes prudent use of antibiotics. They suggested a need for information, education, dissemination and proper implementation and enforcement of legislation at all levels of the drug delivery and disposal system in order to improve antibiotic use and prevent pharmaceutical contamination of the environment.

VDVishal Diwan
Vishal Diwan
NHNada Hanna
Nada Hanna
MPManju Purohit
Manju Purohit
SCSalesh Chandran
Salesh Chandran
EREmilia Riggi
Emilia Riggi
CLCecilia Stålsby Lundborg
Cecilia Stålsby Lundborg
Objectives: To characterize the seasonal variation, over one year, in water-quality, antibiotic residue levels, antibiotic resistance genes and antibiotic resistance in Escherichia coli isolates from water and sediment of the Kshipra River in Central India. Methods: Water and sediment samples were collected from seven selected points from the Kshipra River in the Indian city of Ujjain in the summer, rainy season, autumn and winter seasons in 2014. Water quality parameters (physical, chemical and microbiological) were analyzed using standard methods. High-performance liquid chromatography–tandem mass spectrometry was used to determine the concentrations of antibiotic residues. In river water and sediment samples, antibiotic resistance and multidrug resistance patterns of isolated E. coli to 17 antibiotics were tested and genes coding for resistance and phylogenetic groups were detected using multiplex polymerase chain reaction. One-way analysis of variance (ANOVA) and Fisher tests were applied to determine seasonal variation. Results: In river water, seasonal variation was significantly associated with various water quality parameters, presence of sulfamethoxazole residues, bacteria resistant to ampicillin, cefepime, meropenem, amikacin, gentamicin, tigecycline, multidrug resistance and CTX-M-1 gene. The majority of the Extended Spectrum Beta-Lactamase (ESBL)-producing E. coli isolates from river water and sediment in all different seasons belonged to phylogenetic group A or B1. Conclusions: Antibiotic pollution, resistance and resistance genes in the Kshipra River showed significant seasonal variation. Guidelines and regulatory standards are needed to control environmental dissemination of these “pollutants” in this holy river.