Browsing by Author "Saurabh Kumar Patel"

Now showing 1 - 7 of 7

Acid exposure induces multiplication of salmonella enterica serovar typhi
(American Society for Microbiology, 2014) Suneel Kumar Ahirwar; Chandra Bhan Pratap; Saurabh Kumar Patel; Vijay K. Shukla; Indarjeet Gambhir Singh; Om Prakash Mishra; Kailash Kumar; Tej Bali Singh; Gopal Nath
Salmonella enterica serovar Typhi faces several environmental stresses while going through the stomach (acidic pH) to the small intestine (basic pH) and intracellularly in macrophages (acidic pH) in humans. The acidic pH followed by alkaline pH in the small intestine might be responsible for expression of certain stress-induced genes, resulting in not only better survival but also induction of multiplication and invasion of the bacterium in the small intestine. Based on this hypothesis, we developed a process wherein we exposed the blood, urine, and stool specimens from 90 acute typhoid fever patients and 36 chronic typhoid carriers to acidic pH to see the effect on isolation rate of S. Typhi. About 5 g of freshly passed unpreserved stool, a centrifuged deposit of 15 ml of urine, and 5 ml of blood clot were subjected to 5 ml of Luria-Bertani (LB) broth (pH 3.5) for 20 min, followed by enrichment in bile broth-selenite F broth. When the combined isolation from all 3 specimens, i.e., blood, urine, and stool, after acid exposure was considered, a total of 77.7% of the acute typhoid patients were observed to be positive for the isolation of the S. Typhi serotype, compared to 8.8% by the conventional method. Similarly, 42% (15/36) of chronic carriers yielded positive for S. Typhi growth after acid exposure, compared to 5.5% (2/36) by the conventional method. It therefore can be concluded that acid shock triggers the multiplication of the bacteria, resulting in better isolation rates from blood clot, stool, and urine specimens. Copyright © 2014, American Society for Microbiology. All Rights Reserved.
Diagnosis of Helicobacter pylori: What should be the gold standard?
(WJG Press, 2014) Saurabh Kumar Patel; Chandra Bhan Pratap; Ashok Kumar Jain; Anil Kumar Gulati; Gopal Nath
Since the discovery of Helicobacter pylori (H. pylori ) in 1983, numerous detection methods for the presence of the bacterium have been developed. Each one of them has been associated with advantages and disadvantages. Noninvasive tests such as serology, 13C urea breath test (UBT) and stool antigen tests are usually preferred by the clinicians. Serology has its own limitation especially in endemic areas while 13C UBT is technically very demanding. The stool antigen detection method, although specific, is usually associated with poor sensitivity. The 13C UBT is believed to be specific, but with present revelation of the fact that stomach is colonized by many other urease producing bacteria makes it questionable. Histology, culture, rapid urease test and polymerase chain reaction (PCR) are the tests which are carried out on antral biopsies collected by invasive means. Histology has been proposed to be very sensitive and specific but the question is how by simply looking the morphology of the bacteria in the microscope, one can claim that the curved bacterium is exclusively H. pylori. Rapid urease test (RUT), the doctor's test, is also challenged because the presence of other urease producing bacteria in the stomach cannot be denied. Moreover, RUT has been reported with poor sensitivity specially, when density of the bacterium is low. Isolation of H. pylori is essential to investigate its growth requirements, antibiotic susceptibility testing, studying virulence factor to develop vaccine and many more explorations. It has also got several disadvantages i.e., special condition for transporting, media, incubation and few days waiting for the colonies to appear, apart from the speed essentially needed to process the specimens. Till date, majority of the microbiological laboratories in the world are not equipped and trained to isolate such fastidious bacterium. The option left is PCR methods to detect H. pylori's DNA in gastric mucosa, gastric juice, saliva, dental plaques and environmental specimens. There are speculations for false positivity due to detection of non-pylori Helicobacters due to genetic sharing; and false negativity due to low bacterial counts and presence of PCR inhibitors. However, specimen collection, transportation and processing do not require speed and special conditions. PCR based diagnosis may be considered as gold standard by designing primers extremely specific to H. pylori and targeting at least more than one conserved genes. Similarly specificity of PCR may be improved by use of internal Primers. Further, nested PCR will take care of false negatives by countering the effect of PCR inhibitors and low bacterial counts. Therefore, nested PCR based methods if performed properly, may be proposed as gold standard test. © 2014 Baishideng Publishing Group Inc. All rights reserved.
Distribution of Hepatitis B virus genotypes among healthy blood donors in eastern part of North India
(2011) Kailash Kumar; Manoj Kumar; Sk.H. Rahaman; T.B. Singh; Saurabh Kumar Patel; Gopal Nath
Aim: We evaluated the distribution HBV genotypes among non-remunerated healthy blood donors in eastern North India. Materials and Methods: During screening of donated blood, 176 consecutive HBsAg positive, samples comprised the study. HBV-DNA was quantitative detected in 150 samples by PCR. HBV genotype was determined by identifying genotype-specific DNA band using nested PCR. Results: Majorities were of age group 31-40 yrs (65.3%). Males (92.7%) outnumbered females (7.3%) and were HbeAg-negative HBsAg carriers. Over all, genotype-A was the most prevalent (54%) followed by D (21.3%). We did not find genotype-G and H. Districts under study, divided into four zones: Zone-I genotype-A was most common (62.3%) followed by D (18.8%); Zone-II genotype-C (41.2%) was more frequent followed by D (20.6% and A (17.7%). Zone-III in adjoining Bihar state close to Zone-I, A was more prevalent (81.8%) followed by B and C (9.1%). In Zone-IV adjoining Zone- II had genotype-A (100%) only. Genotype-D had more sporadic distribution. Genotype-E and F were prevalent in Zone I and II (3/150, 2%). Conclusions: Among blood donors HBV genotype-A followed by D was the most prevalent in eastern North India. Genotype-A had pattern of distribution signifying common focus, while D was more sporadic and C had single large pocket (Zone-II) probably common focus but restricting to particular area. Evidences are suggestive of association of HBV genotype in liver dysfunction. An effective treatment and preventive strategies based of genotypes will reduce the disease burden and increase the blood safety.
Drug resistance in Salmonella enterica serotype Typhi isolated from chronic typhoid carriers
(2012) Chandra Bhan Pratap; Saurabh Kumar Patel; Vijay K. Shukla; Sunil Kumar Tripathi; Tej Bali Singh; Gopal Nath
[No abstract available]
Helicobacter pylori is not eradicated after triple therapy: A nested PCR based study
(Hindawi Publishing Corporation, 2014) Saurabh Kumar Patel; Girish Narayan Mishra; Chandra Bhan Pratap; Ashok Kumar Jain; Gopal Nath
Detection of Helicobacter pylori after triple therapy is usually carried out by either rapid urease test (RUT), urea breath test (UBT), histology, bacterial isolation, and single round PCR or serological tests. In this study, antral biopsy specimens from 25 patients were tested for H. pylori by RUT, culture, histology, and nested PCR in their antral biopsy specimens before and after treatment. Three genes, namely, heat shock protein (hsp60), phosphoglucosamine mutase (ureC), and flagellar export ATP synthase (fliI) of H. pylori were targeted. Of the 25 antral biopsy specimens, the RUT, culture, histology, and nested PCR positivity dropped from 81.8% to 12%, 31% to 0%, 100 to 84%, and 100% to 92%, respectively, before and after therapy. Further, hsp60 specific amplicons from 23 out of 25 patients gave identical restriction pattern, while 6 fliI and 1 ureC specific amplicon produced different restriction pattern. Furthermore, variations in fliI gene sequences in H. pylori after treatment were also confirmed by sequencing and compared in silico. Nested PCR based detection of H. pylori is more sensitive method to detect H. pylori after therapy than culture, RUT, and histology. Further, this study suggests that H. pylori is not eradicated completely after triple therapy. © 2014 Saurabh Kumar Patel et al.
Microbial endophytes: Their resilience for innovative treatment solution to neglected tropical diseases
(Springer India, 2014) Ajay Kumar Verma; Saurabh Kumar Patel; Chandra Bhan Pratap; Mayank Gangwar; Gopal Nath
Fungal endophytes are relatively overlooked as a platform for discovering bioactive molecules against some major neglected tropical diseases, until some recent reports. Looking their potential as prolific producer of bioactive compounds against array of diseases and ailments makes them a suitable platform for such explorations. A major part of third world countries are facing growing problems of neglected tropical diseases (NTDs). More than two billion people of tropical and subtropical countries are facing serious health problems caused by lymphatic filariasis, onchocerciasis, echinococcosis, and other helminthic and zoonotic infections. Increasing side effects and appearance of resistance to the synthetic anthelmintics stimulates researchers for exploration of novel natural alternatives from medicinal plants and their associated endophytic microbes as a useful alternative. In this chapter, some aspects with respect to novel chemistry of endophytes and their structure activity relationship (SAR) toward tropical diseases like antiparasitic, antimalarial, and other neglected tropical diseases have been discussed. © 2014 Springer India. All rights reserved.
Pseudomonas fluorescens -like bacteria from the stomach: A microbiological and molecular study
(Baishideng Publishing Group Co, 2013) Saurabh Kumar Patel; Chandra Bhan Pratap; Ajay Kumar Verma; Ashok Kumar Jain; Vinod Kumar Dixit; Gopal Nath
AIM: To characterize oxidaseand urease-producing bacterial isolates, grown aerobically, that originated from antral biopsies of patients suffering from acid peptic diseases. METHODS: A total of 258 antral biopsy specimens were subjected to isolation of bacteria followed by tests for oxidase and urease production, acid tolerance and aerobic growth. The selected isolates were further characterized by molecular techniques viz. amplifications for 16S rRNA using universal eubacterial and HSP60 gene specific primers. The amplicons were subjected to restriction analysis and partial sequencing. A phylogenetic tree was generated using unweighted pair group method with arithmetic mean (UPGMA) from evolutionary distance computed with bootstrap test of phylogeny. Assessment of acidity tolerance of bacteria isolated from antrum was performed using hydrochloric acid from 10-7 mol/L to 10-1 mol/L. RESULTS: Of the 258 antral biopsy specimens collected from patients, 179 (69.4%) were positive for urease production by rapid urease test and 31% (80/258) yielded typical Helicobacter pylori (H. pylori) after 5-7 d of incubation under a microaerophilic environment. A total of 240 (93%) antral biopsies yielded homogeneous semi-translucent and small colonies after overnight incubation. The partial 16S rRNA sequences revealed that the isolates had 99% similarity with Pseudomonas species. A phylogenetic tree on the basis of 16S rRNA sequences denoted that JQ927226 and JQ927227 were likely to be related to Pseudomonas fluorescens (P. fluorescens). On the basis of HSP60 sequences applied to the UPGMA phylogenetic tree, it was observed that isolated strains in an aerobic environment were likely to be P. fluorescens, and HSP60 sequences had more discriminatory potential rather than 16S rRNA sequences. Interestingly, this bacterium was acid tolerant for hours at low pH. Further, a total of 250 (96.9%) genomic DNA samples of 258 biopsy specimens and DNA from 240 bacterial isolates were positive for the 613 bp amplicons by targeting P. fluorescens-specific conserved putative outer membrane protein gene sequences. CONCLUSION: This study indicates that bacterial iso lates from antral biopsies grown aerobically were P. fluorescens, and thus acid-tolerant bacteria other than H. pylori can also colonize the stomach and may be implicated in pathogenesis/protection. © 2013 Baishideng. All rights reserved.