O Sethabutr

Armed Forces Research Institute of Medical Sciences, Krung Thep, Bangkok, Thailand

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Publications (41)221.75 Total impact

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    ABSTRACT: Noroviruses (NoVs) are an important human pathogen associated with acute viral gastroenteritis worldwide. NoVs display a significant amount of genetic heterogeneity, making it difficult to develop comprehensive detection assays. In this study, primer sets and probes were designed for a TaqMan®-based real-time reverse transcription-polymerase chain reaction (RT-PCR) for norovirus detection purposes. The assay was optimized and utilized as a multiplex real-time RT-PCR assay for genogroup I (GI) detection, and a singleplex real-time RT-PCR assay for genogroup II (GII) detection. The assays showed high specificity for NoV detection and no cross-reactivity was observed between GI and GII. The detection limit of the assay was as low as 10 and 50 RNA copies per reaction for GI and GII, respectively. The optimized protocol was employed to assess the presence of NoV strains in clinical samples collected throughout Thailand during December 2005 to November 2006. The percentage of NoV infections among children with acute gastroenteritis (case) was 23.8% (119/500) and for children without acute gastroenteritis (control) it was 6.8% (30/441). The frequency of NoV infections varied geographically, with the highest frequency observed in the central region and the lowest frequency in the northern region (P>0.0001). Of the 149 positive case and control specimens, GII was found to be the predominant genogroup (98.6%). Partial capsid sequences were successfully obtained from 67 NoV-positive specimens and a phylogenetic analysis was performed to genotype the viral strains. GII.4 was the most common genotype detected.
    Journal of virological methods 09/2013; 194(1-2). DOI:10.1016/j.jviromet.2013.08.033 · 1.88 Impact Factor
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    ABSTRACT: Detection of diarrheagenic Escherichia coli (DEC) typically depends on identification of virulence genes from stool cultures, not on stool itself. We developed a multiplex polymerase chain reaction (PCR) assay that detects key DEC virulence genes (stx1, stx2, eae, bfpA, ipaH, LT, STh, aaiC, aatA). The assay involved a multiplex PCR reaction followed by detection of amplicon(s) using Luminex beads. The assay was evaluated on over 100 colony and broth specimens. We then evaluated the assay using DNA extracted from stool, colony pools, and Gram-negative broths, using stool spiked with known quantities of DEC. Performance of the assay on stool DNA was most quantitative, while stool broth DNA offered the lowest limit of detection. The assay was prospectively evaluated on clinical specimens in Tanzania. Stool DNA yielded higher sensitivity than colony pools compared with broth DNA as the standard. We propose using this assay to screen for DEC directly in stool or stool broths.
    Diagnostic microbiology and infectious disease 04/2012; 73(2):121-8. DOI:10.1016/j.diagmicrobio.2012.03.008 · 2.57 Impact Factor
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    ABSTRACT: Cyclospora, Cystoisospora, and Microsporidia are eukaryotic enteropathogens that are difficult to detect in stool samples because they require special stains and microscopy. We developed a multiplex polymerase chain reaction (PCR) reaction with 4 primer sets to amplify Cyclospora cayetanensis, Cystoisospora belli, Enterocytozoon bieneusi, and Encephalitozoon intestinalis. Detection of the amplicon is through specific probes coupled to Luminex beads. Sensitivity of the assay was evaluated using Encephalitozoon intestinalis spores and revealed detection of 10(1) spores spiked into stool. No cross-reactivity was observed. We evaluated the assay on diarrheal specimens from Thailand, Tanzania, Indonesia, and the Netherlands that had been previously tested by microscopy, and the assay yielded 87-100% sensitivity and 88-100% specificity. Microscopy-negative/PCR-positive samples had lower Luminex values, suggesting they were true but with lower burden infections. In summary, this is a convenient single PCR reaction that can detect Cyclospora, Cystoisospora, and Microsporidia without the need for cumbersome microscopic analysis.
    Diagnostic microbiology and infectious disease 12/2011; 71(4):386-90. DOI:10.1016/j.diagmicrobio.2011.08.012 · 2.57 Impact Factor
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    ABSTRACT: Assessment of microbial hazards associated with certain environmental matrices, livelihood strategies, and food handling practices are constrained by time-consuming conventional microbiological techniques that lead to health risk assessments of narrow geographic or time scope, often targeting very few pathogens. Health risk assessment based on one or few indicator organisms underestimates true disease burden due a number of coexisting causative pathogens. Here, we employed molecular techniques in a survey of Cryptosporidium parvum, Giardia lamblia, Campylobacter jejuni, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., Shigella spp., Vibrio cholera, and Rotavirus A densities in canal water with respect to seasonality and spatial distribution of point-nonpoint pollution sources. Three irrigational canals stretching across nearly a 150-km(2) periurban landscape, traditionally used for agricultural irrigation but function as vital part of municipal wastewater stabilization in recent years, were investigated. Compiled stochastic data (pathogen concentration, susceptible populations) and literature-obtained deterministic data (pathogen dose-response model parameter values) were used in estimating waterborne gastroenteritis burden. Exposure scenarios include swimming or fishing, consuming canal water-irrigated vegetables, and ingesting or inhaling water aerosols while working in canal water-irrigated fields. Estimated annual gastroenteritis burden due individual pathogens among the sampling points was -10.6log(10) to -2.2log(10) DALYs. Aggregated annual gastroenteritis burden due all the target pathogens per sampling point was -3.1log(10) to -1.9log(10) DALYs, far exceeding WHO acceptable limit of -6.0log(10) DALYs. The present approach will facilitate the comprehensive collection of surface water microbiological baseline data and setting of benchmarks for interventions aimed at reducing microbial hazards in similar landscapes worldwide.
    EcoHealth 09/2011; 8(3):349-64. DOI:10.1007/s10393-011-0724-8 · 2.27 Impact Factor
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    ABSTRACT: Shigella is a frequent cause of bacterial dysentery in the developing world. Treatment with effective antibiotics is recommended for shigellosis, but options become limited due to globally emerging resistance. One of the mechanisms for the development of resistance utilizes integrons. This study described the antibiotic susceptibility and the presence of class 1 and 2 integrons in S. flexneri and S. sonnei isolated in Uzbekistan. We studied 31 isolates of S. flexneri and 21 isolates of S. sonnei isolated in Uzbekistan between 1992 and 2007 for the susceptibility or resistance to ampicillin (Am), chloramphenicol (Cl), tetracycline (Te), co-trimoxazole (Sxt), kanamycin (Km), streptomycin (Str), gentamicin (Gm), cefazolin (Czn), cefoperazone (Cpr), cefuroxime (Cur), ceftazidime (Ctz), nalidixic acid (NA) and ciprofloxacin (Cip). Am/Str/Cl/Te and Am/Str/Cl/Te/Sxt resistance patterns were found most frequently in S. flexneri. Single isolates were resistant to aminoglycoside, quinolones and cephalosporins. The resistance patterns were different in the two species. Integrons were detected in 93.5% of S. flexneri (29/31) and 81.0% of S. sonnei (17/21) isolates. In addition, 61.3% of S. flexneri (19/31) isolates and 19.0% of S. sonnei (4/21) isolates carried both classes of integrons. In 29.0% of S. flexneri (9/31) isolates, only class 1 integrons were identified. In S. flexneri isolates, the presence of class 1 integrons was associated with resistance to ampicillin and chloramphenicol. Only Class 2 integrons were present in 61.9% of S. sonnei (13/21) isolates. Our study documents antibiotic resistance among Shigella spp. in Uzbekistan. Ninety percent of Shigella strains were resistant to previously used antibiotics. Differences among S. flexneri and S. sonnei isolates in patterns of antimicrobial resistance to routinely used shigellosis antibiotics were observed. The majority of S. flexneri were resistant to ampicillin, chloramphenicol, tetracycline and streptomycin. Class 1 and 2 integrons were widely present in these Shigella strains. Resistance to ampicillin/chloramphenicol was associated with the presence of class 1 integrons. Though several mechanisms are possible, the resistance of Shigella isolates to ampicillin/chloramphenicol may be associated with the expression of genes within class 1 integrons.
    Gut Pathogens 12/2010; 2(1):18. DOI:10.1186/1757-4749-2-18 · 2.07 Impact Factor
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    ABSTRACT: A new species of parvovirus, tentatively named human bocavirus 4 (HBoV4), was genetically characterized. Among 641 feces samples obtained from children and adults, the most commonly detected bocavirus species were, in descending order, HBoV2, HBoV3, HBoV4, and HBoV1, with an HBoV2 prevalence of 21% and 26% in Nigerian and Tunisian children, respectively. HBoV3 or HBoV4 species were found in 12 of 192 patients with non-polio acute flaccid paralysis in Tunisia and Nigeria and 0 of 96 healthy Tunisian contacts (P = .01). Evidence of extensive recombination at the NP1 and VP1 gene boundary between and within bocavirus species was found. The high degree of genetic diversity seen among the human bocaviruses found in feces specimens, relative to the highly homogeneous HBoV1, suggest that this worldwide-distributed respiratory pathogen may have recently evolved from an enteric bocavirus after acquiring an expanded tropism favoring the respiratory tract. Elucidating the possible role of the newly identified enteric bocaviruses in human diseases, including acute flaccid paralysis and diarrhea, will require further epidemiological studies.
    The Journal of Infectious Diseases 06/2010; 201(11):1633-43. DOI:10.1086/652416 · 5.78 Impact Factor
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    ABSTRACT: A new species of parvovirus, tentatively named human bocavirus 4 (HBoV4), was genetically characterized. Among 641 feces samples obtained from children and adults, the most commonly detected bocavirus species were, in descending order, HBoV2, HBoV3, HBoV4, and HBoV1, with an HBoV2 prevalence of 21% and 26% in Nigerian and Tunisian children, respectively. HBoV3 or HBoV4 species were found in 12 of 192 patients with non-polio acute flaccid paralysis in Tunisia and Nigeria and 0 of 96 healthy Tunisian contacts (P p). Evidence of extensive recombination at the NP1 and VP1 gene boundary between and within bocavirus .01 species was found. The high degree of genetic diversity seen among the human bocaviruses found in feces specimens, relative to the highly homogeneous HBoV1, suggest that this worldwide-distributed respiratory pathogen may have recently evolved from an enteric bocavirus after acquiring an expanded tropism favoring the respiratory tract. Elucidating the possible role of the newly identified enteric bocaviruses in human diseases, including acute flaccid paralysis and diarrhea, will require further epidemiological studies.
    The Journal of Infectious Diseases 06/2010; 201(11):1633-1643. · 5.78 Impact Factor
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    ABSTRACT: High rates of Campylobacter fluoroquinolone resistance highlight the need to evaluate diagnostic strategies that can be used to assist with clinical management. Diagnostic tests were evaluated with U.S. soldiers presenting with acute diarrhea during deployment in Thailand. The results of bedside and field laboratory diagnostic tests were compared to stool microbiology findings for 182 enrolled patients. Campylobacter jejuni was isolated from 62% of the cases. Clinical and laboratory findings at the time of presentation were evaluated to determine their impact on the posttest probability, defined as the likelihood of a diagnosis of Campylobacter infection. Clinical findings, the results of tests for inflammation (stool occult blood testing [Hemoccult], fecal leukocytes, fecal lactoferrin, plasma C-reactive protein), and the numbers of Campylobacter-specific antibody-secreting cells in peripheral blood failed to increase the posttest probability above 90% in this setting of Campylobacter hyperendemicity when these findings were present. Positive results by a Campylobacter-specific commercial enzyme immunoassay (EIA) and, less so, a research PCR were strong positive predictors. The negative predictive value for ruling out Campylobacter infection, defined as a posttest probability of less than 10%, was similarly observed with these Campylobacter-specific stool-based tests as well the fecal leukocyte test. Compared to the other tests evaluated, the Campylobacter EIA is a sensitive and specific rapid diagnostic test that may assist with diagnostic evaluation, with consideration of the epidemiological setting, logistics, and cost.
    Journal of clinical microbiology 05/2008; 46(4):1418-25. DOI:10.1128/JCM.02168-07 · 4.23 Impact Factor
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    ABSTRACT: To get a real number of the disease burden caused by Shigella in Kaeng-Khoi District, Saraburi Province, Thailand, real time-PCR was used to detect Shigella-associated DNA. Randomly selected rectal swabs from 20 Shigella culture-positive and from 300 Shigella culture-negative patients detected in population-based surveillance of patients seeking care for diarrhea were processed using real time PCR. The target of the primer pair is the invasion plasmid antigen H gene sequence (ipalI) carried by all 4 Shigella species and enteroinvasive Escherichia coli. IpaHwas detected in l9 out of 20 (95%) Shigella culture-positive specimens compared to 48 out of 300 (16%) culture-negative patients free of dysentery @
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    ABSTRACT: Amplified fragment length polymorphism (AFLP) can be used to assess the genetic diversity of closely related microbial genomes. In this study, the first of its kind for identification of Shigella, the high discriminatory power of AFLP has been used to determine the genetic relatedness of 230 isolates of Shigella flexneri and Shigella sonnei strains. An AFLP database was generated to demonstrate its utility in the discrimination of closely related strains. Based on AFLP, S. flexneri strains could be grouped into separate clusters according to their serotypes. Within each serotype, strains demonstrated 80-100% similarity indicating that identical strains and closely related strains could be distinguished by this technique. S. flexneri 6 formed a distinct cluster with 55% similarity to the rest of the S. flexneri strains showing significant divergence from the rest of the S. flexneri strains. Significantly, S. sonnei isolates formed a distinct group and showed approximately the same level of genetic linkage to S. flexneri as Escherichia coli strains. Untypable isolates that showed conflicting agglutination reactions with conventional typing sera were identifiable by AFLP. Thus AFLP can be used for genetic fingerprinting of Shigella strains and aid in the identification of variant untypable isolates.
    Journal of Microbiological Methods 01/2007; 67(3):487-95. DOI:10.1016/j.mimet.2006.05.004 · 2.10 Impact Factor
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    ABSTRACT: Shigella spp. are exquisitely fastidious gram-negative organisms which frequently escape detection by traditional culture methods. To get a more complete understanding of the disease burden caused by Shigella in Nha Trang, Vietnam, real-time PCR was used to detect Shigella DNA. Randomly selected rectal swab specimens from 60 Shigella culture-positive patients and 500 Shigella culture-negative patients detected by population-based surveillance of patients seeking care for diarrhea were processed by real-time PCR. The target of the primer pair is the invasion plasmid antigen H gene sequence (ipaH), carried by all four Shigella species and enteroinvasive Escherichia coli. Shigella spp. could be isolated from the rectal swabs of 547 of 19,206 (3%) patients with diarrhea. IpaH was detected in 55 of 60 (93%) Shigella culture-positive specimens, whereas it was detected in 87 of 245 (36%) culture-negative patients free of dysentery (P < 0.001). The number of PCR cycles required to detect a PCR product was highest for culture-negative, nonbloody diarrheal specimens (mean number of cycles to detection, 36.6) and was lowest for children with culture-positive, bloody diarrheal specimens (mean number of cycles, 25.3) (P < 0.001). The data from real-time PCR amplification indicate that the culture-proven prevalence of Shigella among patients with diarrhea may underestimate the prevalence of Shigella infections. The clinical presentation of shigellosis may be directly related to the bacterial load.
    Journal of Clinical Microbiology 06/2004; 42(5):2031-5. DOI:10.1128/JCM.42.5.2031-2035.2004 · 4.23 Impact Factor
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    ABSTRACT: A novel ceuE-based multiplex PCR system was developed as an efficient diagnostics test to detect and differentiate C. jejuni and C. coli. There is no cross reactivity between C. jejuni and C. coli. In addition, the assay does not produce a positive signal from other enteric bacteria including Salmonella, Shigella and Escherichia coli strains. Campylobacter detection sensitivity was determined to be equivalent to previously reported PCR for other enteric bacteria. We also noticed that silicon dioxide extraction can improve Campylobacter detection sensitivity from infected stool samples. It was demonstrated that the PCR assay developed in this study had a much better Campylobacter detection rate than the traditional culturing method (77% versus 56%). However, we also identified small numbers of culture positive stools (8%, or 16 out of 202 samples) that did not yield PCR positive results for Campylobacter. These PCR negative/culture positive stools were proven to be inhibitory to PCR amplification.
    Diagnostic Microbiology and Infectious Disease 04/2001; 40(1-2):11-9. DOI:10.1016/S0732-8893(01)00251-6 · 2.57 Impact Factor
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    ABSTRACT: PCR techniques applied to diarrheal stools reliably diagnose Shigella and enteroinvasive Escherichia coli (EIEC) infections. Identification of PCR products using agarose gel electrophoresis (AGE) and hybridization with DNA probes has several shortcomings. Automated methods of identifying PCR products that process larger numbers of specimens can facilitate epidemiologic studies and standardize results. In this study, we used ELISA following PCR to detect ipaH gene sequences of Shigella and EIEC from 89 diarrheal stools. Results of ELISA were compared with AGE with and without DNA probe, and with culture. Two specimen preparation methods were compared as well: boiling/centrifugation, and purification with silicon dioxide (SiO(2)). Both PCR product-detection methods identified significantly more infections than did culture. PCR-ELISA detected significantly more infections than PCR-AGE when processed using SiO2 (P = 0.014). PCR-ELISA allows screening of larger numbers of specimens, automates test results, and avoids use of mutagenic reagents. PCR-ELISA is faster than PCR-AGE when testing large numbers of specimens, although not when testing small numbers of specimens.
    Diagnostic Microbiology and Infectious Disease 06/2000; 37(1):11-6. DOI:10.1016/S0732-8893(00)00122-X · 2.57 Impact Factor
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    ABSTRACT: Polymerase chain reaction (PCR) diagnostic methods have rarely been used in epidemiologic studies of Shigella and enteroinvasive Escherichia coli (EIEC) infections. In this study, amplification of the invasion plasmid antigen H (ipaH) gene by PCR and standard culture methods was used to identify Shigella species or EIEC among 154 patients with dysentery, 154 age-matched controls, and family contacts in Thailand. The ipaH PCR system increased the detection of Shigella species and EIEC from 58% to 79% among patients with dysentery and from 6% to 22% among 527 family contacts; 75% of infections in family members were asymptomatic. Detection of the ipaH gene was statistically associated with dysentery. Household contacts of patients with shigellosis diagnosed only by PCR had significantly higher rates of shigellosis than household contacts of patients who did not have Shigella or EIEC infections. Detection of the ipaH gene by PCR is far more sensitive than detection by standard culture and is highly correlated with evidence of Shigella transmission among family contacts.
    The Journal of Infectious Diseases 11/1997; 176(4):1013-8. DOI:10.1086/516531 · 5.78 Impact Factor
  • H S Houng, Orntipa Sethabutr, Peter Echeverria
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    ABSTRACT: A simple polymerase chain reaction (PCR) procedure using IS630-specific primers was developed as a general diagnostic probe to detect Shigella and enteroinvasive Escherichia coli (EIEC). However, IS630 and the other two previously reported molecular probes, ipaH and ial, cannot be used to differentiate among Shigella serotypes and EIEC strains that cause dysentery. The sensitivity of PCR protocol was determined to be 100-200 shigellae for each PCR reaction. An enrichment incubation would allow the detection of shigellae in stool samples with low bacterial concentration; i.e., < 10(4) CFU/gram. Serotype-specific primers derived from the rfc genes of differentiate among Shigella serotypes in the laboratory, such as S. sonnei, S. flexneri, and S. dysenteriae 1. It was demonstrated further that the multiplex PCR system containing rfc-specific primers can efficiently identify the most prominent Shigella serotypes in raw stool samples of acute diarrheal patients.
    Diagnostic Microbiology and Infectious Disease 06/1997; 28(1):19-25. DOI:10.1016/S0732-8893(97)89154-7 · 2.57 Impact Factor
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    ABSTRACT: A coccidian organism assigned to the genus Cyclospora has been increasingly recognized in association with prolonged diarrhea in humans throughout the world. Confusion surrounds the taxonomy of this fastidious organism, despite the availability of morphology and sporulation characteristics. The small subunit rRNA coding region from cyclosporan oocysts purified from a human fecal specimen was amplified and sequenced. The same sequence was present in specimens from 8 other patients with cyclosporan oocysts but absent in specimens from asymptomatic subjects and from cryptosporidiosis patients. Phylogenetic analysis of rDNA sequences reveals that the human-associated Cyclospora is closely related to members of the Eimeria genus. These results allow predictions concerning Cyclospora host specificity, life cycle, and epidemiology as well as the development of a specific polymerase chain reaction-based diagnostic assay.
    The Journal of Infectious Diseases 03/1996; 173(2):440-5. DOI:10.1093/infdis/173.2.440 · 5.78 Impact Factor
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    ABSTRACT: A total of 148 Vibrio cholerae isolates from a major shrimp production area in Southern Thailand were examined by colony hybridisation for genes encoding heat-stable enterotoxin (NAG-ST) and cholera toxin (CT). Only non-O1 V. cholerae strains were found to harbour NAG-ST (14 of 146) whereas no strains hybridised with the CT probe. NAG-ST-positive V. cholerae non-O1 strains were isolated from shrimp farms situated close to urban areas. Five different O serogroups were found among NAG-ST positive non-O1 strains. Southern blot and restriction endonuclease analysis of NAG-ST-positive strains revealed a high degree of genetic divergence. A total of seven classes of enterotoxin gene patterns were found with HindIII and EcoRI restriction endonucleases. Enterotoxin gene patterns correlated with O-antigen expression in 84% of isolates tested. In combination with other molecular techniques Southern blot analysis with an NAG-ST oligonucleotide probe could be useful for studying the molecular epidemiology of V. cholerae non-O1 strains.
    Journal of Medical Microbiology 10/1995; 43(3):216-20. DOI:10.1099/00222615-43-3-216 · 2.27 Impact Factor
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    ABSTRACT: In developed countries, serotypes (or G types) have been identified in > 70% of group A rotavirus using monoclonal enzyme immunoassays (MEIAs); however, these assays have identified < 50% of rotavirus G types from developing countries presumably because the VP7 antigens were damaged by freezing and thawing during transportation of specimens. The VP7 (G) serotypes of rotavirus in unfrozen stool collected from children with acute diarrhea in Bangkok were determined using MEIA and compared to hybridization with alkaline phosphatase-labeled oligonucleotide probes. Reverse transcription of dsRNA coding for VP7 followed by polymerase chain reaction amplification of cDNA was used as an additional step prior to hybridization for 98 specimens that did not hybridize with the oligonucleotide probes. Of 251 rotavirus specimens, 208 (83%; 99% Cl = 76-89%) hybridized with G type specific oligonucleotides compared to 146 (58%; 99% Cl = 50-66%) that were typeable by MEIA. Forty-five (82%) of 55 stools containing G type 1, 80 of 84 (95%) containing G type 2, 0 of 3 containing G type 3, and 2 of 4 (50%) containing G type 4 as identified by MEIA hybridized with G type specific oligonucleotides. Differences in nucleotide sequences coding for VP7, in addition to destruction of the VP7 antigen by freezing and thawing of the specimen, may explain why not all rotavirus hybridized with G type specific probes.
    Journal of Medical Virology 01/1995; 45(1):117-20. DOI:10.1002/jmv.1890450121 · 2.22 Impact Factor
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    ABSTRACT: The rate of detection of Shigella and enteroinvasive Escherichia coli (EIEC) using a PCR technique was compared with the rate detected by standard microbiological methods (bacteriology plus hybridization of E. coli colonies with a 17 kb EIEC probe) among patients with dysentery before and after antibiotic therapy. The PCR amplified DNA sequences encoding IpaH, a multiple copy sequence located on the chromosome and the invasion plasmid. Shigella or EIEC were detected using the IpaH PCR system among 72 (61%) of 119 patients with dysentery on the first day they were seen at hospital, compared to 50 (42%) using standard microbiological methods (p = 0.006). After three days of antibiotic therapy, IpaH sequences were detected in stools from 38 percent of patients, compared to 10 percent using standard microbiology (p < 0.001). After seven days of therapy, the rates were 26 percent vs. 8 percent respectively (p < 0.001). The IpaH PCR system appeared to be specific for Shigella or EIEC based on low rates of positive reactions among non-diarrhoea controls, and a strong correlation between persistently positive reactions and antibiotic resistance of bacterial isolates. IpaH sequences were detected in 10 (8%) of 119 drinking water samples from homes of patients with disease; none of these specimens were positive for Shigella or EIEC by standard microbiology. In conclusion, PCR amplification of IpaH sequences and detection of target DNA with a non-radioactive probe increased the rates of identification of Shigella and EIEC by 45% in initial clinical specimens and by nearly 300% in specimens obtained from patients receiving antibiotic therapy.
    Journal of diarrhoeal diseases research 01/1995; 12(4):265-9.
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    ABSTRACT: There have been three significant technical developments in the molecular genetic diagnosis of infectious diarrhea. The first was the replacement of polynucleotide probes with more specific synthetic oligonucleotide probes. The second was the replacement of radiolabeled markers with nonradiolabeled markers, and the third was PCR amplification. In the PCR procedure, it is possible to increase the quantity of target nucleotide sequences to quantities easily detectable with nonradioactive oligonucleotide probes. It is now possible to amplify nucleotide sequences of more than one enteric pathogen with different primers simultaneously and to detect these amplified nucleotide sequences with nonradiolabeled oligonucleotide probes. With a scanning laser system, the results of enteric PCRs will be used to identify enteric pathogens on a routine basis in clinical and public health laboratories. Computers need to be used to analyze these results and transfer this information rapidly to clinicians and public health officials.
    Gastroenterology Clinics of North America 10/1993; 22(3):661-82. · 1.92 Impact Factor