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Se describen los grupos de Escherichia coli enteropatógena, con especial atención a EC. enterohemorrágica. Algunos serotipos de E. Coli verotoxigénica son capaces de producir enteritis hemorrágica, que puede complicarse con el síndrome hemolítico urémico. Esta complicación, se da en particular en los niños y presenta una elevada letalidad. La transmisión a través de los alimentos y la capacidad de producir brotes epidémicos junto a la gravedad de las complicaciones de las enteritis confieren a este microorganismo una gran importancia en salud pública. Se revisa la epidemiología del microorganismo en nuestro país.

A percentage of hepatitis C virus (HCV)-infected patients fail direct acting antiviral (DAA)-based treatment regimens, often because of drug resistance-associated substitutions (RAS). The aim of this study was to characterize the resistance profile of a large cohort of patients failing DAA-based treatments, and investigate the relationship between HCV subtype and failure, as an aid to optimizing management of these patients. A new, standardized HCV-RAS testing protocol based on deep sequencing was designed and applied to 220 previously subtyped samples from patients failing DAA treatment, collected in 39 Spanish hospitals. The majority had received DAA-based interferon (IFN) α-free regimens; 79% had failed sofosbuvir-containing therapy. Genomic regions encoding the nonstructural protein (NS) 3, NS5A, and NS5B (DAA target regions) were analyzed using subtype-specific primers. Viral subtype distribution was as follows: genotype (G) 1, 62.7%; G3a, 21.4%; G4d, 12.3%; G2, 1.8%; and mixed infections 1.8%. Overall, 88.6% of patients carried at least 1 RAS, and 19% carried RAS at frequencies below 20% in the mutant spectrum. There were no differences in RAS selection between treatments with and without ribavirin. Regardless of the treatment received, each HCV subtype showed specific types of RAS. Of note, no RAS were detected in the target proteins of 18.6% of patients failing treatment, and 30.4% of patients had RAS in proteins that were not targets of the inhibitors they received. HCV patients failing DAA therapy showed a high diversity of RAS. Ribavirin use did not influence the type or number of RAS at failure. The subtype-specific pattern of RAS emergence underscores the importance of accurate HCV subtyping. The frequency of "extra-target" RAS suggests the need for RAS screening in all three DAA target regions., Competing Interests: Declaration of competing interest We declare that no public or private company has had any role in the study design, data collection, experimental work, data analysis, decision to publish, or preparation of the manuscript. Roche Diagnostics S.L. provided support in the form of a salary for one of the authors [Josep Gregori], but the company did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. No other Competing Interests to declare. Thus, our adherence to Antiviral Research policies on sharing data and materials is not altered., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: In addition to HPV, high parity and hormonal contraceptives have been associated with cervical cancer (CC). However, most of the evidence comes from retrospective case-control studies. The aim of this study is to prospectively evaluate associations between hormonal factors and risk of developing cervical intraepithelial neoplasia grade 3 (CIN3)/carcinoma in situ (CIS) and invasive cervical cancer (ICC)., Methods and Findings: We followed a cohort of 308,036 women recruited in the European Prospective Investigation into Cancer and Nutrition (EPIC) Study. At enrollment, participants completed a questionnaire and provided serum. After a 9-year median follow-up, 261 ICC and 804 CIN3/CIS cases were reported. In a nested case-control study, the sera from 609 cases and 1,218 matched controls were tested for L1 antibodies against HPV types 11,16,18,31,33,35,45,52,58, and antibodies against Chlamydia trachomatis and Human herpesvirus 2. Multivariate analyses were performed to estimate hazard ratios (HR), odds ratios (OR) and corresponding 95% confidence intervals (CI). The cohort analysis showed that number of full-term pregnancies was positively associated with CIN3/CIS risk (p-trend = 0.03). Duration of oral contraceptives use was associated with a significantly increased risk of both CIN3/CIS and ICC (HR = 1.6 and HR = 1.8 respectively for ≥ 15 years versus never use). Ever use of menopausal hormone therapy was associated with a reduced risk of ICC (HR = 0.5, 95%CI: 0.4-0.8). A non-significant reduced risk of ICC with ever use of intrauterine devices (IUD) was found in the nested case-control analysis (OR = 0.6). Analyses restricted to all cases and HPV seropositive controls yielded similar results, revealing a significant inverse association with IUD for combined CIN3/CIS and ICC (OR = 0.7)., Conclusions: Even though HPV is the necessary cause of CC, our results suggest that several hormonal factors are risk factors for cervical carcinogenesis. Adherence to current cervical cancer screening guidelines should minimize the increased risk of CC associated with these hormonal risk factors.

We report here the results of the diagnostic performances of Vitros Syphilis TPA (a chemiluminescence treponemal assay) compared with those of two treponemal enzyme immunoassays and of traditional versus reverse syphilis algorithms. Ease of use, automation, and high throughput make the Vitros Syphilis TPA assay a good choice for syphilis screening in high-volume laboratories., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

To evaluate prospectively the association between serological markers of selected infections, including HPV, and risk of developing cervical cancer (CC) and precancer, we performed a nested case-control study within the European Prospective Investigation into Cancer and Nutrition (EPIC) study that included 184 cases of invasive CC (ICC), 425 cases of cervical intraepithelial neoplasia (CIN) grade 3 or carcinoma in situ (CIS), and 1,218 matched control women. At enrollment participants completed lifestyle questionnaires and provided sera. Subjects were followed-up for a median of 9 years. Immunoassays were used to detect serum antibodies to Human Herpes Virus 2 (HHV-2), Chlamydia trachomatis (CT), Chlamydia pneumoniae, L1 proteins of mucosal and cutaneous HPV types, E6/E7 proteins of HPV16/18, as well as to four polyomaviruses. Adjusted odds ratios (OR) [and 95% confidence intervals (CI)] for CIN3/CIS and ICC risk were respectively: 1.6 (1.2-2.0) and 1.8 (1.1-2.7) for L1 seropositivity to any mucosal HPV type, 1.0 (0.4-2.4) and 7.4 (2.8-19.7) for E6 seropositivity to HPV16/18, 1.3 (0.9-1.9) and 2.3 (1.3-4.1) for CT seropositivity, and 1.4 (1.0-2.0) and 1.5 (0.9-2.6) for HHV-2 seropositivity. The highest OR for ICC was observed for HPV16 E6 seropositivity [OR = 10.2 (3.3-31.1)]. Increasing number of sexually transmitted infections (STIs) was associated with increasing risk. Non-STIs were not associated with CC risk. In conclusion, this large prospective study confirms the important role of HPV and a possible contribution of CT and HHV-2 in cervical carcinogenesis. It further identifies HPV16 E6 seropositivity as the strongest marker to predict ICC well before disease development., (© 2013 UICC.)

Cell culture is still the gold standard for the diagnosis of human enteroviruses (HEVs) although molecular techniques are required for detection of some serotypes. Due to the diversity of HEVs, a single cell line is not susceptible to all serotypes, and several lines are required to optimize the isolation of HEVs. In this study, the results of HEV isolation during the last 25 years are reported. A total of 1,192 HEVs were isolated and isolation rates varied depending on the cell line used. MRC5 cells yielded the best results (70.7%), followed by A549 cells (52.6%), RD cells (37.5%), and HEp-2 cells (29.7%). A total of 521 HEVs were characterized, and HEV-B was the most frequent species (81%). Polioviruses (PV) and HEV-A were isolated less frequently (17% and 1%, respectively). None of the cell lines detected all the enteroviruses. MRC5 cells were the most susceptible for isolation of echoviruses (85.7%) and PVs (85.4%), whereas HEp2 was the most susceptible for Coxsackieviruses B (82.6%). Some serotypes were isolated in one cell line only. 40.5% of echoviruses were isolated in MRC5 cells whereas 42.3% and 23.9% of Coxsackieviruses B were isolated in RD cells and HEp2 cells, respectively. Although A549 cells did not achieve the best performance for any enterovirus serotypes, they isolated 52.6% of the total HEVs. In view of these results, MRC5 cells, A549 cells, and RD cells should be combined to optimize isolation of HEVs., (Copyright © 2012 Wiley Periodicals, Inc.)

Background: Quantification and description of patients recently infected by HIV can provide an accurate estimate of the dynamics of HIV transmission. Between 2006 and 2008 in Catalonia, we estimated the prevalence of recent HIV infection among newly diagnosed cases, described the epidemiological characteristics of the infection according to whether it was recent, long-standing or advanced, and identified factors associated with recent infection., Methods: A Test for Recent Infection (TRI) was performed in serum samples from patients newly diagnosed with HIV. Two different TRI were used: the Vironostika-LS assay (January 2006-May 2007) and the BED-CEIA CEIA (June 2007 onwards). Samples were obtained within the first 6 months of diagnosis. Patients whose samples tested positive in the TRI were considered recently infected., Results: Of 1125 newly diagnosed patients, 79.9% were men (median age, 35.4 years), 38.7% were born outside Spain, 48.9% were men who have sex with men (MSM) and 10.6% presented other sexually transmitted infections. The overall percentage of recent infection was 23.0%, which increased significantly, from 18.1% in 2006 to 26.2% in 2008. This percentage was higher for patients from South America (27.6%). Factors associated with recent infection were acquiring infection through sexual contact between MSM [odds ratio (OR) 2.0; 95% confidence interval (95% CI) 1.1-3.9], compared with acquiring infection through heterosexual relations and being under 30 years of age (OR 5.9; 95% CI 1.9-17.4), compared with being over 50 years of age., Conclusion: The highest percentage of recent infection was identified in MSM, suggesting either a higher incidence or a greater frequency of HIV testing. Information regarding testing patterns is necessary to correctly interpret data from recently infected individuals. Systems to monitor the HIV epidemic should include both parameters.

Objectives: The objectives of this study were to assess the prevalence of transmitted HIV-1 drug resistances (TDR) and HIV-1 subtypes in recently infected patients in Catalonia between 2003 and 2005 and to describe the characteristics of these patients according to the presence or absence of TDR and HIV-1 subtype., Methods: After application of the Serological Testing Algorithm for Recent HIV Seroconversion (STARHS), residual aliquots of serum samples from recently infected antiretroviral-naïve individuals were genotyped. FASTA sequences were analyzed using the HIVDB Program. The World Health Organization 2009 List of Mutations for Surveillance of Transmitted HIV-1 Drug Resistant HIV Strains was used to estimate the prevalence of TDR., Results: Of 182 recently infected patients, 14 (7.7%) presented TDR. Seven (3.8%) had genotypic evidence of TDR against non-nucleoside reverse transcriptase inhibitors, 6 (3.3%) against nucleoside reverse transcriptase inhibitors, 3 (1.6%) against protease inhibitors (PIs), and only 2 individuals (1.1%) presented TDR against more than one class of drugs. Thirty-five (19.2%) patients were infected with a non-B HIV-1 subtype., Conclusion: This is the first study to estimate the prevalence of TDR in recently infected patients in Catalonia. The results are similar to those of studies performed in other Spanish regions. Correct monitoring of these parameters requires systematic epidemiologic surveillance of transmitted resistance., (Copyright © 2010 Elsevier España, S.L. All rights reserved.)

Unlabelled: Prophylactic and pre-emptive therapy with oral valganciclovir for cytomegalovirus infection in renal transplant recipients., Background: Cytomegalovirus infection is a very important health problem in solid organ transplant recipients (SOT). Once-daily valganciclovir has been shown to be as clinically effective and well tolerated as oral ganciclovir tid in the prevention of CMV infection in high risk SOT recipients., Methods: The aim of the present study was to evaluate the incidence and severity of CMV disease in 150 renal transplant recipients that received either prophylactic [high risk group (HR), N = 66] or pre-emptive [low risk group (LR), N = 84] therapy with oral valganciclovir (900 mg/day vo) for three months according to their basal risk. Patients were monitored for signs and symptoms of CMV disease and CMV plasma viral load was assessed weekly., Results: A total of 31 patients (47%) of the HR and 26 patients (31%) of the LR presented a positive CMV PCR result. Twelve patients (14.3%) in the LR that had a high viral load (CMV PCR > 1,000 copies/mL) but remained asymptomatic received pre-emptive therapy. Four patients (4.7%) in the LR, after an average time of 35 days after transplant and two patients (4.5%) in the HR, after prophylactic treatment was completed, developed CMV disease. The disease was mild-moderate in most of the cases. Those patients that developed CMV disease responded to treatment with iv ganciclovir for 14 days followed by treatment with oral valganciclovir for up to three months., Conclusion: Prophylactic treatment with oral valganciclovir for CMV prevention is only required in high risk solid organ transplant recipients.

Respiratory viruses (RVs) are known to be major causes of morbidity and mortality in recipients of hematopoietic stem cell transplants (HSCTs), but prospective long-term studies are lacking. We prospectively screened all adult HSCT recipients (172 allogeneic [alloHSCT] and 240 autologous [autoHSCT]) who underwent transplantation during a 4-year period (1999 to 2003) for the development of a first episode of symptomatic upper respiratory tract infections and/or lower respiratory tract infections (LRTI) by an RV. RVs studied were influenza A and B viruses (n=39), human respiratory syncytial virus (n=19), human adenoviruses (n=11), human parainfluenza viruses 1 to 3 (n=8), human enteroviruses (n=5), human rhinoviruses (n=3), and the recently discovered human metapneumoviruses (n=19). During the study, 51 and 32 cases of RV symptomatic infections were identified of alloHSCT and autoHSCT recipients (2-year incidence, 29% and 14%, respectively). Risk factors for progression of upper respiratory tract infection to LRTI included severe (<0.2x10(9)/L) and moderate (<0.2x10(9)/L) lymphocytopenia in alloHSCT (P=.02) and autoHSCT (P=.03). Death from LRTI was attributed to an RV in 8 alloHSCT recipients. Symptomatic RV had no effect on 2-year outcomes, with the possible exception of influenza A and B virus infections in autoHSCT: these were associated with nonrelapse mortality (P=.02). In conclusion, this prospective trial allows an estimation of the minimum incidence of a first RV infection in adult HSCT recipients and identifies risk factors for acquisition of an RV infection and progression to LRTI; this should aid in the design of future studies. In addition, human metapneumovirus should be added to the potentially serious causes of RV infections in HSCT.

Background: Isolated case reports have shown that recipients of allogeneic hematopoietic stem cell transplants (HSCTs) who develop toxoplasmosis may have circulating Toxoplasma gondii DNA in peripheral blood before the onset of clinical symptoms., Methods: We prospectively studied 106 T. gondii-seropositive adult recipients of HSCTs for the incidence of reactivation of toxoplasmosis in the first 6 months after transplantation. Toxoplasmosis infection (TI) was defined by a positive result of polymerase chain reaction (PCR) of peripheral blood specimens, whereas toxoplasmosis disease (TD) was defined as an invasive infection., Results: The incidence of TI was 16% (95% confidence interval [CI], 8%-21%), whereas the incidence of TD was 6% (95% CI, 1%-10%). In the 16 patients with TI, the incidence of disease was 38%, whereas it was 0% in patients without TI (P<.0001). In most patients, the onset of TD or treatment for TI was preceded by an increase in the parasite load in peripheral blood samples, as determined by quantitative PCR., Conclusions: Toxoplasmosis occurs more commonly after HSCT than has previously been suggested, and routine PCR testing of peripheral blood specimens may be an appropriate tool for guiding preemptive therapy in patients at very high risk of developing invasive disease.

In vitro susceptibility to acyclovir of 96 strains of herpes simplex virus isolated from 80 immunocompromised patients attended in our hospital was studied by the cytopathic effect reduction assay. Ninety-eight percent (61/62) of herpes simplex virus 1 strains and 91% (31/34) of herpes simplex virus 2 strains were inhibited by acyclovir concentrations lower than 3 mg/l. In 5% of the patients herpes simplex strains resistant to acyclovir (ID(50) >3 mg/l) were isolated. Ninety-eight percent of the lesions caused by herpes simplex viruses susceptible to acyclovir (ID(50) <3 mg/l) resolved independently of treatment. In two cases, the cytopathic effect reduction assay was not able to predict treatment failure and persistance of the lesions was not always associated with isolation of a resistant strain in vitro. In four cases, isolation of a strain resistant to acyclovir was not indicative of treatment failure. In conclusion, we believe there is no need to routinely test susceptibility of herpes simplex viruses to acyclovir and that susceptibility testing should be indicated only in patients in whom lesions persist and other causes have been ruled out.

Background: Bacterial meningitis is a severe infection of the central nervous system (CNS), most frequently caused by Neisseria meningitidis in our setting. Microbiologic diagnosis of bacterial meningitis is not enough sensitive because its efficiency can be affected by the therapeutic regimen given to the patient. Polymerase chain reaction (PCR) can provide a more sensitive diagnosis and allow us to get an earlier result., Objectives: To assess the sensitivity and specificity of a PCR technique for the diagnosis of meningitis caused by N. meningitidis and Haemophilus influenzae., Material and Methods: Ninety-six patients who were attended because of suspected bacterial meningitis on the Hospital de Sant Joan de Déu, Corporació Sanitària Parc Taulí and Hospital de la Santa Creu i Sant Pau, and had negative results by conventional laboratory methods, were selected for the study. A total of 99 cerebrospinal fluid samples (CSF) were obtained and evaluated for PCR. DNA extracts of the CSF samples were amplified by universal primers. Amplification products were hybridized with specific probes for Haemophilus genus and N. meningitidis. Positive and negative controls were included to asses the reliability of PCR., Results: Eight of the 99 CSF samples (8%) were positive by PCR and subsequent hybridization with the specific probe of N. meningitidis. None of the amplicons hybridized with the probe of Haemophilus genus. Thirteen percent of the patients (8/59) with clinical suspicious of non-neonatal sepsis or meningitis were diagnosed by PCR, amongst them, 36% of the cases (4/11) with initial diagnosis of meningococcal sepsis or meningitis., Conclusions: The sensitivity and the specificity of the PCR technique afford a complementary method to conventional ones, in special for the diagnosis of meningococcal meningitis in the group of pediatric patients.

We report three patients who developed a generalized rash with oral, genital or perianal ulcerations as a result of acute infection due to HIV. The primary infection was diagnosed by seroconversion (by means of EIA and Western blot techniques). Definitive diagnosis was established on days 52, 85 and 97 after the appearance of the rash. The p24 protein of the HIV was only detected in the early phase of the disorder in the two cases in which this study was carried out.

Objective: To determine the number of strains of classic enteropathogenic E. coli (EPEC) that have the eae gene, that is considered a pathogenicity factor., Material and Methods: The presence of the eae gene has been evaluated on 62 EPEC strains of ten different serogroups, isolated from children with gastroenteritis., Results: Amplification of the eae gene was positive in 10 out of 62 EPEC strains analyzed (16%) corresponding to seven different serogroups., Discussion: The low frequency of the detection of the eae gene on EPEC strains shows the limited correlation between the pathogenicity and the serogroup of the strains and would corroborate the need to reexamine this subject prospectively in our country.

Groups of Escherichia coli enteropathogen are described, with special attention to Escherichia coli enterohaemorragic. Some serotypes of Escherichia coli verocitotoxin-producing are able to produce haemorrhagic enteritis, which can develop a complication with hemolityc uraemic syndrome. This complication is most frequent in children and has a high mortality rate. The transmission takes place via food and its capacity to cause epidemic outbreaks together with the seriousness of the complications caused by enteritys make this microorganism of great importance to Public Health. The epidemiology of this microorganism in Spain is reviewed.

Background: The aim of the study was to describe the etiology of enteropathogenic agents over a four-year period (1992-1995) in a University Hospital in Barcelona., Methods: We studied 12,793 stool samples, 4519 were obtained from patients under 15 years and 8274 were obtained from patients over 14 years. The specimens were examined for bacteriological, parasitological and virological enteropathogens., Results: In 3380 specimens of 12,793 stool samples studied were identified an enteropathogen (26.4%). Polymicrobial associations were observed in the 6.8% of the cases. Pathogens were identified in 45% of children samples and 16.3% of adults samples. The etiological enteritis agents more frequently detected in the paediatric patients were Campylobacter (13.5%), rotavirus (11.3%) and Salmonella (10.2%); and Salmonella (4.9%), Campylobacter (3.1%) and Giardia intestinalis (2.1%) in adults. Cryptosporidium (13.5%) was the most frequent cause of gastrointestinal tract infections in HIV-infected subjects. In the children with stools positives, the presence of red and white blood cells were more frequent than the adults with stools positives (73% versus 26.6%)., Conclusions: The enteropathogenic agents such as Campylobacter, Salmonella, and Giardia were the most frequent cause of gastroenteritis in our environment. In the children, rotavirus infections predominated during the cold months. The most frequent cause of gastroenteritis in HIV-infected patients was Cryptosporidium followed by Campylobacter.

Objective: To determine, using polymerase chain reaction (PCR) amplification, if Mycobacterium tuberculosis complex DNA is present in the skin biopsy specimens of lobular granulomatous panniculitis., Design: A retrospective descriptive study., Setting: A university-based hospital., Patients: From the 65 patients included in the study, we examined 72 paraffin-embedded skin biopsy specimens with a histologic diagnosis of erythema induratum or nodular vasculitis. The biopsy specimens were from the histopathological archives of the Departments of Dermatology and Pathology of the Hospital de la Santa Creu i Sant Pau, Barcelona, Spain, from 1976 to 1994. Twenty-two biopsy specimens were excluded from the final analysis because we could not amplify the internal control., Main Outcome Measures: Detection of a 123-base pair fragment of the IS6110 insertion sequence specific for M tuberculosis complex., Results: The results of PCR amplification were positive for M tuberculosis complex DNA in 77% of the skin biopsy specimens. No significant difference could be detected with respect to the age of the patients, ulceration of the nodules, reactivity to purified protein derivative, abnormal results of a chest x-ray examination, personal and family history of tuberculosis, and PCR results. The presence and degree of necrosis on histologic examination were significantly higher in the PCR-positive group (P = .04). None of the following variables were associated with PCR results: presence of vasculitis, degree of granulomatous infiltrates, number of giant cells, and presence of well-organized granulomas., Conclusions: The DNA of M tuberculosis can be detected in a considerable number of skin biopsy specimens of lobular granulomatous panniculitis. None of the clinical and histologic variables evaluated could accurately predict the results of PCR amplification.

Background: Erythema induratum of Bazin (BEI), is included in the group of cutaneous granulomatous lobulillar panniculitis. The aethiopathogenic association between EI and tuberculosis can not rely on the clinicohistological features of these panniculitis and M. tuberculosis has never been isolated from BEI lesions. Detection of the mycobacterial DNA by PCR on cutaneous biopsy samples would allow to confirm this association., Patients and Methods: Fourteen patients with clinical BEI were chosen retrospectively. Seventeen lesional biopsy samples were obtained, stained with the Kinyoun carbolfuchsin acid-fast technique and haematoxylin and eosin and tested by PCR. A fragment of the IS6110 insertion sequence specific of M. tuberculosis was amplified and confirmed by digestion with Sal I restriction endonuclease. The efficiency of the procedure, the presence of inhibitory substances and the preservation of DNA were checked by PCR of the beta-actin gene., Results: M. tuberculosis DNA was detected in 12 of the 17 samples tested (70.5%) which corresponded to 10 of the 14 patients (71.4%). According to beta-actin PCR results, the rate of extracted DNA was inadequate on four of the five negative biopsies., Conclusions: The results of these series suggest the probable involvement of M. tuberculosis on the BEI pathogenesis and give support to the usefulness of the PCR in the diagnosis of this pathology concerning the need of specific treatment.

Verotoxin-producing Escherichia coli strains (VTEC) cause hemorrhagic colitis and hemolytic-uremic syndrome in humans. Laboratory diagnosis by conventional methods is slow and cumbersome. The results of a new rapid enzyme immunoassay (EIA Premier EHEC) for verotoxin detection both in isolated strains and in clinical samples are presented, and they are compared with cell culture (CC) and polymerase chain reaction (PCR) techniques. Fifty-four strains have been analyzed by both EIA and PCR, and 33 by all three methods. The kit has also been evaluated for experimentally infected stool samples directly and after their enrichment on MacConkey broth. Nineteen, out of the 54 strains, were positive by EIA and 20 by PCR. The results of the 33 strains evaluated by the three techniques were coincident with one exception. The latter was uninterpretable by CC, negative by EIA and positive by PCR. The sensitivity of the kit for experimentally infected stool samples was approximately 5 x 10(7) bacteria/ml in the direct test, and 5 x 10(4) bacteria/ml after broth enrichment. EIA sensitivity and specificity were similar to those of CC and PCR. The diagnostic times were 18h for EIA, 3 days for PCR and 5 days for CC. Sensitivity, rapidity and ease of performance make this technique especially valuable for clinical diagnosis.

Hemorrhagic colitis is an enteritis caused by verotoxigenic strains of Escherichia coli. Conventional diagnosis requires the identification of the microorganism and the demonstration of verotoxin production. The determination of toxigenicity in isolated strains and in direct stool samples by the polymerase chain reaction (PCR) technique may simplify the diagnosis. Conventional coprocultures were performed for the detection of verotoxigenic E. coli O157:H7 from three stool samples of a patient with hemorrhagic colitis and hemolytic-uremic syndrome. The production of verotoxin was determined by cell culture and the presence of VT1 and VT2 genomic sequences by PCR. Likewise, the latter technique was applied to a direct stool sample for detection of the verotoxin codiying genes. The specificity of the amplified sequences was confirmed by enzyme restriction digestion. Escherichia coli O157:H7 was isolated in two of the three samples studied. The strains were toxigenic in the cell culture test at titers higher than 1/500 and PCR showed an amplified band of 479 pb corresponding to the VT2 codifying gene. The digestion of amplified sequences with the EcoRV enzyme led to two bands of 390 and 89 pb confirming the specificity of the results. One of the two stool samples studied directly by PCR was positive for VT2 with the result being obtained 48 hours after arrival to the laboratory. The preliminary results of this study give support to the usefulness of the polymerase chain reaction technique in the detection of verotoxin from isolated strains of Escherichia coli and in direct stool samples.