Evaluation of initial virological response to adefovir and development of adefovir-resistant mutations in patients with chronic hepatitis B

The aims of the present study were to assess initial virological response (IVR) to adefovir (ADV) treatment for chronic hepatitis B, to identify patients with suboptimal response and to determine the incidence of ADV-resistant mutants. All patients treated with ADV for at least 12 months were evaluated for virological response and ADV resistance. IVR was defined as a reduction > or = 4 log10 IU/mL in hepatitis B virus (HBV)-DNA at month 6. Forty-two patients were analysed. Mean treatment duration was 23 +/- 7 months; 50% had prior lamivudine (LAM) therapy (LAM resistance 62%); 88% were hepatitis B e antigen (HBeAg)-negative; and 76% carried genotype D. IVR was seen in 40.5% of patients. Higher baseline ALT level was the only factor associated with IVR (P = 0.043). Patients with IVR achieved undetectable HBV-DNA at month 12 in 77% of cases compared with only 5% of those without IVR (P < 0.001). Five (12%) patients developed ADV-resistant mutations: rtN236T in four cases and one case with an rtV207L change, which has not been previously reported. This mutation was accompanied by viral rebound and alanine aminotransferase (ALT) flare. The cumulative probability of ADV-resistant mutations at 12 and 24 months was 5% and 17% respectively. IVR defined as a reduction > or = 4 log10 IU/mL in HBV-DNA at month 6 is a useful tool to predict virological response at month 12 and to identify patients with suboptimal response to ADV. Cumulative probability of ADV resistance is higher than previously reported for nucleos(t)ide-naïve patients.

Evaluation of initial virological response to adefovir and development of adefovir-resistant mutations in patients with chronic hepatitis B

The aims of the present study were to assess initial virological response (IVR) to adefovir (ADV) treatment for chronic hepatitis B, to identify patients with suboptimal response and to determine the incidence of ADV-resistant mutants. All patients treated with ADV for at least 12 months were evaluated for virological response and ADV resistance. IVR was defined as a reduction > or = 4 log10 IU/mL in hepatitis B virus (HBV)-DNA at month 6. Forty-two patients were analysed. Mean treatment duration was 23 +/- 7 months; 50% had prior lamivudine (LAM) therapy (LAM resistance 62%); 88% were hepatitis B e antigen (HBeAg)-negative; and 76% carried genotype D. IVR was seen in 40.5% of patients. Higher baseline ALT level was the only factor associated with IVR (P = 0.043). Patients with IVR achieved undetectable HBV-DNA at month 12 in 77% of cases compared with only 5% of those without IVR (P < 0.001). Five (12%) patients developed ADV-resistant mutations: rtN236T in four cases and one case with an rtV207L change, which has not been previously reported. This mutation was accompanied by viral rebound and alanine aminotransferase (ALT) flare. The cumulative probability of ADV-resistant mutations at 12 and 24 months was 5% and 17% respectively. IVR defined as a reduction > or = 4 log10 IU/mL in HBV-DNA at month 6 is a useful tool to predict virological response at month 12 and to identify patients with suboptimal response to ADV. Cumulative probability of ADV resistance is higher than previously reported for nucleos(t)ide-naïve patients.

[Prophylactic and pre-emptive therapy for cytomegalovirus infection in kidney transplant patients using oral valganciclovir]

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.

Unmasking influenza virus infection in patients attended to in the emergency department

Background:

Infection by the influenza virus may pass undetected in many adult patients attended to in the emergency department because its diagnosis usually relies on clinical manifestations, which can be distorted by symptoms of a preexisting disease, superposed complications or nontypical manifestations of influenza virus infection (confusing symptoms).

Patients and Methods:

We performed this observational, prospective study with an antigen detection test by indirect immunofluorescence assay (IFA) to estimate the presence of influenza virus infection in such patients. No confirmatory test was performed to validate a positive or negative IFA result. Then we compared those who were antigen positive to those who were negative and also analyzed those who were positive classified by age, comorbidity and clinical presentation. We also evaluated the use of medical and hospital resources and vaccination status. Posterior pharynx swab specimens from 136 consecutive adult patients, 74 women and 62 men with a mean age of 68.7 ± 17.9 (range: 18–97) years attended to in the emergency department of a university hospital in Barcelona during the 1999–2000 influenza epidemic were examined. Tested patients presented either a classical influenza syndrome, a deterioration of a previous condition or any abrupt onset of symptoms without an obvious cause.

Results:

Influenza A virus antigen was detected in 99 (72.8%) of the 136 patients included in the study. Confusing symptoms were present in 86 patients with laboratoryconfirmed influenza and 40 of them lacked influenza syndrome. Prostration, aching and fever out of proportion to catarrhal symptoms (disproportionate prostration) and cough were independent predictors for this diagnosis (OR = 5.14; 95% CI: 1.98–13.35, p = 0.001 and OR = 4.40, 95% CI, 1.65–11.75, p = 0.03, respectively). Among the 99 patients who tested positive, 72 were ≥ 65 years of age. This older positive group compared to the 27 also positive < 65 (non-old) had a tendency to show symptoms mediated by cytokines less frequently: malaise was present in 76.4% of the older positive patients vs 92.6% in the non-old positive ones, p = 0.07. The equivalent percentages for muscle ache were: 56.9% vs 77.8%, p = 0.06; for dysthermia: 54.2% vs 70.4%, p = 0.08; for headache: 35.2% vs 66.7%, p = 0.005, and for disproportionate prostration: 47.2% vs 66.7%, p = 0.08. Cough was more frequent in the older positive group: 94.4% vs 77.8%, p = 0.02. Older positive patients were also hospitalized and received antibiotics more frequently than the non-old positive ones: 65.3% vs 40.7%, p = 0.03 and 81.9% vs 63.0%, p = 0.046, respectively. Hospitalization was independently correlated with the presence of complications (OR = 4.5, 95% IC 1.27–15.95, p = 0.02). Patients with the highest comorbidity, evaluated with the Charlson scale, were more inadequately vaccinated than those with moderate or low comorbidity.

Conclusion:

Influenza virus infection has a great and underestimated impact in the emergency department during influenza epidemics. High frequency of confusing symptoms, which overcome classical influenza syndrome in adult people with comorbidity, may explain this effect. Disproportionate prostration and cough are symptoms that independently predict its diagnosis in the global adult population, whereas in the elderly, fever and cough should arouse this suspicion whether or not they present classic symptoms. In our setting, individuals with high comorbidity are inadequately vaccinated.

Antiviral susceptibility of Herpes simplex viruses and its clinical correlates: a single center's experience

The in vitro susceptibility to acyclovir of 204 herpes simplex virus isolates from 165 immunocompromised patients treated at our hospital was determined by the cytopathic effect reduction assay. Approximately 95% of herpes simplex virus 1 and 73% of herpes simplex virus 2 isolates were inhibited by acyclovir at concentrations of <2 microgram/mL. From 8 patients (5%), an isolate with low susceptibility to acyclovir (50% inhibitory dose, >3 microgram/mL) was recovered. Medical records of 83 patients were reviewed. Lesions resolved in most of the patients, independent of treatment. Treatment failures were not always associated with isolation of an in vitro-resistant virus. On the contrary, when a virus with low susceptibility to acyclovir was isolated, resolution of the lesion was the rule. In 9 of 10 patients with subsequent recurrent episodes of disease, the susceptibility of the viruses isolated was similar to that of the first episode. Routine susceptibility testing in our geographic area is not encouraged because of the low incidence of acyclovir-resistant herpes simplex viruses.

Prevalence of Neisseria meningitidis carriers in the school population of Catalonia, Spain

The aim of this study was to determine the prevalence of healthy Neisseria meningitidis pharyngeal carriers in a representative sample of the Catalonian school population, as well as its associated factors. The sample was divided into age groups: < or = 5, 6-7 and 13-14 years old. Parents were given a questionnaire to collect information on sociodemographic and epidemiological variables. Oropharyngeal swabs were collected with a cotton-tipped swab in an Amies transport medium and cultured on Thayer Martin plates at 35 degrees C in 5% CO2. The isolates were serogrouped and sero/subtyped. Of the 1406 children studied, 75 (5.34%) meningococcal carriers were detected: 63 B (4.5%), 9 non groupable (0.7%), 2 29E (0.1%) and 1X (0.07%). No serogroup C meningococci were found in this study, probably due to the high A+C vaccination coverage of up to 68.9% in children 6-7 years old. Bivariate analysis identified six statistically significant risk factors for meningococcal carriage: increasing age, recent upper respiratory tract infection, previous antibiotic treatment, number of students in the class, size of the classroom and social class. Multivariate analysis found that only age and previous antibiotic treatment remained statistically significant when the other factors were controlled.

[Clinical utility of susceptibility testing of herpes simplex virus to acyclovir]

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.

Escherichia coli serotype O15:K52:H1 as a uropathogenic clone

To clarify the clinical and bacteriological correlates of urinary-tract infection (UTI) due to Escherichia coli O15:K52:H1, during a 1-year surveillance period we prospectively screened all 1, 871 significant E. coli urine isolates at the Hospital de la Santa Creu i Sant Pau, Barcelona, Spain, for this serotype and assessed the epidemiological features of community-acquired UTI due to E. coli O15:K52:H1 versus other E. coli serotypes. We also compared the 25 O15:K52:H1 UTI isolates from the present study with 22 O15:K52:H1 isolates from other, diverse geographic locales and with 23 standard control strains (8 strains from the ECOR reference collection and 15 strains of nonpathogenic O:K:H serotypes) with respect to multiple phenotypic and genotypic traits. Although E. coli O15:K52:H1 caused only 1.4% of community-acquired E. coli UTIs during the surveillance period, these UTIs were more likely to present as pyelonephritis and to occur in younger hosts, with similar risk factors, than were UTIs due to other E. coli serotypes. Irrespective of geographic origin, E. coli O15:K52:H1 strains exhibited a comparatively restricted repertoire of distinctive virulence factor profiles (typically, they were positive for papG allele II, papA allele F16, and aer and negative for sfa, afa, hly, and cnf1), biotypes, ribotypes, and amplotypes, consistent with a common clonal origin. In contrast, their antimicrobial resistance profiles were more extensive and more diverse than those of control strains. These findings indicate that E. coli O15:K52:H1 constitutes a broadly distributed and clinically significant uropathogenic clone with fluid antimicrobial resistance capabilities.

Serum thrombopoietin levels in thrombocytopenic and non-thrombocytopenic patients with human immunodeficiency virus (HIV-1) infection

HIV-1 seropositive patients often exhibit thrombocytopenia, considered of multifactorial aetiology. Thrombopoietin (TPO), a recently isolated cytokine, is the main regulator of megakaryocyte and platelet production. The objective of this study was to analyse serum TPO levels in thrombocytopenic and non-thrombocytopenic HIV-1 infected patients. Serum TPO levels were measured by ELISA in 43 healthy individuals and in 88 HIV-1 infected patients: 68 thrombocytopenics and 20 non-thrombocytopenics. Thrombocytopenic HIV-1 infected patients showed higher TPO concentrations (263 +/- 342 pg/ml) than non-thrombocytopenics (191 +/- 86 pg/ml); levels in both groups were significantly higher than those of healthy controls (121 +/- 58 pg/ml). Two subgroups of thrombocytopenic patients, the autoimmune thrombocytopenic purpura (AITP) group and the mild thrombocytopenic group, presented TPO levels similar to those of non-thrombocytopenics. Patients exhibiting pancytopenia showed the highest TPO concentrations. However, there was no correlation between TPO levels and platelet counts in any group of HIV-1 infected patients. TPO levels in HIV-1 seropositive patients were slightly increased and the differences in TPO levels between thrombocytopenic and non-thrombocytopenic patients were generally small. The finding of mildly increased TPO levels along with the recently described recovery of thrombocytopenia following recombinant TPO administration confirms the implication of ineffective platelet production in the origin of HIV-associated thrombocytopenia.

[Haemophilus influenzae type b invasive disease in Catalonia (1996)]

BACKGROUND

The purpose of this study was to find out the incidence and characteristics of H. influenzae type b invasive disease (HibID) in Catalonia, Spain.

MATERIAL AND METHODS

An active surveillance of H. influenzae isolated from normally sterile sites was carried out during 1996. Microbiology laboratories of hospitals of Catalonia were periodically contacted by telephone. The serotype of all the strains was studied.

RESULTS

The incidence of H. influenzae invasive disease (HIID) was 7.1 per 100,000 in children under 5 years and 1.0 per 100,000 in those over 5 years. The incidence of serotype b was 6.4 per 100,000 children under 5 years and 0.2 above this age. Only three strains belonged to types other than b (d, e and f).

CONCLUSIONS

The incidence of HIbID is uncommon in Catalonia, lower than that registered in the prevaccine era in other countries and regions of the same geographical area.

[Evaluation of the polymerase chain reaction technique for the diagnosis of meningitis caused by Neisseria meningitidis and Haemophilus influenzae]

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.

[Mucocutaneous manifestations in acute HIV infection. 3 case reports]

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.

[Detection of pathogenicity factors in strains of classical enteropathogenic Escherichia coli]

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.

Histopathological changes of primary HIV infection. Description of three cases and review of the literature

The histopathological changes observed in the cutaneous rash of three patients who suffered the acute phase of HIV infection are described. In all three patients a perivascular and interstitial inflammatory infiltrate was present in the upper and mid-reticular dermis. In one biopsy isolated areas of epidermal necrosis were observed and in the two other biopsies a perifollicular inflammatory infiltrate was detected with perforation in one case. Furthermore, a periductal infiltrate was observed in one of these biopsies.

[Gastro-hemorrhagic Escherichia coli]

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.

[Etiology of enteritis in a university general hospital in Barcelona (1992-1995)]

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.

Detection of Mycobacterium tuberculosis DNA in lobular granulomatous panniculitis (erythema induratum-nodular vasculitis)

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.

[Usefulness of polymerase chain reaction for the diagnosis of Bazin erythema induratum]

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.

Evaluation of an enzyme immunoassay for verotoxin detection in Escherichia coli

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.

Detection of Mycobacterium tuberculosis complex DNA by the polymerase chain reaction for rapid diagnosis of cutaneous tuberculosis

We assessed the polymerase chain reaction (PCR) technique to detect Mycobacterium tuberculosis complex DNA in 48 paraffin-embedded specimens from 32 patients with different variants of cutaneous tuberculosis, and compared the results with those of culture. A 123 bp product of the IS6110 insertion sequence specific of M. tuberculosis complex was amplified and confirmed by digestion with SalI restriction endonuclease. The time required for the procedure was 3 days. Thirty-seven samples (77.1%) were positive for M. tuberculosis complex DNA. No false positive results were obtained in nine negative controls. Of the 20 specimens tested by PCR and culture, the frequency of positivity was 90% for DNA amplification and 65% for culture. In seven cases of lupus vulgaris, the figures were 100% and 57%, respectively. In the 11 specimens culture negative or not microbiologically tested and PCR negative, evidence for tuberculous infection was provided by the correlation of various relative and absolute criteria. These results show that PCR amplification of the IS6110 insertion fragment is a rapid and accurate means for the detection of M. tuberculosis complex DNA in paraffin-embedded skin biopsies from patients with cutaneous tuberculosis, especially in paucibacillary lesions.

Detection of M. tuberculosis complex DNA in a lesion resembling sarcoidosis

We describe a tuberculin test (PPD) negative patient with a chronic cutaneous lesion with histological features resembling sarcoidosis, in whom M. tuberculosis complex DNA was detected in formalin-fixed paraffin-embedded tissue by polymerase chain reaction (PCR) amplification. The lesion cleared with antituberculous treatment.

[Hemorrhagic colitis caused by verotoxigenic Escherichia coli. Presentation of 9 cases]

OBJECTIVE

To describe the clinical and epidemiological characteristics of nine patients with enteritis caused by verocytotoxin-producing E. coli O157.

PATIENTS AND METHODS

Clinical data of patients was collected retrospectively, the isolated strains were tested for verotoxin production (VT) using Vero cell culture line, and presence of VT1 and VT2 gene sequences was detected using amplification techniques (PCR), biotype was also determined using twelve biochemical tests, and genomic macrorestriction profile (PFGE).

RESULTS

The patients' age ranged from 11 months to 70 years. The mean duration of diarrhea was 4.7 days. All patients but one had abdominal cramps, seven of nine reported hemorrhagic stools and six had fever. Three patients were affected of haematologycal neoplasia and two of them developed hemolytic-uremic syndrome as a complication. All strains produced VT2 and two of them also produced VT1. Epidemiological link between patients has not been established. Three different biotypes had been distinguished between the nine isolated strains. All but two had different macrorestriction profiles.

DISCUSSION

The results obtained showed that clinical manifestations are rather inespecific, including fever (6/9 patients) and there is high association of severe complications. The heterogeneity in PFGE results obtained confirms that the cases are not related.

[Hemolytic-uremic syndrome caused by Escherichia coli O157:H7. Detection in direct sample of verotoxin-coding genes]

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.

Detection of human papillomavirus 16 and 18 DNA in epithelial lesions of the lower genital tract by in situ hybridization and polymerase chain reaction: cervical scrapes are not substitutes for biopsies

Human papillomavirus (HPV) types 16 and 18 in 66 women with histologically documented lesions of the genital tract and 64 control cohorts were investigated. The efficacies of in situ hybridization and polymerase chain reaction (PCR) in detecting HPV 16 and 18 DNA were analyzed. In order to assess the usefulness of replacing biopsies with cervical scrapes, the two samples were compared by PCR. The prevalence rates of HPV infection by PCR were 59.1 and 10.9% in patients and controls, respectively. PCR was three times more sensitive than in situ hybridization (52.6 versus 17.8%). However, the need to improve PCR sensitivity by subsequent dot blot hybridization reduced one of the main advantages of PCR, i.e., expeditious diagnosis. Cervical scrapes were less sensitive than biopsies (13.6 versus 53%), although with four (6.1%) patients with intraepithelial neoplasias, HPV DNA was identified only by means of cervical scraping. We conclude that obtaining biopsy specimens and cervical scraping are complementary sampling procedures.

[Detection of early cytomegalovirus antigen in cell culture]

The reference technique for the diagnosis of active cytomegalovirus infection is the isolation in cellular culture. Its major drawback is the interval between the inoculation of the sample and the development of the characteristic cytopathic effect. Occasionally, this delay may be longer than four weeks. The centrifugation of the sample on the cell monolayer at the time of inoculation and the use of a fluorescein-labeled monoclonal antibody for the detection of the early antigen in cells may considerable reduce the time required for the diagnosis of cytomegalovirus infection. In the present study the technique of detection of the early antigen by immunofluorescence was compared with conventional cell culture in 258 clinical samples referred to the laboratory for study. Fifty-one of them were positive: 28 with both techniques, 12 only with cell culture and 11 only with immunofluorescence. The mean time to obtain positive results was 25 hours for immunofluorescence and 13 days for culture.