ARCHITECT Chagas® as a single test candidate for Chagas disease diagnosis: evaluation of two algorithms implemented in a non-endemic setting (Barcelona, Spain).

OBJECTIVES: To evaluate two algorithms for the diagnosis of chronic and congenital Chagas disease (CD), both including the chemiluminescent microparticle immunoassay ARCHITECT Chagas® (CMIA) as a single test but with an amended signal-to-cut-off ratio (S/CO) of ≥6, instead of an S/CO of ≥1 as indicated by the manufacturer. METHODS: The study encompassed two panels of retrospective samples: 831 sera from 786 adolescents and adults (panel A), and 96 sera from 35 newborn infants with CD-infected mothers (panel B). A CMIA-negative result was deemed conclusive, whereas samples with an S/CO ≥ 0.8 were confirmed by a second test (BioELISA Chagas, ELISAr). RESULTS: In panel A, seropositivity was 13% (102/786); 10 samples gave discordant results for CMIA and ELISAr, all of which were CMIA positive and had CD confirmed through a previous diagnosis by two positive serological tests. In panel B, all newborns were considered non-infected based on both a progressive decrease in antibody titres over time and negative real-time PCR results. CMIA still gave positive results in two infants aged 10 months but no S/CO values ≥6 were observed from 4 months on. CONCLUSIONS: CMIA is a firm candidate for use as a single CD diagnostic test in non-endemic countries. The algorithm with the ≥6 S/CO is as an efficient method for chronic CD diagnosis. CMIA could also be used as a single test to screen infants for congenital infection at the age of 10 months or even earlier if applying the corrected cut-off ratio, although further studies are required.

[Waterborne outbreak of gastroenteritis caused by Norovirus transmitted through drinking water]. / Brote de gastroenteritis por Norovirus causado por el consumo de agua de suministro público.

BACKGROUND: The aim of this study was to conduct an investigation into an outbreak of waterborne disease caused by Norovirus due to the consumption of contaminated drinking water. METHODS: The first week after the school summer holidays we detected an outbreak of gastroenteritis at a school in Borges Blanques (Lleida, Spain). A retrospective cohort study was carried out to investigate: water consumption and food (six items). We assessed RNA Norovirus by RT-PCR in 6 stool samples. The risk of gastroenteritis was assessed by applying adjusted risk ratio (RRa) analysis at 95% confidence intervals (CI). RESULTS: The overall attack rate was 45% (96/213). The main symptoms were: abdominal pain, 88.4% (84/95); nausea, 65.9% (62/94), and vomiting, 64.6% (62/96). The consumption of school drinking water was statistically associated with the disease (RRa: 2.8; 95% CI: 1.3-6.2). The school water tank was dirty, but this drinking water was qualified as potable. Six stool samples gave positive results for Norovirus. CONCLUSIONS: Norovirus caused this waterborne outbreak of gastroenteritis transmitted through treated drinking water. It should be obligatory to regularly clean school drinking water deposit tanks, especially after the summer holidays.

An outbreak of food poisoning due to a genogroup I norovirus.

Norovirus infection is associated with approximately 90% of epidemic non-bacterial acute gastroenteritis. The objective of this study is to describe an outbreak of norovirus genogroup I gastroenteritis which affected workers in a hospital and was attributed to food prepared by an infected food handler. Forty cases were detected, of whom 80% were interviewed. The index case was the cook employed in the hospital cafeteria. The following symptoms were observed: abdominal pain in 90.6%, vomiting in 71.9%, diarrhoea in 71.9%, general indisposition in 62.5%, headaches in 53.1% and fever in 32.4% of cases. The initial symptoms were abdominal pain in 37% and vomiting in 28%. Of the 14 samples analysed by RT-PCR, 12 (86%) were positive for a genogroup I norovirus. After sequencing the strain was identified as genotype Desert Shield. Many of the foodstuffs consumed were made by hand, favouring transmission from the index case to the cafeteria users.

Molecular epidemiology of caliciviruses causing outbreaks and sporadic cases of acute gastroenteritis in Spain.

The molecular epidemiology of human caliciviruses (HuCVs) causing sporadic cases and outbreaks of acute gastroenteritis around eastern Spain (Catalonia and the Valencian Community) was studied by reverse transcription-PCR (RT-PCR) and by sequencing part of the RNA polymerase gene in open reading frame 1. HuCVs were detected in 44 of 310 stool specimens (14.19%) negative for other enteric pathogens obtained from children with acute gastroenteritis. Norwalk-like viruses (NLVs) were the most common cause of the gastroenteritis outbreaks investigated here. They were detected in 14 out of 25 (56%) outbreaks with an identified pathogen. Genotypes producing both sporadic cases and outbreaks were diverse, with a predominance of GGII strains related to genotypes Melksham and Lordsdale. Five strains clustered with a "new variant" designated GGIIb, which was detected circulating throughout quite a few European countries in the years 2000 and 2001. The emergence mechanism of these strains might be the occurrence of intertypic recombinations between different viruses. The nucleotide sequence of part of the capsid gene (ORF2) from three of these strains demonstrated their relationship with Mexico virus.

Antibiotic resistance trends in enteropathogenic bacteria isolated in 1985-1987 and 1995-1998 in Barcelona.

Trends in resistance to antimicrobial agents used for therapy have been evaluated with 3,797 enteropathogenic bacteria, Campylobacter, Salmonella, Shigella, and Yersinia, between 1985-1987 and 1995-1998. The greater increase in the rate of resistance was observed in Campylobacter jejuni for quinolones (from 1 to 82%) and tetracycline (from 23 to 72%) and in gastroenteric salmonellae for ampicillin (from 8 to 44%), chloramphenicol (from 1.7 to 26%), and trimethoprim-sulfamethoxazole and nalidixic acid (from less than 0.5 to 11%). Multidrug resistance was detected in several Salmonella serotypes. In the 1995-1998 period, 76% of Shigella strains were resistant to trimethoprim-sulfamethoxazole, 43% were resistant to ampicillin, and 39% were resistant to chloramphenicol. Seventy-two percent of Yersinia enterocolitica O3 strains were resistant to streptomycin, 45% were resistant to sulfonamides, 28% were resistant to trimethoprim-sulfamethoxazole, and 20% were resistant to chloramphenicol.

Emergence and dissemination of quinolone-resistant Escherichia coli in the community.

We studied the evolution of resistance to quinolones in Escherichia coli from 1992 to 1997 in Barcelona, Spain. An increasing proportion of quinolone-resistant E. coli (QREC) infections was observed. QREC strains were more common in patients with nosocomial infections but also increased in patients with community-acquired infections (9% in 1992 to 17% in 1996). Seventy (12%) of 572 episodes of E. coli bacteremia were due to QREC. Factors significantly associated with QREC bacteremia were the presence of underlying disease, recent exposure to antibiotics, and bacteremia of unknown origin. In the multivariate analysis, only prior exposure to antimicrobial agents (P < 0.001; odds ratio [OR] = 2), specifically, to quinolones (P < 0. 001; OR = 14), and the presence of a urinary catheter (P < 0.001; OR = 2) were significantly associated with QREC bacteremia. Among 16 QREC isolates from cultures of blood of community origin selected at random, 13 different pulsed-field gel electrophoresis patterns were recognized, showing the genetic diversity of these isolates and in turn indicating the independent emergence of QREC in the community. The prevalence of QREC in the feces of healthy people was unexpectedly high (24% in adults and 26% in children). A survey of the prevalence of QREC of avian and porcine origin revealed a very high proportion of QREC in animal feces (up to 90% of chickens harbored QREC). The high prevalence of QREC in the stools of healthy humans in our area could be linked to the high prevalence of resistant isolates in poultry and pork.

[Etiology of enteritis in a university general hospital in Barcelona (1992-1995)]. / Etiología de la enteritis en un hospital general universitario en 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.

Epidemiology of an unusually prolonged outbreak of typhoid fever in Terrassa, Spain.

An unusually prolonged outbreak of typhoid fever, from 1988 to 1994, in Terrassa (Barcelona, Spain), was caused by a casual food handler who was a carrier. The pattern of this outbreak suggested intermittent low-level exposure to Salmonella typhi. We found 70 patients with S. typhi infections, 52 of whom were available for study. Medical records were reviewed and patients were interviewed with use of a standard questionnaire. Phage typing and pulsed-field gel electrophoresis (PFGE) for strain subtyping were used to confirm the epidemiological data. The 27 outbreak strains shared the same phage type and the same PFGE pattern. Four sporadic strains shared the same phage type as the outbreak strain. PFGE was found to be useful for differentiating strains for epidemiological purposes.

Molecular typing of Salmonella enterica serovar typhi.

The efficiencies of different tests for epidemiological markers--phage typing, ribotyping, IS200 typing, and pulsed-field gel electrophoresis (PFGE)--were evaluated for strains from sporadic cases of typhoid fever and a well-defined outbreak. Ribotyping and PFGE proved to be the most discriminating. Both detected two different patterns among outbreak-associated strains.

[Hemorrhagic colitis caused by verotoxigenic Escherichia coli. Presentation of 9 cases]. / Colitis hemorrágica por Escherichia coli verotoxigénica. Presentación de 9 casos.

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.

[Enteroinvasive Escherichia coli. Pathogenesis and epidemiology]. / Escherichia coli enteroinvasiva. Patogenia y epidemiología.

Enteroinvasive Escherichia coli (EIEC) is an intestinal pathogen causing enteritis, with a similar pathogenic mechanism to that of Shigella, which causes an epithelial invasion of the large bowel leading to inflammation and ulceration of the mucosa. The patients often develop the symptoms of bacillary dysentery. The EIEC strains are atypical in their biochemical reactions and may ferment lactose late or not at all, are lysine decarboxilase negative, and non motile. In addition, most EIEC strains express somatic antigens which are either strongly related or identical to Shigella antigens. EIEC invasion is mediated by a large plasmid (140 MDa) coding for the production of several outer membrane proteins involved in invasiveness. These strains have been isolated with some regularity in South America, the Extreme Orient, and Eastern Europe. In Spain the incidence of enteroinvasive E. coli is extraordinarily low (0.2%), the serogroup O124 being the most frequently isolated. EIEC enteritis has been associated to sporadic cases occurring in travellers. Occasional outbreaks related to ingestion of contaminated water or food and person to person have been reported.

[Epidemic outbreak of shigellosis following water intake]. / Brote epidémico de shigelosis por ingesta de agua.

BACKGROUND: To describe the clinical, epidemiologic and microbiologic characteristics of an outbreak of shigellosis. METHODS: Twenty-six patients affected by shigellosis were studied. Upon identification of the outbreak, a questionnaire was carried out in relatives to determine the attack-rate. Studies of the isolated strains included biotype, antibiotype, and in 8 selected strains, plasmid and ribotyping profile. RESULTS: From September 23 to October 21 1991, 26 patients (42% males, 54% under the age of 14 years), 23 of whom drunk water from two nearby fountains were attended for acute gastroenteritis and positive stool culture with isolation of Shigella sonnei strains with identical biochemical pattern and sensitivity. Only 2 required hospital admission and all recovered well. Forty-five percent of the 80 individuals who had drunk water from the fountains were affected. The attack-rate was higher in children (67%) than in adults (27%) (p < 0.001). The plasmid profile was identical in the strains studied. The only discriminative endonuclease used for the ribotyping was Sal I, which allowed the strains corresponding to the outbreak to be differentiated from those used as controls. CONCLUSIONS: An outbreak of shigellosis due to water ingestion is herein reported. The usefulness of plasmid profile as an epidemiologic marker of Shigella is confirmed. Only one of the four enzymes used for the ribotyping was discriminative. A greater susceptibility to infection was observed in children.

[Application of molecular epidemiology techniques in the study of food poisoning caused by Staphylococcus aureus]. / Aplicación de las técnicas de epidemiología molecular en el estudio de una toxiinfección alimentaria por Staphylococcus aureus.

BACKGROUND: The use of molecular epidemiology techniques has provided better knowledge as to the clonal organization of bacterian populations and thus allows better follow up of epidemics. An alimentary toxiinfection in a Barcelona school produced by Staphylococcus aureus was analyzed by the combination of epidemiologic, phenotype and genotype markers with the aim of determining the source of the alimentary contamination. METHODS: Nine strains of Staphylococcus aureus isolated in 6 food manipulators and 3 patients were studied with the following markers: biotype, antibiotype, phagotype, plasmid profile, polymorphism of the size of the restriction fragments of total DNA and ribotype. RESULTS: Epidemiologic study of the strains analyzed showed that both the phenotype markers and the plasmid profile are thecniques of little discriminatory value. The only clearly discriminatory technique used was ribotyping which defined 3 clones in the 9 strains of Staphylococcus aureus studied. CONCLUSIONS: Molecular study of isolated strains of Staphylococcus aureus was able to identify the causal origin of the alimentary toxiinfection in one of the 6 food manipulators studied.

A comparative study of ribotyping and arbitrarily primed polymerase chain reaction for investigation of hospital outbreaks of Acinetobacter baumannii infection.

Arbitrarily primed polymerase chain reaction (AP-PCR) and ribotyping were compared in an investigation of an outbreak of Acinetobacter baumannii infections. Twenty-five clinical isolates shown previously by other criteria to belong to two different groups, and nine randomly selected A. baumannii clinical isolates from other hospitals were investigated. Among the strains analysed, nine different EcoRI rRNA gene restriction pattern fingerprints were observed. While similarity was detected between strains of the same group, these fingerprints differed clearly between the two A. baumannii groups defined in the outbreak. Two of the nine strains selected randomly had the same ribotype as those strains involved in the outbreak, whereas the remaining seven strains each had a different ribotype. When the strains were tested by AP-PCR with 0.25, 0.5 or 1 microM of M13 forward primer, 10 different profiles were obtained. However, 11 profiles were observed if two different primer concentrations (0.25 and 1 microM) were used. It was concluded that ribotyping and AP-PCR exhibited a similar discriminatory power, although AP-PCR had the additional advantages of speed and simplicity.

[Sensitivity of enteropathogenic bacteria to furazolidone]. / Sensibilidad de las bacterias enteropatógenas a furazolidona.

The sensitivity in vitro of 348 strains of 18 enteropathogen agents to furazolidone was investigated during the period of 1987-1989. All strains of Shigella sonnei (17), S. flexneri (17), S. boydii (16), Escherichia coli enteropathogen (40), E. coli enteroinvasive (20), Campylobacter jejuni (50), Vibrio cholerae 01 (5), Vibrio cholerae non 01 (5), V. parahaemolyticus (5), V. alginolyticus (2), Aeromonas hydrophila (5), A. caviae (5), A. sobria (5), and Plesiomonas shigelloides (12) were sensitive (MIC < or = 8 mg/l), except a strains of E. coli enteropathogen (MIC 16 mg/l). The 15.5% of the 51 strains of Salmonella enterica belonging to the type I isolated between 1987 and 1989 were resistant (MIC > or = 16 mg/l). A similar degree of resistance was observed in 20 strains of this agent isolated between 1978 and 1980. The 30 strains of Yersinia (including 15 strains of Y. enterocolitica 03) presented extreme values of MICs of 8 and 16 mg/l.