This study investigated the identification and antimicrobial susceptibility testing of Salmonella isolates in Northern Ireland during 2001–2003. All six participating hospital laboratories used similar methods. Identification and antimicrobial resistance of human enteric (n=897) Salmonella isolates were analysed by retrospective collation of laboratory records. Resistance of human Salmonella isolates to nalidixic acid was 16% but resistance to ciprofloxacin or cefotaxime was rare (<1%). Minor inter-laboratory variations in sensitivity testing practices make it difficult to compare antimicrobial sensitivity results reliably and also to monitor for epidemic clones such as S. Typhimurium DT104 with the ACSSuT resistance pattern. The outcome of this study was the adoption of a standardized regional approach to the isolation of salmonella antimicrobial resistance. This should improve epidemiological monitoring of epidemic clones and assure optimum treatment options are available. In cases of treatment failure, MICs to third-generation cephalosporins and ciprofloxacin should be determined.

To evaluate the epidemiology of hospital admissions for varicella in children, a 1-year prospective multicentre study was done in Northern France in the pre-varicella vaccine era. The 405 children aged <16 years seen at local hospitals for varicella or herpes zoster were included. Among them, 143 who had varicella and resided in the district were admitted. Admission incidence rates were 28/100000 children aged <16 years (149/100000 infants aged <1 year, 69/100000 children aged 1–4 years, and 2/100000 children aged 5–15 years). Most admissions (57%) were related to complications, usually skin infection (47%). Independent risk factors for admission were place of residence outside the district [adjusted odds ratio (aOR) 8·7], complication at admission (aOR 5·8), recurrent fever (aOR 4·5), recent varicella in a sibling (aOR 4·0), and previous physician visit for the same condition (aOR 2·0).

We used Western Australian emergency department data linked to hospital morbidity, death and microbiology data to describe the bacteriology of pneumonia according to age. The ‘atypical’ organisms and viruses were not assessed. A total of 6908 patients over a 3-year period were given an emergency department diagnosis of pneumonia, 76·9% were admitted and 6·3% died in hospital. Blood was cultured from 52·9% of patients with 6·4% growing potential pathogens. Streptococcus pneumoniae was the most common organism isolated and accounted for 92% of pathogens in those aged <15 years. Isolation of Enterobacteriaceae species tended to increase with age and accounted for around 25% of isolates from the elderly. Sputum was cultured from 25·3% of patients and bacteria were isolated from 30·3% of samples, commonly Haemophilus influenzae and S. pneumoniae. Isolates from sputum showed no distinct trend across age groups. These patterns question the value of routine blood and sputum cultures and have implications for empiric therapy for the elderly.

A series of transmission studies was conducted to investigate the aetiology, or aetiologies, of emerging fatal epidemic disease syndromes affecting the common frog (Rana temporaria) in Britain. The syndromes, characterized by skin ulceration or systemic haemorrhages, were induced upon exposure to lesion homogenates or cultured ranavirus. The re-isolation of ranavirus from experimentally affected frogs fulfilled Koch's postulates. Aeromonas hydrophila, previously associated with similar lesions, was not significant to disease development. Unexpectedly, disease outcomes were influenced by both the source of agent and the route of exposure, indicating that different ranaviruses with different tissue tropisms and pathogeneses (possibly similar to quasi-species in RNA virus populations) are circulating in the British common frog population. Our findings confirm that ranavirus disease has emerged as an important cause of amphibian mortality in Britain.

Acute respiratory infections (ARIs) are the most important infectious cause of death, but there is less information of their burden in the community. This study describes the burden of ARI in a cohort of 50 Iranian families visited weekly over 2 months. Eighty-one out of 113 (72%) children and 29/103 (28%) adults had a total of 124 episodes of ARI. Seventy-five per cent of the episodes occurring in children were primary/co-primary compared to 40% of those in adults (P<0·01). Children were more likely to be the first symptomatic cases and infections were frequently transmitted within the family. Frequencies were lowest among adults, low among infants aged <6 months and highest among children aged <5 years (P<0·01). Winter episodes occurred more frequently in January (P<0·01). The high frequency and apparent transmissibility of ARI in this cohort highlights its enormous burden in the community.

With reports of hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) continuing to increase and therapeutic options decrease, infection control methods are of increasing importance. Here we investigate the relationship between surveillance and infection control. Surveillance plays two roles with respect to control: it allows detection of infected/colonized individuals necessary for their removal from the general population, and it allows quantification of control success. We develop a stochastic model of MRSA transmission dynamics exploring the effects of two screening strategies in an epidemic setting: random and on admission. We consider both hospital and community populations and include control and surveillance in a single framework. Random screening was more efficient at hospital surveillance and allowed nosocomial control, which also prevented epidemic behaviour in the community. Therefore, random screening was the more effective control strategy for both the hospital and community populations in this setting. Surveillance strategies have significant impact on both ascertainment of infection prevalence and its control.

During investigations of epidemic frog mortality in Britain, a novel fatal systemic haemorrhagic disease of common toads was discovered. This disease resembles a systemic haemorrhagic disease of common frogs in Britain, which is one of a range of fatal disease syndromes, characterized by systemic haemorrhages, skin ulceration or a combination of these lesions, caused by ranavirus infection. Ranavirus previously isolated from diseased toads was inoculated into common frogs to evaluate if this virus could infect and cause disease in common frogs. All virus-inoculated frogs died with systemic haemorrhages between 6 and 8 days post-inoculation, giving similar results to those produced by the inoculation of frogs with ranavirus cultured from naturally diseased frogs. These results indicate that the same, or similar, viruses are affecting both frogs and toads in the field and confirm that ranavirus has emerged as an important cause of amphibian mortality in Britain.

Reduction of the antioxidant capacity of plasma has been linked with the impairment of an effective immune response and so we hypothesized that the carriage rate of Neisseria meningitidis in asymptomatic subjects might correlate with the levels of antioxidants in plasma. To this end we took pharyngeal swabs from 339 children in Marquesado Basic Health Zone, Granada, Spain and in addition determined the total antioxidant capacity (TAC) in plasma samples from these subjects. The overall prevalence of N. meningitidis carriage was 5·9% (mean age 7·1 years) with rates of 10·3% in children aged ⩽3 years, 3·9% between 4 and 7 years and 2·4% in older subjects. Plasma TAC for the ⩽3-year-olds was 0·13 for carriers and 1·10 for non-carrier controls (P=0·04), 0·13 for carriers aged 4–7 years (controls 0·63) and 0·28 for carriers aged >7 years (controls 0·52). We analysed the association between TAC in plasma (<0·37 – 2 s.d.) and the carrier state of N. meningitidis. In the carrier state, the odds ratio for this association (TAC in plasma <0·25) was 8·44 (95% CI 1·5–48·9). These findings may suggest a reduced immune response in the host favourable to nasopharyngeal persistence of meningococci.

Thirty-five isolates of Shigella sonnei from patients with diarrhoea in three geographic regions of Argentina were examined for genetic diversity by pulsed-field gel electrophoresis (PFGE) and plasmid profile. PFGE of XbaI and BlnI DNA digests confirmed the occurrence of outbreaks in two regions caused by two separate predominant clones of S. sonnei. The third region was characterized by three circulating clones, one of which was possibly associated with an outbreak. Similar plasmids were found in distinct clones and in one outbreak clone five different plasmid profiles were identified. Antimicrobial resistance of the isolates varied from fully susceptible to the agents tested, to resistance to cotrimoxazole, ampicillin and ciprofloxacin. Antibiotic resistance did not correlate with plasmid content. This information will form the basis for active surveillance of shigellosis in Argentina and elsewhere in the region through the PulseNet International Network.

Self-report of polysaccharide pneumococcal vaccination is not thought reliable because of the increased risk of adverse events from inadvertent re-vaccination in elderly people. Some studies suggest a high sensitivity of self-report and hence a low risk of adverse events if vaccination is administered when medical records are unavailable. Self-report of pneumococcal and influenza vaccination in a sample of >64-year-olds in the United Kingdom was compared with information in their medical records. Self-report of pneumococcal vaccination, in contrast to some of the other studies had a low sensitivity. The findings here support the need for accurate knowledge of prior vaccine status before offering the polysaccharide pneumococcal vaccine. The study also confirms that self-report of influenza vaccination could be relied upon if rapid knowledge of uptake is required.

Blood culture-based diagnosis can only detect a fraction of the total burden of Salmonella enterica subsp. enterica serovar Typhi. The objective of the study was to detect additional typhoid fever cases through serological tests. A total of 1732 prolonged fever episodes were evaluated using three serological tests, Widal, Tubex® and Typhidot-M® in a typhoid fever endemic area of southern China. A case definition which included a positive Widal test (TO⩾80 & TH>A), a positive Tubex® test (⩾4) and a positive Typhidot-M® test, increased the detection of cases by more than twofold from 13 to 28 cases. The case definition has a specificity of 100% and a sensitivity of 39%. Case definitions based on combinations of serological tests can detect additional typhoid fever cases with higher specificity than a single serological test. Improved case detection is essential to understand the true disease burden and can help to boost the power of intervention trials.

The prevalence of metallo-β-lactamase (MBL) production among Pseudomonas aeruginosa nosocomial isolates from a Brazilian teaching hospital was determined. A total of 512 P. aeruginosa isolates were recovered from 245 patients during a 10-month period. Ninety-four (38·4%, 95% CI 32·2–44·8%) isolates were MBL producers. Most resistance to β-lactams was mediated by MBL. Forty-one (16·7%) were resistant to all drugs except polymyxin B and 33 (80·5%) of these were MBL producers. Clonal dissemination, documented by DNA macrorestriction, played a major role for the spread of MBL isolates. The blaSPM-1 gene was demonstrated by PCR in 14 randomly selected MBL isolates. The extremely high prevalence of MBL production found challenges the choice of therapeutics for P. aeruginosa, and measures to control horizontal dissemination of MBL producers are urgently required.

To enhance the detection of bacterial meningitis in an East Asian surveillance study, we employed cerebrospinal fluid (CSF) bacterial culture, latex agglutination (LA) and polymerase chain reaction–enzyme immunoassay (PCR–EIA) testing for Haemophilus influenzae type b (Hib) and Streptococcus pneumoniae (Sp). The sensitivity and specificity of CSF PCR–EIA testing was compared to LA and culture. A meningitis case was defined by one positive result for any of the three tests. The sensitivity of H. influenzae CSF PCR–EIA, LA, and culture was 100%, 40% and 57·5% respectively; and for Sp CSF PCR–EIA, LA and culture, the sensitivity was 100%, 58·3% and 66·7%, respectively. Hib and Sp specificity was 100% by each method. CSF PCR–EIA was more sensitive than culture or LA for the detection of Hib and Sp meningitis cases increasing their incidence by 74% and 50% compared to culture respectively. CSF PCR–EIA should be included for the detection of bacterial meningitis in surveillance studies.

Estimates of hepatitis C virus (HCV) clearance following acute infection range from 14 to 46%. This wide range is likely to be due to the characteristics of the populations studied and analysis methods. This paper examines how differing definitions of clearance parameters affect estimates of viral clearance in a cohort of 85 injecting drug users with newly acquired HCV infection. Kaplan–Meier estimates of time to HCV clearance were determined using varying definitions of eligible cohort, viral clearance, date of infection and date of clearance. Based on which combinations of definitions were used, the number of subjects eligible for analysis ranged from 27 to 75, clearance rate ranged from 14 to 68% and time to achieving 25% clearance ranged from approximately 5 months to 14 months. Standardized definitions and methodologies are required to enable valid comparisons of rates of clearance across newly acquired HCV infection natural history studies.

The objective of this case-control study was to identify the main risk factors for community-acquired pneumonia (CAP) in a German adult population. A self-administered questionnaire was given to CAP cases provided by the German competence network CAPNETZ and population-based, randomly selected controls (sex- and age-matched). Multivariate analysis showed that in addition to known risk factors such as previous CAP [odds ratio (OR) 1·6, 95% confidence interval (CI) 1·3–2·1], more than one respiratory infection during the previous year (OR 3·6, 95% CI 2·9–4·5), chronic pulmonary diseases (OR 2·3, 95% CI 1·7–3·0), number of comorbidities (OR 1·6, 95% CI 1·4–1·9), and number of children in the household (2 children: OR 2·2, 95% CI 1·5–3·4; ⩾3 children: OR 3·2, 95% CI 1·5–7·0) were independent risk factors for CAP. This was pronounced in particular in people aged ⩽65 years. The most likely explanation for this finding is higher exposure to infectious agents.

Enhanced surveillance for Hib infection, initially covering Wales and five English regions, began in 1990 and in 1995 was extended to the whole of England and Wales. To determine whether changes in the ascertainment of Haemophilus influenzae may have affected estimates of Hib disease incidence, data from January 1990 to December 2003 were analysed. A total of 8887 and 4020 (45%) cases of H. influenzae and Hib respectively were reported. The proportion of isolates that were serotyped increased over time, and therefore reported incidence may have underestimated the true incidence in the early years of the study. Adjusting for this under-ascertainment, the incidence in children aged <5 years declined from a peak of 28·3/100 000 in 1991 to 0·97/100 000 in 1998 and increased to 3·8/100 000 in 2003. Following the implementation of universal vaccination a dramatic decline in the true incidence of invasive Hib disease occurred. The observation of the subsequent resurgence was real but the highest incidence reached was 85% below the corrected incidence in the pre-vaccine era. Continued high-quality surveillance is needed in order to accurately monitor and detect changes in disease incidence.

The aim of this study was to describe a systematic process of record-linkage, cross-validation, case-ascertainment and capture–recapture analysis to assess the quality of tuberculosis registers and to estimate the completeness of notification of incident tuberculosis cases in The Netherlands in 1998. After record-linkage and cross-validation 1499 tuberculosis patients were identified, of whom 1298 were notified, resulting in an observed under-notification of 13·4%. After adjustment for possible imperfect record-linkage and remaining false-positive hospital cases observed under-notification was 7·3%. Log-linear capture–recapture analysis initially estimated a total number of 2053 (95% CI 1871–2443) tuberculosis cases, resulting in an estimated under-notification of 36·8%. After adjustment for possible imperfect record-linkage and remaining false-positive hospital cases various capture–recapture models estimated under-notification at 13·6%. One of the reasons for the higher than expected estimated under-notification in a country with a well-organized system of tuberculosis control might be that some tuberculosis cases, e.g. extrapulmonary tuberculosis, are managed by clinicians less familiar with notification of infectious diseases. This study demonstrates the possible impact of violation of assumptions underlying capture–recapture analysis, especially the perfect record-linkage, perfect positive predictive value and absent three-way interaction assumptions.

The distribution of three putative adhesin genes in 123 Shiga toxin-producing (STEC) strains was determined by PCR. The STEC strains were isolated from human patients (n=90) and food (n=33) and were characterized by serogroup, virulence markers (eae, stx1, stx2) and adherence factors (efa1, lpfAO157, saa) genes. Serogroups O157 (64·4%) and O26 (28·8%) were the most frequent among human strains and the majority (60·6%) of food strains were serologically non-typable. The adhesin genes efa1 (90%) and lpfAO157 (73·3%) were the most common in humans strains and saa (45·5%) in food strains. The presence of these genes in addition to eae in STEC from different sources may suggest a relevant role in their pathogenesis.

Salmonella enterica serotype Abortusovis, an ovine host-specific serotype, rare in most countries, is responsible for epidemic abortion episodes in Spain. With the aim of surveillance and detection of the spread of specific clones, 55 Abortusovis isolates collected during 1996–2001 from flocks in 11 provinces, were studied using XbaI–PFGE. Despite the fact that the strains were geographically and spatially related, PFGE demonstrated an epidemiologically acceptable discriminating power, identifying 20 clones (similarity, 52–96%). Clones Sabv6, 1, 5 were disseminated in seven, five and two areas respectively, while another 17 clones appeared in single places. Clones from nearby geographic regions showed a high relatedness (one band of difference in the PFGE profile) Sabv1-2-3, Sabv5-6, Sabv7-8, and Sabv13-14, suggesting a common ancestor. Co-isolation in the same flock (Sabv5-6, Sabv1-3, Sabv1-6) was detected. PFGE surveillance detected the predominance and widespread distribution of clone Sabv6 in 21 out of the 55 Abortusovis serotype episodes studied in Spain.

Several previous studies of necrotizing fasciitis (NF) have been single-institution investigations suffering from small samples sizes. This study of 216 NF patients hospitalized in Florida, USA, during 2001 was designed to identify risk factors for length of stay (LOS), total patient charges (TC), and mortality, using a statewide database. Robust gamma mixed regression was used to determine the predictors of LOS and TC while simultaneously accounting for outliers and the clustering of patients in 87 hospitals. Relative risks (RR) for hospital mortality were calculated using binomial regression. The NF hospitalization rate in Florida was 1·3/100 000. The median TC was US$54 533 and cumulative charges for all 216 patients were nearly US$20 million. Patients aged ⩾44 years at the time of admission were five times as likely to expire in the hospital than patients who were aged ⩽43 years (adjusted RR 5·08, P=0·03). Unexpectedly, diabetes was associated with a 61% reduction in the risk of hospital mortality (adjusted RR 0·39, P=0·04). Age ⩾44 years was the most powerful predictor of prolonged LOS, elevated TC, and an increased risk of hospital mortality in patients suffering from NF.