Verocytotoxin Escherichia coli-Associated Haemolytic Uraemic Syndrome.

Aims To describe laboratory data on clinical human Verotoxigenic E. coli (VTEC) strains causing haemolytic uraemic syndrome (HUS) and to characterise the VTEC strains, thus contributing to risk mitigation to decrease HUS incidence in Ireland. Methods Laboratory characterisation was performed on isolates from 52 VTEC-associated HUS cases identified in the National clinical VTEC Reference Laboratory (NRL-VTEC) for the years 2012-2014. Data were analysed with respect to age, gender, serogroup and verotoxin type and subtype. Results 52/83 (62.6%) culture positive HUS cases were identified from laboratory data; 30 (57.7%) cases occurred in females. Seven HUS-associated serogroups and eleven patterns of verotoxin subtypes are described. Conclusion Ireland has the highest incidence of VTEC infection in Europe and a variety of VTEC serogroups causing clinical infection, suggesting any viable VTEC may potentially cause HUS. A broad diagnostic approach, to detect uncommon serotypes, should be considered when analysing clinical and food samples for VTEC.

Molecular characterization of Irish E. coli O157:H7 isolates of human, bovine, ovine and porcine origin.

AIMS: To determine the degree of relatedness between isolates of Escherichia coli O157:H7 of human, bovine, ovine and porcine origin. METHODS AND RESULTS: Escherichia coli O157:H7 isolates were compared using (i) PFGE XbaI patterns, (ii) PCR profiles of virulence genes and (iii) the DNA sequences of genes reported to play a role in pathogenicity. The 77 E. coli O157:H7 isolates demonstrated 49 different PFGE patterns of which, eight were common to multiple isolates, and the remaining 41 were distinct. Isolates of different origin did not correlate, except for one cluster consisting of two human and two beef isolates. The majority of animal isolates had the same PCR profiles of virulence genes as those isolated from clinical patients. Single nucleotide polymorphisms (SNPs) were identified in the sequence of a 255-bp region of the vtx2 subunit A gene. CONCLUSIONS: Six SNPs were detected in the vtx2A gene, defining four different haplotypes. One nonsynonymous substitution encoded for an amino acid change from glutamic to aspartic acid. SIGNIFICANCE AND IMPACT OF THE STUDY: Results indicate that although E. coli O157:H7 isolates of differing origin were distinct by PFGE, the DNA sequences of the main virulence genes associated with human clinical illness were conserved.

The impact of blood culture reporting and clinical liaison on the empiric treatment of bacteraemia.

AIMS: To assess the impact of blood culture results and early clinical liaison on the treatment of patients with bacteraemia. METHODS: 123 patients with significant positive blood cultures were followed over a nine month period in a 620 bed teaching hospital. The impact of early blood culture reporting and clinical liaison on the cost and appropriateness of treatment was assessed. RESULTS: Empiric treatment was started before the Gram stain result in 107 (87%) patients. Treatment was altered on the basis of the Gram stain result in 39 (36%) of these patients, and on culture and sensitivity results in 53 (50%). The spectrum of antibiotic treatment was narrowed in 58 (54%) of these; 20 (19%) on Gram stain result alone. This resulted in a 42% reduction in daily antibiotic costs in patients who had received empiric treatment. Empiric treatment did not follow the hospital antibiotic policy in 49 (46%) of the patients treated. In patients where empiric treatment was not in accordance with hospital policy, 21 (44%) had an isolate resistant to the empiric treatment used; while in patients who received agents in accordance with hospital policy only one (1.7%) had a resistant isolate (p < 0.05). Patients who died (11 (9%)) were less likely to have received empiric treatment in accordance with the antibiotic policy, although this did not reach statistical significance (p = 0.1). CONCLUSION: Early reporting of Gram stain results from blood cultures, combined with early clinical liaison, results in more rational and cost effective treatment.

Experience with Enterobacter bacteraemia in a Dublin teaching hospital.

In a review of Enterobacter bacteraemia in a 600-bedded teaching hospital, 22 episodes were identified in 20 patients over a 2-year period. An evaluation of risk factors suggested an association between Enterobacter infection and the presence of central venous catheters or use of H-2 receptor antagonists. These factors together with previous exposure of the patient to gentamicin, and prolonged stay in the intensive care unit, increased the likelihood of gentamicin-resistant Enterobacter bacteraemia. This finding has implications for the choice of antibiotic regimen in the empirical treatment of suspected Gram-negative septicaemia.

Investigation of an outbreak of gastroenteritis caused by Norwalk-like virus, using solid phase immune electron microscopy.

In February 1993, 95 persons (47 patients and 48 staff members) were affected by an hospital outbreak of viral gastroenteritis. Using direct electron microscopy (EM) the causative agent was identified as a small round structured virus. This was confirmed as a Norwalk-like virus using solid phase immune electron microscopy (SPIEM). Of 94 stool samples examined, 12 (13%) samples containing small round structured viruses (SRSV) were SPIEM positive for Norwalk-like virus. A further 25 (27%) samples contained small round featureless virus (SRFV) identified by direct EM and were negative on SPIEM. The illness was characterized by preceding influenza-like symptoms in 76% of cases followed by vomiting (76%), diarrhoea (79%) and abdominal pain (79%). One fatality was recorded. The outbreak lasted for 15 days, with a peak incidence of new cases amongst patients and staff occurring on day 5. It was controlled through a combination of ward closures, patient cohorting, suspension of duties for affected staff and disinfection procedures. Difficulties were encountered in the education of staff and in the implementation of environmental control measures. Screening of hospital catering services and a case control study, carried out among affected staff members, failed to identify a foodborne source. Consumption of tap water in the hospital was commoner among affected staff members than among controls, but this did not reach significance (P = 0.1).

Community and hospital acquired Staphylococcus aureus septicaemia: 115 cases from a Dublin teaching hospital.

Despite advances in diagnostic techniques and antimicrobials, septicaemia due to Staphylococcus aureus remains a common clinical problem with a significant mortality. We retrospectively compared community and hospital acquired cases of S. aureus septicaemia occurring in our 600 bed teaching hospital over a 30 month period. Of 110 episodes 32 (29%) were community acquired and 78 (71%) hospital acquired. A likely primary source was identified in 14 (44%) of community acquired cases and in 73 (94%) of hospital acquired cases. A secondary focus of infection was more common in community acquired cases (17, 53%) than hospital acquired cases (5, 6%). Mortality was significantly higher in community acquired cases (22% vs. 6%). An association was also found between the presence of endocarditis and increased mortality, although this did not reach significance. We also compared hospital acquired septicaemia due to methicillin sensitive and methicillin resistant S. aureus found a significantly higher mortality in the methicillin resistant group (22% vs. 3%, P < 0.05). S. aureus septicaemia remains an important cause of morbidity and mortality, particularly when associated with secondary foci of infection. This study also emphasises the importance of control of methicillin resistant strains in hospital.

Lower prevalence of anti-hepatitis C antibody in dialysis and renal transplant patients in Ireland.

It is well recognised that haemodialysis and renal transplant patients are at increased risk of developing non-A, non-B hepatitis. Recently the genome of hepatitis C virus (HCV), the major causative agent for non-A, non-B hepatitis, has been isolated. Anti-HCV seroprevalence was assessed in all haemodialysis patients (266) in Ireland who in March 1990 had been dialysed for at least 6 months. For comparative purposes, 272 patients who had functioning renal transplants for greater than 6 months were also studied. Potential risk factors such as age, number of blood transfusions and time on dialysis were evaluated. The prevalence of HCV infection as evidenced by antibody detection was only 1.1% for transplant and 1.7% for haemodialysis patients. This compares to a reported incidence of between 10% and 50% found elsewhere. Two of the 5 anti-HCV positive haemodialysis patients and 2 of the 3 transplant patients had biochemical evidence of liver disease. From stored sera it was possible to ascertain when patients acquired HCV. Whether the very low prevalence of anti-HCV in Irish patients is due to the low prevalence of the virus in the general population, the policy of non reimbursement of blood donors, genetic or other factors, remains to be determined.

Occurrence and characteristics of fastidious Campylobacteraceae species in porcine samples.

This study investigated the prevalence and characteristics of Campylobacteraceae including a range of fastidious species in porcine samples. Over a thirteen month period caecal contents (n=402) and pork carcass swabs (n=401) were collected from three pork abattoirs and pork products (n=399) were purchased at point of sale in the Republic of Ireland. Campylobacteraceae isolates were recovered by enrichment, membrane filtration and incubation in antibiotic free media under a modified atmosphere (3% O2, 5% H2, 10% CO2 and 82% N2). Campylobacteraceae isolates were identified as either genus Campylobacter or Arcobacter and then selected species were identified by Polymerase Chain Reaction (PCR). Campylobacteraceae were isolated from 103 (26%) caecal samples, 42 (10%) carcass swabs, and 59 (15%) pork products. Campylobacter coli was the most commonly isolated species found in (37%) all sample types but many fastidious species were also isolated including Campylobacter concisus (10%), Arcobacter butzleri (8%), Campylobacter helveticus (8%), Campylobacter mucosalis (6%), Arcobacter cryaerophilus (3%), Campylobacter fetus subsp. fetus (1%), Campylobacter jejuni subsp. jejuni (1%), Campylobacter lari (0.5%), Campylobacter curvus (0.5%) and Arcobacter skirrowii (0.5%). Among all isolates, 83% contained cadF and 98% flaA. In this study 35% of porcine C. coli were resistant to ciprofloxacin but none of the fastidious species demonstrated any resistance to this drug. The level of resistance to erythromycin was very high (up to 100%) in C. concisus and C. helveticus and this is a real concern as this is the current empiric drug of choice for treatment of severe gastroenteritic Campylobacter infections. The study shows that there is a much wider range of fastidious Campylobacteraceae present in porcine samples than previously assumed with C. concisus the second most common species isolated. The majority of fastidious Campylobacteraceae isolates obtained contained virulence genes and antibiotic resistance indicating potential public health significance.

A survey of antimicrobial susceptibility of clinical isolates of Enterococcus spp. from Irish hospitals.

Nosocomial enterococcal infections are increasing. In order to establish the species distribution and antibiotic resistance patterns of enterococci in clinical specimens from hospitalized patients, we undertook a survey of 23 Irish hospitals. One thousand and five viable enterococcal strains were studied. Nine different species of enterococci were identified, including Enterococcus faecalis (84%); Enterococcus faecium (9%); and Enterococcus hirae (3%). The most common sites of isolation were the urinary tract (66%), wound and soft tissues (23%) and blood stream (3%). Many of the isolates were multiply antibiotic resistant. Ampicillin resistance was detected in 16%. Neither beta-lactamase production, nor high level penicillin resistance was detected. High level gentamicin resistance was evident in 7% of isolates and varied among species, e.g. 4% E. faecalis, 24% E. faecium, and 34% E. hirae. A number of isolates (23%) were also highly resistant to streptomycin. No clinically significant glycopeptide resistance was detected. The species distribution and incidence of multiple resistance was geographically widespread. This emphasizes the need for detailed speciation and in-vitro susceptibility testing along with the evaluation of alternative combination chemotherapeutic regimens for the management of serious enterococcal infection.

Molecular genetic analysis of high-level gentamicin resistance in Enterococcus hirae.

High-level resistance to gentamicin was studied in seven clinical isolates of Enterococcus hirae. In common with other members of the genus Enterococcus, such resistance in E. hirae was associated with single, large, conjugative plasmids. Molecular genetic analysis revealed five distinct plasmid types amongst the seven isolates. The determinant mediating high-level gentamicin resistance in E. hirae was also shown to be homologous to that already characterized for other enterococcal species.

Outbreak of Vero cytotoxin-producing Escherichia coli O157 in a child day care facility.

In December 1998, an outbreak of Vero cytotoxin-producing Escherichia coli (VTEC) O157 in a crèche affected ten out of 45 children and one out of five staff members. Eight cases were symptomatic and three were asymptomatic. There were two asymptomatic adult family contacts of child cases. All specimens were identified as VTEC O157:H7, phage type 32. None of the cases were seriously ill and none developed haemolytic uraemic syndrome (HUS). One child continued to excrete the organism for 14 weeks. The origin of the outbreak was not found but epidemiological investigation was suggestive of person-to-person spread. All children and staff were screened and excluded from the crèche until microbiological clearance was obtained. An inspection of the crèche revealed overcrowding and inadequacies in cleaning and in the food preparation facilities. These problems were remedied before children were re-admitted to the crèche. This outbreak demonstrates the ease with which VTEC O157 can be transmitted between small children. Two specific features of this outbreak were notable: (1) the mild self-limiting nature of the illness and (2) the prolonged shedding of the bacterium by one child.