Fidelma Fitzpatrick

Four country healthcare associated infection prevalence survey 2006: overview of the results

A survey of adult patients was conducted in February 2006 to May 2006 in acute hospitals across England, Wales, Northern Ireland and the Republic of Ireland to estimate the prevalence of healthcare-associated infections (HCAIs). A total of 75 694 patients were surveyed; 5743 of these had HCAIs, giving a prevalence of 7.59% (95% confidence interval: 7.40-7.78). HCAI prevalence in England was 8.19%, in Wales 6.35%, in Northern Ireland 5.43% and in the Republic of Ireland 4.89%. The most common HCAI system infections were gastrointestinal (20.6% of all HCAI), urinary tract (19.9%), surgical site (14.5%), pneumonia (14.1%), skin and soft tissue (10.4%) and primary bloodstream (7.0%). Prevalence of MRSA was 1.15% with MRSA being the causative organism in 15.8% of all system infections. Prevalence of Clostridium difficile was 1.21%. This was the largest HCAI prevalence survey ever performed in the four countries. The methodology and organisation used is a template for future HCAI surveillance initiatives, nationally, locally or at unit level. Information obtained from this survey will contribute to the prioritisation of resources and help to inform Departments of Health, hospitals and other relevant bodies in the continuing effort to reduce HCAI.

Evidence for icaADBC-Independent Biofilm Development Mechanism in Methicillin-Resistant Staphylococcus aureus Clinical Isolates

ABSTRACT Synthesis of a polysaccharide adhesin by icaADBC-encoded enzymes is currently the best-understood mechanism of staphylococcal biofilm development. In four methicillin-resistant Staphylococcus aureus isolates, environmental activation of icaADBC did not always correlate with increased biofilm production. Moreover, glucose-mediated biofilm development in these isolates was icaADBC independent. Apparently, an environmentally regulated, ica-independent mechanism(s) of biofilm development exists in S. aureus clinical isolates.

Secular Trends in Nosocomial Bloodstream Infections: Antibiotic-Resistant Bacteria Increase the Total Burden of Infection

BACKGROUND It is unknown whether rising incidence rates of nosocomial bloodstream infections (BSIs) caused by antibiotic-resistant bacteria (ARB) replace antibiotic-susceptible bacteria (ASB), leaving the total BSI rate unaffected. METHODS We investigated temporal trends in annual incidence densities (events per 100 000 patient-days) of nosocomial BSIs caused by methicillin-resistant Staphylococcus aureus (MRSA), ARB other than MRSA, and ASB in 7 ARB-endemic and 7 ARB-nonendemic hospitals between 1998 and 2007. RESULTS 33 130 nosocomial BSIs (14% caused by ARB) yielded 36 679 microorganisms. From 1998 to 2007, the MRSA incidence density increased from 0.2 to 0.7 (annual increase, 22%) in ARB-nonendemic hospitals, and from 3.1 to 11.7 (annual increase, 10%) in ARB-endemic hospitals (P = .2), increasing the incidence density difference between ARB-endemic and ARB-nonendemic hospitals from 2.9 to 11.0. The non-MRSA ARB incidence density increased from 2.8 to 4.1 (annual increase, 5%) in ARB-nonendemic hospitals, and from 1.5 to 17.4 (annual increase, 22%) in ARB-endemic hospitals (P < .001), changing the incidence density difference from -1.3 to 13.3. Trends in ASB incidence densities were similar in both groups (P = .7). With annual increases of 3.8% and 5.4% of all nosocomial BSIs in ARB-nonendemic and ARB-endemic hospitals, respectively (P < .001), the overall incidence density difference of 3.8 increased to 24.4. CONCLUSIONS Increased nosocomial BSI rates due to ARB occur in addition to infections caused by ASB, increasing the total burden of disease. Hospitals with high ARB infection rates in 2005 had an excess burden of BSI of 20.6 per 100 000 patient-days in a 10-year period, mainly caused by infections with ARB.

Four country healthcare associated infection prevalence survey 2006: risk factor analysis

Point prevalence surveys are useful in detecting changes in the pattern of healthcare-associated infection (HCAI). In 2004 the Hospital Infection Society was asked to conduct a third national prevalence survey, which included England, Wales, Northern Ireland and the Republic of Ireland. A similar but not identical survey was carried out in Scotland. Data were collected on standardised forms using Centres for Disease Control and Prevention definitions. This report considers associations with a wide range of risk factors for all HCAI and for four main categories. The overall prevalence rate of HCAI was 7.6% and increased significantly with age. All risk factors considered were associated with highly significantly increased risk of HCAI, except recent peripheral IV catheter and other bladder instrumentation use. Primary bloodstream infection (PBSI) was associated with antibiotic, central intravenous catheter and parenteral nutrition use. Pneumonia was associated with antibiotic, central catheter, parenteral nutrition use, mechanical ventilation and current peripheral catheter use. Surgical site infection was associated with recent surgery, antibiotic and central catheter use, mechanical ventilation and parenteral nutrition. Urinary instrumentation and antibiotic use were associated with urinary tract infection. Patients under a critical care medicine consultant had the highest prevalence of HCAI (23.2%). This report highlights those areas requiring attention to prevent HCAI, i.e. device-related infections such as PBSI (e.g. central catheters) and pneumonia (e.g. mechanical ventilation) and should influence protocols for future prevalence surveys of HCAI, e.g. the recording of risk factors at the time of assessment only is sufficient.

Candida infection of the central nervous system following neurosurgery: a 12-year review

BackgroundCandida infection of the central nervous system (CNS) following neurosurgery is relatively unusual but is associated with significant morbidity and mortality. We present our experience with this infection in adults and discuss clinical characteristics, treatment options, and outcome.MethodsAll episodes of Candida isolated from the central nervous system were identified by searching our laboratory database. Review of the cases was performed by means of a retrospective chart review.ResultsEleven episodes of Candida CSF infection following neurosurgery were identified over a 12-year period. Candida albicans was the predominant species isolated (n = 8, 73%). All infections were associated with foreign intracranial material, nine with external ventricular drains (82%), one with a ventriculoperitoneal shunt, one with a lumbar drain, and one with Gliadel wafers (1,3-bis [2-chloroethyl]-1-nitrosurea). Fluconazole or liposomal amphotericin B were the most common anti-fungal agents used. The mortality rate identified in our series was 27%.ConclusionsCandida infection following neurosurgery remains a relatively rare occurrence but one that causes significant mortality. These are complex infections, the management of which benefits from a close liaison between the clinical microbiologist and neurosurgeon. Prompt initiation of antifungal agents and removal of infected devices offers the best hope of a cure.

PCR ribotype prevalence and molecular basis of macrolide–lincosamide–streptogramin B (MLSB) and fluoroquinolone resistance in Irish clinical Clostridium difficile isolates

BACKGROUND Antimicrobial use is recognized as a risk factor for Clostridium difficile infection (CDI) and outbreaks. We studied the relationship between PCR ribotype, antimicrobial susceptibility and the genetic basis of resistance in response to exposure to antimicrobial agents. METHODS C. difficile isolates were cultured from 133 CDI patients for whom recent antimicrobial drug exposure had been recorded. Isolates were ribotyped by PCR and assessed for their susceptibility to the macrolide-lincosamide-streptogramin B (MLS(B)) group of compounds (erythromycin and clindamycin) and fluoroquinolone antimicrobials (ciprofloxacin, levofloxacin and moxifloxacin). Where relevant, the genetic basis of resistance was determined. RESULTS Prevalent ribotypes (including 027, 001 and 106) exhibited significantly greater antimicrobial resistance compared with ribotypes 078 and 014, among others. Clindamycin-resistant ribotype 078 was detected for the first time. Ribotypes 027 and 001 were more likely to exhibit MLS(B) resistance, a feature that was associated with the erm(B) gene. Exposure to MLS(B) or fluoroquinolone antimicrobial compounds in the 8 weeks prior to the onset of infection was not associated with specific genetic markers of resistance. Single amino acid substitutions in the A and B subunits of DNA gyrase were noted and were ribotype specific and linked to resistance to moxifloxacin. CONCLUSIONS Resistance to MLS(B) and fluoroquinolone antimicrobial compounds is common among prevalent ribotypes of C. difficile. The genetic basis for antimicrobial resistance appears to be ribotype specific and conserved in the absence of recent antimicrobial selection pressure.

Infection due to C. difficile ribotype 078: first report of cases in the Republic of Ireland

Clostridium difficile is an important healthcare-associated pathogen. Hypervirulent strains such as those belonging to ribotype 027 have been widely reported in recent years. A second strain associated with hypervirulence is ribotype 078 and the prevalence of Clostridium difficile infection (CDI) due to this ribotype appears to be increasing. This report describes an outbreak, in which 15cases of CDI due to ribotype 078 were detected in an Irish hospital and from a nursing home in the hospitals catchment area. C. difficile ribotype 078 accounted for 15% of total isolates submitted for ribotyping. The average age of patients with CDI due to ribotype 078 was 76 years. Forty-six percent of patients experienced recurrence of symptoms within eight weeks of diagnosis and CDI was felt to have directly contributed to five of the eight deaths. Use of enhanced DNA fingerprinting identified clusters within the 15 cases and suggested hitherto unrecognised links between some patients with CDI. Such approaches offer the promise to delineate common sources and transmission routes for C. difficile.

Hospital Infection Society Prevalence Survey of Healthcare Associated Infection 2006: comparison of results between Northern Ireland and the Republic of Ireland

As part of the Third Healthcare Associated Infection (HCAI) Prevalence Survey of the United Kingdom and Ireland, HCAI point prevalence surveys were carried out in Northern Ireland (NI) and the Republic of Ireland (RoI). Here we explore the potential benefits of comparing results from two countries with different healthcare systems, which employed similar methodologies and identical HCAI definitions. Forty-four acute adult hospitals in the RoI and 15 in NI participated with a total of 11 185 patients surveyed (NI 3644 patients and RoI 7541). The overall HCAI prevalence was 5.4 and 4.9 in NI and the RoI, respectively. There was no significant difference in prevalence rates of HCAI, device-related HCAI or HCAI associated with bloodstream infection but there was a difference in meticillin-resistant Staphylococcus aureus-related HCAI (P = 0.02) between the two countries. There were significantly more urinary tract infections and Clostridium difficile infections recorded in NI (P = 0.002 and P < 0.001). HCAIs were more prevalent in patients aged >65 years and in the intensive care unit in both countries. HCAIs were also more prevalent if patients were mechanically ventilated, had had recent non-implant surgery (RoI) or had more recorded HCAI risk factors. This is the first time that HCAI prevalence rates have been directly compared between NI and the RoI. By closely examining similarities and differences between HCAI prevalence rates in both countries it is hoped that this will influence healthcare planning and at the same time reassure the public that HCAI is important and that measures are being taken to combat it.

Laboratory diagnosis of Clostridium difficile-associated disease in the Republic of Ireland : a survey of Irish microbiology laboratories

The Health Protection Surveillance Centre (HPSC) established a group to produce national guidelines for Clostridium difficile in Ireland in 2006. A laboratory questionnaire was distributed to determine current C. difficile diagnostic practices. Twenty-nine out of 44 laboratories providing C. difficile diagnostic services to 34 hospitals responded. Twenty-five out of 29 (86%) laboratories processed specimens for C. difficile and four (13.8%) forwarded specimens to another laboratory. Sixteen laboratories (64%) processed specimens for other healthcare facilities. None routinely examined stool for C. difficile, seven (28%) examined specimens only when requested to do so and 18 (72%) used specific selection criteria, including testing all liquid stools (39%), all nosocomial diarrhoea (44%), specific clinical criteria (28%) and history of antibiotic therapy (22%). All tested stool directly for C. difficile toxin with a variety of enzyme immunoassays, with 24 (96%) detecting both toxin A and B and one detecting toxin A only. Three (12%) laboratories used cytotoxicity assays; none used polymerase chain reaction and six (24%) laboratories performed C. difficile culture but only under specific circumstances. Seven (28%) laboratories had isolates typed during outbreaks, but none had the facilities to do so on-site. The HPSC group will produce national recommendations for laboratory diagnosis, surveillance and management of C. difficile infection. Since there are marked differences in diagnostic practices throughout the country and no national reference laboratory, the implementation of these recommendations will have cost implications that will need to be addressed.

Surveillance and endemic vancomycin-resistant enterococci: some success in control is possible

Vancomycin-resistant enterococci (VRE) are prevalent in many Irish hospitals. We analysed surveillance data from 2001 to 2008 in a centre where VRE is endemic. All clinically significant enterococci were tested for susceptibility to vancomycin. All intensive care unit admissions were screened on admission and weekly thereafter. Interventions included isolating/cohorting VRE patients, monthly prevalence surveys of VRE patients, the introduction of an electronic alert system, programmes to improve hand and environmental hygiene, and the appointment of an antibiotic pharmacist. There was a significant increase in the number of positive VRE screening samples from 2001 (1.96 patients with positive VRE screens per 10 000 bed-days) to 2006 (4.98 per 10 000 bed-days) (P < or = 0.001) with a decrease in 2007 (3.18 per 10 000 bed-days) (P < or = 0.01). The number of VRE bloodstream infections (BSI) increased from 0.09 BSI per 10 000 bed-days in 2001 to 0.78 per 10 000 bed-days in 2005 (P < or = 0.001) but decreased subsequently. Linear regression analysis indicated a significant association between new cases of VRE and non-isolated VRE patients, especially between May 2005 and December 2006 [P=0.009; 95% confidence interval (CI): 0.08-0.46] and between May 2005 and December 2008 (P = 0.008; 95% CI: 0.06-0.46). Routine surveillance for VRE together with other measures can control VRE BSI and colonisation, even where VRE is endemic, and where facilities are constrained.