Role of occupational health staff in investigation of invasive group A streptococcal infection hospital outbreak.

Healthcare workers (HCWs) are commonly implicated as index cases during investigation of invasive group A streptococcus (GAS) hospital outbreaks. Staff screening may be needed but guidelines on implementation vary. We conducted an analysis to find common exposures in patients infected with a rare type of GAS and staff were asked to self-screen. Swabs were negative, but as the outbreak continued, specific HCWs were asked to attend the occupational health department. The index case was then identified as having a skin disorder infected with same rare GAS. We describe the importance of occupational health clinical review of HCWs during an outbreak.

Lessons from a large norovirus outbreak: impact of viral load, patient age and ward design on duration of symptoms and shedding and likelihood of transmission.

BACKGROUND: Hospital norovirus outbreaks cause significant financial and operational disruption which should be minimised by optimal handling of affected areas and use of isolation facilities. AIM: To identify factors associated with increased duration of symptoms and viral excretion and increased probability of transmission. METHODS: Retrospective observational study of a large norovirus outbreak at a UK teaching hospital in the winter of 2009-2010 where patients were diagnosed using a real-time polymerase chain reaction (PCR) assay. FINDINGS: Symptom duration was significantly associated with patient age (Spearman rank correlation coefficient: 0.197; P = 0.002) but not with PCR cycle threshold (C(T)) value. Duration of viral excretion was found to be longer in patients with higher viral loads. Transmission within a ward bay was not significantly associated either with age or with C(T) value but was more likely to occur in some ward blocks than others, which may relate to differences in ward design. Transfer of patients into isolation rooms or cohorted area within two days of symptom onset did not significantly influence probability of onward transmission (52% vs 47%; P = 0.67). CONCLUSIONS: The presented data suggest that C(T) value may guide timing of repeat sample collection if ongoing gastrointestinal symptoms may relate to other pathologies, and that patients developing symptoms of norovirus may remain in their current bay rather than being moved into isolation facilities. The bay or ward should be closed to new admissions but it should be anticipated that duration of symptoms and therefore closure will be longer when the outbreak involves elderly patients.

Vibrio vulnificus: an unusual mode of acquisition and novel use of rapid susceptibility testing.

Infection with Vibrio vulnificus is uncommon in Europe but is associated with necrotising wound infections and life-threatening septicaemia. This case is one of infection most likely to have been acquired from a thermal pool in Turkey without preceding exposure to seawater or shellfish. The report also describes how early management was optimised using gradient diffusion antibiotic strips to provide rapid susceptibility data.

Evaluation of ChloraPrep (2% chlorhexidine gluconate in 70% isopropyl alcohol) for skin antisepsis in preparation for blood culture collection.

OBJECTIVES: Blood culture contamination is a significant adverse event. This study evaluated whether using ChloraPrep (2% alcoholic chlorhexidine) instead of 70% isopropyl alcohol wipes reduced contamination rates on two Medical Assessment Units (MAU1 and MAU2). METHODS: ChloraPrep was introduced for 2 to 3-month intervention periods, initially on MAU1 and MAU2 and subsequently on MAU1 only. Contamination rates were compared with a matched time period in the preceding year and the three month period before ChloraPrep introduction. Education regarding venepucture technique was delivered. RESULTS: Contamination rates for the time matched pre-intervention period were 17.3% (51/295), MAU1 and 13.5% (31/230), MAU2. During the initial period of ChloraPrep use, rates declined (MAU1; 6.6% [P<0.001], MAU2; 8.5% [P=0.11] both Fisher's Exact Test). However, rates had already started to fall prior to ChloraPrep introduction. There was a non-significant difference between contamination rates in the comparator period immediately prior to ChloraPrep introduction and rates during the first intervention period (MAU1 and MAU2; P>0.05). During the second intervention period, absence of ChloraPrep on MAU2 did not significantly affect contamination (P=0.41) on this ward. CONCLUSIONS: ChloraPrep skin antisepsis did not give a significant reduction in blood culture contamination, but education may have led to the trend to lower contamination.

Invasive pneumococcal disease and the potential for prevention by vaccination in the United Kingdom.

OBJECTIVES: Invasive pneumococcal disease (IPD) is associated with a high mortality despite antimicrobial therapy, but may be preventable by pneumococcal vaccination. The extent of previous exposure to pneumococcal capsular polysaccharide vaccination prior to an episode of IPD in hospitalised adults in the United Kingdom is unclear. METHODS: We conducted a retrospective cohort study in adults with IPD admitted to either of two teaching hospitals in Sheffield, United Kingdom during 1992-2000. Receipt of pneumococcal vaccination, risk factors for IPD, death and disability were determined. RESULTS: The number of cases of IPD was 552 and 187/230 patient records from one site were reviewed. According to UK pneumococcal vaccination guidelines 59% of patients should have received the vaccine and 76% of patients if updated guidelines, which include age>65 years as an indication, are applied. In patients with known risk factors, excluding age, only 8% had been vaccinated. The mortality from IPD was 21% and an additional 6% suffered major complications. CONCLUSIONS: In patients hospitalised with IPD there is a high rate of pre-existing risk factors and a low rate of administration of pneumococcal vaccination. IPD incurs significant mortality, morbidity and economic cost and there is potential for reducing this by improved uptake of pneumococcal vaccination.

Phenotypic detection of beta-lactamase-mediated resistance to oxyimino-cephalosporins in Enterobacteriaceae: evaluation of the Mastascan Elite Expert System.

OBJECTIVES: The aim of this study was to evaluate phenotypic detection of beta-lactamase-mediated resistance to oxyimino-cephalosporins in Enterobacteriaceae using the Mastascan Elite Expert System challenged with a battery of genotypically characterized organisms. METHODS: Isolates (n = 120) were identified to species level and antimicrobial susceptibilities were determined using agar incorporation methods and Mastascan Elite. Phenotypes were examined using an Expert System (ES) and putative genotypes were suggested using interpretative reading. RESULTS: Identification was correct in 119 of 120 isolates. The ES was able to identify the correct beta-lactam phenotype (as deduced from molecular methods) in a single choice in 98 of 120 (81.7%) isolates. In an additional 15 (12.5%) cases, the ES identified the correct beta-lactam phenotype within two or more choices. The detected phenotype was incorrect in seven (5.8%) isolates, but three of these were not inherent to the ES. CONCLUSIONS: The Mastascan Elite ES is relatively inexpensive and flexible and can identify the mechanism of resistance to oxyimino-cephalosporins in the majority of Enterobacteriaceae without recourse to molecular methods.

Immunoglobulin A1 proteases: a structure-function update.

IgA1 (immunoglobulin A1) antibodies are the first line of defence against microbial pathogens such as Neisseria meningitidis and Haemophilus influenzae. However, these bacteria secrete a site-specific protease that is capable of cleaving human IgA1 and interacting with other host components. The IgA proteases are released by the type V secretion pathway, which involves translocation through two membranes and an autolytic, post-translational processing step. Results reported recently throw light on the type V secretion pathway and on the roles of the multifunctional IgA protease. The IgA1 protease-recognition sequence is present within the IgA1 hinge region as well as in the variable sequence connecting the IgA1 protease to its translocator domain. Recent results suggest that neisserial IgA1 proteases are capable of cleaving substrates lacking the classical recognition sequence. This review will cover recent advances in the IgA protease field.

Helicobacter pylori antimicrobial resistance in the United Kingdom: the effect of age, sex and socio-economic status.

BACKGROUND: Helicobacter pylori antimicrobial resistance is the most common reason for eradication failure. Small studies have shown metronidazole resistance to be more prevalent in certain population groups. AIM: To determine the resistance rates in a large cohort of patients from a single centre in the UK, and to evaluate resistance patterns over time, according to age, sex and socio-economic status. METHODS: Consecutive patients with H. pylori-positive antral gastric biopsy samples were studied from 1994 to 1999. Susceptibility testing was performed to metronidazole, tetracycline, macrolide and amoxicillin by the modified disk diffusion METHOD: The Jarman under-privileged area score was used as a measure of socio-economic status. RESULTS: A total of 1064 patients were studied. Overall metronidazole resistance was 40.3%, decreasing with age (P < 0.0001, odds ratio for patients over 60 years 0.63, 95% CI: 0.48-0.80). Women were more likely to have metronidazole resistant strains (P=0.003, odds ratio 1.5, 95% CI: 1.15-1.91), but there was no association with Jarman score. Macrolide resistance was associated with metronidazole resistance (P=0.03, odds ratio 2.14, 95% CI: 1.07-4.28). CONCLUSIONS: Metronidazole resistance in H. pylori is highly prevalent and more common in women and the young, but does not appear to be related to socio-economic status.

Identification of a novel transcriptional silencer in the protein-coding region of the human CYP2C9 gene.

A novel regulatory element (27 bp) which confers transcriptional repression was identified within the protein-coding region immediately after the translation start codon in the human cytochrome P450 (CYP) 2C9 gene. Deletion of this element increased transcriptional activity in HepG2 cells by transient transfection assay. Nuclear protein extracts from HepG2 cells and human liver were found in electrophoretic mobility shift assays to bind specifically to the 27 bp element. A putative binding protein was partially purified by DNA-affinity chromatography and was determined by Southwestern blotting to have a molecular weight of approx. 100 kDa. Studies with mutated competitor oligonucleotides established that binding of the nuclear protein to the 27 bp cis-element was dependent upon two 6 bp direct repeats (5'-CTTGTG-3') that were separated by three bases. It is possible that this novel cis-acting element may be involved in the negative regulation of CYP2C9.