Infection of surgical wounds in the maxillofacial region and free flap donor sites with methicillin-resistant Staphylococcus aureus.

We studied the acquisition of methicillin-resistant Staphylococcus aureus (MRSA) in two groups of patients who had free flap reconstructions of defects after excision of lesions in the head and neck. The first group (n=31) was given a 5-day perioperative course of antibiotic prophylaxis (long-term) and the second (n=33) a 24-h course (short-term). MRSA was the main infecting organism. Seventeen of the 64 patients (27%) developed an infection with MRSA, including seven at donor sites of free flaps. All infections were acquired after operation, and delayed healing or discharge in five patients with MRSA and four with infections with other organisms. The median length of hospital admission was greater for patients that acquired MRSA (p=0.005). There were significantly fewer patients with wounds infected by MRSA in the short-term group (4/33 compared with 13/31, p=0.01). We recommend the short-term use of an antibiotic for surgical prophylaxis and the application of cross-infection control measures on the ward.

Can urine dipstick testing for urinary tract infection at point of care reduce laboratory workload?

AIM: The University Hospitals of Leicester NHS Trust microbiology laboratory receives 150 000 urine samples each year, approximately 80% of which prove to be culture negative. The aim of this study was to reduce the proportion of culture negative urines arriving in the laboratory, by producing local evidence based guidelines for the use of urine dipstick testing at point of care within the trust's three acute hospitals. METHODS: One thousand and seventy six unborated urine samples were dipstick tested at the point of care using an automatic strip reader. Quantitative results for the four infection associated markers-leucocyte esterase, nitrite, blood, and protein-were compared with the results of conventional laboratory microscopy and culture. RESULTS: The performance of different marker combinations was calculated against the routine laboratory methods. One hundred and seventy five (16.3%) samples were negative for all four markers. Of these dipstick negative samples, only three (1.7% of all true positives) were positive by culture. The absence of all four infection associated markers was found to have a greater than 98% negative predictive value and a sensitivity and specificity of 98.3% and 19.2%, respectively. CONCLUSIONS: A urinary dipstick testing algorithm for infection associated markers was derived for use in hospital patients to screen out negative urines. Two years after distributing the algorithm and promoting access to reagent strips and strip readers, a reduction in the urine workload has been seen against an otherwise increasing laboratory specimen load.

The acquisition of methicillin-resistant Staphylococcus aureus (MRSA) in vascular patients.

OBJECTIVE: the aim of this study was to establish at which point during a hospital admission MRSA acquisition occurs in vascular patients. METHOD: a consecutive series of 100 patients undergoing arterial surgery were screened for MRSA carriage on admission to hospital, on exit from theatre, on discharge from ITU, weekly whilst an inpatient and on hospital discharge. Screening was with moistened swabs from nose, throat, perineum and open wounds that were pooled for microbiological culture. RESULTS: four patients (4%) screened positive for MRSA on admission to hospital. Of the remaining 96, 16 (17%) acquired MRSA during their hospital stay as follows: exit from theatre, one; exit from ITU, six; on the ward postoperatively, nine. Comparing MRSA acquisition (n=16) with non acquisition (n = 80) the following characteristics were noted, length of stay 16 (4-66) vs 7 (2-50) days (Mann-Whitney p < 0.001); admission to ITU 13/16 vs 46/80 (Fishers chi-squared p = 0.10); length of ITU stay 3 (1-20) vs 3 (1-14) days (Mann-Whitney p = 0.41). Frequent hospital attendance, age, emergency admission, diabetes or renal failure were not commoner in those with MRSA acquisition. CONCLUSIONS: these data indicate that 4% of patients undergoing arterial surgery are pre-existing carriers of MRSA. Length of hospital stay is the single most important determinant of MRSA acquisition.

Collaborative investigation of an outbreak of Salmonella enterica serotype Newport in England and Wales in 2001 associated with ready-to-eat salad vegetables.

In June 2001, as part of a microbiological study of bagged, ready-to-eat salad products, Salmonella enterica serotype Newport was isolated from a sample of pre-packed green salad distributed by a major supermarket retailer. The strain was characterised by phage typing, plasmid profile typing and pulsed-field gel electrophoresis. Other isolates of S. Newport from cases of human infection in England and Wales in the first six months of 2001 were similarly characterised. Of 60 strains from cases of human infection, 19 were found to be indistinguishable from that isolated from the salad product. This study highlights the benefits of an integrated approach to outbreak investigations, involving the various elements of the PHLS and the Food Standards Agency, and acknowledges the full co-operation of the retailer in ensuring the rapid withdrawal of the contaminated product.

Near patient testing for Helicobacter pylori: a detailed evaluation of the Cortecs Helisal Rapid Blood test.

OBJECTIVE: To evaluate the Cortecs Helisal Rapid Blood test for accuracy overall and in specific subgroups by age and ethnic origin. Additionally, to assess readability of results, including inter-observer error, with consideration also given to usability and acceptability. DESIGN: A prospective evaluation using four reference tests. SETTING: A hospital endoscopy unit. METHODS: Two hundred patients attending for endoscopy were recruited for H. pylori testing with the Helisal test, plus antral biopsies for CLO test, culture and histology and serology using a commercial enzyme-linked immunosorbent assay (ELISA). The Helisal test was carried out and results read strictly according to the manufacturer's instructions. Two or more reference tests positive were taken as a gold standard positive; all results negative as negative and any remaining cases were regarded as equivocal. Performance figures were calculated twice, treating patients with equivocal status as either positive or negative. Results were in most cases double-read, blinded, by two observers and readings subsequently compared. RESULTS: The test was considered convenient, easy to use and acceptable to symptomatic patients, but a notable proportion (10%) of results were very difficult to read. Sensitivity was acceptable (91-92% overall, 95% confidence interval (CI) 82-97%), but specificity was poor overall (56-62%, 95% CI 45-72%), and particularly in patients aged 45 years or over (44-51%) and those of South Asian origin (42-50%). CONCLUSION: The test could be appropriate for testing younger symptomatic patients. Its usefulness was, however, found to be limited by poor readability of some results and poor specificity. Reading of some results as equivocal would be appropriate.

Antibiotic policies--relevance to general practitioner prescribing. Family Health Services Authority, Great Britain.

In the UK rational antimicrobial prescribing in General Practice requires effective communication between the Family Health Services Authority (FHSA), microbiologists and General Practitioners (GPs). Many FHSAs now have a Pharmaceutical Adviser to assist the FHSA Medical Adviser in providing pharmaceutical advice, setting and monitoring of indicative prescribing amounts and fundholding drug budgets. They are also increasingly involved in developing practice formularies. Reviews of local prescribing often show significant differences between antimicrobial usage and local recommendations from microbiologists which are generally based on their interpretation of local laboratory susceptibility data. The efforts of two FHSAs working with local microbiologists to communicate a rational antimicrobial policy are described. This has involved conducting prescribing audit, publishing guidelines, practice visits and arranging meetings between GPs, microbiologists and FHSA staff.

Comparison of Signal and Bactec NR-660 blood culture systems.

The Signal blood culture system was compared with the Bactec NR-660. A total of 1617 blood culture sets yielded 143 (8.8%) significant isolates; 113 (79.0%) were from positive bottles in both the Bactec and Signal systems. Twelve organisms (8.4%) were detected and isolated from the Signal system only and another 18 (12.6%) from the Bactec system only. Of these 18, five were Signal-positive but the organism was not recovered and four organisms were isolated from negative Signal bottles on terminal subculture. The time taken to detection for each system was similar; the Signal system detected 68% and the Bactec 63% of significant positives within 24 h. At 48 h Bactec detected 91% and the Signal 85%. A significantly-reduced number of bottles which gave a positive signal but were negative by microscopical and cultural methods was found, compared with previous reports. The 1 h incubation period prior to the insertion of the Signal growth indicator device was considered to be the cause of this reduction in the proportion of false positives. Fifty-five percent (42/77) of the Bactec false positives were due to delta growth value. This is when there is an increase in the growth index of > or = 15 without the positive threshold level of 30 being attained. This occurred in the anaerobic bottle on day 2 with 42 bottles. Another 40% (31/77) of the false positives had a growth value between the positive threshold of 30 and a value of 35. Eighty (4.9%) of Bactec and 65 (4.0%) of Signal sets yielded clinically non-significant isolates.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of Sentinel and Bactec blood culture systems.

AIMS: To evaluate the Sentinel automated blood culture system and to compare its performance with that of Bactec. METHODS: The Sentinel blood culture system was evaluated in three centres. The performance of the system was assessed in comparison with the routine blood culture method used in these centres, the Bactec system. RESULTS: Blood culture sets (n = 2180) consisting of Sentinel aerobic and anaerobic, and Bactec aerobic and anaerobic bottles yielded 218 (10%) clinically important isolates. One hundred and fifty five (71%) of the isolates were detected by both systems; 35 (16%) were detected by Sentinel only; and 28 (13%) by Bactec only. For the duration of the evaluation, the Sentinel system was deliberately configured so that it was impossible to detect positive results during the first 12 hours. The times to positivity after the first 12 hours were similar. Data gathered during and subsequent to the evaluation have been used by the manufacturer to refine the algorithm so that positive results can be detected at a minimum of 2.25 hours. CONCLUSIONS: After a period of familiarization the Sentinel system was considered easy to use. Sentinel is a useful addition to the methods available for the detection of bacteria in blood cultures.

Endotoxaemia and serum tumour necrosis factor as prognostic markers in severe acute pancreatitis.

Endotoxaemia and circulating tumour necrosis factor are important prognostic factors in severe sepsis and are implicated in the pathogenesis of septic shock. Because clinical and pathological features in acute pancreatitis are similar to septic shock this study sought to determine whether endotoxin and tumour necrosis factor were prognostic factors in 38 patients with prognostically severe acute pancreatitis. Endotoxaemia, present in 19/37 (51%) patients on day 1, was more common in nonsurvivors than survivors (10/11, 91% v 9/26, 35%, p = 0.003). Day 1 serum endotoxin concentrations were higher in patients with a severe outcome (median (interquartile range) 314 (173-563) pg/ml v 0 (0-185) pg/ml, p<0.01) and in non-survivors (266 (173-586) pg/ml v 0 (0-165) pg/ml, p<0.01). Serum tumour necrosis factor was detectable in 47 of 109 samples (43%) from 38 patients (median 35 pg/ml, range 5-943 pg/ml). Day 1 serum tumour necrosis factor correlated with a worse prognostic score and a severe outcome in all patients (n = 38, r = 0.36, p = 0.027; r = 0.33, p<0.05) and with mortality in patients with gall stones (n = 23, r = 0.50, p = 0.02). Our data suggest that endotoxin and tumour necrosis factor could be prognostic factors in severe acute pancreatitis.

Recurrence of Listeria monocytogenes meningitis.

A case of Listeria monocytogenes meningitis in a 3-year-old boy which relapsed after chloramphenicol treatment is described. The patient was subsequently successfully treated with ampicillin and gentamicin and made a complete recovery. In vitro studies confirmed the inadequacy of chloramphenicol therapy. The value of combination therapy, as evidenced by chessboard and killing-curve techniques with the strain, is discussed.