Methicillin-resistant Staphylococcus aureus bacteraemia in Western Australian teaching hospitals, 1997-1999: risk factors, outcomes and implications for management.

The aim of this study was to document the evolution of methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia at teaching hospitals in Perth, Western Australia (WA), and determine the risk factors and outcomes of the disease. We performed a retrospective case series analysis of all laboratory-confirmed episodes of S. aureus bacteraemia at Perth teaching hospitals between 1 July 1997 and 30 June 1999 by linking laboratory data with hospitalization data from the state's Hospital Morbidity Data System. Episodes of S. aureus bacteraemia were stratified according to methicillin susceptibility and the relationship between methicillin resistance and key factors or outcomes was determined. Almost 11% of episodes of S. aureus bacteraemia (55/509) were caused by MRSA. On age-adjusted multivariate analysis, Aboriginality (RR 6.71, 95% CI 3.20-14.10, P<0.001), geriatric unit admission (RR 5.74, 95% CI 2.01-16.37, P=0.001), female sex (RR 1.88, 95% CI 1.03-3.42, P=0.04) and healthcare-associated disease (RR 1.93, 95% CI 1.01-3.70, P=0.05) were independently associated with MRSA bacteraemia. Outcomes among those with MRSA bacteraemia included death in 15 patients and re-admission for an MRSA-related complication in five. Empirical use of vancomycin needs consideration in at-risk patients in whom Gram-positive bacteraemia is suspected clinically, with prompt review of therapy once antibiotic susceptibility results are known. The rates of re-admission after discharge for MRSA bacteraemia could be used as a clinical indicator to monitor the quality of care in hospitals.

Antibiotic resistance in Helicobacter pylori.

OBJECTIVE: To describe antibiotic resistance patterns in Helicobacter pylori. DESIGN: Culture and antibiotic sensitivity testing of antral and gastric body biopsy samples from patients having gastroscopy. PARTICIPANTS: Consecutive consenting patients aged 18 years or more presenting for gastroscopy from 1 July 1998 to 30 June 1999. SETTING: An open-access gastroscopy service at an urban university tertiary hospital. MAIN OUTCOME MEASURES: Number of H. pylori isolates showing resistance to antibiotics; correlates of such resistance with demographic and clinical information. RESULTS: Of 1580 patients undergoing endoscopy, 434 agreed to participate in the study. 108 (24.9%) had positive cultures for H. pylori, and 88 of these isolates (81%) were available for further testing. Resistance to metronidazole and clarithromycin was detected in 36% and 11%, respectively. No resistance was found to tetracycline or amoxycillin. Metronidazole resistance was commoner in younger patients (P = 0.0004) and macrolide resistance was commoner in those born outside Australia or New Zealand (P = 0.03). CONCLUSIONS: We found substantial resistance to metronidazole, and emerging clarithromycin resistance, but complete susceptibility to amoxycillin, tetracycline, gentamicin and cefaclor. These factors may influence the effectiveness of presently recommended eradication regimens.

A hospital-based education programme for infection control in Australia.

Fremantle Hospital, a 400-bed teaching hospital has offered an infection control course for registered nurses since 1984. The number of nurses practising infection control in the state of Western Australia has increased from seven in 1984 to over 100. Country areas now have access to appropriate advice. The course is hospital-based and multidisciplinary and is constantly evolving. It lasts for two weeks, is economic and wastage is low due to careful selection of candidates. Basic infection control standards have improved, but teaching of medical and allied health staff and line managers has not yet been addressed. Nurses from overseas are now applying for the course and a regional network of infection control practitioners is a major aim.

The emergence of erythromycin resistance in Streptococcus pyogenes in Fremantle, Western Australia.

Erythromycin resistance in Streptococcus pyogenes is unusual except in Japan. Since January 1, 1985, a dramatic increase has occurred in the prevalence of erythromycin-resistant Strept. pyogenes infections in the outpatients who have presented to Fremantle Hospital, Western Australia. In 1985, 1% of isolates of Strept. pyogenes was erythromycin-resistant. This had risen to 9.1% of isolates in 1986 and to 17.6% of isolates in 1987. Several M- and T-types of Strept. pyogenes were involved. Treatment failure now can be expected when erythromycin is prescribed for the treatment of common infections in outpatients at this hospital. Laboratories that use disc methods of antimicrobial susceptibility testing may not detect erythromycin resistance in these organisms.

Mycotic aneurysm of the thoracic aorta caused by Salmonella typhimurium.

A fatal case of mycotic aneurysm of the thoracic aorta is described. Salmonella typhimurium was isolated from blood cultures and from cultures of a post-mortem sample of the aneurysm. A review of the literature showed that while endovascular infection is a recognized complication of salmonellal septicaemia in the elderly, infection of the thoracic aorta by Salmonella spp. is rare. A combination of surgery and antibiotic therapy always is required for a successful outcome.

Attempt to fulfil Koch's postulates for pyloric Campylobacter.

A volunteer with histologically normal gastric mucosa received pyloric campylobacter by mouth. A mild illness developed, which lasted 14 days. Histologically proven gastritis was present on the tenth day after the ingestion of bacteria, but this had largely resolved by the fourteenth day. The syndrome of acute pyloric campylobacter gastritis is described. It is proposed that this disorder may progress to a chronic infection which predisposes to peptic ulceration.

Pyloric Campylobacter infection and gastroduodenal disease.

In 1982, a new spiral Gram-negative bacterium which was similar to those of the genus Campylobacter was isolated from the gastric mucosa of 11 patients with gastritis. From then on, the organism was isolated in a further 114 of 267 patients who underwent antral biopsy in Fremantle Hospital between January 1983 and September 1984. During 1984, the bacterium was cultured from 88% of patients in whom it was detected histologically, and was not cultured from any patient with histologically normal gastric mucosa. The new bacterium, pyloric campylobacter, grew in three days on brain-heart infusion blood-agar at 37 degrees C in an atmosphere with added CO2. All isolates tested were sensitive to penicillin, erythromycin, tetracycline, cephalosporins, gentamicin and bismuth citrate; 80% of isolates were sensitive to metronidazole or tinidazole. It is suggested that pyloric campylobacter infection is a major factor in the causation of dyspeptic disease and peptic ulceration. Antibacterial regimens directed against the bacterium may provide a permanent cure for these chronic disorders.

Assuring rational antibiotic use: the impact of a joint microbiology-pharmacy surveillance program.

A comprehensive antibiotic surveillance program conducted in cooperation with the Microbiology and Pharmacy departments in a teaching hospital is described. The program consists of a number of interrelated processes including the personal advice of specialists including a Clinical Microbiologist, Infection Control Nurse and Ward Pharmacists, re-educative strategies and non restrictive administrative policies. The program does not involve the use of formularies or published guidelines, and retains complete clinical freedom of choice for antibiotics. Studies, including antibiotic prevalence and prescribing surveys, indicate that the program has been an effective means of improving antibiotic use, reducing costs and promoting infection control. This has been achieved by educative means through the provision of relevant information on antibiotic principles, and opportunities for prescribers to improve their problem solving skills, resulting in long term attitudinal change.

Standards of antimicrobial prescribing for prophylaxis in selected surgical operations: A study conducted in a teaching hospital.

A study of the prescribing habits of the surgeons of Fremantle Hospital for antimicrobial prophylaxis was conducted in the period from July to October, 1979. In selected operations, an assessment of use was made according to generally accepted principles of prophylaxis. In 109 "clean" surgical operations and in 38 cholecystectomies, antimicrobial agents were rarely used for prophylaxis. It was concluded that there was no overusage of prophylactic antimicrobial agents in surgery. In 58 operations on the appendix and large bowel, it was found that administration of the antimicrobial agents was started either too late or the choice of agent was illogical in 15 cases. In 12 total hip replacements, the prescribing was satisfactory, but, in 21 Richards' pin-and-plate operations and in 35 minor orthopaedic implants, prophylaxis was continued for longer than 48 hours in 33 of 41 courses of therapy. The mean duration of a course was 6.5 days for pin-and plate and 6.7 days for minor implants. In only seven of 30 hysterectomies were patients covered for Bacteroides fragilis infection at the time of operation, the mean duration of a course was 5.5 days. It is suggested that a reduction in costs and increase in quality of care are most likely to be achieved by surgical teams adopting a protocol in operations where prophylaxis is of proven value.

Bacterial infection and acrylic cement in the rat.

In thirty-one rat tibiae, plugs of plain acrylic cement were inoculated with Staphylococcus aureus; these all remained contaminated at the end of two weeks when the animals were killed. Inoculation with known strains of Pseudomonas, Proteus and Gp. G Streptococcus resulted in 70 to 93 per cent persisting contamination. Gentamicin, to which the organisms were fully sensitive, was efficacious in controlling the infection (90 per cent plugs proving sterile after two weeks). Fucidin was less successful against Staphylococcus aureus although effective in vitro. Intravenous inoculation with a suspension of Staphylococcus aureus succeeded in contaminanting 70 per cent of sixty plain cement plugs when injected into the tail vein half an hour after closure of the leg wounds. Only 11 per cent of sixty-four plugs were so contaminanted when the injection was delayed for two weeks. This animal model is submitted as a possible future means of testing different antibiotic-cement combinations against infection.

Antibiotic-loaded acrylic cement.

Laboratory experiments and clinical investigations have confirmed the various claims made originally by Buchholz and Engelbrecht (1970) that antibiotic-loaded acrylic cement releases the antibiotic into the surroundings in useful concentrations. Palacos R cement released higher concentrations than CMW, Simplex and Sulfix brands of cement and over longer periods. Concentrations of gentamycin and fucidin were sufficient to penetrate dead cortical bone. These conclusions need to be assessed with animal studies, mechanical testing and clinical results before the ideal place of antibiotic-loaded acrylic cement is established.