G. L. French

Hong Kong strains of methicillin-resistant and methicillin-sensitive Staphylococcus aureus have similar virulence

While most authorities agree that methicillin-resistant Staphylococcus aureus (MRSA) are as pathogenic as methicillin-sensitive strains (MSSA), some believe that MRSA are relatively avirulent opportunists, and that their importance has been exaggerated. We present evidence that Hong Kong strains of MRSA and MSSA are equally pathogenic: they have similar virulence in animal models; they are isolated in similar proportions from both deep and superficial clinical sites including blood; in patients with hospital-acquired bacteraemias mortality rates are similar when adjusted for clinical factors; and in both animals and patients with systemic MRSA infection, mortality rates are significantly reduced by vancomycin therapy. Efforts to control the spread of MRSA are justified, and in invasive sepsis early treatment with vancomycin may be life-saving.

Measurement of the costs of hospital infection by prevalence surveys

Data from seven single-day prevalence surveys were used to assess the costs of hospital-acquired infection (HAI) by matching infected cases with controls and reviewing patient case notes for details of mortality, length of hospitalization and antibiotic treatment costs. Many cases with a high risk of HAI could not be matched and probably had inevitable infection. Cases that could be matched had the same risks of HAI as the controls, and these infections were potentially avoidable. Compared with controls, infected patients had an excess mortality rate of 7.4%, an average excess hospital stay of 23 days and an average excess antibiotic expenditure of US

Methicillin-resistant Staphylococcus aureus bacteraemia in Hong Kong

190. By extrapolation we calculate that the annual costs of avoidable HAI at Prince of Wales Hospital is now approximately 130 lives, 42 000 bed-days and US

Prevalence survey of infection in a Hong Kong hospital using a standard protocol and microcomputer data analysis

0.3m of antibiotics; costs of a similar magnitude have already been saved by a programme of hospital infection control. We conclude that hospital-acquired infection is very expensive, infection control is highly cost-effective, and prevalence surveys are practical tools for the measurement of rates and costs of hospital infection.

Aeromonas septicaemia in Hong Kong species distribution and associated disease

In the first 22 months of operation at the Prince of Wales Hospital, 26 (46%) of 56 hospital-acquired Staphylococcus aureus bacteraemias were due to methicillin-resistant organisms (MRSA). There were 10 plasmid profiles amongst 24 of the MRSA strains analysed. MRSA bacteraemias were first seen in the hospital 1 year after opening when the isolation rate of MRSA from all sites had risen to about 1% of patient admissions. During the last 3 months of the study period, 17 out of 18 S. aureus bacteraemias were due to methicillin-resistant strains. Patients with MRSA bacteraemia were significantly more likely than those with methicillin-sensitive S. aureus bacteraemia to have had a severe underlying disease, a poor clinical prognosis, prolonged hospitalization, and prior antimicrobial therapy, especially with aminoglycosides. They also had a significantly longer hospital stay after infection, a significantly higher cost of antimicrobial therapy and a higher mortality rate. The lower mortality rate in MRSA patients treated with vancomycin (18%) compared with those treated with other antimicrobials (40%) confirms that, at present, vancomycin is the treatment of choice for invasive MRSA infections.

Vibrio vulnificus septicaemia presenting as spontaneous necrotising cellulitis in a woman with hepatic cirrhosis.

A 1-day prevalence survey of hospital infection was performed in June 1985 at a new general teaching hospital in Hong Kong. The 1980 British national survey protocol was used, and the results were analysed by microcomputer. The major part of the survey was carried out by nine people over a period of 3 days and was completed within 6 weeks. The rate of hospital-acquired infection was 8.9% and of community-acquired infection was 16.5%. Antibiotics were mainly used in infected patients. The British protocol is suitable for Hong Kong hospitals, and with microcomputer data analysis such surveys can be completed quickly and accurately even with limited resources.

Eikenella corrodens as a Cause of Brain Abscess

During a 5-year study of 2211 patients with clinically significant positive blood cultures in Hong Kong. Aeromonas spp. were isolated in 40 cases. Among 26 episodes in which a single species was isolated. 17 (65.4%) were identified as Aeromonas hydrophila. 8 (30.8%) as A. sobria and one (3.8%) as A. caviae. There were 14 episodes with a mixture of species. Of these, nine (64.3%) were identified as A. hydrophila, two (14.3%) as A. sobria, and two (14.3%) as A. caviae. One (7.1%) was an infection with both A. sobria and A. hydrophila. These polymicrobial infections were usually combined with the presence of Enterobacteriaceae. Hepatobiliary disease was the underlying problem in 24 cases (60.0%) and malignant neoplasia in 14 (35.0%) cases. Most patients presented with fever and leucocytosis. The mortality rate for A. sobria septicaemia was not significantly different from the average rate for all septicaemias. A total of 30 isolates was available for sensitivity testing with 17 antibiotics. More than 86.0% were resistant to ampicillin, and the addition of the beta-lactamase inhibitor sulbactam did not restore its activity. All strains tested were sensitive to cefotaxime, ceftazidime, aztreonam, imipenem, norfloxacin and ciprofloxacin.

RNA-electrophoresis as a typing method for nosocomial rotavirus infection in a special-care baby unit

Vibrio vulnificus is a virulent marine organism commonly found in Hong Kong coastal waters which contaminates local sea-food. It may produce a primary septicaemia, often associated with secondary skin lesions, following ingestion of raw shell fish. We report a rapidly fatal case of primary V. vulnificus septicaemia in a 50-year-old housewife with post-hepatitic cirrhosis presenting as spontaneous necrotising cellulitis of the legs. V. vulnificus infection should be considered in patients with a history of liver disease with acute septicaemia and characteristic skin lesions.

Special precautions reduce oropharyngeal contamination in bronchoalveolar lavage for bacteriologic studies

A case of brain abscess due to Eikenella corrodens in a 67-year-old woman is reported. To our knowledge, this is the first case in which the causative organism has been isolated from the occipital lobe. E. corrodens may be the cause of apparently sterile brain abscesses encountered in neurosurgery and should be considered in the differential etiology of brain abscess.

DEVELOPMENT OF TRIMETHOPRIM-RESISTANCE IN SALMONELLA TYPHI DURING THERAPY

During January and February 1988 an outbreak of nosocomial rotavirus infection occurred in a special-care baby unit (SCBU). Seven infants were affected, of whom five had symptoms of diarrhoea. Typing by RNA electrophoresis (electropherotyping) demonstrated that a single rotavirus strain was responsible for the outbreak. The epidemic electropherotype was introduced by an infant with diarrhoea admitted directly into the SCBU from the community. Eight other electropherotypes were identified during January and February in patients with community-acquired rotavirus diarrhoea on other paediatric wards, but the outbreak strain occurred only on the SCBU. Electropherotyping is a useful and rapid method for tracing the epidemiology of hospital-acquired rotavirus infection.