Non-multiresistant and multiresistant methicillin-resistant Staphylococcus aureus in community-acquired infections

OBJECTIVE

To survey Staphylococcus aureus strains isolated from patients presenting from the community, comparing clinical features and antibiotic sensitivity profiles between multiresistant and non-multiresistant methicillin-resistant and methicillin-sensitive isolates.

DESIGN

Retrospective case series.

PARTICIPANTS AND SETTING

Patients who presented to emergency or dermatology departments in hospitals served by the South Western Sydney Area Health Service between 1 May 1998 and 30 April 1999. All patients with methicillin-resistant S. aureus (MRSA) and the first 100 with methicillin-sensitive S. aureus were eligible.

MAIN OUTCOME MEASURES

Patient demographic characteristics; risk factors; clinical presentation; treatment; outcome; and isolate antibiotic susceptibility.

RESULTS

139 patients were eligible, and 122 had clinical records available. Ten of these 122 (8%) had multiresistant MRSA, 26 (21%) non-multiresistant MRSA and 86 (70%) methicillin-sensitive S. aureus. Among patients with non-multiresistant MRSA, 29% (7/24) were born in New Zealand, Samoa or Tonga, a higher proportion than among those with multiresistant MRSA or methicillin-sensitive S. aureus (P= 0.03). Nearly half (44%) of non-multiresistant MRSA strains were community-acquired in patients with no risk factors. Two-thirds of patients with non-multiresistant MRSA (17/26) presented with cellulitis or abscess, and 58% (11/19 evaluable patients) required surgical treatment.

CONCLUSIONS

Non-multiresistant MRSA strains are common, especially among people born in New Zealand, Samoa or Tonga, and are usually community acquired. Medical practitioners should routinely swab all staphylococcal lesions for culture and sensitivity.

Community-acquired, non-multiresistant oxacillin-resistant Staphylococcus aureus (NORSA) in South Western Sydney

Community-acquired oxacillin-resistant Staphylococcus aureus (ORSA) infections are an emerging problem in the 1990s in Sydney, Australia. Laboratory data pertaining to all specimens that grew S. aureus between 1/1/1990 and 31/12/1999 were analysed. A total of 12,909 isolates of S. aureus were obtained. The proportions that were nonmultiresistant oxacillin-resistant S. aureus (NORSA) increased from 0.09% in 1990 to 5.5% in 1999. Resistance of NORSA strains to erythromycin was 8.5%, ciprofloxacin 8.4%, tetracycline 13%, rifampicin 0.7%, and fusidic acid 5.3%. A chart review was performed for cases of NORSA infection which occurred 1/1/1998-3/5/1998. Isolates from these cases underwent E-test oxacillin MIC testing, mecA determinant PCR, phage typing and pulsed-field gel electrophoresis. All nine of the patients with NORSA were Polynesians, and all had serious soft tissue infections. Bacteraemia was not seen. Only one patient received vancomycin yet all recovered. Isolates from all nine patients contained the mecA determinant. Oxacillin MICs were 1-8 mg/l. Strain differentiation with phage typing and pulsed-field gel electrophoresis showed isolates from eight patients were closely related and were similar to New Zealand WSPP1 and WSPP2 strains. Medical practitioners should take specimens for culture and sensitivity from lesions where infection with S. aureus is likely. Empirical treatment of staphylococcal infections in Polynesians needs to cover NORSA. Methods to detect oxacillin resistance need to be robust.

Varicella-zoster virus infection in Australia

OBJECTIVE

To determine the epidemiology of varicella-zoster virus (VZV) infection in Australia using currently available data sources.

DESIGN

Analysis of national death data (23 years), congenital and neonatal cases (one year) and attendances at sentinel general practices (two years); hospital admissions in NSW and SA (six years); serological studies in 1995 involving antenatal clinics in Sydney and Brisbane and child-care centre staff and refugees in Sydney; and case-ascertainment in 1995 in South Western Sydney among public hospital staff, child-care centre staff and the community.

RESULTS

In Australia, there have been an average of 3.5 deaths from chickenpox (mostly children) and 11 from herpes zoster (mostly older people) each year since 1980. The crude death rate for chickenpox has declined (p > 0.05). In 1995, there were 14 cases of neonatal and two of congenital varicella. Average annual admission rates for NSW and SA showed 1,200 hospital bed-days used for chickenpox, more than 20% with complications, and more than 7,300 bed days for zoster; annually more than 880 in-patient admissions were complicated by VZV. Most people encounter the virus in their first 15 years, but some remain susceptible into their 20s; 25% of cases and 37% of hospital admissions for chickenpox occur in people > or = 15 years of age.

CONCLUSION

VZV infection involves people of all ages. It causes substantial morbidity and mortality, particularly at the extremes of life. The death rate from chickenpox but not zoster has fallen since the introduction of acyclovir in the 1980s. Surveillance of VZV infection must be given priority once vaccines become available, to monitor changes in morbidity and mortality.

Rare disease surveillance

Rare diseases in children account for disproportionate morbidity and mortality and are particularly demanding of both families and health resources. Surveillance may provide data on their epidemiology, aetiology, management and outcome and on the support requirements of affected children. Existing methods for rare disease surveillance include mandatory and voluntary notification schemes, which may be active or passive, hospital discharge databases and death certification data. The recent establishment of the Australian Paediatric Surveillance Unit has facilitated active, prospective, national case ascertainment by voluntary notification of selected rare conditions. Information obtained should enable estimation of incidence rates, evaluation of prevention and management strategies, extend data collected by existing methods and help estimate future health needs.