Infection spreads outside hospitals

THE rapid spread of a drug-resistant infection may cause a serious public health problem, scientists warn.

Methicillin-resistant staphylococcus, or golden staph, has long plagued hospital patients, and now an equally virulent related strain is infecting people who have had no hospital contact.

The infection, known as community-associated MRSA, causes severe boils and abscesses and, sometimes, life-threatening blood poisoning and pneumonia, a Queensland-led study, published in the latest Medical Journal of Australia found.

The study tracked the spread of CA-MRSA over six months last year and compared the results with similar surveys in 2000 and 2002. The strain had grown to be "a major clinical and public health problem", nearly doubling in occurrence from 2000 to 2005, the research found. The study was led by Queensland Health Pathology Service's director of microbiology, Associate Professor Graeme Nimmo.

The strain's prevalence was more marked in Perth, Darwin and Brisbane, and the infection was acquiring resistance to antimicrobial medicine, Associate Professor Nimmo said.

Medical treatment of CA-MRSA would become even more difficult in the future, he said.

"The large distances between Australian cities have been no barrier to the rapid spread of the major epidemic strains," he said.

"It's even possible that more staphylococcal strains will become methicillin resistant, similar to the spread of penicillin resistance in staphylococci seen in the latter half of the 20th century, which led to penicillin resistance levels of greater than 80 per cent."

His advice was echoed by Associate Professor Paul Johnson, deputy director of the infectious diseases department at Austin Health in Melbourne.

"We are likely to see increasing rates of CA-MRSA in coming years," Associate Professor Johnson said. "Some of this change results from the over-use of antibiotics, and some is the inevitable result of rapid bacterial evolution to which we will have to adapt."

Professor Nimmo conducted the study with scientists from all parts of the country.

AAP

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At the beginning of April 2005, a 37-year-old woman was admitted to the University Hospital Policlinico in Rome because of fever, cough, and headache. Her medical history was unremarkable. She was a teacher in a school for foreign students in Rome, smoked 3 cigarettes per day for 15 years, and reported no recent travel abroad. Her 5-year-old daughter had influenzalike symptoms in the previous week. At hospital admission, her temperature was 39°C, heart rate was108 beats/min, respiratory rate was 32 breaths/min, and blood pressure was 105/70 mmHg. Arterial blood gas analysis showed mild hypoxemia and hypocapnia (PaO₂ 73 mm Hg and PaCO₂ 34 mm Hg on room air). Leukocyte count was 24,360 cells/μL (81% polymorphonuclear cells), and platelet count was 506,000/μL. Chest radiograph showed infiltrates in the right upper and lower lobes and left lower lobe. Empiric treatment with clarithromycin and ceftriaxone was started, but the patient's clinical conditions did not improve. Culture of sputum samples obtained at admission yielded growth of MRSA. Computed tomographic scan showed multiple lung cavitary lesions, indicating necrotizing pneumonia. On day 3 of admission, antimicrobial drug therapy was changed to linezolid (600 mg 2 times a day). Fever resolved, and the patient's condition rapidly improved. The patient was discharged after 14 days of linezolid treatment. At discharge, leukocyte count was 6,040 cell/μL (58% polymorphonuclear cells), and arterial blood gas analysis showed PaO₂ of 88 mm Hg.<