Intensive care patients are especially vulnerable to picking up infections in hospital, due to their poor health. Researchers from the Karolinska Institutet in Sweden found that 70% of intensive care patients studied were colonized with bacteria from other patients in the unit.

The researchers investigated the transmission of several strains of Staphylococcus bacteria, called CoNS. These strains are the primary cause of circulatory infections picked up in hospitals, and the third most common cause of all hospital infections. "These species have the ability to survive in the ICU surroundings on medical devices and equipment for weeks up to months," say the researchers. "They are specifically prone to causing catheter-related infections."

The team, led by Professor Charlotta Edlund, took swabs from the upper and lower airways of 20 intensive care patients that had required mechanical ventilation for at least three days. The researchers cultured the bacteria from these swabs and analysed the genetic fingerprints of Staphylococcus strains to identify bacteria that were identical or closely related. They could then assess the transmission rates of bacteria between patients, by seeing which patients harboured the same bacterial strains.

17 of the patients were colonised by CoNS during their hospital stay. In six of these cases, the bacteria had colonised the lower airways after the patient was ventilated, suggesting that the procedure itself had introduced the bacteria. 14 of the patients had either passed on a bacterial strain to another patient or received a bacterial strain from another patient. Worryingly, one patient passed on bacteria
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BioMed Central
21-Dec-2003