Outbreak of In-Hospital Linezolid-Resistant Staphylococcus Aureus Contained Through Isolation, Reduced Antibiotic Use: Presented at ICAAC/IDSA

Outbreak of In-Hospital Linezolid-Resistant
Staphylococcus Aureus Contained Through Isolation,
Reduced Antibiotic Use: Presented at
ICAAC/IDSA

By Ed Susman

WASHINGTON, DC -- October 30, 2008 -- An in-hospital outbreak of 12 cases of linezolid-resistant methicillin-resistant Staphylococcus aureus (MRSA) in Madrid, Spain -- possibly the first such outbreak reported -- was contained by the use of strict barrier precautions, according to researchers reporting here at the 48th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) and Infectious Diseases Society of America (IDSA) 46th Annual Meeting.

Miguel Sanchez, MD, Hospital Clinico San Carlos, Madrid, Spain, said the cases were discovered at his institution between April and June of 2008. Half of the patients who were infected eventually died in the hospital, Dr. Sanchez noted at his late-breaker poster presentation on October 27.

Eleven of the 12 cases were full-blown infections, including 5 cases of ventilator-associated pneumonia, 5 cases of bacteraemia, and 1 case of catheter-related sepsis. The remaining case was a simple colonisation and did not result in disease. All of the MRSA infections were acquired in the hospital, Dr. Sanchez stated.

While isolated instances of resistance to linezolid have been seen, "to the best of our knowledge this is the first clinical outbreak" of linezolid-resistant MRSA, Dr. Sanchez said.

Dr. Sanchez and his hospital colleagues instituted strict barrier precautions and a "drastic reduction in the use of linezolid" as they faced the serious health hazard, which demonstrated resistance to 1 of the "last resort" drugs. Since June 27, 2008, there have been no further cases, Dr. Sanchez said.

"Half of the patients died in the hospital, so it's an important event," said Dr. Sanchez, "but the other message is that we were capable of controlling it relatively quickly."

Hospital pathology identified 3 clones of resistant MRSA in the 11 cases where disease resulted, and 9 patients had the same clone, suggesting transmission from patient to patient. Dr. Sanchez said that all of the clones proved susceptible to a range of other antibiotics, including vancomycin and tigecycline. Clinicians were able to clear all of the infections.

Dr. Sanchez noted that the mortality attributable to the infections was 0, but 42% of the patients succumbed to underlying diseases. Hospital mortality was 50%.

The average stay in the intensive care unit was 34 days before the patients developed the linezolid-resistant strain.

The major clinical implication of the report, Dr. Sanchez concluded, is that doctors must be careful not to overuse antibiotics. In Hospital Clinico San Carlos, the use of linezolid went from 202 daily defined doses in April 2008 to 25 doses in July 2008.

[Presentation title: Outbreak of Linezolid-Resistant Staphylococcus Aureus in Intensive Care. Abstract C2-1835a]

Source: DGNews | Posted 1 week ago