According a study in Clinical Infectious Diseases, antibiotics were ineffective both in reducing Staphylococcus aureus in the lower airway and preventing ventilator-associated tracheobronchitis and pneumonia in ventilated patients, Healio reports.

In a study of 48 patients, 21 were colonized with MRSA, and 27 were colonized methicillin-susceptible S. aureus (MSSA). All patients were treated with “appropriate” anti-staphylococcal antibiotics for at least 2 days.

Of the 18 patients with MRSA treated with vancomycin, only one experienced reduced bacterial burden. The other three patients with MRSA received linezolid, which did not yield a microbiological response.

Of the 15 patients with MSSA treated with vancomycin, nine did not respond. The remaining six received vancomycin along with one or two other antibiotics and showed bacterial counts with a decreasing tendency, from heavy to light.

Of the 39 patients colonized only by S. aureus, 13 were diagnosed with ventilator-associated tracheobronchitis (VAT) and 15 with ventilator-associated pneumonia (VAP). Five of those initially diagnosed with tracheobronchitis progressed to pneumonia.