A Study of Multidrug-Resistant, Colistin-Only-Sensitive Infections in Intubated and Mechanically Ventilated Patients Over 2 Years

BACKGROUND AND AIMS: Multidrug-resistant, Gram-negative infections are increasingly common in the intensive care unit (ICU). This study compares the occurrence and outcome of colistin-only-sensitive (COS) infections among mechanically ventilated patients at a tertiary hospital ICU. METHODS: The study included adult patients admitted over a period of 2 years, who were intubated and mechanically ventilated for more than 48 h. They were divided into two groups, those with COS infections and those without, and their GCS and Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, ICU length of stay, leukocyte count, and mortality were compared. COS patients were divided into neurosurgery, neurology, respiratory, and sepsis with bacteremia groups. The COS organisms in each group, their sources, ICU length of stay, ventilator-free days, and mortality were analyzed. RESULTS: Three hundred and one patients were selected, of whom 41 (13.6%) had COS infections. COS patients had a longer ICU length of stay than non-COS patients (P = 0.001) but comparable APACHE II and GCS scores, leukocyte count, and mortality. The sepsis group accounted for 8 out of 15 (53%) deaths among COS patients (P = 0.03). Acinetobacter baumannii accounted for 61% of the COS infections, Klebsiella pneumonia: 24.4%, Pseudomonas aeruginosa: 12.2%, and Escherichia coli: 2.4%. Endotracheal secretion cultures accounted for 65.8% of COS isolates, urine cultures 17%, pus cultures 7.3%, and blood cultures 4.9%. ICU length of stay, ventilator-free days, and mortality were similar between each COS organism. CONCLUSION: Intubated patients with multidrug-resistant, COS infections have a longer stay in ICU than non-COS patients. COS infections associated with bacteremia have high mortality.