Methods: 169 KP isolates and respiratory samples were collected from patients admitted to King Chulalongkorn Memorial Hospital, Bangkok, Thailand from Jun 2017 to Dec 2017. The automated PCR test was performed directly from respiratory specimens. The results were compared with in-house PCR for detection of carbapenemase genes performed on KP colonies isolated from respiratory specimens as our reference method. Patient and clinical characteristics between patients with CPK and non-CPK were also analyzed.
Results: The prevalence of CPK was 10.6% (18/169 isolates). The automated PCR test had 91.12% accuracy, 66.7% sensitivity (95% CI, 40.9 to 86.6), 94.0% specificity (95% CI, 88.9 to 86.6), 57.1% positive predictive value (95% CI, 39.5 to 73.1) and 95.9% negative predictive value (95% CI, 92.48 to 97.85). Of 18 isolates, blaOXA-48 was the most common carbapenemase gene (17 isolates; 94.4%), followed by blaNDM-1 (7 isolates; 38.9%). A combination of blaOXA-48 and blaNDM-1 was detected in 6 isolates (33.3%). There were 7 (38.8%) colonizations and 11 (61.1%) infections. The significant risk factors for CPK included post-surgery (p=0.04) and prior antibiotics exposure (p=0.04). There was a trend toward higher mortality in patients with CPK albeit not significantly (33% vs. 24.5%, p=0.41).
Conclusion: The automated PCR test has an acceptable accuracy with fair sensitivity for the detection of carbapenemase genes. It is unique that OXA-48 and OXA-48/NDM-1 are the most common carbapenemases in our institute. This diagnostic test may be use for rapid diagnosis or infection control purposes. Exposure to antibiotics associated with colonization or infection with CPK. Patients with CPK had higher mortality.
G. Suwanpimolkul, None
T. Chatsuwan, None