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BackgroundProcalcitonin (PCT) is a diagnostic biomarker for bacterial infections in critically-ill patients. However, the cut-off value of PCT for the diagnosis of bacterial infections is unclear and unreliable. This study aimed to determine the optimal cut-off value of PCT for the diagnosis of bacterial infections in critically-ill patients.Materials and MethodsWe conducted a retrospective study involving 311 adult patients who had been admitted to the medical or surgical intensive care unit for more than 24 hours from 2013 to 2015. At least one blood test for PCT level was performed for all patients within the first 24 hours of suspecting an infection.ResultsOne hundred and fifty-seven patients had bacterial infections, while 154 did not. Patients with bacterial infections had a significantly higher median PCT level than those without bacterial infections (1.90 ng/mL vs. 0.16 ng/mL, P <0.001). The area under the receiver operating characteristic curve of PCT for discriminating between bacterial and non-bacterial infections was 0.874 (95% confidence interval: 0.834, 0.914; P <0.001). The optimal cut-off value of PCT for differentiating between fevers due to bacterial infections from those due to non-bacterial infections was 0.5 ng/mL, with a sensitivity of 84.7%, specificity of 79.9%, positive predictive value of 81.1%, and negative predictive value of 83.7%.ConclusionPCT was found to be an accurate biomarker for the diagnosis of bacterial infections among patients admitted to medical and surgical intensive care units. The optimal cut-off value of PCT for the diagnosis of bacterial infections was 0.5 ng/mL.

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Methicillin-resistant Staphylococcus aureus (MRSA) is a common pathogen in human diseases. Thirtyseven clinical clones from different patients were tested for a molecular study of the mecA gene and multilocus sequence types (ST). Total genomic extraction, followed by a polymerase chain reaction (PCR) for DNA amplification with specific primers for mecA, and specific primers for various ST were used. Molecular typing for the study of genetic relationships among clones was performed by enterobacterial repetitive intergenic consensus (ERIC)-PCR. Antimicrobial susceptibility testing for all clones to 9 drugs was performed by the disk diffusion and vancomycin Etest. The presence of mecA was detected in all clones. The most common ST was MRSA-ST30, accounting for 81.1% of all MRSA tested, followed by MRSA-ST8/ST97/ST779 (8.1%), MRSA-ST239 (2.7%) and MRSA-nontypeable clones (8.1%). Molecular typing by ERIC-PCR demonstrated DNA fingerprints with corresponding results with sequence types. All clones were susceptible (70-100%) to fosfomycin, fusidic acid, gentamicin, tetracycline, trimethoprimsulfamethoxazole and vancomycin [minimal inhibitory concentration (MIC) range, MIC 50 and MIC 90 were 0.25-1.0, 0.5 and 0.75 µg/ml, respectively by using E-test] but resistant to ciprofloxacin, clindamycin and erythromycin. Inducible macrolide, lincosamide-type B streptogramin resistance (iMLSB) phenotype was 5.4% while constitutive MLSB phenotype was 91.9%. For MRSA-ST30 clones, 96.7% were multi-drug resistant (MDR) with the most common pattern being resistant to ciprofloxacin, clindamycin and erythromycin. These results suggest the importance of MRSA in the field of epidemiology at a hospital in Thailand.

Gentamicin removal during intermittent peritoneal dialysis was studied in 13 uremic patients. The peak serum level after 80 mg of gentamicin intravenous drip was 6.00 ± 1.3 μg/ml with a serum half-life of 13.6 ± 4.07 h. The gentamicin dialysate level did not correlate with the corresponding serum concentration. The peritoneal gentamicin clearance (10.0 + 3.65 ml/min) correlated with the rate of protein loss, but not with the peritoneal clearances of urea and creatinine. When 4% glucose dialysate was used, the clearance of the drug increased considerably along with the ultrafiltration rate. Adding gentamicin (5 μg/ml) to the dialysate resulted in a sustained serum drug level. The mechanism of gentamicin transport through the peritoneal membrane is discussed. The study demonstrated significant removal of gentamicin during intermittent peritoneal dialysis.