No abstract

Acinetobacter baumannii primarily causes colonization, yet it can be an opportunistic pathogen associated with hospital-acquired infections. Many countries report rapid spread of carbapenem-resistant Acinetobacter baumannii (CRAb) which limits treatment options, with colistin frequently being the last line treatment option. The aim of our study was to evaluate a recently developed rapid method, namely the Rapid ResaPolymyxin test, for detection of colistin resistance (ColR) in Acinetobacter baumannii. This test was used for rapid screening of colistin resistance in a clinical setting where there is endemicity of CRAb isolates. A total of 82 A. baumannii clinical isolates were included in the evaluation. The majority of them were resistant to carbapenems (75/82, 91.5%). A total of 37 isolates (45.1%) were resistant to colistin, all being resistant to carbapenems. None of the ColR isolates carried the plasmid-mediated mcr-1 to-5 genes. The Rapid ResaPolymyxin NP test reached a 95.1% categorical agreement with results of reference broth microdilution method, with 93.3% sensitivity and specificity, and positive and negative predictive values being respectively at 92.3% and 97.7%. The Rapid ResaPolymyxin NP test performed well on our collection of clinical and surveillance CRAb isolates from the Central Slovenia region. The test is inexpensive and easy to integrate into laboratory workflow. The main value of the test is rapid categorization of susceptibility and resistance which has important implications with respect to the treatment strategy as well as the infection control measures.

rt-PCR on plasma and other samples performed significantly better than culture for the detection of pneumococcal pneumonia (p < 0.0005) in children and adults.

Early postoperative prosthetic valve endocarditis due to Stenotrophomonas maltophilia was diagnosed in seven patients (two men) aged from 68 to 84 years (mean age 78.1 years) over a three-year period. All patients had undergone aortic valve replacement. S. maltophilia was isolated from at least two blood cultures per patient. Four patients experienced CNS embolic complications. Three patients died. All patients were treated with ceftazidime, one in combination with amikacin, one with ciprofloxacin and one with levofloxacin. Because a common source of infection in the operating theater was suspected, 24 environmental samples were taken, of which two contained S. maltophilia. Six of the seven clinical isolates from the patients and two isolates from the environment were analyzed using molecular typing by pulsed-field gel electrophoresis (PFGE). The patients' isolates were resistant to gentamicin, ciprofloxacin, trimethoprim/sulfamethoxazole and, except in one case, to amikacin and piperacillin/tazobactam and susceptible to ceftazidime and levofloxacin. In contrast, the environmental isolates were resistant to ceftazidime, showed intermediate susceptibility to ciprofloxacin, and were susceptible to trimethoprim/sulfamethoxazole. PFGE demonstrated indistinguishable or closely related (1-3 band difference) PFGE patterns in isolates from the patients, but a different pattern in the environmental isolates. No common source of infection was found despite intensive investigation. Extensive cleaning and other measures of infection control were carried out and no new cases were recorded in the two year follow-up period.