Pan et al. Journal of Medical Case Reports 2011, 5:377 http://www.jmedicalcasereports.com/content/5/1/377 susceptibility to the antibiotics were provided simulta- neously (Table 1). In this case, the R. pickettii isolate was susceptible to cefoperazone sodium-sulbactam sodium, ceftazidime, and imipenem according to the disk diffusion method. The pathogen was resistant to amikacin, ceftriaxone, ciprofloxacin, mezlocillin, aztreo- nam, and gentamicin. Our patient received an antibiotic course of intravenous cefoperazone sodium-sulbactam sodium for eighteen days and imipenem-cilastatin for twelve days. A repeat chest X-ray performed forty-eight days later revealed resolution of the pulmonary abscess and improvement of pneumonia. The patient remained afebrile and free of respiratory symptoms at follow-up two months later. Discussion Human infection with R. pickettii without exposure to contaminated solutions is rare and isolation of the organism in culture alone is often attributed to labora- tory contamination rather than to infection. Therefore, infection with R. pickettii is typically diagnosed when treatment targeting the organism and/or removal of an infected source is associated with clinical improvement. For example, a recently reported case of R. pickettii infection in a pediatric oncology unit described clinical improvement only with catheter removal and appropri- ate antimicrobial therapy [10]. In this case, isolation of R. pickettii in culture from a sterile site coupled with clinical improvement following thoracentesis and tar- geted antimicrobial therapy increases the likelihood that the organism was the pathogenic source. In our case, there had been no use of respiratory therapy solutions excluding the possibility of exposure to fluids contami- nated with R. pickettii. R. pickettii is generally believed not to be the pri- mary pathogen and, alone, its infectivity is very low. Recent reports show that it can lead to a number of potentially serious infections, nosocomial outbreaks [4,11] and even death [3]. Antimicrobial susceptibility patterns reported for R. pickettii vary widely. R. Page 3 of 4 pickettii can produce extended-spectrum b-lactamases, which are not commonly sensitive to inhibitors of b- lactamase [12-15]. They show that the organism is resistant in different degrees to ciprofloxacin, tri- methoprim-pyrimidine, sulfamethoxazole, piperacillin- tazobactam, imipenem and cilastatin, ceftazidime. Fol- lowing susceptibility studies, our patient was success- fully treated with intravenous cefoperazone sodium- sulbactam sodium for eighteen days and imipenem- cilastatin for twelve days. Conclusion We describe the case of an older man who developed R. pickettii infection in the absence of an obvious nosoco- mial source demonstrating the possibility that such de novo cases will become more common in the future. Although it is of low virulence, it has been identified as causing many potentially harmful infections, and even death. The pathogen was resistant to many antibiotics, so its sensitivity to the common antibiotics should be monitored regularly. Consent Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal. Abbreviations CLSI: Clinical and Laboratory Standards Institute; CT: computed tomography; R. Pickettii: Ralstonia pickettii. Acknowledgements We thank Baofa Wang, Yadong Yuan (Hebei Medical University), Jessica A. Hennessey and Chuan Wang (Duke University Medical Center) for helping in writing this manuscript. Author details 1Department of Respiratory Medicine, the Second Hospital of Hebei Medical University, Shijiazhuang, China. 2Department of Reproductive Medicine, the Second Hospital of Hebei Medical University, Shijiazhuang, China. 3Department of Internal Medicine, the Affiliated Hospital of Hebei University of Science and Technology, Shijiazhuang, China. Table 1 Breakpoints used to determine resistance and susceptibility to antimicrobial therapy Antimicrobial Agent Disk Content Zone Diameter Breakpoints, nearest whole mm mezlocillin ceftazidime cefoperazone ceftriaxone imipenem aztreonam gentamicin ciprofloxacin 75 μg 30 μg 75 μg 30 μg 10 μg 30 μg 10 μg 5 μg S ≧ 16 ≧ 18 ≧ 21 ≧ 21 ≧ 16 ≧ 22 ≧ 15 ≧ 21 I - 15-17 16-20 14-20 14-15 16-21 13-14 16-20 R ≦ 15 ≦ 14 ≦ 15 ≦ 13 ≦ 13 ≦ 15 ≦ 12 ≦ 15