Intra-abdominal bacterial growth and detection of bacteria by fluorescence in situ hybridization in patients with secondary peritonitis

Abstract

Abstract Background Patients with secondary peritonitis are treated by surgery and intravenous antibiotics depending on the micro-organisms cultured from abdominal fluid samples. However, such samples may not be representative of the origin of the intra-abdominal infection. Therefore, this study determined (1) whether different micro-organisms are cultured from abdominal fluid, peritoneum and blood samples, and (2) whether fluorescence in situ hybridization (FISH), with 16S ribosomal RNA-targeted probes applied on peritoneum samples, is more efficient than standard culturing techniques. Methods In a pilot study, samples of abdominal fluid, peritoneum and blood were obtained from two groups of patients: six patients with secondary peritonitis (peritonitis group) and five patients without peritonitis (control group). Results Standard culturing techniques revealed coagulase-negative staphylococci (CNS) and yeast in abdominal fluid samples in three of six patients; Escherichia coli, enterococci, CNS and Citrobacter in peritoneum samples in five of six patients; and no micro-organisms in the blood samples from the peritonitis group. In the control group, CNS were cultured from the abdominal fluid samples in one of five patients, while no micro-organisms were cultured from peritoneum samples and CNS were cultured from the blood samples in one of five patients. The FISH technique revealed a large number of various anaerobic bacteria in peritoneum samples in one of six patients in the peritonitis group. In the control group no bacteria were detected. Conclusion Micro-organisms cultured from abdominal fluid differ from those cultured from peritoneum samples. The FISH technique confirmed these findings in only one case. However, it is a promising technique for the identification and localization of bacteria causing secondary peritonitis.