- Summary Objectives Simkania negevensis , a Chlamydia-like microorganism that has been associated with respiratory infections in children and adults, can multiply within free-living amoebae; moreover, it has been detected in domestic water supplies. The aim of this study was to determine whether there is similarity between Simkania organisms found in water and those detected in clinical samples. Methods PCR, membrane immunoassay for the detection of Simkania antigen, and isolation in cell culture were used for the detection of S. negevensis in nasopharyngeal wash samples (NPW) of 34 children with pneumonia and in domestic water samples from their homes. Sequencing of PCR amplicons was used for comparison of Simkania strains isolated from clinical samples and from water samples. Results In 26 cases (76%) both NPW and water were positive, and partial 16S rDNA sequences suggested that they may be the same organisms. Conclusion Simkania found in domestic water supplies may be transmitted to children .