title: Haemophilus segnis polymicrobial and monomicrobial bacteraemia identified by 16S ribosomal RNA gene sequencing.
abstract: This paper reports a case of Haemophilus segnis polymicrobial bacteraemia and a case of H. segnis monomicrobial bacteraemia identified by 16S ribosomal RNA gene sequencing. In the first case, a gram-negative aerobic coccobacillus was isolated with Streptococcus intermedius and S. sanguis from the blood culture of a 32-year-old intravenous drug addict with left thoracic empyema. In the second case, a gram-negative aerobic coccobacillus was isolated from the blood culture of an 82-year-old woman with Clostridium difficile colitis and septicaemic shock. Both gram-negative coccobacilli grew on chocolate agar as colonies of 1 mm in diameter after incubation for 24 h at 37 degress C in air with CO2 5%, but only to pinpoint sizes on blood agar under the same incubation conditions. Both strains were factor V-dependent, but not factor X-dependent. For the first isolate, the Vitek system (NHI) showed that it was 56% likely to be Actinobacillus actinomycetemcomitans and 40% Neisseria subflava; whereas the API system (NH) showed that it was 58% likely to be H. aphrophilus/paraphrophilus and 42% H. parainfluenzae. For the second isolate, the Vitek system (NHI) showed that it was 95% likely to be H. influenzae VIII; whereas the API system (NH) showed that it was 58% likely to be H. aphrophilus/paraphrophilus and 42% H. parainfluenzae. 16S rRNA gene sequencing showed that there were four base differences between isolate 1 and H. segnis and two base differences between isolate 2 and H. segnis, indicating that both isolates most closely resembled a strain of H. segnis. Only two cases of H. segnis bacteraemia were found in the English scientific literature, one in a case of infective endocarditis and the other in a case of pancreatic abscess. Including the present two cases, the overall mortality of H. segnis bacteraemia was 50%.
authors.affiliation: Department of Microbiology, University of Hong Kong, Queen Mary Hospital, and Department of Microbiology, Tuen Mun Hospital, Hong Kong.
authors.forename: Susanna Kar-Pui
authors.initials: SK
authors.lastname: Lau
authors.affiliation: Department of Microbiology, University of Hong Kong, Queen Mary Hospital, and Department of Microbiology, Tuen Mun Hospital, Hong Kong.
authors.forename: Patrick Chiu-Yat
authors.initials: PC
authors.lastname: Woo
authors.affiliation: Department of Microbiology, University of Hong Kong, Queen Mary Hospital, and Department of Microbiology, Tuen Mun Hospital, Hong Kong.
authors.forename: Benedict Yin-Leung
authors.initials: BY
authors.lastname: Chan
authors.affiliation: Department of Microbiology, University of Hong Kong, Queen Mary Hospital, and Department of Microbiology, Tuen Mun Hospital, Hong Kong.
authors.forename: Ami Mei-Yuk
authors.initials: AM
authors.lastname: Fung
authors.affiliation: Department of Microbiology, University of Hong Kong, Queen Mary Hospital, and Department of Microbiology, Tuen Mun Hospital, Hong Kong.
authors.forename: Tak-Lun
authors.initials: TL
authors.lastname: Que
authors.affiliation: Department of Microbiology, University of Hong Kong, Queen Mary Hospital, and Department of Microbiology, Tuen Mun Hospital, Hong Kong.
authors.forename: Kwok-Yung
authors.initials: KY
authors.lastname: Yuen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000382:microbiology; D003092:Colitis / Q000382:microbiology / Q000473:pathology; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D016724:Empyema, Pleural / Q000382:microbiology; D005260:Female; D006190:Haemophilus / Q000145:classification* / Q000235:genetics / Q000254:growth & development; D006192:Haemophilus Infections / Q000382:microbiology*; D006801:Humans; D008297:Male; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000235:genetics*; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S