Haemophilus segnis polymicrobial and monomicrobial bacteraemia identified by 16S ribosomal RNA gene sequencing

• Published in: Journal of medical microbiology Vol. 51; no. 8; pp. 635 - 640
• Main Authors: LAU, SUSANNA KAR-PUI, WOO, PATRICK CHIU-YAT, CHAN, BENEDICT YIN-LEUNG, FUNG, AMI MEI-YUK, QUE, TAK-LUN, YUEN, KWOK-YUNG
• Format: Journal Article
• Language: English
• Published: Reading Soc General Microbiol 01.08.2002; Society for General Microbiology
• Subjects: Adult; Aged; Aged, 80 and over; Bacteremia - microbiology; Bacterial diseases; Bacterial endocarditis, myocarditis and pericarditis. Bacterial diseases of the aorta, limb vessels and lymphatic vessels; Biological and medical sciences; Colitis - microbiology; Colitis - pathology; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; Empyema, Pleural - microbiology; Female; Haemophilus - classification; Haemophilus - genetics; Haemophilus - growth & development; Haemophilus Infections - microbiology; Human bacterial diseases; Humans; Infectious diseases; Male; Medical sciences; Phylogeny; Polymerase Chain Reaction; RNA, Ribosomal, 16S - chemistry; RNA, Ribosomal, 16S - genetics; Sequence Analysis, DNA; Sequence Homology, Nucleic Acid; Infection; Pasteurellaceae; Case study; Human; Mixed infection; Bacteriosis; Bacteria; Identification; Haemophilus segnis; Bacteremia
• ISSN: 0022-2615; 1473-5644
• DOI: 10.1099/0022-1317-51-8-635

Department of Microbiology, University of Hong Kong, Queen Mary Hospital, and Department of Microbiology, Tuen Mun Hospital, Hong Kong Corresponding author: Dr K-Y. Yuen (e-mail: hkumicro{at}hkucc.hku.hk ). Received 29 June 2001; revised version received 2 Jan. 2002; accepted 9 Jan. 2002. 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°C in air with CO 2 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%.