Haemophilus seminalis sp. nov., isolated from human semen

Abstract

Two <i>Haemophilus</i>-like isolates with similar biochemical characteristics, designated strains SZY H1^T and SZY H2, were isolated from human semen specimens. Cells were Gram-negative, non-motile, non-acid-fast, pleomorphic rods or coccobacilli. The major fatty acids (>10 %) were C_{16 : 0}, C_{14 : 0}, iso-C_{16 : 0} and/or C_{14 : 0} 3-OH and C_{16 : 1} <i>ω</i>6<i>c</i> and/or C_{16 : 1} <i>ω</i>7<i>c</i>. The polar lipids were determined to be phosphatidylethanolamine, phosphatidylglycerol, an unidentified phospholipid, an unidentified aminophospholipid, two unidentified polar lipids and four unidentified aminolipids. The major polyamine was found to be cadaverine. The near-full-length (1462 nt) 16S rRNA gene sequences analysis showed the two isolates were nearly identical (>99.8 %), and closely matched <i>Haemophilus haemolyticus</i> ATCC 33390^T with 98.9-99.1 % sequence similarities. Phylogenetic analysis based on 16S rRNA gene sequences and concatenation of 30 protein markers also revealed that the isolates clustered together with <i>H. haemolyticus</i> ATCC 33390^T, and formed a distinct lineage well separated from the other members of the genus <i>Haemophilus</i>. Further, the average nucleotide identity values between the two isolates and their related species were below the established cut-off values for species delineation (95 %). Based on these findings, the two isolates are considered to represent a new species of the genus <i>Haemophilus</i>, for which name <i>Haemophilus seminalis</i> sp. nov. is proposed. The type strain is SZY H1^T (=NBRC 113782^T=CGMCC 1.17137^T).