Identification and Characterization of “ Haemophilus quentini ” Strains Causing Invasive Disease in Ontario, Canada (2016 to 2018)

Abstract

Haemophilus influenzae is a well-established human pathogen capable of causing a range of respiratory and invasive diseases. Since the 1970s, it has been observed that a nontypeable cryptic genospecies of H. influenzae, most often biotype IV, has been associated with the genitourinary tracts of females and with invasive neonatal infections. This distinct genospecies has been provisionally named “Haemophilus quentini.” Here, we report seven cases of invasive H. quentini disease in patients from Ontario, Canada, over a 2-year period. Significantly, while most reports of invasive disease with H. quentini to date have been in neonates, we observed five cases in adults (three in women of childbearing age and two in seniors) as well as two in neonates. Identification of H. quentini is challenging and was not possible for frontline laboratories, requiring work at the reference laboratory level. We describe in detail the biochemical results, matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-Tof MS) results, and PCR results with several targets, including the 16S rRNA gene and multilocus sequence typing (MLST) genes, for the seven Ontario H. quentini isolates and several controls. Our data, combined with those of other publications, support the fact that H. quentini is distinct from H. influenzae and Haemophilus haemolyticus. This organism is recognized as a pathogen of neonates, but we hypothesize that it may be underrecognized as an important pathogen in adults as well, particularly pregnant women. By sharing the detailed descriptions of these isolates, we hope to enable other laboratories to better identify H. quentini so that the true prevalence of this organism and disease can be explored.

Invasive Haemophilus influenzae Infections after 3 Decades of Hib Protein Conjugate Vaccine Use

“…H. quentini has also been isolated from urine and urethral cultures in adult males (224). Between 2016 and 2018, the Public Health Ontario laboratory in Toronto identified seven cases of invasive H. quentini infection (225). Two of the isolates were from neonates, three were from adult females of childbearing age (2 were known to be pregnant), and one was from an elderly female.…”

“…H. quentini strains were identified as nontypeable, biotype IV, possessed sodC, and lacked fucK, with detection of the H. quentini-specific 16S rRNA gene and near-full-length 16S rRNA gene sequencing, tests which require referral to a reference laboratory. Given the need for testing not generally available in routine diagnostic laboratories, H. quentini may well be an underrecognized pathogen in adults, especially in pregnant women (225).…”

Invasive non-typeable Haemophilus influenzae infection due to endometritis associated with adenomyosis

“…Martin and colleagues described a case of NTHi bacteremia due to acute endometritis, in which the uterus appeared to be the nidus of NTHi infection with no known primary focus [14]. Also, it has been reported that Haemophilus quentini, a NTHi biotype IV isolate, may have a predilection for female urogenital tract [15]. While identification of H. quentini isolates are not currently feasible at frontline laboratories, it is worth noting that NTHi could be an important causative pathogen of gynecological infections.…”

Haemophilus seminalis sp. nov., isolated from human semen

“…Some of the genital specificity of serologically non-typable H. influenzae biotype IV were considered to represent a new Haemophilus species, named as ‘ Haemophilus quentini ’ [8, 9, 12, 13]. In this report, we describe a novel Haemophilus species isolated from human semen, which is phylogenetically related to H.…”