Biotypes and serotypes of Haemophilus influenzae ocular isolates

Abstract

Aim: To determine which subtypes of Haemophilus influenzae are most commonly associated with ocular disease, and whether the site of ocular H influenzae infection is correlated with specific subtypes of the organism. Methods: The biotypes and serotypes of ocular H influenzae isolates collected at the Francis I Proctor Foundation between March 1989 and January 2000 were examined. A total of 62 ocular isolates were retrieved from frozen storage and plated on chocolate agar. Biotypes were assigned based upon the ability of the isolates to produce indole, urease, and ornithine decarboxylase. Capsular subtypes a-f were determined by slide agglutination using commercially available subtype specific antisera. Identified biotypes and serotypes were then analysed with regard to site of infection. Results: Patient age ranged from 1 to 92 years with a median age of 45 years. 38 (61%) of the isolates were biotype II, 23 (37%) were biotype III, and one (2%) was biotype VII. All of the isolates were non-encapsulated and thus serologically non-typable. H influenzae biotype II was found in 28 of 48 (58%) conjunctivitis cases, five of eight (63%) keratitis cases, and two of two (100%) endophthalmitis cases. Biotype III was found in 20 of 48 (42%) conjunctivitis cases, two of eight (25%) keratitis cases, and a single case of dacryocystitis. Biotype VII was associated with one of eight (13%) keratitis cases. Conclusion: Most ocular H influenzae isolates appear to be serologically non-typable strains from biotypes II and III, less virulent subtypes that frequently colonise the nasopharynx. In addition, the site of ocular H influenzae infections appears to be largely independent of species subtype.H aemophilus influenzae is responsible for a number of human diseases ranging from chronic respiratory infection to meningitis. Eight biotypes and six serotypes of H influenzae have been identified. Biotyping and serotyping have been used to investigate patterns of colonisation of H influenzae, as well as to identify strains of the bacterium that appear to be associated with more severe infection. Biotype I, serotype b, for instance, is often associated with severe meningitis in children.1 In contrast, non-serotypable strains of H influenzae, particularly biotypes II and III, are frequently commensal to the upper respiratory tract. While colonisation with biotypes II and III usually does not progress to disease, these same biotypes have been implicated in the pathogenesis of sinusitis, otitis media, acute and chronic exacerbations of lower respiratory tract infection, and acute and chronic conjunctivitis. 2-4The relation between H influenzae and specific ophthalmological diagnoses has not been studied. The purpose of this study was to define what subtypes of H influenzae are common in ocular disease, and to determine whether there is a correlation between various H influenzae subtypes and the site of ophthalmic H influenzae infection. METHODSThe organisms included in this study were isolated form clinical samples submitted to the microbiol...

Polymorphisms in Chlamydia trachomatis tryptophan synthase genes differentiate between genital and ocular isolates

“…In contrast to the flora of the female genital tract, however, the ocular microflora are more limited in diversity (57,58), and of those associated with trachoma only H. influenza is an established producer of indole (59). Perhaps there are alternate sites of infection in the eye than the conjunctival epithelium, and the trachoma serovars have adapted a strategy of interacting with these different cellular environments that allows for both productive and persistent infection.…”

Phenotypic diversity of Haemophilus influenzae and Haemophilus parainfluenzae isolates depending on origin and health condition

“…This may be due to the biotype holding a specific affinity to the ciliated epithelium cells [43,47]. This biotype was also sometimes seen as being associated with severe meningitis or cystic fibrosis, in children [1,44], and, generally, with other invasive infection situations [16] induced by H. influenzae (such as sepsis or meningitidis) [54].…”

“…Other researchers put forward that upper respiratory tractassociated H. influenzae isolates usually belong to biotypes II and III and are a part of normal throat microbiome, or, at the same time, are an etiologic factor of a variable number of infections e.g. : sinusitis, otitis media, acute and chronic exacerbations of lower respiratory tract infection, as well as acute or chronic conjunctivitis [1,34,47]. In the most described cases of Haemophilus spp.-induced infections, H. influenzae biotype II was the most frequent, and most of the non-typeable H. influenzae (NTHi) isolates belonged into biotypes II-VI.…”

High nasopharyngeal carriage of β-lactamase-negative ampicillin-resistant Haemophilus influenzae in north Indian school-going children

“…A number of studies have reported that H. infl uenzae type b and biotype I are commonly associated with meningitis in children, and biotype II and III are commonly associated with upper respiratory tract infections. 4,5 Abstract Development of ampicillin resistance in Haemophilus infl uenzae is a cause of serious concern. Ampicillin resistance in H infl uenzae is β-lactamase mediated except in some isolates.…”

“…For example, Weiser 9 reported that more virulent strains were unable to colonize the nasopharynx, whereas our data and other previous studies suggested that the virulent bacteria are circulating widely in the healthy population. 4,5 In USA, the BLNAR H. infl uenzae strains were identifi ed in <2% of strains until the 1990s. The prevalence of BLNAR increased up to 2.5%-10.1% in 1994-1995.…”