Antimicrobial susceptibility of Haemophilus influenzae ocular isolates collected from outpatients in paediatric hospital

Abstract number: p791

Makri  A., Guajardo  T., Papavasileiou  H., Iliadis  H., Varzakakos   I., Manios  N., Voyatzi  A.

Introduction: 

Haemophilus influenzae (HI) is responsible for a number of human diseases, ranging from chronic respiratory infection to meningitis, which affect children. Eight biotypes and six serotypes of HI have been identified. Biotyping and serotyping have been used to investigate patterns of colonization of HI, as well as to identify stains of the bacterium that appear to be associated with more severe infections.

Objectives: 

To determine which subtypes and biotypes of HI are most commonly associated with ocular disease and to monitor the patterns of antimicrobial sensitivity in children with eye infections.

Material and methods: 

Ocular swabs were collected from the examined population, aged 1 month to 14 years old, who visited our children hospital during the period 2002–2005. Identification and biotyping isolates were performed by classical microbiological methods and by API NH strips (bioMerieux). Capsular subtypes a–f were determined by slide agglutination using commercially available subtype specific antiserum. b-Lactamase production was determined by the chromogenic cephalosporin test with nitrocefin as substrate.

Results: 

A total of 151 HI isolates were recovered from 755 ocular samples submitted to our microbiological department. The majority of the isolates were serologically non typable. The prevalent biotype of HI isolates was biotype II 48.3% (73/151) followed by biotype III accounted 22.5% (34/151). The remaining biotypes were biotype I 12% (18/151), biotype IV 6.6% (10/151), biotype V 4.6% (7/151) and from each one isolate 2% for biotypes VI–VIII. A significant resistance to cotrimoxazole (25%) and in lower rate to clarithromycin (8%) was observed. All the isolates resistant to ampicillin (8%) were b-lactamase producers and susceptible to cefuroxime, cefotaxime, ciprofloxacin and chloramphenicol.

Conclusions: 

This study showed that biotypes II and III are the predominant biotypes of HI found in ocular infection. There is a low prevalence of b-lactamase production and resistance of macrolides while all isolates were sensitive to chloramphenicol. Surveillance is necessary to monitor rates of resistance in the community in order to tailor empiric therapeutic recommentators.