RESUMO
BACKGROUND: Here, we report the frequency of capsulated ampicillin-resistant Haemophilus influenzae strains isolated from children in Tunisia, particularly capsular serotype b, by polymerase chain reaction (PCR) to determine the molecular mechanisms underlying ampicillin resistance. METHODS: We considered 22 capsulated H influenzae strains selected from a series of 91 ampicillin-resistant H influenzae strains isolated from children between 2010 and 2011 in Tunisia. The capsular serotypes of these strains were identified by slide agglutination and PCR. RESULTS: By PCR, 19 (20.88%) serotype b, 1 (1.1%) serotype a, 2 (2.2%) serotypes d and f and 69 (75.82%) non-typeable strains were found among the 91 ampicillin-resistant H influenzae strains. 100% of the assumption between the consequences of antigenic examinations and PCR was found. The serotype b strains showed biotypes I, II, III, IV, VI, and VIII. The other capsulated strains showed biotypes IV and VIII. Thirteen of the serotype b strains created ß-lactamase (14.28%). The 19 serotype b ampicillin-resistant H influenzae strains were subdivided into 3 bunches as indicated: The gathering of the ß-lactamase positive, ampicillin-resistant where 11 strains (57.89%) were ß-lactamase positive blaTEM-1 (+) and ftsI (+). The second gathering of the ß-lactamase negative, ampicillin-resistant strains, where 6 isolates (31.58%) were ß-lactamase negative blaTEM-1 (-) and ftsI (-), and lastly, the gathering of the ß-lactamase positive, amoxicillin-clavulanate resistant where 2 isolates (10.52%) were ß-lactamase positive blaTEM-1 (+) and ftsI (-). CONCLUSION: PCR should be used in our country because it may contribute to decreasing the probability of transmission of these strains, especially those showing the two mechanisms of resistance among children in Tunisia.
