[Detection methods for drug-resistant bacteria in routine examination--BLNAR].
The characteristics of resistance, trend of prevalence and current status of beta-lactamase-negative, ampicillin-intermediate or -resistant(BLNAR) strains of Haemophilus influenzae are summarized by our retrospectively analyzed data. The mechanism of this type of ampicillin-resistance is due to altered penicillin-binding proteins(PBPs). Standardized susceptibility tests may differentiate ampicillin-resistant, beta-lactamase-producing strains from beta-lactamase-negative, ampicillin-susceptible strains(BLNAS), but may not differentiate some strains of BLNAR from those of BLNAS. In the cases of serious infections, such as meningitis due to H. influenzae both beta-lactamase activity and ampicillin susceptibility should be confirmed by the MIC procedure.