Monitoring the prevalence of antibiotic resistance
provides information from which empirical antibiotic therapy strategies should
be reassessed.
Latest data from the Alexander Project, a worldwide
surveillance programme of susceptibility in community-acquired lower
respiratory tract infection (LRTI), show that the prevalence and degree of
resistance in key pathogens – Streptococcus
pneumoniae, Haemophilus influenzae
and Moraxella catarrhalis – vary
across Europe and the USA. There are continued high rates of
penicillin-non-susceptible S. pneumoniae
(MIC ³0.12 mg/l) in some regions, particularly
centres in Spain (47%) and France (62%). Of further concern is the recent
emergence of strains exhibiting penicillin MICs ³8 mg/l. In contrast, the
prevalence of penicillin-non-susceptible S.
pneumoniae strains does not exceed 10% in centres in Germany and the Czech
Republic. There are also an increasing number of reports of macrolide-resistant
S. pneumoniae (erythromycin MIC ³1 mg/l) in some European countries, in many
cases the rates of macrolide resistance are higher than those of penicillin.
Data from the Alexander Project show high levels of beta-lactamase-producing H. influenzae strains. In M. catarrhalis, beta-lactamase-producing
strains dominate with the prevalence exceeding 90% in many European countries.
There is evidence that in isolates from children the prevalence of resistance
is even higher than that seen in adults.
Analysis of MIC90 data for a range of
antibiotics shows that some agents, such as amoxicillin, have maintained good
activity against S. pneumoniae,
including penicillin-non-susceptible strains, compared with some cephalosporins
and with macrolides. The combination of amoxicillin plus clavulanate is highly
active against H. influenzae and M. catarrhalis, including
beta-lactamase-producing strains. In contrast, the higher MIC90 of
macrolides against H. influenzae
indicates their relatively low intrinsic activity, suggesting they are less
suitable empirical therapy choices for RTIs.
These findings emphasize the need for continued
epidemiological surveillance of antibiotic resistance, both globally and
locally and within defined patient populations such as children.