Community prescribing and resistant Streptococcus pneumoniae

Abstract

We investigated the association between prescribing antimicrobial agents and antimicrobial resistance of Streptococcus pneumoniae among children with acute otitis media in southern Israel. During a 6-year period, all prescriptions of a sample of approximately 20% of Jewish and Bedouin children <5 years of age were recorded and all pneumococcal isolates from middle ear fluid were collected. Although antimicrobial drug use was significantly higher in Bedouin children, the proportion of S. pneumoniae isolates with penicillin MIC = or > 1.0 microg/mL was significantly higher in Jewish children. In both populations, antimicrobial prescriptions were markedly reduced over time, especially for penicillins and erythromycin. In contrast, azithromycin prescriptions increased from 1998 to 2001 with a parallel increase in macrolide and multidrug resistance. Penicillin resistance was associated with macrolide resistance. These findings strongly suggest that azithromycin affects increased antimicrobial resistance, including multidrug resistance, in S. pneumoniae.

Figure 1

Antimicrobial drug prescription rates for Bedouin and Jewish children <5 years of age in southern Israel from 1998 through 2003. Amoxi, amoxicillin; Amoxi-clav, amoxicillin-clavulanate; Pen, phenoxymethyl penicillin; Azithro, azithromycin; Ceph, cephalosporins (cefazolin, cefaclor, cephalexin monohydrate, and cefuroxime-axetil); Ery, erythromycin.

Figure 2

Proportions of penicillin-resistant Streptococcus pneumoniae isolated during episodes of acute otitis media in Bedouin and Jewish children <5 years of age in southern Israel from 1999 through 2003. Pen-MIC, penicillin MIC (μg/mL); Pen-NS, penicillin-nonsusceptible.

Figure 3

Proportions of erythromycin-resistant and multidrug-resistant Streptococcus pneumoniae isolated during episodes of acute otitis media in Bedouin and Jewish children <5 years of age in southern Israel from 1999 through 2003. Ery-R, erythromycin resistance; MDR, multidrug resistance (resistance to ≥3 antimicrobial classes).

Figure 4

Distribution of penicillin MICs (μg/mL) in erythromycin-susceptible and erythromycin-resistant Streptococcus pneumoniae isolated during episodes of acute otitis media in Bedouin and Jewish children <5 years of age in southern Israel from 1999 through 2003. P was calculated for the difference in overall distribution of penicillin MICs between erythromycin-susceptible and erythromycin-resistant isolates, as well as for difference in relative contribution of isolates with MICs ≥1.0 μg/mL to both groups (p<0.001, Ery-S versus Ery-R in both Bedouin and Jewish children). Ery-S, erythromycin susceptible; Ery-R, erythromycin resistant; Pen-MIC, penicillin MIC.