Has the licensing of respiratory quinolones for adults and the 7-valent pneumococcal conjugate vaccine (PCV-7) for children had herd effects with respect to antimicrobial non-susceptibility in invasive Streptococcus pneumoniae?
OBJECTIVE
The aim of the study was to analyse the evolution of antibiotic non-susceptibility in Spanish invasive Streptococcus pneumoniae after licensure of respiratory-quinolones for adults and 7-valent pneumococcal conjugate vaccine (PCV-7) for immunization of children.


METHODS
All invasive pneumococci received in the Reference Laboratory (January 2000-August 2007; n = 12 957 isolates) were serotyped, and susceptibility to penicillin/erythromycin/levofloxacin was determined. Antibiotic consumption and PCV-7 doses/year were provided by IMS and the manufacturer, respectively.


RESULTS
In 2000-07, PCV-7 distribution (doses/1000 inhabitants </=59 months age/year) increased from 0.0 to 411.90, and antibiotic consumption (DDD/1000 inhabitants/day) was maintained for beta-lactams ( approximately 16), decreased for macrolides (from 4.4 to 2.7) and increased for respiratory fluoroquinolones (from 0.3 to 2.7). The increase in PCV-7 distribution correlated with a decrease in PCV-7 serotypes prevalence among invasive isolates in children (r = -0.976; P < 0.001) and adults (r = -0.905; P = 0.002). This decrease in PCV-7 serotypes correlated with a decrease in penicillin non-susceptibility in children (r = 0.929; P < 0.001) and adults (r = 0.905; P = 0.002) and with erythromycin non-susceptibility in children (r = 0.833; P = 0.010). Penicillin/erythromycin non-susceptibility in 2000 was significantly higher in paediatric versus adult isolates (penicillin: 51.4% versus 29.2%; erythromycin: 39.5% versus 20.4%), but similar in 2006-07 (20% to 24%). The increase in respiratory quinolones consumption correlated with the increase in levofloxacin non-susceptibility in adults (r = 0.926; P = 0.008) but not in children, with different non-susceptibility rates in 2007 (1.6% versus 0.0%; P = 0.013).


CONCLUSIONS
This ecological analysis suggests that PCV-7 vaccination in children had a herd effect in adults, but consumption of respiratory quinolones in adults had no effect on pneumococcal susceptibility to levofloxacin in children. Penicillin/erythromycin non-susceptibility decreased along the studied period among paediatric invasive S. pneumoniae isolates to a level similar to that seen in adults.
Fenoll
A
A
Spanish National Reference Pneumococcal Laboratory, Instituto de Salud Carlos III, ctra. Majadahonda-Pozuelo Km. 2, 28220 Majadahonda, Madrid, Spain.
Aguilar
L
L
Granizo
J J
JJ
Giménez
M J
MJ
Aragoneses-Fenoll
L
L
Mendez
C
C
Tarragó
D
D
D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use*; D002648:Child; D024881:Drug Resistance, Bacterial; D004917:Erythromycin / Q000494:pharmacology; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D008826:Microbial Sensitivity Tests; D010406:Penicillins / Q000494:pharmacology; D011008:Pneumococcal Infections / Q000382:microbiology* / Q000635:transmission*; D022242:Pneumococcal Vaccines / Q000276:immunology*; D015363:Quinolones / Q000494:pharmacology / Q000627:therapeutic use*; D012703:Serotyping; D013030:Spain; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects* / Q000276:immunology* / Q000302:isolation & purification
D000900:Anti-Bacterial Agents; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D010406:Penicillins; D022242:Pneumococcal Vaccines; D015363:Quinolones; D004917:Erythromycin