Serotype and genotype replacement among macrolide-resistant invasive Pneumococci in adults: mechanisms of resistance and association with different transposons.
The aim of this study was to analyze trends in adult invasive pneumococcal disease (IPD) due to macrolide-resistant strains and to study the evolution of serotypes, genotypes, and macrolide-resistant determinants of strains collected in a prospective study between 1999 and 2007 in Barcelona, Spain. IPD due to macrolide-resistant strains of serotypes included in the 7-valent conjugate vaccine (PCV7) decreased from 2.16/100,000 (pre-PCV7 period, 1999 to 2001) to 0.80/100,000 (late-PCV7 period, 2005 to 2007) (P = 0.001), whereas IPD due to macrolide-resistant strains of non-PCV7 serotypes increased from 1.08/100,000 to 2.83/100,000 (P < 0.001). These changes were related to a fall of clones of PCV7 serotypes (ST81 [P < 0.05], ST90, ST315, and ST17) and an increase in new clones of serotypes 19A and 24F (ST230) and 33F (ST717) in the late-PCV7 period. The most common phenotype was MLS(B) (90.9%), related to the erm(B) gene. The frequent association between MLS(B) phenotype and tetracycline resistance [tet(M) gene], was related to transposons of the Tn916-family such as Tn6002 or Tn3872. In conclusion, overall adult IPD rates due to macrolide-resistant pneumococci stabilized between 1999 and 2007 in Barcelona. The decrease in macrolide-resistant PCV7 pneumococci was balanced by the increase in macrolide-resistant non-PCV7 pneumococci.
Microbiology Department, Institut d'Investigació Biomèdica de Bellvitge, University of Barcelona, Barcelona, Spain.
Laura
L
Calatayud
Carmen
C
Ardanuy
Fe
F
Tubau
Dora
D
Rolo
Immaculada
I
Grau
Román
R
Pallarés
Rogelio
R
Martín
Josefina
J
Liñares
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015373:Bacterial Typing Techniques; D016172:DNA Fingerprinting; D004251:DNA Transposable Elements; D024881:Drug Resistance, Bacterial; D005260:Female; D005838:Genotype; D006801:Humans; D018942:Macrolides / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D012703:Serotyping; D013030:Spain / Q000453:epidemiology; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000302:isolation & purification; D055815:Young Adult
D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D018942:Macrolides