Antibiotic-resistant invasive pneumococcal clones in Italy.
A total of 105 multiple-antibiotic-resistant invasive pneumococcal isolates recovered in Italy from 2001 to 2003 were genetically characterized. Of these, 40 were penicillin-nonsusceptible (PNSSP) and 65 were penicillin-susceptible (PSSP) Streptococcus pneumoniae strains. Among the PNSSP isolates, 8 and 11 different restriction profiles were obtained for the pbp2b and pbp2x genes, respectively. Clonal groups were established on the basis of analysis of both pulsed-field gel electrophoresis (PFGE) types and multilocus sequence typing (MLST). Several international clones, such as Spain(23F)-1/ST81, Spain(6B)-2/ST90, Spain(9V)-3/ST156, and Sweden(15A)-25/ST63 [corrected] were identified among the PNSSP isolates. Other, smaller clones, such as the minor Spanish 19F clone/ST88 and Denmark(14)-32/ST230, were also found. Among the PSSP isolates, clones related to England(14)-9/ST9, Greece(6B)-22/ST273, and Portugal(19F)-21/ST177 were found. In addition, two large clones comprised nonvaccine serotypes. One, comprising serotype 3 isolates, corresponded to the clone Netherlands(3)-31/ST180; the other, comprising serotype 15B/C isolates, ST474, was not related to any previously described clone. Two small clusters related to the newly described clones Greece(21)-30/ST193 and Netherlands(15B)-37/ST199 included isolates with unrelated PFGE profiles. An unusual finding was the inability to obtain the MLST allelic profile for an isolate of serotype 19A, belonging to the Sweden(15A)-25/ST63 [corrected] clone, due to a large deletion of the xpt gene. Capsular switching was observed among both PNSSP and PSSP isolates and involved also serotypes not included in the 7-valent pneumococcal conjugate vaccine (PCV7), such as serotypes 15B/C and 19A. Since antibiotic-resistant nonvaccine serotype clones are present in Italy, continuous monitoring of pneumococcal epidemiology should be carried out in the PCV7 era.
Gherardi
Giovanni
G
Department of Laboratory Medicine and Microbiology, Università Campus Biomedico, Rome, Italy.
Fallico
Loredana
L
Del Grosso
Maria
M
Bonanni
Federica
F
D'Ambrosio
Fabio
F
Manganelli
Riccardo
R
Palù
Giorgio
G
Dicuonzo
Giordano
G
Pantosti
Annalisa
A
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D007558:Italy / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010403:Penicillin Resistance; D046915:Penicillin-Binding Proteins / Q000235:genetics; D010406:Penicillins / Q000494:pharmacology; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects* / Q000235:genetics*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D046915:Penicillin-Binding Proteins; D010406:Penicillins