Clonal Analysis ofStreptococcus pneumoniaeNonsusceptible to Penicillin at Day-Care Centers with Index Cases, in a Region with Low Incidence of Resistance: Emergence of an Invasive Type 35B Clone among Carriers

Abstract

The nasopharyngeal carriage rate of potential respiratory pathogens was studied in 36 index children with a pneumococci nonsusceptible to penicillin (PNSP), in 595 healthy children, and in 123 personnel at 16 day-care centers (DCCs) with index cases in the Stockholm area, an urban area with a low incidence of antibiotic resistant pneumococci, during the winter of 1997-1998. The spread and clonality of PNSP, Haemophilus influenzae and Moraxella catarrhalis, were studied by analyzing antibiotic susceptibility and serotype, and for PSNP also by using pulsed-field electrophoresis (PFGE) and multilocus sequence typing (MLST). In contrast to the low carriage rate found among the adult contacts (2%), 40% of the children harbored pneumococci, of which 20% were PNSP. Nasopharyngeal colonization decreased with age. The 49 PNSP isolates consisted of 20 clones, of which 10 could be identified in more than one child attending the same or different DCCs. In five DCCs, we observed a spread of PNSP from the index case. A novel PNSP clone of type 35B, found to cause invasive disease in several states in the United States, was found to emerge among several carriers at two DCCs . A high proportion of PNSP isolates were multiresistant to antibiotics (34%), which has implications for treatment regimens, even in a country like Sweden where the proportion of PNSP currently is low (3-4%). One PNSP clone of type 9V found among the carriers, has been shown to cause invasive disease in Sweden as well as in other countries, suggesting that one reason for the occurrence of invasive PNSP clones may be their ability to colonize and spread among healthy carriers. Other internationally spread antibiotic resistant pneumococcal clones found were of types 9V, 19F, and 23F.

Trends in Drug Resistance, Serotypes, and Molecular Types of Streptococcus pneumoniae Colonizing Preschool-Age Children Attending Day Care Centers in Lisbon, Portugal: a Summary of 4 Years of Annual Surveillance

“…We can only speculate that the nurses who collected the samples have been mastering their sampling technique, yielding higher pneumococcal recovery rates. Similar high rates of pneumococcal carriage in DCC children have been reported in other countries such as Iceland (50%) (23), Sweden (52%) (22), Lithuania (51%) (23), France (54.7%) (12), Israel (63%) (45), and Greece (48%) (44).…”

Determination of Accessory Gene Patterns Predicts the Same Relatedness among Strains of Streptococcus pneumoniae as Sequencing of Housekeeping Genes Does and Represents a Novel Approach in Molecular Epidemiology

“…All pneumococcal isolates were serotyped at the Swedish Institute for Infectious Disease Control by gel diffusion as described previously (7).…”

“…It is also a common colonizer of the respiratory tract, and up to 60 to 70% of healthy children may harbor this organism in the nasopharynx (7). To assess the capability of pneumococci to cause disease and to study their spread, several studies have been conducted to compare invasive disease and carrier isolates, thereby estimating the abundances of the two groups (1,2,9).…”

Clinical manifestations of invasive pneumococcal disease by vaccine and non-vaccine types

“…To calculate the odds ratio for causing invasive disease, 550 nasopharyngeal carriage isolates (collected from children attending day care centres) and 165 invasive isolates from children (<18 years of age) from the Stockholm area collected between 1997 and 2004 prior to vaccination were included [22,23].…”