Interaction of the heptavalent pneumococcal conjugate vaccine and the use of individual antibiotics among children on nasopharyngeal colonization with erythromycin-resistant Streptococcus pneumoniae

Risk Factors for Carriage of Antibiotic-resistant Bacteria in Healthy Children in the Community: A Systematic Review

BACKGROUND

In addition to health care settings, antibiotic resistance has also been increasing in the community. Healthy children represent an important potential reservoir of antibiotic-resistant (AR) bacteria. However, strategies to reduce the spread of AR bacteria often fail to specifically address the factors that promote the carriage of AR bacteria in this population.The objective of this review was to Identify risk factors for carriage of AR bacteria by healthy children.

METHODS

We did a systematic search of MEDLINE, Embase and PubMed for studies in developed (OECD) countries that assessed risk factors for carriage of AR bacteria in healthy children in the community. We excluded studies done before 1998 and studies of AR Streptococcus pneumoniae carriage in the absence of pneumococcal conjugate vaccination.

RESULTS

Of 1234 studies identified, 30 were eligible for inclusion. These studies assessed the impact of 49 risk factors on AR strains of S. pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Streptococcus pyogenes and Escherichia coli. The majority of these risk factors were assessed in 2 or fewer studies per bacteria. Recent antibiotic consumption was associated with carriage of resistant respiratory bacteria (S. pneumoniae, H. influenzae); however, it was not consistently associated with carriage of AR bacteria in skin or stool (S. aureus and E. coli). For AR S. aureus, transmission within households appeared to have a greater impact than individual antibiotic use.

CONCLUSIONS

The factors that promote carriage of AR bacteria by healthy children differed between bacterial species. To reduce reservoirs of AR bacteria in the community, it is essential for intervention strategies to target the specific risk factors for different bacteria.

Evolution of pneumococcal infections in adult patients during a four-year period after vaccination of a pediatric population with 13-valent pneumococcal conjugate vaccine

OBJECTIVES

To describe the distribution of vaccine and non-vaccine pneumococcal serotypes from adult patients for different clinical scenarios, after the introduction of the 13-valent pneumococcal conjugate vaccine (PCV-13) for children.

METHODS

This was a prospective study of pneumococcal infections in adult patients (January 2010 to April 2014) in Hospital Son Llàtzer, Mallorca (Spain). Two different periods of time were compared, the first before (first period) and the second after (second period) the introduction of PCV-13. Information related to clinical characteristics, outcomes of infection, pneumococcal serotypes, and antibiotic susceptibility was collected.

RESULTS

We studied 407 episodes (371 patients), 201 in the first period and 206 in the second period. The majority of patients were male; the median patient age was 68 (range 15-99) years. Infections due to PCV-13 serotypes decreased from 59.7% to 47.6% (p=0.014), mainly serotypes 3, 7, 18C, 19F, and 23F. In the second period, PCV-13 serotypes were the cause of pneumonia in 58.2% of cases and in 40.8% of invasive infections, but these serotypes were not related with any outcome variable. No differences in hospital or intensive care unit admission, severity, or mortality were observed between the two periods. Susceptibility to penicillin (98.2% vs. 95.1%, p=0.03) and amoxicillin (96.5% vs. 91%, p=0.007) was slightly higher in the first period.

CONCLUSIONS

Although a reduction in infections due to vaccine serotypes was observed, close to half of infections in adult patients were caused by PCV-13 serotypes. Even after pediatric vaccination with PCV-13, vaccine serotypes were still responsible for most pneumonia and invasive disease, underscoring the importance of implementing current guidelines and extending vaccination to other risk groups.

Macrolide resistance determinants among Streptococcus pneumoniae isolates from carriers in Central Greece

Background

We sought to characterize the temporal trends in nasopharyngeal carriage of macrolide-resistant pneumococci during a period with increased heptavalent pneumococcal conjugate vaccine (PCV7) coverage in Central Greece.

Methods

Streptococcus pneumoniae isolates were recovered from 2649 nasopharyngeal samples obtained from day-care center attendees in Central Greece during 2005–2009. A phenotypic and genotypic analysis of the isolates was performed, including the identification of macrolide resistance genes mef(A), subclasses mef(A) and mef(E), as well as erm(B).

Results

Of the 1105 typeable S. pneumoniae isolates, 265 (24%) were macrolide-resistant; 22% in 2005, 33.3% in 2006, 23.7% in 2007, and 20.5% in 2009 (P=0.398). Among these macrolide-resistant pneumococci, 28.5% possessed erm(B), 24.3% erm(B)+mef(E), 41.8% mef(E), and 5.3% mef(A). A mef gene as the sole resistance determinant was carried by 31% of macrolide-resistant isolates belonging to PCV7 serotypes and 75.8% of the non-PCV7 serotypes. Across the 4 annual surveillances, pneumococci carrying mef(A) gradually disappeared, whereas serotype 19F isolates carrying both erm(B) and mef(E) persisted without significant yearly fluctuations. Among isolates belonging to non-PCV7 serotypes, macrolide-resistance was observed in those of serotypes 6A, 19A, 10A, 15A, 15B/C, 35F, 35A, and 24F. In 2009, ie 5 years after the introduction of PCV7 in our country, 59% of macrolide-resistant pneumococci belonged to non-PCV7 serotypes.

Conclusions

Across the study period, the annual frequency of macrolide-resistant isolates did not change significantly, but in 2009 a marked shift to non-PCV7 serotypes occurred. Overall, more than half of the macrolide-resistant isolates possessed erm(B) either alone or in combination with mef(E). erm(B) dominated among isolates belonging to PCV7 serotypes, but not among those of non-PCV7 serotypes.