[Nasopharyngeal carriage, antibiotic susceptibility and serotyping of Streptococcus pneumoniae and Haemophilus influenzae in children attending day care centers]

Colonization rate of Streptococcus pneumoniae, its associated factors and antimicrobial susceptibility pattern among children attending kindergarten school in Hawassa, southern Ethiopia

OBJECTIVE

The aim of this study was to determine the colonization rate of Streptococcus pneumoniae, antimicrobial susceptibility pattern and associated risk factors among children attending kindergarten school in Hawassa, Ethiopia.

RESULTS

Out of 317 study participants, 68 (21.5%) were colonized with S. pneumoniae. Colonization rate was significantly associated with factors such as age (3 to 4 years old) (P = 0.01), having a sibling whose age was less than 5 years (P = 0.011), sharing a bed with parents (P = 0.005), cooking within bedroom (P = 0.002), and previous hospitalization (P = 0.004). Forty-four (64.6%), 33 (48.5%), and 2942.6%) of S. pneumoniae isolated were resistant to cotrimoxazole, penicillin, and tetracycline respectively.

Follow-up of serotype distribution and antimicrobial susceptibility of Streptococcus pneumoniae in child carriage after a PCV13-to-PCV10 vaccine switch in Belgium

BACKGROUND

A three year pneumococcal carriage study was set up in Belgium when the vaccination programme switched from a 13-valent (PCV13) to a 10-valent (PCV10) vaccine. We compared the first follow-up period (October 2016 - June 2017, year 2, Y2) for nasopharyngeal carriage, serotype distribution and antimicrobial susceptibility of S. pneumoniae with the baseline (January-July 2016, year 1, Y1).

MATERIALS/METHODS

A single nasopharyngeal swab was taken in children (6-30 months), either attending one of the 112 day-care centres (DCCs), or visiting one of the 21 physicians for an acute otitis media (AOM). S. pneumoniae were cultured, screened for antimicrobial susceptibility, and serotyped.

RESULTS

In Y2, 1218 samples were collected. The majority of the Y2-children (>85%) was vaccinated appropriately for their age. Children in Y2 received either PCV13 only (DCC: 23.5%; AOM: 24.6%), PCV10 only (DCC: 29.8%; AOM: 37.7%), or a mix of both vaccines (DCC: 31.9%; AOM: 25.4%). Pneumococcal carriage rates were high (Y2, DCC: 68.2%; AOM: 64.8%). Among carriers, prevalence of PCV13 serotypes was low (Y2 vs Y1, DCC: 3.5% vs 5.4%; AOM: 7.6% vs 7.7%). Although prevalence of PCV13-non-PCV10 serotypes did not increase significantly compared to Y1 (Y2 vs Y1, DCC: 1.6% vs 0.9%; Y2 vs Y1, AOM: 5.1% vs 0.0%), the proportion of serotypes 3, 6A, 19A among PCV13 serotype carriers in DCC was significantly higher in Y2 (46.2% vs Y1: 16.0%, p-value = 0.034). Serotypes 23B and 15B were the predominant non-vaccine serotypes (Y2). Among detected strains, non-susceptibility to at least one of five antibiotics tested (penicillin, tetracycline, erythromycin, levofloxacin, cotrimoxazole) was comparable to Y1 (Y2 vs Y1, DCC: 41.3% vs 42.4%; AOM: 49.4% vs 48.1%).

CONCLUSION

After completion of the PCV13-to-PCV10 vaccine switch in Belgium, the proportion of PCV13-non-PCV10 serotypes (mainly 19A) significantly increased among PCV13 serotype carriers in DCC, stressing the need for strengthened surveillance as the PCV10-vaccinated population grows.

Effectiveness of a Hand Hygiene Program at Child Care Centers: A Cluster Randomized Trial

OBJECTIVES

Respiratory infections (RIs) are an important cause of morbidity and excessive antibiotic prescriptions in children attending day care centers (DCCs). We aimed to assess the effectiveness of an educational and hand hygiene program in DCCs and homes in reducing RI incidence and antibiotic prescriptions in children.

METHODS

A cluster, randomized, controlled, and open study of 911 children aged 0 to 3 years attending 24 DCCs in Almería (Spain) with an 8-month follow-up. Two intervention groups of DCC families performed educational and hand hygiene measures, 1 with soap and water (SWG; n = 274), another with hand sanitizer (HSG; n = 339), and the control group (CG; n = 298) followed usual hand-washing procedures. RI episode rates were compared through multilevel Poisson regression models. The percentage of days missed were compared with Poisson exact tests.

RESULTS

There were 5211 RI episodes registered. Children in the HSG had less risk of RI episodes (incidence rate ratio [IRR]: 0.77; 95% confidence interval [CI]: 0.68-0.88) and antibiotic prescriptions (IRR: 0.69; 95% CI: 0.57-0.84) compared with the those in the CG. Children in the SWG had a higher risk of RI episodes (IRR: 1.21; 95% CI: 1.06-1.39) and antibiotic prescriptions (IRR: 1.31; 95% CI: 1.08-1.56) than those in the HSG. Pupils missed 5186 DCC days because of RIs, and the percentage of days absent was significantly lower in the HSG compared with the CG (P < .001) and the SWG (P < .001).

CONCLUSIONS

Hand hygiene programs that include hand sanitizer and educational measures for DCC staff, children, and parents, reduce absent days, RIs, and antibiotic prescriptions for these infections in children at DCCs.

Nasopharyngeal s. pneumoniae carriage and density in Belgian infants after 9 years of pneumococcal conjugate vaccine programme

BACKGROUND

In Belgium, the infant pneumococcal conjugate vaccine (PCV) programme changed from PCV7 (2007-2011) to PCV13 (2011-2015) and to PCV10 (2015-2016). A 3-year nasopharyngeal carriage study was initiated during the programme switch in 2016. Main objective of the year 1 assessment was to obtain a baseline measurement of pneumococcal carriage prevalence, carriage density, serotype distribution and antibiotic resistance.

MATERIALS/METHODS

Two infant populations aged 6-30 months and without use of antibiotics in the seven days prior to sampling were approached: (1) attending one of 85 randomly selected day-care centres (DCC); (2) presenting with AOM at study-trained general practitioners and paediatricians. Demographic and clinical characteristics were documented and a single nasopharyngeal swab was taken. S. pneumoniae were cultured, screened for antibiotic resistance and serotyped, and quantitative Taqman real-time PCR (qRT-PCR) targeting LytA was performed.

RESULTS

Culture-based (DCC: 462/760; 60.8% - AOM: 27/39; 69.2%) and LytA-based (DCC: 603/753; 80.1% - AOM: 32/39; 82.1%) carriage prevalence was high. Average pneumococcal DNA load in LytA-positive day-care samples was 6.5 × 10⁶ copies/µl (95%CI = 3.9-9.2 × 10⁶, median = 3.5 × 10⁵); DNA load was positively associated with signs of common cold and negatively with previous antibiotic use. Culture-based frequency of 13 pneumococcal vaccine (PCV) serotypes was 5.4% in DCC and 7.7% in AOM, with 19F and 14 being most frequent, and frequencies below 0.5% for serotypes 3, 6A, 19A in both populations. Predominant non-PCV serotypes were 23B and 23A in day-care and 11A in infants with AOM. In day-care, resistance to penicillin was rare (<0.5%) and absent against levofloxacin; 32.7% and 16.9% isolates were cotrimoxazole- and erythromycin-resistant respectively.

CONCLUSION

Four years after PCV13 introduction in the vaccination programme, PCV13 serotype carriage was rare in infants throughout Belgium and penicillin resistance was rare. Continued surveillance in the context of a PCV programme switch is necessary.

Analysis of antimicrobial resistance and class 1 integrons among strains from upper respiratory tract of healthy adults

OBJECTIVE

The distribution and characterization of integrons among opportunistic pathogens from nasopharynx of healthy adults.

METHODS

A total of 1,019 nasopharyngeal samples from healthy adults were collected; bacteria were identified by API system; antibiotic susceptibility were tested by K-B method; class 1, 2 and 3 integrons were examined by degenerate primers of the genetic content of integrons were analyzed by PCR and DNA sequencing.

RESULTS

Out of the 1,019 cases, 743 (72.9%) opportunistic pathogens were isolated. The top five commons organism identified were Coagulase-negative staphylococcus (n=404), Staphylococcus aureus (n=109), Haemophilus influenzae (n=74), Streptococcus pneumoniae (n=49) and Klebsiella pneumoniae (n=32). Eight (25.0%) isolates of K. pneumoniae produced the ESBLs. The isolated rates of S. aureus and H. influenzae were decreased with aging. 6.3% (2/32) K. pneumoniae isolates and 16.7% (1/8) Proteus isolates carried class 1 integrons. Among intI1-positive strains, sequencing analysis revealed that one of the integron positive K. pneumoniae isolates harbored gene cassette aadA5-dfrA17. Proteus isolates harbored gene cassette aadA2-dhfrXII.

CONCLUSIONS

The results stressed the need for continued surveillance of bacteria from the asymptomatic carriers.

Pathogen diversity and hidden regimes of apparent competition

Competition through cross-reacting host immune responses, a form of apparent competition, is a major driver of pathogen evolution and diversity. Most models of pathogens have focused on intraspecific interactions to explain observed patterns. Two recent experiments suggested that Haemophilus influenzae, a common nasopharyngeal colonizer of humans, might alter the immune environment in a way that favors otherwise less fit serotypes of another common pathogen, pneumococcus. Using a computational model, we demonstrate that H. influenzae, if it consistently raises the fitness of the less fit serotypes, can strongly promote pneumococcal diversity. However, the effects of H. influenzae are so sensitive to the prevalence of H. influenzae that this species is unlikely to be the main driver of serotype coexistence. Interactions that significantly affect diversity could furthermore be extremely difficult to detect through co-occurrence analysis alone. These results suggest that small differences in strains' adaptations to different immunological regimes, which are shaped by coinfections with other pathogens, can have dramatic effects on strain dynamics and patterns of phenotypic variation. Studies of microbial communities might therefore benefit from the use of varied approaches to infer the presence of indirect interactions.

Pneumococcus infections: is the burden still as heavy?

The death rate of invasive pneumococcal infections decreased by 100 fold in one century. This tremendous improvement was due mainly to antibiotic use and multiple attempts at antipneumococcal vaccinations; thus, this was true only for developed countries. However, in France, the incidence has increased, over the last 10 years, in all age classes except for children vaccinated by the heptavalent pneumococcal conjugate vaccine. The incidence of these infections remains high, when associated to some risk factors such as HIV infection, malignant blood diseases, solid cancers, bronchial diseases, or alcohol abuse. The pneumococcal vaccine should be prescribed first to patients with those risk factors. A change of serotypes distribution has been observed in children with a decrease of vaccine serotypes and predominance of related or non-vaccine serotypes. This reflects the effectiveness of vaccination and the need of to regularly update the vaccine. Thus, pneumococcal infections have been increasing and vaccination should be more widely proposed.

The continuing role of Haemophilus influenzae type b carriage surveillance as a mechanism for early detection of invasive disease activity

Prior to the introduction of Haemophilus influenzae type b (Hib) conjugate vaccines, Hib was the leading cause of bacterial meningitis in children under five years of age worldwide. In countries that have adopted Hib vaccination schedules, invasive disease has reduced markedly. Oro-naso pharyngeal carriage is recognized as the most significant source of infection. Hib carriage is significantly associated with poverty, such as overcrowding, poor ventilation in houses, lack of running water, and high smoking rates. Additionally, many Indigenous minority groups report high rates of Hib carriage. A resurgence of Hib disease among Alaskan children in the 1990s, lead to a change in approach to eliminate Hib disease and carriage in high-risk populations. This new approach identifies strategies for eliminating Hib disease focusing on the reservoirs of colonization within families and communities. Monitoring Hib carriage continues to offer an early warning system, whereby intervention could prevent invasive disease resurgence.