Nasopharyngeal Carriage of Methicillin-Resistant Staphylococcus aureus (MRSA) among Sickle Cell Disease (SCD) Children in the Pneumococcal Conjugate Vaccine Era.

Nicholas T K D Dayie,Kevin Kofi Adutwum-Ofosu,John Ahenkorah,Fleischer C N Kotey,Mary-Magdalene Osei,Deborah N K Sekoh,Beverly Egyir,Patience B Tetteh-Quarcoo,Eric S Donkor

doi:10.3390/idr13010022

Abstract

The aim of this cross-sectional study was to investigate Staphylococcus aureus nasopharyngeal carriage epidemiology in relation to other nasopharyngeal bacterial colonizers among sickle cell disease (SCD) children about five years into pneumococcal conjugate vaccine 13 (PCV-13) introduction in Ghana. The study involved bacteriological culture of nasopharyngeal swabs obtained from 202 SCD children recruited from the Princess Marie Louise Children’s Hospital. S. aureus isolates were identified using standard methods and subjected to antimicrobial susceptibility testing using the Kirby-Bauer disc diffusion method. Cefoxitin-resistant S. aureus isolates were screened for carriage of the mecA, pvl, and tsst-1 genes using multiplex polymerase chain reaction. The carriage prevalence of S. aureus was 57.9% (n = 117), and that of methicillin-resistant S. aureus (MRSA) was 3.5% (n = 7). Carriage of the mecA, pvl, and tsst-1 genes were respectively demonstrated in 20.0% (n = 7), 85.7% (n = 30), and 11.4% (n = 4) of the cefoxitin-resistant S. aureus isolates. PCV-13 vaccination (OR = 0.356, p = 0.004) and colonization with coagulase-negative staphylococci (CoNS) (OR = 0.044, p < 0.0001) each protected against S. aureus carriage. However, none of these and other features of the participants emerged as a determinant of MRSA carriage. The following antimicrobial resistance rates were observed in MRSA compared to methicillin-sensitive S. aureus: clindamycin (28.6% vs. 4.3%), erythromycin (42.9% vs. 19.1%), tetracycline (100% vs. 42.6%), teicoplanin (14.3% vs. 2.6%), penicillin (100% vs. 99.1%), amoxiclav (28.6% vs. 3.5%), linezolid (14.3% vs. 0.0%), ciprofloxacin (42.9% vs. 13.9%), and gentamicin (42.9% vs. 13.0%). The proportion of S. aureus isolates that were multidrug resistant was 37.7% (n = 46). We conclude that S. aureus was the predominant colonizer of the nasopharynx of the SCD children, warranting the continuous monitoring of this risk group for invasive S. aureus infections.

Highlights

Staphylococcus aureus, though a commensal, has over the years evolved into a very important human pathogen, causing mild to severe infections, including folliculitis and furunculosis, meningitis, septicaemia, pneumonia, endocarditis, and osteomyelitis [1,2].As a commensal, it is predominantly isolated from the anterior nares, and co-colonizes the nasopharynx with other microbiota, such as Haemophilus influenzae, Moraxella catarrhalis, and the predominant nasopharyngeal colonizer—Streptococcus pneumoniae [3,4,5]
As S. pneumoniae carriage is especially high in young children [20,21,22], who bear the brunt of its high disease burden and case fatality [23,24,25], pneumococcal conjugate vaccines (PCVs) were incorporated into paediatric vaccination programmes to protect the children against S. pneumoniae carriage and infections [23,25,26]
This study investigated S. aureus nasopharyngeal carriage epidemiology in relation to other nasopharyngeal bacterial colonizers among sickle cell disease (SCD) children about five years into

Summary

Introduction

Staphylococcus aureus, though a commensal, has over the years evolved into a very important human pathogen, causing mild to severe infections, including folliculitis and furunculosis, meningitis, septicaemia, pneumonia, endocarditis, and osteomyelitis [1,2] As a commensal, it is predominantly isolated from the anterior nares, and co-colonizes the nasopharynx with other microbiota, such as Haemophilus influenzae, Moraxella catarrhalis, and the predominant nasopharyngeal colonizer—Streptococcus pneumoniae [3,4,5]. Given the antagonism between S. aureus and S. pneumoniae, there are concerns that S. aureus could potentially replace S. pneumoniae vaccine serotypes and emerge as the dominant colonizer of the nasopharynx as coverage of PCVs increases [6,7,29,30,31] This raises legitimate concerns, as S. aureus is frequently implicated in respiratory tract infections, and its presence in the nasopharynx significantly predicts subsequent invasive infections [31,32]. Infections with MRSA are often in tandem with extended hospital stays, increased healthcare costs, and high mortality rates [39,40,41]

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