Nasal Carriage of <i>Staphylococcus aureus</i> among Children in the Ashanti Region of Ghana

<div><p>Background</p><p>Nasal carriage with <i>Staphylococcus aureus</i> is a common risk factor for invasive infections, indicating the necessity to monitor prevalent strains, particularly in the vulnerable paediatric population. This surveillance study aims to identify carriage rates, subtypes, antimicrobial susceptibilities and virulence markers of nasal <i>S</i>. <i>aureus</i> isolates collected from children living in the Ashanti region of Ghana.</p><p>Methods</p><p>Nasal swabs were obtained from children < 15 years of age on admission to the Agogo Presbyterian Hospital between April 2014 and January 2015. <i>S</i>. <i>aureus</i> isolates were characterized by their antimicrobial susceptibility, the presence of genes encoding for Panton-Valentine leukocidin (PVL) and toxic shock syndrome toxin-1 (TSST-1) and further differentiated by <i>spa</i>-typing and multi-locus-sequence-typing.</p><p>Results</p><p>Out of 544 children 120 (22.1%) were colonized with <i>S</i>. <i>aureus</i>, with highest carriage rates during the rainy seasons (27.2%; p = 0.007), in females aged 6–8 years (43.7%) and males aged 8–10 years (35.2%). The 123 isolates belonged to 35 different <i>spa</i>-types and 19 sequence types (ST) with the three most prevalent <i>spa</i>-types being t355 (n = 25), t84 (n = 18), t939 (n = 13), corresponding to ST152, ST15 and ST45. Two (2%) isolates were methicillin-resistant <i>S</i>. <i>aureus</i> (MRSA), classified as t1096 (ST152) and t4454 (ST45), and 16 (13%) were resistant to three or more different antimicrobial classes. PVL and TSST-1 were detected in 71 (58%) and 17 (14%) isolates respectively.</p><p>Conclusion</p><p><i>S</i>. <i>aureus</i> carriage among Ghanaian children seems to depend on age, sex and seasonality. While MRSA rates are low, the high prevalence of PVL is of serious concern as these strains might serve not only as a source for severe invasive infections but may also transfer genes, leading to highly virulent MRSA clones.</p></div

Antibiotic resistance profile of nasal <i>Staphylococcus aureus</i> isolates (n = 123).

<p>Antibiotic resistance profile of nasal <i>Staphylococcus aureus</i> isolates (n = 123).</p

Demographic characteristics of study participants.

<p>Demographic characteristics of study participants.</p

Characterization of nasal <i>Staphylococcus aureus</i> isolates (n = 123).

<p>Characterization of nasal <i>Staphylococcus aureus</i> isolates (n = 123).</p

Temporal distribution of <i>spa</i>-types.

<p>Distribution of <i>spa</i>-types (n = 123) by month. The black line indicates the <i>Staphylococcus aureus</i> prevalence (n = 544).</p

Weekly notification of suspected cholera cases.

<p>The Disease Surveillance Service of the Ghana Health Service reports 20,120 cholera cases according to the WHO case definition between May 2014 and December 2014 with a peak number of 2,853 cases in the 35^th calendar week (25–31 August).</p

Spatial and temporal location of suspected cholera cases (Mai 2014-December 2014; n = 20,120).

<p>As notified to the Disease Surveillance Service of the Ghana Health Service according to the WHO case definition suspected cholera cases are plotted by district by 5-week period panels. The figure was produced with Arc GIS 10.0 (ESRI: ArcGis Desktop: Release 10.2011).</p

Age and sex distribution of <i>spa</i>-types.

<p>Distribution of <i>spa</i>-types (n = 123) and nasal <i>Staphylococcus aureus</i> prevalence by 2-years age-groups and sex (n = 544). Girls (continuous line) are colonized when they are approximately 2 years younger than boys (dashed line).</p

Antimicrobial resistance for each antibiotic (A) and resistance profile (B) of <i>Vibrio cholerae</i> isolates, by year of disease onset (n = 92).

<p>Antimicrobial resistance for each antibiotic (A) and resistance profile (B) of <i>Vibrio cholerae</i> isolates, by year of disease onset (n = 92).</p

Minimum spanning tree of multilocus variable-number tandem-repeat (VNTR) analysis (MLVA) for <i>Vibrio cholerae</i> isolates (n = 45) by year of disease onset.

<p>Clonal complexes (CC 1, CC 2, CC 3) were defined as isolates connected through a chain of single-locus variants. Grey figures indicate the number of different alleles. Three-digit codes present the laboratory isolate number.</p