550. Analysis of Staphylococcus aureus resistance patterns and antibiotic prescribing practices in a single tertiary pediatric center in South Florida
Authors: Sanguineti Giancarlo Giovannini , Villavicencio Karen Hanze , Calderon Rebeca , Laufer Marcelo 
Published: December 2022

Abstract

Background
Staphylococcus aureus antibiotic resistance in pediatric populations is a dynamic problem that affects the morbidity and mortality of all children. Local efforts to understand its patterns as well as the antibiotic prescribing trends, as well as their relationship, are cornerstone for the development of mitigation strategies.

Methods
We conducted a retrospective observational study of 11,964 clinical isolates at a tertiary pediatric care center in South Florida collected from 2008 to 2019 to determine the antibiotic susceptibility of Staphylococcus aureus, compare antibiotic resistance patterns between MRSA and MSSA isolates and evaluate antibiotic prescribing practices from 2013 to 2019.

Results
Methicillin resistance was present in 47.9% (±0.63) isolates with no significant temporal trend. Resistance to clindamycin was on average 24.8% (±1.08), to erythromycin 66.9% (±1.68), to levofloxacin 35.5% (±1.61) and to gentamicin 6.8% (±1.11). MRSA isolates had higher resistance rates to most antibiotics than MSSA (p&lt; 0.05) except for clindamycin for which both had similar rates. Resistance to clindamycin and gentamicin increased significantly from 20% to 25% and from 5 to 15%, respectively, among MRSA and quinolone resistance rose among MSSA from 7% to 13%. Antibiotic prescription rate increased from 56 prescriptions per 1,000 patients to 136 prescriptions per 1,000 patients from 2013 to 2019. There was a positive correlation between erythromycin resistance rate among MRSA and macrolide prescription frequency (p&lt; 0.05). Figure 1.Antibiotic resistance in S aureus isolates from pediatric patients between 2008 and 2019.
The trends in erythromycin and gentamicin resistance were statistically significant (p&lt;0.05); all other trends shown were not significant. Figure 2.Comparative annual resistance rate among MSSA and MRSA isolates from pediatric patients between 2008 and 2019
The trend in levofloxacin resistance among MSSA was statistically significant, as well as the trends in erythromycin, clindamycin, and gentamicin in MRSA; all other trends were not significant. Figure 3.Annual antibiotic prescription frequency as a percent of all antibiotics prescribed in outpatient facilities and emergency department at Nicklaus Children’s Hospital between 2013 and 2019Beta-Lactams are expressed as the summation of cephalosporins and penicillins. The frequency at which penicillins, cephalosporins and macrolides were prescribed changed significantly; all other frequencies did not change significantly.

Conclusion
Pediatric Staphylococcus aureus isolates showed high and stable rates of methicillin resistance during the study period. There is growing clindamycin and gentamicin resistance among MRSA isolates as well as increasing levofloxacin resistance in MSSA isolates. Antibiotic prescribing increased significantly in this population during the study period in South Florida.

Disclosures
All Authors: No reported disclosures.