Retrospective report of antimicrobial susceptibility observed in bacterial pathogens isolated from ocular samples at Mount Sinai Hospital, 2010 to 2015

Abstract

BackgroundAntimicrobial resistance has emerged as a major threat to global public health. Thus, the surveillance of changes in antimicrobial resistance in local and global settings is a paramount necessity. While many studies have tracked antimicrobial resistance, only a small percentage surveyed ocular isolates. The purpose of this study was to report the in vitro susceptibility of bacterial pathogens isolated from ocular samples in New York, NY from 2010 to 2015.MethodsA retrospective review of ocular isolates was conducted. All organisms were collected by 25 separate inpatient wards and outpatient clinics, and were analyzed by the clinical microbiology laboratory at Mount Sinai Hospital. Clinical Laboratory and Standards Institute (CLSI) guidelines were followed for susceptibility testing and breakpoint interpretations.ResultsA total of 549 bacterial organisms were isolated from 1664 cultures (33%) during the 6-year study period. Of these, 358 isolates (65.2%) underwent susceptibility testing. 182 (50.8%) isolates were Gram-positive. The most common Gram-positive bacterium was Staphylococcus aureus (62.1%). Methicillin-resistance decreased in S. aureus isolates (31.3% in 2010, 14.1% in 2015) but was without significant change (p = 0.25). When analyzing all S. aureus isolates recovered during the study period, there were significantly more methicillin-resistant S. aureus (MRSA) isolates resistant to fluoroquinolones (p <0.0001), erythromycin (p <0.0001), and trimethoprim/sulfamethoxazole (TMP/SMZ; p <0.05). Overall, Streptococcus pneumoniae isolates showed reduced susceptibility to erythromycin, but were otherwise susceptible to the other antimicrobials tested. Haemophilus influenzae (26.1%) and Pseudomonas aeruginosa (23.9%) were the most common Gram-negative bacteria isolated. Resistance to ampicillin and TMP/SMZ was observed in several of the H. influenzae isolates. P. aeruginosa isolates did not show high resistance overall, however, it was noted that isolates resistant to meropenem were also resistant to other antimicrobials (p < 0.01).ConclusionOverall, antimicrobial resistance was infrequent for the Gram-negative and Gram-positive bacteria analyzed. While the MRSA isolates demonstrated increased resistance to multiple antimicrobial classes, this is expected for this pathogen. Due to the continued use of broad-spectrum oral and systemic antimicrobials to treat ocular infections, findings of this study and other surveillance studies specific to ocular isolates should be used as resources in effective decision making in the treatment of ocular disease.

Antibiotic Resistance Rates by Geographic Region Among Ocular Pathogens Collected During the ARMOR Surveillance Study

“…Comparisons of cumulative MIC 90 s showed wide variations among fluoroquinolones, particularly against staphylococci, with newer fluoroquinolones having lower MIC 90 s than older fluoroquinolones and besifloxacin having an MIC 90 most comparable to that of vancomycin. Although not analyzed, MIC 90 s did not appear to differ by region and were consistent (within few dilutions) with the previous reports of ARMOR, other single-study reports of ocular isolates, and national systemic surveys [ 9 , 13 – 15 , 18 – 22 ]. Besifloxacin, a chlorofluoroquinolone for which interpretive breakpoints are not available, was approved by the US Food and Drug Administration for use in 2009 [ 19 ], and in vitro MIC 90 s have not varied substantially since its introduction [ 9 , 13 , 14 , 19 ].…”

Antibiotic Resistance Among Pediatric-Sourced Ocular Pathogens: 8-Year Findings From the Antibiotic Resistance Monitoring in Ocular Microorganisms (ARMOR) Surveillance Study

“…Notable among these was the finding of an approximately 2-fold higher resistance to imipenem among pediatric P. aeruginosa isolates and a lower resistance to methicillin among pediatric S. aureus isolates (24.3% vs. 36.6%, respectively), which was expected given the reported greater prevalence of ocular MRSA among older patients. 29,51 Again, consistent with prior reporting, 30 all staphylococcal isolates in the pediatric dataset were susceptible to vancomycin; this finding is reassuring given that compounded vancomycin is commonly utilized by ophthalmologists when treating particularly resistant ocular infections. As reported previously, MR significantly increases the likelihood of concurrent resistance to other antibiotic classes.…”

High antimicrobial resistant rates among Gram-negative pathogens in intensive care units

“…The availability of regional data on the resistance rates is fundamental to implementing effective treatment protocols against infectious agents and might help to prevent infections with MDR pathogens at the local level. 9 , 14 …”