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


METHODS
A 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.


RESULTS
A 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 wasStaphylococcus aureus(62.1%). Methicillin-resistance decreased inS. aureusisolates (31.3% in 2010, 14.1% in 2015) but was without significant change (p= 0.25). When analyzing allS. aureusisolates recovered during the study period, there were significantly more methicillin-resistantS. aureus(MRSA) isolates resistant to fluoroquinolones (p<0.0001), erythromycin (p<0.0001), and trimethoprim/sulfamethoxazole (TMP/SMZ;p<0.05). Overall,Streptococcus pneumoniaeisolates showed reduced susceptibility to erythromycin, but were otherwise susceptible to the other antimicrobials tested.Haemophilus influenzae(26.1%) andPseudomonas aeruginosa(23.9%) were the most common Gram-negative bacteria isolated.Resistance to ampicillin and TMP/SMZ was observed in several of theH. influenzaeisolates.P. aeruginosaisolates did not show high resistance overall, however, it was noted that isolates resistant to meropenem were also resistant to other antimicrobials (p< 0.01).


CONCLUSIONS
Overall, 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.
Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, NY USA.
Marko
M
Oydanich
Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, NY 10029 USA.
Tanis C
TC
Dingle
Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, NY 10029 USA.
Camille L
CL
Hamula
Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, NY USA.
Claudia
C
Ghisa
Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, NY USA.
Penny
P
Asbell
Antimicrobial; Multi-drug resistance; New York; Ocular isolates; Susceptibility