Spectrum and susceptibilities of microbiologic isolates in the Endophthalmitis Vitrectomy Study.
OBJECTIVE
To determine the microbiologic spectrum and antibiotic susceptibilities of infecting organisms in postoperative endophthalmitis and to evaluate the effects of operative factors on the microbiologic spectrum.


METHODS
Patients with bacterial endophthalmitis presenting within six weeks of cataract extraction or secondary intraocular lens implantation (IOL) were evaluated. Cultures and Gram stains were performed on intraocular specimens and susceptibility tests on the isolates.


RESULTS
Confirmed microbiologic growth was demonstrated from intraocular specimens from 291 of 420 patients (69.3%). Gram-positive bacteria were isolated from 274 patients (94.2%) with confirmed growth and gram-negative bacteria from 19 (6.5%). Two hundred twenty-six of the 323 isolates obtained (70.0%) were gram-positive, coagulase-negative micrococci, 32 (9.9%) Staphylococcus aureus, 29 (9.0%) Streptococcus species, seven (2.2%) Enterococcus species, ten (3.1%) miscellaneous gram-positive species, and 19 (5.9%) gram-negative species. All gram-positive isolates tested were susceptible to vancomycin. Seventeen gram-negative isolates (89%) were susceptible to both amikacin and ceftazidime and two (11%) were resistant to both. Anterior chamber or secondary IOL implantations were associated with higher rates of infection with gram-positives other than coagulase-negative micrococci than were posterior chamber IOL implantations (P = .022) or primary cataract extractions (P = .024).


CONCLUSIONS
Gram-positive, coagulase-negative micrococci predominated in this series. Vancomycin was active against all gram-positive isolates tested. Amikacin and ceftazidime showed equivalent activity against gram-negative isolates. Secondary or anterior chamber lens implantations were associated with a possible spectrum shift toward gram-positive organisms other than the coagulase-negative micrococci.
Han
D P
DP
Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, USA.
Wisniewski
S R
SR
Wilson
L A
LA
Barza
M
M
Vine
A K
AK
Doft
B H
BH
Kelsey
S F
SF
D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001082:Aqueous Humor / Q000382:microbiology; D015373:Bacterial Typing Techniques; D002387:Cataract Extraction / Q000009:adverse effects; D009877:Endophthalmitis / Q000382:microbiology* / Q000628:therapy; D015818:Eye Infections, Bacterial / Q000382:microbiology* / Q000628:therapy; D006090:Gram-Negative Bacteria / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification*; D006094:Gram-Positive Bacteria / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification*; D006801:Humans; D007910:Lenses, Intraocular; D008826:Microbial Sensitivity Tests; D011183:Postoperative Complications / Q000382:microbiology* / Q000628:therapy; D011446:Prospective Studies; D014821:Vitrectomy; D014822:Vitreous Body / Q000382:microbiology
D000900:Anti-Bacterial Agents