Experimental prophylaxis of Staphylococcus aureus endophthalmitis after vitrectomy: the use of antibiotics in irrigating solution.
OBJECTIVE
To test the efficacy of clindamycin and gentamicin in irrigating solution during vitrectomy to prevent experimental Staphylococcus aureus endophthalmitis.


METHODS
Thirty-six New Zealand white rabbits were divided into six groups. Vitrectomy using two different irrigating solutions was followed by intravitreal injection of S. aureus: Group 1, balanced salt solution (BSS) followed by 1,000 colony-forming units (CFU) S. aureus; Group 2, BSS fortified with clindamycin, 10 microg/mL, and gentamicin, 8 microg/mL (CGBSS), followed by intravitreal injection of 1,000 CFU S. aureus; Group 3, BSS followed by 2,000 CFU S. aureus; Group 4, CGBSS followed by 2,000 CFU S. aureus; Group 5, BSS followed by 4,000 CFU S. aureus; and Group 6, CGBSS followed by 4,000 CFU S. aureus. The eyes were examined clinically after surgery. Vitreous samples were cultured and histologic studies were performed.


RESULTS
Severe endophthalmitis developed in all eyes in Groups 1, 3, and 5 (not given antibiotics). No endophthalmitis developed in Group 2. In Group 4, five of the six eyes were normal and one eye had endophthalmitis. In Group 6, one eye had clear vitreous and fundus, three eyes had moderate vitreous haze, and the other four eyes demonstrated severe endophthalmitis. Bacterial growth in Groups 1, 2, 3, 4, 5, and 6 were 4/4, 0/4, 6/6, 1/6, 4/6, and 2/8 eyes, respectively.


CONCLUSIONS
When 1,000 to 2,000 CFU S. aureus were injected after vitrectomy, clindamycin and gentamicin in the irrigating solution significantly diminished the intraocular inflammation and the rate of positive bacterial culture. Clindamycin and gentamicin in the irrigating solution were not significantly effective when 4,000 CFU bacteria was injected; however, the degree of inflammation was less severe than in the control group.
Liang
C
C
LSU Eye Center, Louisiana State University Medical Center School of Medicine, New Orleans 70112-2234, USA.
Peyman
G A
GA
Sonmez
M
M
Molinari
L C
LC
D000085:Acetates / Q000627:therapeutic use; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D002981:Clindamycin / Q000008:administration & dosage / Q000627:therapeutic use; D004338:Drug Combinations; D009877:Endophthalmitis / Q000382:microbiology* / Q000473:pathology / Q000517:prevention & control*; D005123:Eye / Q000473:pathology; D005839:Gentamicins / Q000008:administration & dosage / Q000627:therapeutic use; D008903:Minerals / Q000627:therapeutic use; D011183:Postoperative Complications / Q000517:prevention & control*; D011817:Rabbits; D012965:Sodium Chloride; D013203:Staphylococcal Infections / Q000473:pathology / Q000517:prevention & control*; D007507:Therapeutic Irrigation; D014821:Vitrectomy
D000085:Acetates; D000900:Anti-Bacterial Agents; C030660:BSS solution; D004338:Drug Combinations; D005839:Gentamicins; D008903:Minerals; D002981:Clindamycin; D012965:Sodium Chloride