Inflammatory Response in Experimental Staphylococcus andPseudomonas Endophthalmitis

Abstract

Staphylococcus epidermidis [2.0 × 10⁴ colony-forming units (CFU)/0.1 ml] and Pseudomonas aeruginosa (2.0 × 10³ CFU/ml) were inoculated in the vitreous humor of rabbits. In S. epidermidis endophthalmitis, the numbers of microorganisms reached a maximum (4.1 × 10⁷ CFU/ml) at day 2 after inoculation and then declined spontaneously. However, clinical scores were observed to be worst at day 5. In P. aeruginosa endophthalmitis, the numbers of microorganisms reached a maximum (9.3 × 10⁶ CFU/ml) 36 h after inoculation. However, culture results were persistently positive until day 15. Electroretinogram (ERG) b-wave amplitudes in S. epidermidis endophthalmitis continued to decrease from day 3 (>24%) until day 5, and then recovered to the preinoculative level of amplitudes at day 7. ERG b-wave amplitudes in P. aeruginosa endophthalmitis continued to decrease after 24 h (>24%). ERG b-wave amplitudes from day 7 to day 15 were flat. The inflammatory response continued under the absence of microorganisms in S. epidermidis endophthalmitis. The time in which a maximum in the number of microorganisms was reached was earlier than that in the clinical examination scores in both S. epidermidis and P. aeruginosa endophthalmitis.