Use of polymerase chain reaction (PCR) and DNA probe hybridization to determine the gram reaction of the infecting bacterium in the intraocular fluids of patients with endophthalmitis
Ar. Anand et al., Use of polymerase chain reaction (PCR) and DNA probe hybridization to determine the gram reaction of the infecting bacterium in the intraocular fluids of patients with endophthalmitis, J INFECTION, 41(3), 2000, pp. 221-226
Objectives: To evaluate polymerase chain reaction (PCR) combined with DNA p
robe hybridization to determine the Gram reaction of the bacterium in intra
ocular specimens from patients with infectious endophthalmitis.
Methods: Fifty-seven intraocular specimens - 17 aqueous humor (AH) and 40 v
itreous fluid (VF) - from 55 patients with clinically diagnosed infectious
endophthalmitis and 25 control intraocular specimens from non-infectious oc
ular disorders (10 BH and 15 VF) were evaluated by microscopy, culture and
PCR-DNA probe hybridization to detect the Gram reaction of the bacterium.
Results: PCR-DNA probe hybridization was specific and sensitive to detect 3
0 fg of both Gram-positive and Gramnegative bacterial DNA. None of the cont
rols showed bacteria by microscopy, culture or PCR. Of the 57 intraocular s
pecimens, conventional microbiological methods could detect a bacterial aet
iology in 32 (56.1%), while PCR-DNA probe hybridization could detect 52 (91
.2%) specimens. This difference was statistically significant (P=0.003). In
bacteriologically positive specimens, there was absolute correlation of th
e Gram reaction between the results of smear and culture methods and PCR-DN
A probe hybridization. Of the 25 bacteriologically negative specimens, 20 (
80%) were positive by PCR-DNA probe hybridization, of which seven (35%) wer
e Gram-positive, 12 (60%) Gram-negative and one (5%) positive by both. Resu
lts of PCR on AH and VF were not significantly different.
Conclusion: PCR and DNA probe hybridization to determine the Gram reaction
of the bacterium in intraocular fluids is a specific and sensitive method i
n the diagnosis of bacterial endophthalmitis. AH is an ideal specimen for P
CR, since its collection is a simple and safe office procedure. (C) 2000 Th
e British Infection Society.