Polymerase chain reaction in the diagnosis of bacterial endophthalmitis

Abstract

Background-Microbiological investigations of vitreous fluid (VF) and aqueous humour (AH) specimens have often failed to detect the infecting agent in infectious endophthalmitis, resulting in a clinical dilemma regarding therapy. In this study, the polymerase chain reaction (PCR) was evaluated in the diagnosis of bacterial and Propionibacterium acnes endophthalmitis. Methods-58 intraocular specimens (30 VF and 28 AH) from 55 cases of endophthalmitis and 20 specimens (14 VF and 6 AH) as controls from non-infective disorders were processed for microbiological investigations. Nested PCR directed at the 16S rDNA using universal primers for eubacterial genome was done. PCR for P acnes was performed on specimens microbiologically negative by conventional techniques but eubacterial genome positive. Results-Of the 20 controls from noninfective cases, one (5%) was positive using eubacterial primers and none with P acnes primers. PCR for eubacterial genome showed 100% correlation with 20 (34.5%) bacteriologically positive specimens. Eubacterial genome, was detected in 17 (44.7%) of 38 bacteriologically negative specimens and nine (52.9%) out of the 17 were positive for P acnes genome. Among the 21 eubacterial PCR negative specimens, seven were fungus positive. By inclusion of PCR, microbiologically positive specimens increased from 46.5% to 75.8%. PCR on AH was as sensitive as that on VF for the detection of both eubacterial and the P acnes genome. Conclusion-PCR performed on AH and VF is a reliable tool for the diagnosis of bacterial and P acnes endophthalmitis particularly in smear and culture negative specimens.

Management of endophthalmitis with retained intraocular foreign body

“…Polymerase chain reaction of the vitreous aspirate may have been useful in this study as it can often identify the causative organism when cultures are negative. 17 Patient 7 had a poor final acuity (LP). However, he had a poor initial visual acuity, retinal detachment, and cataract at the time of surgery and a large foreign body (6 mm), which are all factors associated with poor visual outcome.…”

Molecular biology applied to the laboratory diagnosis of bacterial endophthalmitis

“…Soon after, various authors showed how the utilization of PCR for the direct detection of pathogens from aqueous and vitreous humor samples could impact effectively the diagnosis of bacterial endophthalmitis, mainly by increasing significantly the number of cases that were characterized microbiologically with the use of PCR but that were shown to be negative by microscopy or culture (11,(13)(14)(15)(19)(20)(21)(22) (Table 2). The nested PCR method was later used in specimens of vitreous (n=30) and aqueous (n=28) humor collected from 55 patients with clinical diagnosis of endophthalmitis (21) .…”

“…The nested PCR method was later used in specimens of vitreous (n=30) and aqueous (n=28) humor collected from 55 patients with clinical diagnosis of endophthalmitis (21) . This study utilized universal primers for the bacterial 16S rRNA gene and a set of species-specific primers for P. acnes.…”

Surveillance of endophthalmitis following cataract surgery in the UK

“…Should subsequent microbiological cultures prove to be negative, this still does not rule out an infectious aetiology as a significant percentage of infectious cases are not bacteriologically identified by using conventional culture techniques. [12][13][14] One recent study showed that by using the polymerase chain reaction in the diagnosis of bacterial endophthalmitis, 54.8% more samples were positive for bacteria compared to conventional culture methods. 14 Both culture negative and culture positive cases were therefore included in the data analysis for this study.…”

“…[12][13][14] One recent study showed that by using the polymerase chain reaction in the diagnosis of bacterial endophthalmitis, 54.8% more samples were positive for bacteria compared to conventional culture methods. 14 Both culture negative and culture positive cases were therefore included in the data analysis for this study.…”