Comparison of methods for identifying causative bacterial microorganisms in presumed acute endophthalmitis: conventional culture, blood culture, and PCR

Abstract

BackgroundIdentification of bacterial pathogens in endophthalmitis is important to inform antibiotic selection and treatment decisions. Hemoculture bottles and polymerase chain reaction (PCR) analysis have been proposed to offer good detection sensitivity. This study compared the sensitivity and accuracy of a blood culture system, a PCR approach, and conventional culture methods for identification of causative bacteria in cases of acute endophthalmitis.MethodsTwenty-nine patients with a diagnosis of presumed acute bacterial endophthalmitis who underwent vitreous specimen collection at King Chulalongkorn Memorial Hospital were enrolled in this study. Forty-one specimens were collected. Each specimen was divided into three parts, and each part was analyzed using one of three microbial identification techniques: conventional plate culture, blood culture, and polymerase chain reaction and sequencing. The results of the three methods were then compared.ResultsBacteria were identified in 15 of the 41 specimens (36.5%). Five (12.2%) specimens were positive by conventional culture methods, 11 (26.8%) were positive by hemoculture, and 11 (26.8%) were positive by PCR. Cohen’s kappa analysis revealed p-values for conventional methods vs. hemoculture, conventional methods vs. PCR, and hemoculture vs. PCR of 0.057, 0.33, and 0.009, respectively. Higher detection rates of Enterococcus faecalis were observed for hemoculture and PCR than for conventional methods.ConclusionsBlood culture bottles and PCR detection may facilitate bacterial identification in cases of presumed acute endophthalmitis. These techniques should be used in addition to conventional plate culture methods because they provide a greater degree of sensitivity than conventional plate culture alone for the detection of specific microorganisms such as E. faecalis. Trial registrationThai Clinical Trial Register No. TCTR20110000024.

Utility of broad-range 16S rRNA PCR assay versus conventional methods for laboratory diagnosis of bacterial endophthalmitis in a tertiary care hospital

“…In one of our previous study, the bacterial detection using conventional and automated culture in endophthalmitis was 13.33% vs 33.33%, respectively 18. In other studies the bacterial detection rate by conventional and automated culture was 12.2% (5/41) vs 26.8% (11/41) from Thailand,2 16.8% (81/483) vs 31.1% (150/483) from Chennai, India,4 33% (47/140) vs 55% (77/140) from the UK,19 35% (14/40) vs 65% (26/40) from Tehran17 and 53.9% (7/13) vs 69.2% (9/13) from Israel,3 respectively. Since a significant increase in the isolation rate of bacteria occurs using automated culture method, wherever molecular methods are not feasible automated culture method should be ideally used for microbial diagnosis of endophthalmitis.…”

“…Other studies have found CoNS are the most common bacteria among all detected pathogens: 44% (23/50) from Hyderabad (India),23 17.34% (17/98) from Chennai (India),23 17.6% (6/34) from Turkey,2 48% (17/97) from Brazil2 and 70% from the USA 1. Among these CoNS groups, S. epidermidis was the most common bacterial species in our study, comprising 67.39% of all CoNS isolates and 24.4% of all bacteria.…”

“…The rapid progression of infection often results in a poor visual outcome despite treatment. Accurate microbiological diagnosis and bacterial antibiotic susceptibility pattern are critical in initiating optimal therapy and preventing complications 2. However some bacterial species are difficult to isolate, or are slow-growing, while others may not be isolated because of prior antimicrobial therapy.…”

Post-intravitreal injection endophthalmitis secondary to Turicella otitidis: a case report

“…Prior work shows that blood culture and PCR have a higher diagnostic yield for endophthalmitis than conventional plate culture in vitreous specimens [14], and blood culture requires a larger volume specimen than PCR. Aqueous specimens typically are smaller in volume than vitreous specimens, but obtaining an aqueous specimen is technically easier than obtaining a vitreous specimen, and a diagnostic anterior chamber paracentesis may be less likely than a vitreous tap to cause an associated retinal detachment.…”

Antibiotic prophylaxis for preventing endophthalmitis after intravitreal injection: a systematic review

“…A limitation of our review is that we did not plan to perform separate analyses of culture-positive and culturenegative endophthalmitis. In fact, this complication is usually diagnosed on the basis of a spectrum of clinical features including pain, decreased visual acuity, hypopyon and posterior segment inflammation, and is frequently underestimated by culture tests [52].…”