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

Pear Pongsachareonnont,Tanittha Chatsuwan,Worawalun Honglertnapakul

doi:10.1186/s12879-017-2264-5

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.

Highlights

Identification of bacterial pathogens in endophthalmitis is important to inform antibiotic selection and treatment decisions
Identification of the causative bacterial pathogens in cases of acute bacterial endophthalmitis increases the likelihood of successful treatment because appropriate antibiotics can be selected
Forty-one specimens were collected from 29 cases of presumed acute bacterial endophthalmitis

Summary

Introduction

Identification of bacterial pathogens in endophthalmitis is important to inform antibiotic selection and treatment decisions. 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. The prognosis of patients with endophthalmitis depends on various factors, including the patient’s baseline condition, the source of infection, the severity of clinical symptoms, and the causative bacterial pathogen [1,2,3]. The common causative pathogens of acute bacterial endophthalmitis vary depending on geographic location and on the specific infection source. Identification of the causative bacterial pathogens in cases of acute bacterial endophthalmitis increases the likelihood of successful treatment because appropriate antibiotics can be selected

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