Impact of pre-operative antimicrobial treatment on microbiological findings from endocardial specimens in infective endocarditis

Abstract

Treatment of infective endocarditis (IE) should be initiated promptly. This might hamper the chances to identify the causative organism in blood cultures. Microbiological sampling of infected valve in patients undergoing surgery might identify the causative organism. The impact of pre-operative antimicrobial treatment on the yield of valve samples is not known. This study evaluated the impact of the duration of the pre-operative antibiotic treatment on valve culture and 16S rRNA PCR findings from resected endocardial samples. Patients meeting the modified Duke criteria of definite or possible IE and undergoing valve surgery due to IE during 2011–2016 were included from Southern Finland. Eighty-seven patients were included. In patients with shorter than 2 weeks of pre-operative antimicrobial treatment, PCR was positive in 91% ( n = 42/46) and valve culture in 41% ( n = 19/46) of cases. However, in patients who had 2 weeks or longer therapy before operation, PCR was positive in 53% ( n = 18/34) and all valve cultures were negative. In 14% of patients, PCR had a diagnostic impact. In blood-culture negative cases ( n = 13), PCR could detect the causative organism in ten patients (77%). These included five cases of Bartonella quintana , one Tropheryma whipplei , and one Coxiella burnetii . Long pre-operative antimicrobial treatment was shown to have a negative impact on microbiological tests done on resected endocardial material. After 2 weeks of therapy, all valve cultures were negative, but PCR was positive in half of the cases. PCR aided in diagnostic work-up, especially in blood culture negative cases. Electronic supplementary material The online version of this article (10.1007/s10096-018-03451-5) contains supplementary material, which is available to authorized users.

The diagnostic benefit of 16S rDNA PCR examination of infective endocarditis heart valves: a cohort study of 146 surgical cases confirmed by histopathology

“…In addition, valve PCR can substantiate earlier results of blood culture positive infective endocarditises [ 13 ]. Halavaara et al describe 62% of surgical patients with such confirmed results [ 21 ], while we found concordant findings of blood cultures and valve PCRs in 63/146 (43%) of surgical infective endocarditises. The majority of cases with different microorganisms detected by blood culture and valve PCR in our study occurred when skin commensals appeared in blood culture but were refuted by valve PCR, which identified a typical pathogen on the valve (Table S3); for these patients valve PCR provided a diagnostic benefit.…”

“…Our results also confirm observations by Fournier et al and Goldenberg et al that blood culture-negative endocarditises benefit from detection through valve PCR and that blood culture positive infective endocarditises can be substantiated by concordant valve PCRs [ 8 , 13 ]. Valve PCR was also significantly more successful in pathogen identification than valve culture, a tendency that has already been described [ 21 , 22 ].…”

“…These cases either had negative blood cultures beforehand or had a more plausible pathogen in valve PCR than had been previously detected in blood cultures [ 22 ]. Halavaara et al also described a benefit of valve PCR for 14% of surgical blood culture-negative endocarditises [ 21 ], while valve culture was of no diagnostic benefit. This agrees with our results, where valve PCR was significantly ( p < 0.001) more likely to provide clinically relevant information than valve culture.…”

“…Even though PCR is a growth-independent method and less susceptible to antibiosis than culturing, the yield of PCR differs depending on the duration of effective antibiotic treatment that has been applied before the examination of valve material. Halavaara et al describe 16S rDNA valve PCR being positive in 91% and valve culture in 41% of endocarditis patients receiving < 2 weeks of preoperative antibiosis; in all patients with ≥ 2 weeks of treatment only 53% of PCRs were positive and valve culture remained negative altogether [ 21 ]. Vollmer et al also proposes that valve PCR is the more suitable method after prolonged antibiosis, even if the yield is reduced [ 12 ].…”

Rapid molecular detection of pathogenic microorganisms and antimicrobial resistance markers in blood cultures: evaluation and utility of the next-generation FilmArray Blood Culture Identification 2 panel

“…In total, 103 blood culture bottles (BacT/Alert, bioMérieux, France), one bottle per patient, confirmed to contain either Gram-negative bacteria, Gram-positive rods, Gram-positive diplococci, cocci in chains, yeast, or polymicrobial growth by Gram-staining and evaluation by a clinical microbiologist, were analyzed between November 2020 and January 2021 with the FilmArray BCID2 assay and routine reference methods. Routine methods included subculture from the signal-positive bottle on rich universal agars, such as blood, chocolate, and fastidious anaerobe agar plates with incubation at 35 °C in normal atmosphere as well as in elevated CO 2 and in anaerobic conditions for 24 to 48 h. Microbial isolates were identified by Vitek MS (bioMérieux, France) and in case of unclear result confirmed by 16S rDNA sequencing [21]. Antimicrobial susceptibilities were determined using disc (Oxoid, UK) and/or MIC-gradient (M.I.C.E, Oxoid, Basingstoke, UK, and ETest, bioMérieux, France) diffusion tests on Mueller-Hinton agar (BD, USA) at 35 °C for 24 to 48 h. Phenotypic susceptibility profile for each isolate was interpreted according to the EUCAST standard [22].…”