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Comparative study of diagnosis of PD peritonitis by quantitative polymerase chain reaction for bacterial DNA vs
Gemma Johnson1, Mark Wilks, Simon Warwick
1Department of Medical Microbiology, Barts and The London NHS Trust, Whitechapel, UK.
Introduction:
Peritonitis remains one of the main complications that afflict peritoneal dialysis patients. We conducted a pilot study to determine the feasibility and potential advantages of quantitative PCR (qPCR) assays for the presence of bacterial DNA in this clinical scenario.
Methods:
14 patients attending with 'cloudy bags' had PD fluid analyzed in accordance with Renal Association Standards. In addition, quantitative bacterial DNA analysis was performed on 50 mL samples of PD fluid. DNA was extracted using a Qiagen kit. Quantitative PCR assays using primers and probes targeted at 16S rDNA were used to measure the levels of bacterial DNA. Samples from 13 patients attending the department for other reasons served as negative controls. Laboratory staff were blinded to clinical details at the time of analysis.
Results:
We determined a threshold of bacterial DNA whereby 11 of 13 negative controls were 'negative'. Significant bacterial DNA was found in 6 of 9 culture positive' peritonitis cases (p < 0.05 by chi(2). The 3 cases of 'no growth' peritonitis had 'insignificant' bacterial DNA. Serial DNA analysis was performed in 8 patients. Of the 6 patients who were 'cured' with standard antibiotic therapy, only 1 showed a rise in bacterial DNA from Day 1 to 5. But the 2 patients who relapsed after antibiotics had marked rises in bacterial DNA (p < 0.05 by chi(2).
Discussion:
We showed that results from quantitative bacterial DNA PCR assays correlate with current microbiological tests despite the small size of this study. We also suggest that this technology might be clinically useful as an adjunct for cases of 'no growth' peritonitis and to identify those patients likely to relapse despite apparent clinical improvement with standard antibiotic therapy.
Insights
Quantitative PCR (qPCR) assays for bacterial DNA show promise in diagnosing peritonitis in peritoneal dialysis patients. This method may help identify difficult cases and predict relapse.
Area of Science:
- Nephrology
- Clinical Microbiology
- Molecular Diagnostics
Background:
- Peritonitis is a major complication for patients undergoing peritoneal dialysis (PD).
- Current diagnostic methods have limitations, particularly in 'no growth' cases.
Purpose of the Study:
- To evaluate the feasibility and advantages of quantitative PCR (qPCR) assays for detecting bacterial DNA in PD fluid.
- To assess the correlation of qPCR results with traditional microbiological tests.
Main Methods:
- PD fluid samples from 14 patients with suspected peritonitis and 13 controls were analyzed.
- Quantitative bacterial DNA analysis was performed using 16S rDNA-targeted qPCR.
- Laboratory staff were blinded to clinical information.
Main Results:
- qPCR detected significant bacterial DNA in 6 of 9 culture-positive peritonitis cases.
- Cases of 'no growth' peritonitis showed insignificant bacterial DNA levels.
- Serial qPCR analysis indicated potential for predicting relapse in patients treated with antibiotics.
Conclusions:
- Quantitative bacterial DNA PCR assays correlate with current microbiological tests.
- qPCR may serve as an adjunct diagnostic tool for 'no growth' peritonitis.
- This technology could help identify patients at risk of relapse.
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