The sensitivity and specificity of fecal and cecal culture for the detection of Campylobacter in Dutch broiler flocks quantified by Bayesian analysis

Abstract

Dutch broiler flocks are routinely tested for the presence of thermotolerant Campylobacter spp. using a standard cultural procedure for fecal and cecal samples. The objective of this study was to estimate the sensitivity and specificity of fecal and cecal culture for detection of Campylobacter colonization in broiler flocks in absence of a gold standard. Data from 1600 flocks were used from two different populations, whereby only flocks with both fecal and cecal culture results were included in the analysis. Latent class analysis using Bayesian inference was applied to generate the test characteristics of fecal and cecal culture. Two statistical models assuming conditional dependence of both tests on Campylobacter status were used to compare the results. On flock level, the sensitivity of the fecal culture was found to be 21% (95% CI: 12, 31) and 23% (95% CI: 13, 60), and the specificity was 98% (95% CI: 94, 99) and 97% (95% CI: 92, 99) for the two models, respectively. The sensitivity of the cecal culture was 64% (95% CI: 37, 89) and 66% (95% CI: 39, 90), and the specificity was 98% (95 CI: 94, 99) and 95% (95% CI: 72, 99) in respective models. The implications of a low sensitivity as in the case of the fecal culture is important for the design and interpretation of monitoring programmes and may result in excessive false negative test results. Although cecal culture is the more sensitive test, substantial misclassification of infected flocks may still occur.

Bayesian analysis of culture and PCR methods for detection of Campylobacter spp. in broiler caecal samples

“…For samples where both species are present, there will be greater underestimation of C. jejuni than C. coli ( Table 6). Specificity of culture was found to be close to that obtained by a previous study (∼98%) [20], although it was higher for C. coli than C. jejuni. One possible cause of false positives and thus imperfect specificity of culture is the misclassification of species due to the hippurate test.…”

“…There is a potential lack of identifiability in the infection status of samples that were C. jejuni positive for culture but C. jejuni negative for PCR. However, the estimate of specificity of 0·74 is not credible in the light of previous work [20] or the recent EU survey on Campylobacter in broilers, with apparent prevalence in pooled caecal samples being as low as 2% in one MS [21].…”

Assessment of two different types of sample for the early detection and isolation of thermophilicCampylobacterin broiler farms

“…However, detection was better when using cloacal swab samples, probably due to a lower regrowth of accompanying microbiota that, although not frequent when using mCCDA plates, can sometimes mask Campylobacter colonies hampering its detection. Other authors have reported that the sensitivity of caecal culture was higher than the sensitivity of the faecal culture (Woldemariam et al, 2008); nevertheless samples were obtained at the end of the rearing cycle of the flock (at partial or final depopulation) at farm or at the slaughterhouse. Also, fewer faecal samples than caecal samples were obtained, which may have decreased the herd sensitivity.…”

The change in prevalence of Campylobacter on chicken carcasses during processing: A systematic review

“…This might have influenced individual study results and the degree of heterogeneity among results from different studies. Because Campylobacter can be difficult to culture (i.e., low sensitivity; Woldemariam et al, 2008), a negative result could be either a true negative sample or could represent a false negative. Direct plating has recently been shown to greatly underestimate Campylobacter prevalence of postchill broiler carcass rinsates Richardson et al, 2009).…”