Molecular prevalence of Coxiella burnetii in bulk-tank milk from bovine dairy herds: Systematic review and meta-analysis.

Coxiella burnetii is an obligate intracellular zoonotic bacterium that causes Q fever. Ruminants, including cattle, are broadly known to be reservoirs for this bacterium. Since 2006, many research groups have evaluated the herd-level prevalence of C. burnetii in cattle by molecular techniques on composite milk samples. This study explored the global C. burnetii herd-level prevalence from studies done on bovine bulk-tank milk (BTM) samples using PCR-based analysis. Also, moderators were investigated to identify sources of heterogeneity. Databases (CAB Abstracts, Medline via Ovid, PubMed, Web of Science and Google Scholar) were searched for index articles on C. burnetii prevalence in BTM samples by PCR published between January-1973 and November-2018. Numerous studies (1054) were initially identified, from which seventeen original publications were included in the meta-analysis based on the pre-defined selection criteria. These studies comprised 4031 BTM samples from twelve countries. A random-effects model was used because of considerable heterogeneity (I 2 = 98%) to estimate the herd-level prevalence of C. burnetii as 37.0%(CI95%25.2-49.5%). The average herd size appeared to account for a high level of the heterogeneity. No other moderators (geographic location, gross national income or notification criteria for Q fever) seemed to be determinant. This systematic evaluation demonstrated a high molecular prevalence of C. burnetii in BTM samples both in European and non-European countries, evidencing a widespread herd-level circulation of this agent in bovine dairy farms around the world. Meta-regression showed herd size as the most relevant moderator with the odds of a BTM sample testing positive doubling with every unit increase.

Clinical and epidemiological use of nested PCR targeting the repetitive element IS1111 associated with the transposase gene from Coxiella burnetii

ABSTRACT Q fever is a worldwide zoonosis caused by Coxiella burnetii—a small obligate intracellular Gram-negative bacterium found in a variety of animals. It is transmitted to humans by inhalation of contaminated aerosols from urine, feces, milk, amniotic fluid, placenta, abortion products, wool, and rarely by ingestion of raw milk from infected animals. Nested PCR can improve the sensitivity and specificity of testing while offering a suitable amplicon size for sequencing. Serial dilutions were performed tenfold to test the limit of detection, and the result was 10× detection of C. burnetti DNA with internal nested PCR primers relative to trans-PCR. Different biological samples were tested and identified only in nested PCR. This demonstrates the efficiency and effectiveness of the primers. Of the 19 samples, which amplify the partial sequence of C. burnetii, 12 were positive by conventional PCR and nested PCR. Seven samples—five spleen tissue samples from rodents and two tick samples—were only positive in nested PCR. With these new internal primers for trans-PCR, we demonstrate that our nested PCR assay for C. burnetii can achieve better results than conventional PCR.

Clinical and epidemiological use of nested PCR targeting the repetitive element IS1111 associated with the transposase gene from Coxiella burnetii

Q fever is a worldwide zoonosis caused by Coxiella burnetii—a small obligate intracellular Gram-negative bacterium found in a variety of animals. It is transmitted to humans by inhalation of contaminated aerosols from urine, feces, milk, amniotic fluid, placenta, abortion products, wool, and rarely by ingestion of raw milk from infected animals. Nested PCR can improve the sensitivity and specificity of testing while offering a suitable amplicon size for sequencing. Serial dilutions were performed tenfold to test the limit of detection, and the result was 10× detection of C. burnetti DNA with internal nested PCR primers relative to trans-PCR. Different biological samples were tested and identified only in nested PCR. This demonstrates the efficiency and effectiveness of the primers. Of the 19 samples, which amplify the partial sequence of C. burnetii, 12 were positive by conventional PCR and nested PCR. Seven samples—five spleen tissue samples from rodents and two tick samples—were only positive in nested PCR. With these new internal primers for trans-PCR, we demonstrate that our nested PCR assay for C. burnetii can achieve better results than conventional PCR.(AU)

Clinical and epidemiological use of nested PCR targeting the repetitive element IS1111 associated with the transposase gene from Coxiella burnetii.

Q fever is a worldwide zoonosis caused by Coxiella burnetii-a small obligate intracellular Gram-negative bacterium found in a variety of animals. It is transmitted to humans by inhalation of contaminated aerosols from urine, feces, milk, amniotic fluid, placenta, abortion products, wool, and rarely by ingestion of raw milk from infected animals. Nested PCR can improve the sensitivity and specificity of testing while offering a suitable amplicon size for sequencing. Serial dilutions were performed tenfold to test the limit of detection, and the result was 10× detection of C. burnetti DNA with internal nested PCR primers relative to trans-PCR. Different biological samples were tested and identified only in nested PCR. This demonstrates the efficiency and effectiveness of the primers. Of the 19 samples, which amplify the partial sequence of C. burnetii, 12 were positive by conventional PCR and nested PCR. Seven samples-five spleen tissue samples from rodents and two tick samples-were only positive in nested PCR. With these new internal primers for trans-PCR, we demonstrate that our nested PCR assay for C. burnetii can achieve better results than conventional PCR.