First isolation of Coxiella burnetii from clinical material by cell-free medium (ACCM2)

Management of zoonoses in research institutions - lessons learned from a Coxiella burnetii outbreak case

When biomedical research investigates the human surgical situation in the need of a chronic course, it is more often possible to do so using large animal models. The use of farm animals always poses special challenges for the institution conducting the research in terms of infection prevention and occupational safety. Especially for the zoonotic disease coxiellosis it is important to be aware of the constant risk of pathogen introduction by small ruminants and to take appropriate precautions. In this way, personal injury should be avoided or at least be kept to a minimum in the event of infection since then sustainable zoonosis control can be immediately initiated. Using the example of a Q fever outbreak at a research facility, we want to share with this extended case report the importance of central emergency structures, provisions and the inclusion of relevant experts and disciplines in a crisis team. Its primary purpose is to support the affected facility and coordinate the implementation of necessary cleaning, disinfection and decontamination measures in close contact with the responsible local authorities. The aim is to inactivate the pathogen in a systematic and controlled manner in few steps of action only and to keep the interruption of the facility's operations as short as possible.

Treatment of persistent focalized Q fever: time has come for an international randomized controlled trial

Q fever is a worldwide zoonosis due to Coxiella burnetii, responsible for endocarditis and endovascular infections. Since the 1990s, the combination hydroxychloroquine + doxycycline has constituted the curative and prophylactic treatment in persistent focalized Q fever. This combination appears to have significantly reduced the treatment's duration (from 60 to 26 months), yet substantial evidence of effectiveness remains lacking. Data are mostly based on in vitro and observational studies. We conducted a literature review to assess the effectiveness of this therapy, along with potential alternatives. The proposed in vitro mechanism of action describes the inhibition of Coxiella replication by doxycycline through the restoration of its bactericidal activity (inhibited in acidic environment) by alkalinization of phagolysosome-like vacuoles with hydroxychloroquine. So far, the rarity and heterogeneous presentation of cases have made it challenging to design prospective studies with statistical power. The main studies supporting this treatment are retrospective cohorts, dating back to the 1990s-2000s. Retrospective studies from the large Dutch outbreak of Q fever (>4000 cases between 2007 and 2010) did not corroborate a clear benefit of this combination, notably in comparison with other regimens. Thus, there is still no consensus among the medical community on this issue. However insufficient the evidence, today the doxycycline + hydroxychloroquine combination remains the regimen with the largest clinical experience in the treatment of 'chronic' Q fever. Reinforcing the guidelines' level of evidence is critical. We herein propose the creation of an extensive international registry, followed by a prospective cohort or ideally a randomized controlled trial.

Occurrence of Coxiellosis in ruminants and its associated risk factors

Coxiellosis in animals is caused by the zoonotic pathogen, Coxiella burnetii. Although the disease is of public health importance it remains underdiagnosed and underreported. The cross- sectional study was aimed to estimate the occurrence of the disease in livestock of study area and also to identify the risk factors associated with the disease in animals. Blood, serum, and vaginal swabs samples were collected from 200 ruminants (cattle, sheep, and goats), across various farms in Karnataka, India. These samples were then screened using ELISA and PCR (com1 and IS1111). A questionnaire was administered to the farm owners to collect the risk factor-related information. About 5.26 % cattle, 12.3 % sheep, and 12.5 % goats were positive by ELISA. By PCR, 9.47 % cattle, 9.3 % sheep, and 10 % goats were positive. Overall, the occurrence of 14.73 %, 18.46 % and 17.5 % was estimated in cattle, sheep and goat, respectively. PCR targeting the IS1111 gene detected higher number of samples as positive as compared to the com1 gene PCR. Higher number of vaginal swab samples were detected as positive as compared to blood. History of reproductive disorders (OR: 4.30; 95 %CI:1.95- 9.46), abortion (OR: 30.94; 95 %CI:6.30- 151.84) and repeat breeding (OR:11.36; 95 %CI:4.16- 30.99) were significantly associated with coxiellosis (p < 0.005). Multivariable analysis by logistic regression model analysis suggested retained abortion, repeat breeding and rearing of animal in semi-intensive system as factors significantly associated with the infection. Cultural identification of the PCR positive samples were cultured using embryonated egg propagation and cell culture techniques and positivity was confirmed in six samples. Phylogenetic analysis of the com1 and IS1111 gene revealed clustering based on similar geographic locations. The study estimated the occurrence of the disease in the study area and identified the potential risk factors.

Detection of Coxiella burnetii in the mammary gland of a dairy goat

The zoonotic bacterium Coxiella (C.) burnetii can be excreted by infected goats through birth products and milk. The detection of C. burnetii DNA in the mammary gland tissue of infected dairy goats and intermittent milk shedders has been reported, but confirmation of C. burnetii bacteria in the udder remained pending. The pathogen caused abortions in a 152-head dairy goat herd, resulting in the vaccination against C. burnetii of the entire herd with annual boosters. To monitor the C. burnetii shedding at herd level, monthly bulk tank milk (BTM) samples were analyzed using PCR (IS1111). Despite vaccination, C. burnetii DNA was detected in BTM samples within the first 16 months of the study. Therefore, individual milk samples were tested on four different occasions several months apart to identify potential intermittent milk shedders. Only one goat (#67455) tested positive three times. This goat was necropsied to investigate the presence of C. burnetii in the udder and other organs. PCR detected C. burnetii DNA solely in both mammary glands and the left teat cistern. Immunohistological examination identified C. burnetii antigen in mammary gland tissue, confirmed by the detection of C. burnetii bacteria in the mammary epithelial cells using fluorescence in situ hybridization. The removal of goat #67455 led to negative BTM samples until the end of the study. The findings demonstrate the occurrence of C. burnetii in the mammary gland of a naturally infected and vaccinated goat. The presence possibly contributed to intermittent milk shedding of goat #67455, and the mammary gland tissue may serve as a replicative niche for C. burnetii.

Spinning sugars in antigen biosynthesis: characterization of the Coxiella burnetii and Streptomyces griseus TDP-sugar epimerases

The sugars streptose and dihydrohydroxystreptose (DHHS) are unique to the bacteria Streptomyces griseus and Coxiella burnetii, respectively. Streptose forms the central moiety of the antibiotic streptomycin, while DHHS is found in the O-antigen of the zoonotic pathogen C. burnetii. Biosynthesis of these sugars has been proposed to follow a similar path to that of TDP-rhamnose, catalyzed by the enzymes RmlA, RmlB, RmlC, and RmlD, but the exact mechanism is unclear. Streptose and DHHS biosynthesis unusually requires a ring contraction step that could be performed by orthologs of RmlC or RmlD. Genome sequencing of S. griseus and C. burnetii has identified StrM and CBU1838 proteins as RmlC orthologs in these respective species. Here, we demonstrate that both enzymes can perform the RmlC 3'',5'' double epimerization activity necessary to support TDP-rhamnose biosynthesis in vivo. This is consistent with the ring contraction step being performed on a double epimerized substrate. We further demonstrate that proton exchange is faster at the 3''-position than the 5''-position, in contrast to a previously studied ortholog. We additionally solved the crystal structures of CBU1838 and StrM in complex with TDP and show that they form an active site highly similar to those of the previously characterized enzymes RmlC, EvaD, and ChmJ. These results support the hypothesis that streptose and DHHS are biosynthesized using the TDP pathway and that an RmlD paralog most likely performs ring contraction following double epimerization. This work will support the elucidation of the full pathways for biosynthesis of these unique sugars.

Current approaches for the detection of Coxiella burnetii infection in humans and animals

Q fever (coxiellosis), caused by Coxiella burnetii, is an emerging or re-emerging zoonotic disease of public health significance and with worldwide distribution. As a causal agent of the one among the 13 global priority zoonoses, having the infectious dose as low as one bacterium, C. burnetii has been regarded as an obligate intracellular bacterial pathogen. The agent has been classified as a Group B bioterrorism agent by the Centre for Disease Control and Prevention (CDC), and the disease is included in the World Organisation for Animal Health (OIE) list of notifiable diseases. It is mainly transmitted through airborne route in humans and animals. Isolation of C. burnetii, using standard routine laboratory culture techniques was impossible until formulation of axenic-based medium. However, it is still to be included among routinely isolated laboratory pathogen, accounting prolonged incubation period (~7 days) and requirement of specific oxygen concentration (2.5% O₂). Therefore, indirect diagnostic tools have been mainly used for its diagnosis. So far serology has been mostly used for testing for C. burnetii infection. The detection of C. burnetii DNA by PCR in various clinical samples have also been widely used. The disease has remained largely under-reported, underdiagnosed and as a masked zoonosis; and therefore, needs to be explored through well-planned scientific studies for knowing its true status and likely it impact in humans and animals by employing state-of-the-art diagnostics, identifying its diverse and new host range, as well as risk factors involved in different geo-climatic, behavioural and social settings as well as risk groups. Here, we reviewed the current approaches used for the detection of C. burnetii infection in humans and animals at the population and individual level.

Molecular epidemiology of Rickettsia sp. and Coxiella burnetii collected from Hyalomma asiaticum in Bactrian camels (Camelus bactrianus) in inner Mongolia of China

The purpose of the present study was to determine the presence of Rickettsia sp. and Coxiella burnetii in Hyalomma asiaticum collected from Bactrian camels (Camelus bactrianus) in Inner Mongolia of China. A total of 385 H. asiaticum adults collected from Bactrian camels from Alxa in Inner Mongolia from 2017 to 2018 were examined using PCR combined with sequencing. The results indicated that 18 (4.7 %) and 5 (1.3 %) samples tested positive for Rickettsia and C. burnetii, respectively. The corresponding nucleotide identities among detected genes ranged between 99.7 % and 100 % for the sequences of 17 kD and ompB from Rickettsia and 16S rRNA and FtsX from C. burnetii. Two representative strains-Rickettsia IMA-1 strain and C. burnetii IMA-1 strain-were used for subsequent analysis. NCBI BLAST and phylogenetic analyses demonstrated that the detected strain Rickettsia IMA-1 may represent a novel species of spotted fever group (SFG) rickettsiae. The C. burnetii IMA-1 strain was grouped with Coxiella burnetii str. RSA439 (GenBank: CP040059.1). In addition, the Rickettsia sp. was successfully isolated from the ticks in Vero cells incubated at 28 °C. These findings indicate that the H. asiaticum collected off Bactrian camels in Inner Mongolia carried SFG Rickettsia species and C. burnetii and could contribute to the etiology of febrile illness in animals and humans.

Acute phase proteins, proinflammatory cytokines and oxidative stress biomarkers in sheep, goats and she-camels with Coxiella burnetii infection-induced abortion

Acute phase proteins (APPs) and oxidative stress are helpful markers in diagnosis of several infectious diseases. APPs, proinflammatory cytokines and oxidative stress markers were evaluated for their role in the diagnosis of naturally acquired Coxiella burnetii (Q fever) associated with abortion in sheep, goats and she-camels. Blood, aborted materials and vaginal swabs were collected from mixed herds in the Eastern Province of Saudi Arabia. Antioxidant biomarkers showed significant decline in cases of abortion compared to control animals at delivery time. The correlation between disease status and all parameters ranged from moderate to high. The APPs, cytokines and the oxidative stress marker malondialdehyde (MDA) displayed a high degree of distinction between aborted sheep and goat and normal delivered animals (AUC > 0.90). However, only MDA showed a high degree of differentiation (AUC > 0.90) between aborted she-camels and normal delivered controls. In conclusion, results from our study allow us to recommend using APPs, cytokines and oxidative stress markers as an additional tool for diagnosis of naturally occurring C. burnetii infection in sheep, goats and she-camels. However, it does not replace standard procedures for detection of C. burnetii.

Quantitation of viableCoxiella burnetiiin milk products using a liquid medium-based MPN-PCR assay

This Technical Research Communication describes a new method by which thermally treatedCoxiellain milk products may be grown in a liquid growth medium and quantitated using an MPN-PCR assay.Coxiellais generally not used in studies on thermal and non-thermal processing of milk due to the need for specialized and highly laborious techniques such as animal assays and tissue culture for determining viability. Recently, a liquid growth medium (ACCM-2) and modified atmosphere were used to growCoxiellafrom pure cultures, infected mouse tissues, and clinical samples, however, the ability to growCoxiellafrom a food such as milk has not been shown. The potential ability to enrichCoxielladirectly from contaminated milk presents a new avenue for conducting pasteurization research in which the viability of heat-treated or injured cultures could be more easily determined through direct enrichment ofCoxiellain ACCM-2. ACCM-2 medium allowed enrichment ofCoxiellafrom bovine whole milk and cream, whole goat, and whole camel milks but not whole water buffalo milk. Enrichment was possible from whole bovine milk containing as few as 6Coxiellage/ml of milk. The applicability of this ACCM-2 enrichment method was shown when using an MPN-PCR assay to quantitate the number of viableCoxiellaremaining in whole bovine milk after 64 °C thermal treatment for up to 10 min.

Critical Aspects for Detection of Coxiella burnetii

Coxiella burnetii is a globally distributed zoonotic γ-proteobacterium with an obligatory intracellular lifestyle. It is the causative agent of Q fever in humans and of coxiellosis among ruminants, although the agent is also detected in ticks, birds, and various other mammalian species. Requirements for intracellular multiplication together with the necessity for biosafety level 3 facilities restrict the cultivation of C. burnetii to specialized laboratories. Development of a novel medium formulation enabling axenic growth of C. burnetii has facilitated fundamental genetic studies. This review provides critical insights into direct diagnostic methods currently available for C. burnetii. It encompasses molecular detection methods, isolation, and propagation of the bacteria and its genetic characterization. Differentiation of C. burnetii from Coxiella-like organisms is an essential diagnostic prerequisite, particularly when handling and analyzing ticks.

From Q Fever to Coxiella burnetii Infection: a Paradigm Change

Coxiella burnetii is the agent of Q fever, or "query fever," a zoonosis first described in Australia in 1937. Since this first description, knowledge about this pathogen and its associated infections has increased dramatically. We review here all the progress made over the last 20 years on this topic. C. burnetii is classically a strict intracellular, Gram-negative bacterium. However, a major step in the characterization of this pathogen was achieved by the establishment of its axenic culture. C. burnetii infects a wide range of animals, from arthropods to humans. The genetic determinants of virulence are now better known, thanks to the achievement of determining the genome sequences of several strains of this species and comparative genomic analyses. Q fever can be found worldwide, but the epidemiological features of this disease vary according to the geographic area considered, including situations where it is endemic or hyperendemic, and the occurrence of large epidemic outbreaks. In recent years, a major breakthrough in the understanding of the natural history of human infection with C. burnetii was the breaking of the old dichotomy between "acute" and "chronic" Q fever. The clinical presentation of C. burnetii infection depends on both the virulence of the infecting C. burnetii strain and specific risks factors in the infected patient. Moreover, no persistent infection can exist without a focus of infection. This paradigm change should allow better diagnosis and management of primary infection and long-term complications in patients with C. burnetii infection.

Genotyping and Axenic Growth of Coxiella burnetii Isolates Found in the United States Environment

Coxiella burnetii is a gram-negative bacterium that is the etiologic agent of the zoonotic disease Q fever. Common reservoirs of C. burnetii include sheep, goats, and cattle. These animals shed C. burnetii into the environment, and humans are infected by inhalation of aerosols. A survey of 1622 environmental samples taken across the United States in 2006-2008 found that 23.8% of the samples contained C. burnetii DNA. To identify the strains circulating in the U.S. environment, DNA from these environmental samples was genotyped using an SNP-based approach to derive sequence types (ST) that are also compatible with multispacer sequence typing methods. Three different sequence types were observed in 31 samples taken from 19 locations. ST8 was associated with goats and ST20 with dairy cattle. ST16/26 was detected in locations with exposure to various animals and also in locations with no direct animal contact. Viable isolates were obtained for all three sequence types, but only the ST20 and ST16/26 isolates grew in acidified citrate cysteine medium (ACCM)-2 axenic media. Examination of a variety of isolates with different sequence types showed that ST8 and closely related isolates did not grow in ACCM-2. These results suggest that a limited number of C. burnetii sequence types are circulating in the U.S. environment and these strains have close associations with specific reservoir species. Growth in ACCM-2 may not be suitable for isolation of many C. burnetii strains.

The contribution of genomics to the study of Q fever

Coxiella burnetii is the etiological agent of Q fever, a worldwide zoonosis that can result in large outbreaks. The birth of genomics and sequencing of C. burnetii strains has revolutionized many fields of study of this infection. Accurate genotyping methods and comparative genomic analysis have enabled description of the diversity of strains around the world and their link with pathogenicity. Genomics has also permitted the development of qPCR tools and axenic culture medium, facilitating the diagnosis of Q fever. Moreover, several pathophysiological mechanisms can now be predicted and therapeutic strategies can be determined thanks to in silico genome analysis. An extensive pan-genomic analysis will allow for a comprehensive view of the clonal diversity of C. burnetii and its link with virulence.