Mycoplasma mycoides subsp. mycoides biotype large colony isolates from healthy and diseased goats: Prevalence and typing

Contagious Agalactia In Sheep And Goats: Current Perspectives

Contagious agalactia (CA) is a disease caused equally by four Mycoplasma species, in single or mixed infections. Clinical signs are multiple, including mastitis, arthritis, keratoconjunctivitis, pneumonia, and septicemia, non-specific, and expressed differently depending whether sheep or goats are affected, on causative mycoplasmas as well as type of husbandry. CA has been reported worldwide and its geographic distribution maps to that of small ruminant breeding areas. However, as current diagnostic tests are expensive and difficult to implement, it is certainly underdiagnosed and prevalence data are only available for a few countries. CA control relies on vaccines, chemotherapy and good herd management practices. It requires long-term commitment but is often unsuccessful, with frequent clinical relapses. The persistence of the etiological agents, despite their overall susceptibility to antimicrobials, comes from their genetic plasticity and capacity to escape the host immune response. The existence of asymptomatic carriers and the numerous sources of infections contribute to rapid spread of the disease and complicate the control and prevention efforts. Here we review all these aspects in order to highlight recent progress made and identify gaps in knowledge or tools needed for better disease management. Discussion also underlines the detrimental effect of contagious agalactia on small ruminant welfare.

Proteases as Secreted Exoproteins in Mycoplasmas from Ruminant Lungs and Their Impact on Surface-Exposed Proteins

Many mycoplasma species are isolated from the ruminant lungs as either saprophytes or true pathogens. These wall-less bacteria possess a minimal genome and reduced metabolic capabilities. Accordingly, they rely heavily on their hosts for the supply of essential metabolites and, notably, peptides. Seven of 13 ruminant lung-associated Mycoplasma (sub)species were shown to possess caseinolytic activity when grown in rich media and assessed with a quantitative fluorescence test. For some species, this activity was detected in spent medium, an indication that proteases were secreted outside the mycoplasma cells. To identify these proteases, we incubated concentrated washed cell pellets in a defined medium and analyzed the supernatants by tandem mass spectrometry. Secreted-protease activity was detected mostly in the species belonging to the Mycoplasma mycoides cluster (MMC) and, to a lesser extent, in Mycoplasma bovirhinis Analyzing a Mycoplasma mycoides subsp. capri strain, chosen as a model, we identified 35 expressed proteases among 55 predicted coding genes, of which 5 were preferentially found in the supernatant. Serine protease S41, acquired by horizontal gene transfer, was responsible for the caseinolytic activity, as demonstrated by zymography and mutant analysis. In an M. capricolum mutant, inactivation of the S41 protease resulted in marked modification of the expression or secretion of 17 predicted surface-exposed proteins. This is an indication that the S41 protease could have a role in posttranslational cleavage of surface-exposed proteins and ectodomain shedding, whose physiological impacts still need to be explored.IMPORTANCE Few studies pertaining to proteases in ruminant mycoplasmas have been reported. Here, we focus on proteases that are secreted outside the mycoplasma cell using a mass spectrometry approach. The most striking result is the identification, within the Mycoplasma mycoides cluster, of a serine protease that is exclusively detected outside the mycoplasma cells and is responsible for casein digestion. This protease may also be involved in the posttranslational processing of surface proteins, as suggested by analysis of mutants showing a marked reduction in the secretion of extracellular proteins. By analogy, this finding may help increase understanding of the mechanisms underlying this ectodomain shedding in other mycoplasma species. The gene encoding this protease is likely to have been acquired via horizontal gene transfer from Gram-positive bacteria and sortase-associated surface proteases. Whether this protease and the associated ectodomain shedding are related to virulence has yet to be ascertained.

Contagious agalactia monitoring in caprine herds through regular bulk tank milk sampling

Surveillance and control of Mycoplasma spp. responsible for contagious agalactia (CA) in caprine herds are important challenges in countries with a large small-ruminant dairy industry. In the absence of any clinical signs, being able to determine the potential circulation of mycoplasmas within a herd could help to prevent biosecurity issues during animal exchanges between farms and improve health management practices. The objective of this study was to determine whether regular sampling of bulk tank milk was suitable for such surveillance. Twenty farms were sampled once a month for 2 yr and CA-responsible mycoplasmas were detected by real-time PCR on DNA extracted from milk, using 3 different DNA extraction methods. The pattern of mycoplasma excretion in bulk tank milk was assessed over time and several herd characteristics were recorded together with any event occurring within the herds. In general, the results obtained with the different detection methods were comparable and mainly agreed with the culture results. Several patterns of excretion were observed but were not related to herd characteristics (size, breed, and so on). Recurrence of the same (sub)species and same pulsed-field gel electrophoresis subtype during the 2-yr period is indicative of the considerable persistence of mycoplasmas. This persistence was associated with intermittent excretion. In conclusion, bulk tank milk sampling could be valuable for controlling CA in caprine herds provided it is repeated several times, yet to be defined, per year and analyzed using an appropriate methodology and the right cut-off for interpretation.

Mycoplasma conjunctivae in insect vectors and anatomic locations related to transmission and persistence

Mycoplasma conjunctivae is an obligate microparasite that causes Infectious Keratoconjunctivitis (IKC) in Caprinae species. IKC is a long-recognised disease, but little attention has been paid to the mechanisms of transmission of the mycoplasma and its occurrence in locations other than the eyes. In this study, the presence of M. conjunctivae is assessed in the eyes, external ear canals (EEC), nasal cavity, and vagina of host species as well as in potential vectors, which may be involved in the transmission and persistence of infection within the host. M. conjunctivae was detected by qPCR in 7.2 % (CI 95% 4.7-11.0) of the ear swabs and 9.5 % (CI 95% 6.4-13.9) of the nasal swabs from Pyrenean chamois, Iberian ibex, domestic sheep and mouflon without statistical differences between species. Mycoplasma detection in nasal swabs was mostly associated with ocular infection (95.6%), but this was not the case for EEC (52.6%). Among the eye-positive ruminants, 27.3% were positive in ear swabs and 64.7% in nasal swabs, and the threshold cycle values of the qPCR were correlated only between eye and nasal swabs (p < 0.01; r₂ = 0.56). M. conjunctivae was detected in 1.7% - 7.1 % of Musca spp. captured during an IKC outbreak in Iberian ibex and in one out of three endemic sheep flocks. The results indicate that the transmission of M. conjunctivae may occur by direct contact with eye or nasal secretions and/or indirectly through flies. The M. conjunctivae DNA detection in EEC suggests that it can colonise the auditory tract, but the significance for its persistence within the host should be further assessed.

Survey of Victorian small ruminant herds for mycoplasmas associated with contagious agalactia and molecular characterisation of Mycoplasma mycoides subspecies capri isolates from one herd

OBJECTIVE

Regarded as one of the most expensive production diseases of dairy sheep and goats, contagious agalactia (CA) is caused by any of four agents: Mycoplasma agalactiae, M. mycoides subspecies capri (Mmc), M. capricolum subspecies capricolum (Mcc) and M. putrefaciens. Although CA is worldwide in distribution, it has not been reported in Australia, even though studies between the 1950s and 1980s isolated each agent from sheep or goats without any clinical signs associated with it. The aim of this study was to examine sheep and goats in Victoria, Australia, for the presence of CA-associated mycoplasmas and to investigate the evolutionary relationships of these isolates by comparing their genetic differences with their counterparts from other parts of the world.

METHODS

A 3-year epidemiological survey of small ruminant populations in Victoria, Australia, was conducted for the presence of CA-associated mycoplasmas and the isolates obtained were genotyped by multilocus sequence typing (MLST).

RESULTS

Mmc was the only CA-associated agent isolated from the 1358 samples analysed in the study, but was not associated with CA on the property where it was found. MLST analyses of Mmc strains revealed a distinct clustering of Australian isolates into a novel clade, with the closest relatives being strains from Europe. The distinct clustering is consistent with the absence of clinical disease in Australia.

CONCLUSION

The isolation of Mmc indicates that this subspecies persists in Australian small ruminant populations. However, full genome sequencing and in vitro animal experimentation are needed to unequivocally demonstrate the avirulence of Australian strains.

Identification and Characterization of Mycoplasma feriruminatoris sp. nov. Strains Isolated from Alpine Ibex: A 4th Species in the Mycoplasma mycoides Cluster Hosted by Non-domesticated Ruminants?

The genus Mycoplasma, a group of free-living, wall-less prokaryotes includes more than 100 species of which dozens are primary pathogens of humans and domesticated animals. Mycoplasma species isolated from wildlife are rarely investigated but could provide a fuller picture of the evolutionary history and diversity of this genus. In 2013 several isolates from wild Caprinae were tentatively assigned to a new species, Mycoplasma (M.) feriruminatoris sp. nov., characterized by an unusually rapid growth in vitro and close genetic proximity to ruminant pathogenic species. We suspected that atypical isolates recently collected from Alpine ibex in France belonged to this new species. The present study was undertaken to verify this hypothesis and to further characterize the French ibex isolates. Phylogenetic analyses were performed to identify the isolates and position them in trees containing several other mycoplasma species pathogenic to domesticated ruminants. Population diversity was characterized by genomic macrorestriction and by examining the capacity of different strains to produce capsular polysaccharides, a feature now known to vary amongst mycoplasma species pathogenic to ruminants. This is the first report of M. feriruminatoris isolation from Alpine ibex in France. Phylogenetic analyses further suggested that M. feriruminatoris might constitute a 4th species in a genetic cluster that so far contains only important ruminant pathogens, the so-called Mycoplasma mycoides cluster. A PCR assay for specific identification is proposed. These French isolates were not clonal, despite being collected in a restricted region of the Alps, which signifies a considerable diversity of the new species. Strains were able to concomitantly produce two types of capsular polysaccharides, β-(1→6)-galactan and β-(1→6)-glucan, with variation in their respective ratio, a feature never before described in mycoplasmas.

Infectious keratoconjunctivitis in wild Caprinae: merging field observations and molecular analyses sheds light on factors shaping outbreak dynamics

Background

Infectious keratoconjunctivitis (IKC) is an ocular infectious disease caused by Mycoplasma conjunctivae which affects small domestic and wild mountain ruminants. Domestic sheep maintain the pathogen but the detection of healthy carriers in wildlife has raised the question as to whether M. conjunctivae may also persist in the wild. Furthermore, the factors shaping the dynamics of IKC outbreaks in wildlife have remained largely unknown. The aims of this study were (1) to verify the etiological role of M. conjunctivae in IKC outbreaks recorded between 2002 and 2010 at four study sites in different regions of France (Pyrenees and Alps, samples from 159 Alpine ibex Capra ibex, Alpine chamois Rupicapra rupicapra and Pyrenean chamois Rupicapra pyrenaica); (2) to establish whether there existed any epidemiological links between the different regions through a cluster analysis of the detected strains (from 80 out of the 159 animals tested); (3) to explore selected pathogen, host and environmental factors potentially influencing the dynamics of IKC in wildlife, by joining results obtained by molecular analyses and by field observations (16,609 animal observations). All of the samples were tested for M. conjunctivae by qPCR, and cluster analysis was based on a highly variable part of the lppS gene.

Results

We documented infections with M. conjunctivae in epidemic and endemic situations, both in symptomatic and asymptomatic animals. The identified M. conjunctivae strains were site-specific and persisted in the local wild population for at least 6 years. In epidemic situations, peaks of cases and disease resurgence were associated with the emergence of new similar strains in a given area. Social interactions, seasonal movements and the landscape structure such as natural and anthropogenic barriers influenced the spatio-temporal spread of IKC. Adults were more affected than young animals and host susceptibility differed depending on the involved strain.

Conclusion

Our study indicates that IKC is a multifactorial disease and that M. conjunctivae can persist in wildlife populations. The disease course in individual animals and populations is influenced by both host and mycoplasma characteristics, and the disease spread within and among populations is shaped by host behavior and landscape structure.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-017-0972-0) contains supplementary material, which is available to authorized users.

Multilocus sequence typing of Mycoplasma mycoides subsp. capri to assess its genetic variability in a contagious agalactia endemic area

Mycoplasma mycoides subsp. capri (Mmc) is one of the main causative agents of caprine contagious agalactia. Besides, the absence of accurate control methods eases its dispersion between different herds within endemic areas of this disease. In this context, there is a need to implement molecular typing schemes which offer valuable information useful to establish control measures and enables the surveillance of this pathogen. The aim of this study was to assess the genetic variability of different strains of Mmc from a contagious agalactia endemic area through multilocus sequence typing (MLST). For this purpose, five house-keeping genes (fusA, glpQ, gyrB, lepA, rpoB) from 39 field isolates were analysed. These isolates were obtained from different geographic areas of Spain, between the years 2004 and 2015. The results obtained in this study suggest that the selected MLST scheme could be a useful technique to monitor the genetic variability of Mmc in endemic areas. Despite the significant differences found between the assessed field isolates, they could be classified according to their geographical origin. Moreover, it was also possible to detect genetic differences between Mmc strains coming from the same herd at the same sampling time, which may need to be taken into consideration when designing or arranging prophylactic strategies.

Diversity and variation in antimicrobial susceptibility patterns over time in Mycoplasma agalactiae isolates collected from sheep and goats in France

AIMS

Mycoplasma agalactiae is responsible for Contagious Agalactia, a severe syndrome affecting small ruminants worldwide and resulting in significant economic losses in countries with an important dairy industry. The aim of this study was to examine the antimicrobial susceptibility patterns of M. agalactiae isolates in France, their evolution over the last 25 years and their relationships with the genetic diversity of isolates and their origin (geographical and animal host).

METHODS AND RESULTS

Susceptibility patterns were determined by measuring minimal inhibitory concentrations (MICs) of several antimicrobials used against mycoplasmas. Caprine M. agalactiae strains showed increased MICs over time for most of the antimicrobials tested, except fluoroquinolones. This susceptibility loss was homogeneous despite the considerable genetic and geographical heterogeneity of the isolates. In contrast, all the ovine isolates originating from a single clone and the same region showed increased MICs only to some macrolides.

CONCLUSIONS

MICs have evolved differently depending on the origin of the isolates but the overall loss in susceptibility has remained far more moderate than that of Mycoplasma bovis, a cattle pathogen closely related to M. agalactiae.

SIGNIFICANCE AND IMPACT OF THE STUDY

Several hypotheses are proposed to explain the differences in susceptibility patterns, such as local, specific, nonmycoplasma-targeting antibiotic treatments and the genetic background of isolates in connection with their animal host.

Proteomic approach for identification of immunogenic proteins of Mycoplasma mycoides subsp. capri

In this study, an immunoproteomic approach was used to identify immunodominant proteins from Mycoplasma mycoides subsp. capri isolates. Membrane proteins, extracted through TX-114 phase partitioning, were separated using mono- and two-dimensional electrophoresis and detected by Western blotting with pooled sera from naturally infected goats. A total of 27 immunoreactive spots, corresponding to 13 different proteins, were identified using nanoLC-ESI-MSMS. Function annotation revealed that most of these proteins were metabolic enzymes involved in carbohydrate and energy metabolism. The immunogenic proteins identified in this study: pyruvate dehydrogenase, dihydrolipoamide acetyltransferase, dihydrolipoyl dehydrogenase, phosphate acetyltransferase, phosphopyruvate hydratase, adenine phopshoribosyltransferase, transketolase, translation elongation factor G, translation elongation factor Ts, FMN-dependent NADH-azoreductase, peptide methionine sulfoxide reductase, inorganic diphosphatase and trigger factor may be used as biomarkers for the serological diagnosis of contagious agalactia caused by M. mycoides subsp. capri.

Draft Genome Sequences of Mycoplasma auris and Mycoplasma yeatsii, Two Species of the Ear Canal of Caprinae

We report here the draft genome sequences of Mycoplasma auris and Mycoplasma yeatsii, two species commonly isolated from the external ear canal of Caprinae.

Contagious agalactia due to Mycoplasma spp. in small dairy ruminants: epidemiology and prospects for diagnosis and control

Contagious agalactia (CA) is a serious disease of small dairy ruminants that has a substantial economic impact on the goat and sheep milk industries. The main aetiological agent of the disease is Mycoplasma agalactiae, although other species, such as Mycoplasma mycoides subsp. capri, Mycoplasma capricolum subsp. capricolum and Mycoplasma putrefaciens, are pathogenic in goats. There are two clinical-epidemiological states of CA in sheep and goats; herds and flocks may exhibit outbreaks of CA or may be chronically infected, the latter with a high incidence of subclinical mastitis and only occasional clinical cases. The complex epidemiology of CA is related to the genetic characteristics and mechanisms of molecular variation of the Mycoplasma spp. involved, along with presence of CA-mycoplasmas in wild ruminant species. In goats, the situation is particularly complex and asymptomatic carriers have been detected in chronically infected herds. The coexistence of other non-pathogenic mycoplasmas in the herd further complicates the diagnosis of CA and the design of efficient strategies to control the disease. Routes of infection, such as the venereal route, may be involved in the establishment of chronic infection in herds. Current challenges include the need for improved diagnostic methods for detection of chronic and subclinical infections and for the design of more efficient vaccines.

Molecular characterization of Mycoplasma agalactiae reveals the presence of an endemic clone in Spain

Mycoplasma agalactiae isolates from Spain were genetically characterized to investigate their genomic diversity and to better understand their relationship to isolates from other countries. Molecular typing revealed a high genomic homogeneity in Spanish M. agalactiae isolates, which clearly shows the circulation of one endemic clonal population.

Unexpected genetic diversity of Mycoplasma agalactiae caprine isolates from an endemic geographically restricted area of Spain

Background

The genetic diversity of Mycoplasma agalactiae (MA) isolates collected in Spain from goats in an area with contagious agalactia (CA) was assessed using a set of validated and new molecular typing methods. Validated methods included pulsed field gel electrophoresis (PFGE), variable number of tandem repeats (VNTR) typing, and Southern blot hybridization using a set of MA DNA probes, including those for typing the vpma genes repertoire. New approaches were based on PCR and targeted genomic regions that diverged between strains as defined by in silico genomic comparisons of sequenced MA genomes.

Results

Overall, the data showed that all typing tools yielded consistent results, with the VNTR analyses being the most rapid method to differentiate the MA isolates with a discriminatory ability comparable to that of PFGE and of a set of new PCR assays. All molecular typing approaches indicated that the Spanish isolates from the endemic area in Murcia were very diverse, with different clonal isolates probably restricted to separate, but geographically close, local areas.

Conclusions

The important genetic diversity of MA observed in infected goats from Spain contrasts with the overall homogeneity of the genomic background encountered in MA from sheep with CA in Southern France or Italy, suggesting that assessment of the disease status in endemic areas may require different approaches in sheep and in goats. A number of congruent sub-typing tools are now available for the differentiation of caprine isolates with comparable discriminatory powers.

Comparative assessment of two commonly used commercial ELISA tests for the serological diagnosis of contagious agalactia of small ruminants caused by Mycoplasma agalactiae

Background

Contagious agalactia (CA) of sheep and goats caused by Mycoplasma agalactiae is a widely occurring economically important disease that is difficult to control. The ELISA is commonly used for the serological detection of CA but it has some limitations and the performance of the available tests have not been properly evaluated.

Two commercial ELISA kits are widely used, one involving a fusion protein as target antigen and the other a total antigen. The objectives were to compare these tests by evaluating:

i. Their diagnostic sensitivity and specificity, the relevance of the recommended cut-off points, the correlation between the two tests, and, the correlation between serology data and the milk shedding of M. agalatiae;

ii. The influence of extrinsic factors such as the targeted animal species, geographical origin of the samples, intra-specific variability of M. agalactiae and concurrent mycoplasma infections.

A sample of 5900 animals from 211 farms with continuous CA monitoring for 20 years and no prior vaccination history was used. The infection status was known from prior bacteriological, epidemiological and serological monitoring with a complementary immunoblotting test.

Results

The average diagnostic sensitivity was 56% [51.8–59.8] for the fusion protein ELISA and 84% [81.3–87.2] for the total antigen ELISA, with noteworthy flock-related variations. The average diagnostic specificity for the fusion protein ELISA was 100% [99.9–100], and for the total antigen ELISA differed significantly between goats and sheep: 99.3% [97.4–99.9] and 95.7% [93.8–97.2] respectively.

Experimental inoculations with different M. agalactiae strains revealed that the ELISA kits poorly detected the antibody response to certain strains. Furthermore, test performances varied according to the host species or geographical origin of the samples.

Finally, the correlation between milk shedding of M. agalactiae and the presence of detectable antibodies in the blood was poor.

Conclusions

These serological tests are not interchangeable. The choice of a test will depend on the objectives (early detection of infection or disease control program), on the prevalence of infection and the control protocol used. Given the variety of factors that may influence performance, a preliminary assessment of the test in a given situation is recommended prior to widespread use.

Emergence of atypical Mycoplasma agalactiae strains harboring a new prophage and associated with an alpine wild ungulate mortality episode

The bacterium Mycoplasma agalactiae is responsible for contagious agalactia (CA) in small domestic ruminants, a syndrome listed by the World Organization for Animal Health and responsible for severe damage to the dairy industry. Recently, we frequently isolated this pathogen from lung lesions of ibexes during a mortality episode in the French Alps. This situation was unusual in terms of host specificity and tissue tropism, raising the question of M. agalactiae emergence in wildlife. To address this issue, the ibex isolates were characterized using a combination of approaches that included antigenic profiles, molecular typing, optical mapping, and whole-genome sequencing. Genome analyses showed the presence of a new, large prophage containing 35 coding sequences (CDS) that was detected in most but not all ibex strains and has a homolog in Mycoplasma conjunctivae, a species causing keratoconjunctivitis in wild ungulates. This and the presence in all strains of large integrated conjugative elements suggested highly dynamic genomes. Nevertheless, M. agalactiae strains circulating in the ibex population were shown to be highly related, most likely originating from a single parental clone that has also spread to another wild ungulate species of the same geographical area, the chamois. These strains clearly differ from strains described in Europe so far, including those found nearby, before CA eradication a few years ago. While M. agalactiae pathogenicity in ibexes remains unclear, our data showed the emergence of atypical strains in Alpine wild ungulates, raising the question of a role for the wild fauna as a potential reservoir of pathogenic mycoplasmas.

Extended surveillance for CBPP in a free country: Challenges and solutions regarding the potential caprine reservoir

Contagious bovine pleuropneumonia (CBPP) is a severe respiratory disease of cattle and buffalo caused by Mycoplasma mycoides subsp. mycoides "Small Colony" (MmmSC). The agent of CBPP has been isolated from goats in different countries including CBPP-free areas. Goats can therefore be regarded as a putative MmmSC reservoir. No diagnostic test for CBPP surveillance in goats has been proposed as yet. Furthermore, serological tests could be seriously hampered by a widespread caprine infection due to the subspecies M. mycoides subsp. capri (Mmc), which is antigenically very close to MmmSC and displays high levels of genetic variability. A competition ELISA (cELISA) is currently used to screen for CBPP in cattle at the herd level in infected areas. The aim of this study was to see if the same cELISA would be specific enough to be used to screen goats despite the potential concomitant infection with Mmc. The cELISA titers of goats from Mmc-infected and non-infected herds were comparable and negative using the accepted cutoff for bovine sera. In contrast, seroconversion was observed in goats experimentally inoculated with an Mmc strain that cross-reacted with a monoclonal antibody targeting the same epitope as that used in cELISA. The probability of such false positivity occurring under field conditions is very low since Mmc strains with such an atypical antigenic profile emerge only rarely as a result of random nucleotide variation of the epitope-coding region. In conclusion, the commercially available cELISA can be considered specific enough to be used as a primary test to monitor passage of the CBPP agent in goats, but its sensitivity in goats requires further investigation.

Presence of contagious agalactia causing mycoplasmas in Spanish goat artificial insemination centres

Male goats admitted to artificial insemination centres come from herds that have shown no clinical symptoms of contagious agalactia (CA) for the last 6 mo. However, prior reports suggest that this control measure may not be completely effective. This study was designed to detect the presence of CA-causing mycoplasmas in 9 Spanish centres, comprising 159 goats (147 males and 12 teaser does) of 8 different breeds. A microbiological study was conducted during 8 mo on 448 samples (318 ear swabs, 119 semen samples and 11 milk samples). In 86 samples (84 swabs, 1 semen sample and 1 milk sample), CA-causative mycoplasmas were detected by PCR or culture, and 52 animals (49 goat males and 3 teaser does) tested positive. Most of these positive animals were auricular carriers (n = 50), mainly of Mycoplasma mycoides subsp. capri (Mmc), although some M. agalactiae (Ma) and, interestingly, M. capricolum subsp. capricolum (Mcc) carriers were also identified. At least 1 animal infected by CA-causing mycoplasmas was detected in 8 of the 9 centres (88.8%) although in most (66.7%) no infected animals or only 1 or 2 positive animals were identified. Our results indicate the presence of CA carriers as asymptomatic animals in reproductive programmes. These findings have already prompted efficient measures to detect and avoid the entry of these carriers in Spanish centres. We recommend similar measures for all centres in areas where CA is endemic.

Mycoplasmoses of ruminants in France: recent data from the national surveillance network

Background

Ruminant mycoplasmoses are important diseases worldwide and several are listed by the World Organization for Animal Health to be of major economic significance. In France the distribution of mycoplasmal species isolated from clinical samples collected from diseased animals upon veterinary request, is monitored by a network known as VIGIMYC (for VIGIlance to MYCoplasmoses of ruminants). The veterinary diagnostic laboratories collaborating with VIGIMYC are responsible for isolating the mycoplasmas while identification of the isolates is centralized by the French Food Safety Agency (AFSSA) in Lyon. The VIGIMYC framework can also be used for specific surveys and one example, on the prevalence of M. bovis in bovine respiratory diseases, is presented here.

Results

Between 2003 and 2008, 34 laboratories were involved in the network and 1904 mycoplasma isolates, originating from the main ruminant-breeding areas, were identified. For cattle, the high prevalence of M. bovis in bronchopneumonia, notably in young animals, was confirmed by VIGIMYC and an associated specific survey, whereas the non-emergence of species such as M. alkalescens and M. canis was also demonstrated. The etiological agent of bovine contagious pleuropneumonia was never isolated. The principal mycoplasmosis in goats was contagious agalactia with M. mycoides subsp. capri as main agent. Ovine mycoplasmoses, most of which were associated with pneumonia in lambs, were infrequently reported. One exception was ovine contagious agalactia (due to M. agalactiae) that has recently re-emerged in the Pyrénées where it had been endemic for years and was also reported in Corsica, which was previously considered free.

Conclusions

Although VIGIMYC is a passive network and somewhat biased as regards sample collection and processing, it has provided, in this study, an overview of the main mycoplasmoses of ruminants in France. The French epidemiological situation is compared to those existing elsewhere in the world.

Comparison of culture and PCR to detect Mycoplasma agalactiae and Mycoplasma mycoides subsp. capri in ear swabs taken from goats

This study was designed to evaluate the validity of PCR for the direct detection of Mycoplasma (M.) agalactiae and Mycoplasma mycoides subsp. capri (Mmc), as the two species most frequently causing contagious agalactia (CA) in goats. The PCR method was compared with the traditional culture technique to determine which method was most efficient at identifying all auricular carriers present in herds. The samples analyzed were 307 ear swabs taken from goats reared in a CA endemic area. We assessed the validity of each technique to detect each species and agreement between both methods. For each species, the result was taken as true-positive when at least one of the two tests was positive. Of the swabs tested, 246 were scored positive by PCR (235 and 11 for Mmc and M. agalactiae, respectively) and 117 showed a positive culture result (113 for Mmc and 4 for M. agalactiae). 133 of the PCR-positive samples (124 and 9 for Mmc and M. agalactiae, respectively) yielded negative culture results and 4 culture-positive samples tested negative using PCR (2 for each species). Sensitivity and negative predictive values for PCR were 84.62 and 99.32 (for M. agalactiae) and 99.16 and 97.22% (for Mmc) respectively, and for culture were 30.77 and 97.03 (for M. agalactiae) and 47.08 and 36.08% (for Mmc), respectively. PCR proved to be a rapid and sensitive method for the detection of mycoplasmas in the external ear of asymptomatic carriers. Tools such as this are needed to adopt efficient control measures against CA.

Epidemiological surveillance of mycoplasmas belonging to the 'Mycoplasma mycoides' cluster: is DGGE fingerprinting of 16S rRNA genes suitable?

AIMS

The analysis by Denaturing Gradient Gel Electrophoresis (DGGE) of the PCR-amplified V3 region of 16S rRNA gene was previously shown to detect and differentiate a large number of human and animal mycoplasmas. In this study, we further assessed the suitability of the technique for epidemiological surveillance of mycoplasmas belonging to the 'Mycoplasma mycoides' cluster, a phylogenetic group that includes major ruminant pathogens.

METHODS AND RESULTS

The V3 region of 16S rRNA genes from approx. 50 field strains was amplified and analysed by DGGE. Detection and identification results were compared with the ones obtained by antigenic testing and sequence analysis.

CONCLUSIONS

The DGGE technique is robust and valuable as a first-line test, but the patterns obtained for strains belonging to the 'M. mycoides' cluster were too variable within a taxon and in contrast too conserved between taxa to allow an unequivocal identification of isolates without further analysis.

SIGNIFICANCE AND IMPACT OF THE STUDY

Issues raised by the quest for a single universal test able to detect and identify any mycoplasma in one clinical sample are thoroughly documented.

Effects on goat milk quality of the presence of Mycoplasma spp. in herds without symptoms of contagious agalactia

This study was designed to assess the possible effects of mycoplasmas on the quality of milk produced by goat herds in a contagious agalactia (CA) endemic area with absence of classical symptoms. Several factors related to milk quality (percentages of fat, total protein, lactose and total solids, standard plate counts (SPC) and presence of Staphylococcus aureus) were compared in mycoplasma-infected and non-infected herds. To define the CA status of 26 herds on the island of Lanzarote (Spain), where CA is endemic, 570 individual milk samples and 266 bulk tank milk (BTM) samples were microbiologically analysed for the presence of Mycoplasma spp. A herd was considered infected by mycoplasmas when at least a sample (individual or BTM) was positive. BTM samples were also used to determine milk quality parameters. Mycoplasma infection was confirmed in 13 herds. A total of 31, 10 and 11 strains of Mycoplasma mycoides subsp. mycoides LC (MmmLC), Mp. agalactiae and Mp. capricolum subsp. capricolum were isolated. No significant differences were observed between the least square means of the variables fat, total protein, lactose and total solids or SPC recorded for the infected v. non-infected herds. The Staph. aureus status of a herd was also found to be independent of the presence of Mycoplasma spp. Our findings indicate that neither the presence of mycoplasmas in a goat herd with absence of classical symptoms seem to compromise the quality of the BTM.

Suppression-subtractive hybridization as a strategy to identify taxon-specific sequences within the Mycoplasma mycoides Cluster: design and validation of an M. capricolum subsp. capricolum-specific PCR assay

The phylogenetically related Mycoplasma capricolum subsp. capricolum and M. mycoides subsp. mycoides biotype Large Colony are two small-ruminant pathogens involved in contagious agalactia. Their respective contributions to clinical outbreaks are not well documented, because they are difficult to differentiate with the current diagnostic techniques. In order to identify DNA sequences specific to one taxon or the other, a suppression-subtractive hybridization approach was developed. DNA fragments resulting from the reciprocal subtraction of the type strains were used as probes on a panel of M. capricolum subsp. capricolum and M. mycoides subsp. mycoides biotype Large Colony strains to assess their intrataxon specificity. Due to a high intrataxon polymorphism and important cross-reactions between taxa, a single DNA fragment was shown to be specific for M. capricolum subsp. capricolum and to be present in all M. capricolum subsp. capricolum field isolates tested in this study. A PCR assay targeting the corresponding gene (simpA51) was designed that resulted in a 560-bp amplification only in M. capricolum subsp. capricolum and in M. capricolum subsp. capripneumoniae (the etiological agent of contagious caprine pleuropneumonia). simpA51 was further improved to generate a multiplex PCR (multA51) that allows the differentiation of M. capricolum subsp. capripneumoniae from M. capricolum subsp. capricolum. Both the simpA51 and multA51 assays accurately identify M. capricolum subsp. capricolum among other mycoplasmas, including all members of the M. mycoides cluster. simpA51 and multA51 PCRs are proposed as sensitive and robust tools for the specific identification of M. capricolum subsp. capricolum and M. capricolum subsp. capripneumoniae.