Detection of a novel genotype of Chlamydia buteonis in falcons from the Emirates.

Chlamydiaceae are a family of obligate intracellular bacterial pathogens that affect both humans and animals. Recently, a new species named Chlamydia (C.) buteonis was isolated from hawks. In this study, we aimed to investigate the prevalence of Chlamydiaceae in 60 falcons that underwent a routine health check at a specialized clinic in Dubai, United Arab Emirates. Using real-time PCR, we analyzed cloacal and tracheal swabs from these birds and found that 39 of them tested positive for Chlamydiaceae. Subsequent real-time PCR assays specific for C. psittaci, C. abortus, C. avium, and C. gallinacea yielded negative results, while testing positive for C. buteonis. Analysis of ompA and MLST sequences indicated a highly conserved group of strains within this set of samples, but with sequences distinct from the C. buteonis RSHA reference strains and other C. buteonis strains isolated from hawks in the United States. Two strains were further isolated by cell culture and sequenced using whole-genome sequencing, confirming the clustering of these falcon strains within the C. buteonis species, but in a separate clade from the previously identified hawk strains. We also developed a SNP-based PCR-HRM assay to distinguish between these different genotypes. Overall, our findings suggest a high prevalence of C. buteonis in falcons in Dubai and highlight the importance of monitoring this pathogen in birds of prey.

[Update on the zoonotic potential of Chlamydia]. / Update zum Zoonosepotential von Chlamydien.

INTRODUCTION: Knowledge of the obligate intracellular bacteria from the Chlamydiaceae family has increased significantly in recent years. Not only new chlamydia species, such as Chlamydia avium or C. buteonis in birds have been described, but also known chlamydia in new host species, such as C. psittaci in horses. This review article provides an up-to-date overview of the zoonotic potential of C. psittaci, C. abortus, C. caviae and C. felis and summarizes current findings on other chlamydia species in different animal species; supplemented by information on optimal sampling and pathogen detection.

INTRODUCTION: Les connaissances sur les bactéries intracellulaires obligatoires de la famille des Chlamydiaceae ont considérablement augmenté ces dernières années. Non seulement de nouvelles espèces de Chlamydies, telles que Chlamydia avium ou C. buteonis chez les oiseaux, ont été décrites, mais également des Chlamydies déjà connues ont été mises en évidence chez de nouvelles espèces hôtes, telles que C. psittaci chez les chevaux. Cet article de synthèse fournit une vue d'ensemble actualisée du potentiel zoonotique de C. psittaci, C. abortus, C. caviae et C. felis et résume les connaissances actuelles sur d'autres espèces de Chlamydies chez différentes espèces animales ; il est complété par des informations sur l'échantillonnage optimal et la détection des agents pathogènes.

Zoonotic potential of guinea pigs: Outbreak of cryptosporidiosis combined with chlamydiosis in a breeding guinea pig herd.

INTRODUCTION: In a guinea pig herd with 26 breeding animals, several individuals of all age categories died (16/26) after three animals had been newly introduced from another herd. Furthermore, the population suffered of apathy, anorexia, severe weight loss and conjunctivitis, as well as abortions and stillbirths. At the same time, the owner experienced a SARS-CoV-2 infection with pneumonia, which was confirmed by taking a PCR test. Chlamydia caviae was detected from the conjunctiva and vagina/uterus in one juvenile animal together with an intestinal Cryptosporidium wrairi infection. Oocysts were found histologically in the small intestine, which was confirmed by PCR. C. wairi is a parasite adapted to guinea pigs with zoonotic potential, which causes diarrhoea with frequent deaths in larger guinea pig herds. C. caviae is also a zoonotic pathogen and often the cause of conjunctivitis, pneumonia and abortions in guinea pigs and can lead to upper respiratory tract disease, conjunctivitis but also severe pneumonia in humans. The increased death cases and the clinical signs could be traced back to an infection with Cryptosporidium wrairi, complicated by a co-infection of C. caviae. We suspect that the abortions were caused by C. caviae, but since the population was treated with various antibiotics effective against chlamydial infections, it was no longer possible to verify this by PCR testing. Unfortunately, more animals succumbed and finally only two animals of the originally 26 were left. With this case report, we would like to point out to veterinarians that guinea pigs can be an important source of zoonotic infections for various pathogens, especially since they are popular pets and often come into close contact with children where hygiene might not always be strictly followed.

INTRODUCTION: Dans un groupe de cobayes de 26 animaux reproducteurs, plusieurs individus de toutes les catégories d'âge sont morts (16/26) après l'introduction de trois animaux provenant d'un autre groupe. En outre, la population a souffert d'apathie, d'anorexie, de perte de poids sévère et de conjonctivite ainsi que d'avortements et de mortinatalité. La présence de Chlamydia caviae a pu être détectée dans la conjonctive et le vagin/utérus d'un animal juvénile, ainsi qu'une infection intestinale à Cryptosporidium wrairi. Des oocystes ont été trouvés histologiquement dans l'intestin grêle, ce qui a été confirmé par PCR. C. wairi est un parasite adapté aux cobayes avec un potentiel zoonotique, qui provoque des diarrhées avec des morts fréquentes dans les grands groupes de cobayes. C. caviae est également un agent pathogène zoonotique et est souvent à l'origine de conjonctivites, de pneumonies et d'avortements chez les cobayes ; il peut entraîner des maladies des voies respiratoires supérieures, des conjonctivites mais aussi des pneumonies graves chez l'homme. L'augmentation des cas de décès et les signes cliniques pourraient être attribués à une infection par Cryptosporidium wrairi, compliquée par une co-infection par C. caviae. Nous soupçonnons que les avortements ont été causés par C. caviae, mais comme la population a été traitée avec divers antibiotiques efficaces contre les infections à chlamydia, il n'était plus possible de le vérifier par des tests PCR. Malheureusement, d'autres animaux ont succombé et il ne restait finalement que deux animaux sur les 26 d'origine. Avec ce rapport de cas, nous aimerions attirer l'attention des vétérinaires sur le fait que les cochons d'Inde peuvent être une source importante d'infections zoonotiques pour divers pathogènes, d'autant plus qu'il s'agit d'animaux de compagnie populaires qui sont souvent en contact étroit avec des enfants avec lesquels l'hygiène n'est pas toujours strictement respectée.

Intrauterine infusion of killed semen adversely affects uterine blood flow and endometrial gene expression of inflammatory cytokines in mares susceptible to persistent breeding-induced endometritis.

Persistent breeding-induced endometritis (PBIE) is a leading cause of infertility in mares. The objective of the study was to assess genital perfusion and endometrial gene expression of inflammatory cytokines in mares classified as susceptible (n = 5) or resistant (n = 5) to PBIE. Ten mares were examined daily during estrus until 6 d after hCG-induced ovulation for two estrous cycles. Twenty-four hours after application of 1500 IU hCG, 4 mL of killed (by repeated freezing in liquid nitrogen and thawing at 50 °C) deep-frozen semen or sterile saline was instilled into the uterine body and examinations were carried out immediately before and 3, 6, and 12 h after intrauterine infusion. Examinations included blood sampling to determine plasma progesterone (P4) concentrations, and transrectal ultrasonography in B- and color Doppler mode to determine follicular and luteal size and blood flow, the extent of intrauterine fluid, as well as time-averaged maximum velocity (TAMV), blood flow volume (BFV), and blood flow resistance (expressed as pulsatility index, PI) of the uterine arteries. Additionally, endometrial biopsies were obtained at 24 h before, and 2 and 7 d after infusion, and mRNA expressions of IL1B, IL6, IL8, IL10, TNF, CASP3, and COX2 were determined by qRT-PCR. Statistical analyses were performed with mixed models. Intrauterine fluid retention (diameter >20 mm for at least 3 d) was found after infusion of killed semen in five susceptible mares. There was no treatment effect (semen vs saline; P > 0.05) on genital blood flow, plasma P4 concentration, and endometrial gene expression. In comparison to resistant mares, susceptible mares had an increased (P = 0.04) BFV of the uterine arteries at 24 h before intrauterine infusion of killed semen, and an increased (P = 0.03) PI at 2 d after infusion. The TAMV, plasma P4 concentrations, and follicular and luteal size and blood flow did not differ (P > 0.05) between resistant and susceptible mares. Endometrial mRNA expression of IL1B increased (P = 0.05) at 2 d after the infusion of killed semen in the susceptible mares, and the expression of IL10 increased (P = 0.003) at 7 d after the infusion within the resistant mares. Interleukin 6 mRNA was increased (P = 0.05) in susceptible compared to resistant mares at 2 d after infusion. In summary, an intrauterine infusion of killed semen increases uterine blood flow resistance and alters endometrial gene expression of inflammatory cytokines for at least 7 d but does not affect ovarian blood supply and luteal function in mares susceptible to PBIE.

A cluster of Chlamydia serpentis cases in captive snakes.

Following the occurrence of sudden death cases in a zoo reptile collection, histological analyses conducted on tissues from two common adders suggested an infection due to Chlamydia. The survey was extended to 22 individual snakes from the same collection and a PCR analysis targeting a conserved gene in Chlamydiaceae revealed bacterial shedding in six of them. The infection resolved spontaneously in one snake whereas another one succumbed one month later. The antibiotic treatment administered (marbofloxacin) to the remaining four PCR positive animals stopped the mortalities and the shedding. Analysis of the 16S and 23S ribosomal gene sequences identified C. serpentis, a recently described novel chlamydial species in snakes. A PCR tool for a quick and specific identification of this new chlamydial species was developed in this study.

Chlamydiae in febrile children with respiratory tract symptoms and age-matched controls, Ghana.

Members of the Chlamydiales order are obligate intracellular pathogens causing acute and chronic infectious diseases. Chlamydiaceae are established agents of community- and zoonotically acquired respiratory tract infections, and emerging pathogens among the Chlamydia-related bacteria have been implicated in airway infections. The role of both in airway infections in Africa is underexplored. We performed a case -control study on the prevalence of Chlamydiaceae and Chlamydia-related emerging pathogens in children with febrile respiratory tract infections in West Africa, Ghana. Using a pan-Chlamydiales broad-range real-time PCR, we detected chlamydial DNA in 11 (1.9%) of 572 hospitalized febrile children with respiratory tract symptoms and in 24 (4.3%) of 560 asymptomatic age-matched controls (p 0.03). Chlamydiaceae were found to be common among both symptomatic and healthy Ghanaian children, with Chlamydia pneumoniae being the most prevalent species. Parachlamydiaceae were detected in two children without symptoms but not in the symptomatic group. We identified neither Chlamydia psittaci nor Simkania negevensis but a member of a new chlamydial family that shared 90.2% sequence identity with the 16S rRNA gene of the zoonotic pathogen Chlamydia pecorum. In addition, we found a new Chlamydia-related species that belonged to a novel family sharing 91.3% 16S rRNA sequence identity with Candidatus Syngnamydia venezia. The prevalence and spectrum of chlamydial species differed from previous results obtained from children of other geographic regions and our study indicates that both, Chlamydiaceae and Chlamydia-related bacteria, are not clearly linked to clinical symptoms in Ghanaian children.

Ultrasonographic examination reduces the percentage of unsuccessful inseminations in dairy cows.

The objective of this study was to investigate whether confirmation of suitability for service by traditional methods, observation and transrectal palpation, is improved in cattle by additional ultrasonographic examination of the uterus and ovaries. The data from 600 lactating cows from Southern Germany submitted for the first service and alternately assigned to manual (group M, n = 301) and manual and sonographic examination (group S, n = 299) were evaluated. Cows of group M with a large, soft follicle with an estimated diameter of 12.0 to 22.5 mm, without a palpable CL (>10 mm), and with a contractile uterus without palpable content were considered suitable for service and inseminated. Cows of group S with a soft follicle measuring 12.0 to 22.5 mm, without a CL (>10 mm), and with a contractile uterus and no echoic content were inseminated. Pregnancy was determined by ultrasonography at 28 to 35 days after the first service. In group S, 10.9% fewer cows (P = 0.003) were considered suitable for service than in group M. The main reason (29.6%) for exclusion from service in group S was the presence of a CL greater than 10 mm in addition to a preovulatory follicle (12.0-22.5 mm), which was diagnosed less frequently in group M (4.5%; P < 0.0001). The first-service conception rate tended to be higher in group S than in group M (62.7% vs. 54.9%; P = 0.10), and the percentage of open cows, based on all cows submitted for service, was higher in group M than in group S (35.2% vs. 25.1%; P = 0.007). We concluded that sonographic examination of cows submitted for service facilitates the exclusion from service of proestrous and diestrous cows and reduces the number of pointless services.

Detection of Chlamydia pneumoniae in a collection of captive snakes and response to treatment with marbofloxacin.

In a collection of 58 snakes comprising predominantly Eurasian vipers in Switzerland, five snakes died unexpectedly during hibernation from 2009 to 2012. In one snake, organisms resembling chlamydiae were detected by immunohistochemistry in multiple histiocytic granulomas. Real-time quantitative PCR and microarray analysis were used to determine the presence of Chlamydia pneumoniae in tissue samples and cloacal/choanal swabs from snakes in the collection; 8/53 (15.1%) of the remaining snakes were positive. Although one infected snake had suppurative periglossitis, infection with C. pneumoniae did not appear to be associated with specific clinical signs in snakes. Of seven snakes treated with 5 mg/kg marbofloxacin IM once daily, five became PCR negative for C. pneumoniae following treatment, whereas one animal remained positive and one snake was lost to follow-up.

Chlamydiosis in British Garden Birds (2005-2011): retrospective diagnosis and Chlamydia psittaci genotype determination.

The significance of chlamydiosis as a cause of mortality in wild passerines (Order Passeriformes), and the role of these birds as a potential source of zoonotic Chlamydia psittaci infection, is unknown. We reviewed wild bird mortality incidents (2005-2011). Where species composition or post-mortem findings were indicative of chlamydiosis, we examined archived tissues for C. psittaci infection using PCR and ArrayTube Microarray assays. Twenty-one of 40 birds tested positive: 8 dunnocks (Prunella modularis), 7 great tits (Parus major), 3 blue tits (Cyanistes caeruleus), 2 collared doves (Streptopelia decaocto, Order Columbiformes), and 1 robin (Erithacus rubecula). Chlamydia psittaci genotype A was identified in all positive passerines and in a further three dunnocks and three robins diagnosed with chlamydiosis from a previous study. Two collared doves had genotype E. Ten of the 21 C. psittaci-positive birds identified in the current study had histological lesions consistent with chlamydiosis and co-localizing Chlamydia spp. antigens on immunohistochemistry. Our results indicate that chlamydiosis may be a more common disease of British passerines than was previously recognized. Wild passerines may be a source of C. psittaci zoonotic infection, and people should be advised to take appropriate hygiene precautions when handling bird feeders or wild birds.

[The seroconversion of Chlamydia abortus in sheep from the region of Vorarlberg before and after Alpine pasturing]. / Untersuchung der Serokonversion auf Chlamydia abortus von Schafen aus der Region Vorarlberg vor und nach der Alpung.

In total, 796 serum samples of sheep on commune alpine pastures in the region of Vorarlberg were investigated by a commercial ELISA kit for antibodies against Chlamydia abortus, the agent of ovine enzootic abortion. The aim of the study was to determine the seroprevalence within this region and to compare these results with the seroprevalence in the neighboring canton Graubünden as well as to obtain data on the seroconversion after alpine pasturing. Therefore, 421 samples were collected before and 375 samples after alpine pasturing, whereas corresponding serum samples were available from 359 sheep. Within the region of Vorarlberg, a mean seroprevalence of 9.2 % was calculated with a threshold of 60 %. Seroconversion for C. abortus occurred in 5.0 % of animals with corresponding serum samples. Seroprevalence values were comparable to Swiss regions with similar management systems, although the neighboring canton Graubünden is known to have a much more higher seroprevalence of 43 %. In conclusion, the traditional animal exchange between these two regions is not significantly favoring the spread of C. abortus.

Waddlia, Parachlamydia and Chlamydiaceae in bovine abortion.

The etiology remains unknown in many cases of bovine abortion in Switzerland. Bacteria of the Chlamydiales order are known abortive agents, therefore cases of bovine abortion from three representative regions of Switzerland were investigated in this study. Particularly Chlamydiaceae as well as the Chlamydia-like organisms Waddlia and Parachlamydia were of interest, especially because of their possible zoonotic potential. Placenta samples (n=343) were tested for these bacteria by different PCR-methods, immunohistochemistry and serology for Chlamydia abortus. Additionally an attempt for the isolation of Waddlia and Parachlamydia was made by co-cultivation in amoebae. In 67.3% of the 343 cases a necrotizing and/or purulent placentitis was found histologically. By real-time PCR, 0.9% (3/343) of the cases were positive for Waddlia, 13.4% (46/343) positive for Parachlamydia and 14.6% (50/343) positive or questionable positive for Chlamydiaceae. Of these samples, confirmation by immunohistochemistry was possible in 2/3 cases for Waddlia, 25/46 for Parachlamydia and 4/50 for Chlamydiaceae. Of the 50 cases positive or questionable positive for Chlamydiaceae, species-identification by ArrayTube Microarray or 16S rRNA PCR resulted in 41 cases positive for C. abortus whereas the presence of Chlamydia suis was confirmed in four and Chlamydia pecorum in one case. This study brought evidence for the importance of different members of Chlamydiales in different regions of Switzerland although Waddlia is not occurring in a high prevalence. On the other hand mixed infections with different Chlamydiales as well as with other abortigenic agents could be found.

Molecular evidence for chlamydial infections in the eyes of sheep.

Ocular infections by chlamydiae are associated with ocular disease manifestations such as conjunctivitis and keratitis in humans and animals. Limited evidence exists that members of the order Chlamydiales can also cause ocular disease in sheep. In the current study, the prevalence of chlamydiae in the eyes of sheep was investigated by using PCR methods. Data obtained in sheep by broad-range 16S rRNA order Chlamydiales-specific PCR were compared to the prevalence of antibodies against chlamydiae detected by a competitive enzyme-linked immunosorbent assay (cELISA). Flocks tested included a clinically healthy flock and two flocks suffering from ocular disease and with histories of Ovine Enzootic Abortion (OEA). PCR detected DNA of Chlamydophila (Cp.) abortus and Cp. pecorum in the eyes of both healthy and sick animals but also identified Chlamydia (C.) suis and a variety of uncultured chlamydia-like organisms. Good correlation was found between the presence of Cp. abortus DNA in sheep conjunctival samples and seropositivity detected by cELISA. Despite these findings, no association was found between the presence of chlamydial DNA in the sheep conjunctival samples and the onset of clinical disease. These results suggest that the biodiversity of chlamydiae in the eyes of sheep is greater than that previously thought. Further investigations are needed to determine whether a causal relationship between infection by chlamydiae and ocular disease exists in these animals.

Capillary haemangiomas of the scrotum and testicle in boars.

In boars, scrotal haemangiomas have been described frequently, but intratesticular haemangiomas are rare. Of 12 boars with scrotal haemangiomas, three animals also had testicular tumours, as follow: testicular haemangioma (TH) (n=1); TH with intratubular germ cell tumour (ITGT) (n=1); TH with intratubular germ cell-like tumour (ITGLT) and Sertoli cell tumour (n=1). In the nine remaining boars, no testicular tumours were found. Immunohistochemical examination of scrotal and testicular haemangiomas revealed labelling of endothelial cells for vimentin and factor VIII-related antigen. Labelling of smooth muscle actin was occasionally observed in the walls of neoplastic vessels. In the ITGT, no labelling was produced by any of the antibodies used. The Sertoli cell tumour was strongly positive for S-100. Sperm granulomas and degeneration of seminiferous tubules were also observed.

Testicular hypoplasia in a bull persistently infected with bovine diarrhoea virus.

A bull aged 16 months with bilateral testicular hypoplasia and azoospermia was persistently infected with bovine viral diarrhoea virus (BVDV). Viral antigen was detected in serum and semen by ELISA, but the animal was serologically negative. After slaughter, the genital tract was examined histopathologically and by immunohistochemistry, including double immunolabelling with BVDV antibody and either S-100 antibody (for Sertoli cells) or ferritin antibody (for Leydig cells). The seminiferous tubules of both testes were lined by a single layer of Sertoli cells and the germinal epithelium was completely absent except for a few remaining spermatogonia. BVDV antigen was demonstrated (1) in the media of arterial vessel walls of the testis, epididymis, urethra, prostate, and vesicular and bulbourethral glands, (2) in epithelial cells of the ductus epididymidis, the accessory glands and the urethra, and (3) in the testis, mainly in Sertoli cells and to a lesser extent in the spermatogonia that remained, but not in Leydig cells. The testicular hypoplasia was possibly linked to the BVDV infection.

Prevalence of chlamydiae in semen and genital tracts of bulls, rams and bucks.

Chlamydiae infect male genital organs of ruminants. However, little is known about their prevalence. Hence, we investigated fresh and cryopreserved semen (bulls: n=304; rams: n=78; bucks: n=44) by polymerase chain reaction (PCR), as well as genital organs (bulls: n=13; rams: n=10; bucks: n=6) by immunohistochemistry (IHC) and PCR. Sera from bulls (n=104) and small ruminants (n=61) were tested by LPS and rMOMP (recombinant major outer membrane protein) ELISA and competitive ELISA (cELISA), respectively. Three PCR assays were compared in this study for detection of chlamydial DNA in semen: 16S rRNA, IGS-S (intergenic spacer 16S/23S-short), and IGS-L (intergenic spacer 16S/23S-long) PCRs. PCR sensitivity and inhibitory effects were determined by spiking semen with Chlamydophila (Cp.) abortus DNA. In bull semen, detection limits of the 16S, IGS-S and IGS-L PCRs were 10, 10, 100 templates, respectively. However, PCR sensitivity was reduced in ram and buck semen suggesting the presence of potential PCR inhibitors. Of 304 bull semen samples, the 16S PCR revealed DNA of chlamydiae in 20 samples (6.6%), including Cp. abortus (n=2), Cp. psittaci (n=1), Chlamydia suis (n=2), and Chlamydia-like organisms (n=15). In rams, one semen sample was positive for Chlamydia-like organism. All investigated male genital organs were negative for Chlamydia. Serology revealed 47.1% (49/104) positive bulls by LPS ELISA. Of these, 30 samples were positive by rMOMP ELISA, predominantly for Cp. pecorum. In small ruminants, cELISA displayed 34.8% (16/46) and 60% (9/15) positivity for Cp. abortus in rams and bucks, respectively. There was no correlation between serology and PCR of semen. The presence of chlamydiae in semen suggests the possibility of venereal transmission, although risk may be low in Switzerland.

Chlamydia-related abortions in cattle from Graubunden, Switzerland.

In 2001, the first case of bovine chlamydial abortion was reported in canton Graubunden, Switzerland. In this region, Chlamydophila (Cp.) abortus is endemic in small ruminants. Hence, we aimed to investigate the incidence of chlamydia-related abortions in cattle from Graubunden. During breeding seasons of 2003-2004, formalin-fixed and paraffin-embedded placenta specimens (n = 235) from late-term abortions in cattle were analyzed by histopathology, immunohistochemistry with a Chlamydiaceae-specific monoclonal antibody against chlamydial lipopolysaccharide (LPS), and 2 different polymerase chain reaction (PCR) methods (16 S ribosomal ribonucleic acid [rRNA] PCR, intergenic spacer [IGS-S] PCR), followed by PCR product sequencing. In 149 of 235 cases (63.4%), histopathologic lesions such as purulent and/or necrotizing placentitis were observed. Chlamydial antigen was clearly demonstrated in immunohistochemistry in only 1 of 235 cases (0.4%). Cp. abortus or Cp. psittaci was found in 12 of 235 (5.1%) and 10 of 235 cases (4.2%) by 16 S rRNA PCR and IGS-S PCR, respectively. However, we detected, by 16 S rRNA PCR, 43 of 235 cases (18.3%) to be positive for chlamydia-like organisms. In contrast to the situation in small ruminants in the canton Graubunden, bovine abortion from Cp. abortus seems not to play an important role. Nevertheless, zoonotic potential should be taken into account when handling abortion material from cattle. The significance of chlamydia-like isolates other than Waddlia chondrophila remains an open question in abortion and needs further investigation.

Detection of chlamydiae in boar semen and genital tracts.

Chlamydiae cause abortion and reproductive disorders in sows. Although organisms can infect the male genital tract, little is known about the disease situation in boars. Hence, we examined the prevalence of chlamydial infection in semen and genital tracts of boars. Samples collected from Swiss boars (group A: n=42), and boars from Germany (group B: n=39) were examined by bacteriology, LPS-ELISA, immunohistochemistry (IHC) and polymerase chain reaction (PCR). The latter methodology involved use of three PCR assays including 16Sig rDNA, IGS-S (intergenic spacer 16S/23S-Short) and IGS-L (intergenic spacer 16S/23S-Long) PCR for comparison methods. PCR sensitivity and the presence of potential PCR inhibitors were determined by spiking semen with Chlamydophila (Cp.) abortus DNA. Detection limits of the 16Sig and IGS-S PCR were 10 templates, while the IGS-L PCR was less sensitive (100 templates). Of 25 semen samples that were collected from group A, one semen sample was positive for Cp. psittaci and two were positive for Chlamydia-like organisms by 16Sig PCR. Screening of sera from Swiss boars revealed three animals with positive reactions in the LPS-ELISA, although we failed to detect chlamydiae within organs of these or sera-negative animals by IHC or IGS-S PCR. In group B, 10 ejaculates were positive for Chlamydia (C.) suis and two were positive for Chlamydia-like organisms by 16S PCR. The identification of DNA from Chlamydia-like organisms in semen from both groups of boars was surprising and a role for these bacteria in reproductive diseases requires further assessment. In conclusion, the prevalence of chlamydial infection was low in group A animals indicating that venereal transmission may not be significant for Chlamydia-associated reproductive diseases in pigs, although rare cases may occur.