Occurrence of chlamydiae in the genital tracts of sows at slaughter and their possible significance for reproductive failure

A case report: Actinobaculum suis infection associated with formation of pyogranuloma, epididymitis and azoospermia in a boar

BACKGROUND

Actinobaculum suis is a bacterium known to cause infections of the urogenital tract of sows. Infection can occur through close contact to boars, who frequently carry the pathogen in their preputial diverticulum but do not become clinically diseased themselves. In the current case, Actinobaculum suis was isolated from pyogranuloma of inflamed epididymis in a boar with poor fertility.

CASE PRESENTATION

Increased return to oestrus rate, which worsened after the purchase of a new boar, was reported in an organic farm in Switzerland. During herd examination, azoospermia of the boar was diagnosed, and slaughter, followed by examination of its urogenital tract, was carried out. Pathologically, pyogranuloma formation and epididymitis were diagnosed. Bacteriology of the pyogranulomas showed growth of Actinobaculum suis and mixed flora. After the boar was replaced, the return to oestrus rate improved tremendously.

CONCLUSION

A close relative of Actinobaculum suis, namely Actinotignum schaalii, has already been associated with epididymitis in humans. Considering the present case and the parallels in human medicine, Actinobaculum suis should be included in the list of differentials of boars with poor fertility.

Isolation of Tetracycline-Resistant Chlamydia suis from a Pig Herd Affected by Reproductive Disorders and Conjunctivitis

Due to various challenges in diagnosing chlamydiosis in pigs, antibiotic treatment is usually performed before any molecular or antibiotic susceptibility testing. This could increase the occurrence of tetracycline-resistant Chlamydia (C.) suis isolates in the affected pig population and potentiate the reoccurrence of clinical signs. Here, we present a case of an Austrian pig farm, where tetracycline resistant and sensitive C. suis isolates were isolated from four finishers with conjunctivitis. On herd-level, 10% of the finishers suffered from severe conjunctivitis and sows showed a high percentage of irregular return to estrus. Subsequent treatment of whole-herd using oxytetracycline led to a significant reduction of clinical signs. Retrospective antibiotic susceptibility testing revealed tetracycline resistance and decreased susceptibility to doxycycline in half of the ocular C. suis isolates, and all isolates were able to partially recover following a single-dose tetracycline treatment in vitro. These findings were later confirmed in vivo, when all former clinical signs recurred three months later. This case report raises awareness of tetracycline resistance in C. suis and emphasizes the importance of preventative selection of tetracycline resistant C. suis isolates.

Occurrence of reproductive disorders in pig herds with and without Chlamydia suis infection - statistical analysis of breeding parameters

Chlamydiae are frequently encountered Gram-negative intracellular eubacteria that can cause clear manifestations or clinically asymptomatic disorders. C. suis and other chlamydia are primarily isolated in cases of reproductive disorders. This study was performed to estimate the impact of Chlamydia suis infection on reproduction in sows by analyzing reproduction rates and breeding parameters. The test was conducted on first generation (F1) pigs from Polish Landrace (PL) × Polish Large White (PLW). Sixty-four herds were investigated and 500 vaginal swabs were collected. Isolation of DNA was carried out directly from the swabs. All samples were analyzed for Chlamydia suis by real-time PCR with a locked nucleic acid (LNA)-containing probe. To analyze the impact of chlamydia infection on reproductive parameters, evaluation questionnaires were used. Reproductive problems were found in 77.3% of the farms tested. The receiver operating characteristic curve indicated that in the farms with 10 up to 120 sows, there were higher reproductive problems with chlamydia infection than in smaller and bigger pig farms. The most common problems were estrus repetition, which was reported by 57.81% of the surveyed farms, and the birth of dead piglets, which was reported by 31.25% of the investigated pig farms. Abortions, which were reported by 28.12% of the surveyed farms, were the least common reproductive disorders.

Detection of Mycobacteria and Chlamydiae in Granulomatous Inflammation of Reptiles: A Retrospective Study

A retrospective study on reptile tissues presenting with granulomatous inflammation was performed to detect the possible presence of mycobacteria and chlamydiae in these lesions. Ninety cases including 48 snakes, 27 chelonians, and 15 lizards were selected. Mycobacteria were detected by Ziehl-Neelsen (ZN) staining and a broad-range polymerase chain reaction (PCR) followed by DNA sequencing. To detect chlamydiae, immunohistochemistry with monoclonal antibodies against chlamydial lipopolysaccharide (LPS) and a Chlamydiales order-specific PCR and sequencing were applied. Acid-fast bacilli were found in 14 cases (15.6%) by ZN staining and in 23 cases (25.6%) by PCR. Sequence analysis revealed the presence of Mycobacteria other than Mycobacterium tuberculosis complex (MOTT). Chlamydial LPS antigen was observed within granulomas from five samples (5.6%), whereas the PCR screen revealed 58 positive cases (64.4%). Of these, 9 cases (10%) showed 98–99% similarity to Chlamydophila ( Cp.) pneumoniae and 49 cases (54.4%) displayed a high similarity (88–97%) to the newly described “Chlamydia-like” microorganisms Parachlamydia acanthamoebae and Simkania negevensis. Results from this study confirm, on the one hand, that MOTT are probably the most important infectious etiology for granulomatous inflammation in reptiles. On the other hand, they indicate that chlamydia infects reptiles and that Cp. pneumoniae should be considered an etiological agent of granulomatous lesions of reptiles. Because both MOTT and Cp. pneumoniae are human pathogens, the potential of zoonotic transmission from reptiles to humans has to be considered. In contrast, the significance of Chlamydia-like isolates remains completely open, and further studies are needed to evaluate their role.

Genome Sequence of Chlamydia psittaci Strain 01DC12 Originating from Swine

Chlamydia psittaci is the etiological agent of psittacosis and is a zoonotic pathogen infecting birds and a variety of mammalian hosts. Here we report the genome sequence of the porcine strain 01DC12 which is representative of a novel clade of C. psittaci belonging to ompA genotype E.

Chlamydiaceae family, Parachlamydia spp., and Waddlia spp. in porcine abortion

At present, despite extensive laboratory investigations, most cases of porcine abortion remain without an etiological diagnosis. Due to a lack of recent data on the abortigenic effect of order Chlamydiales, 286 fetuses and their placentae of 113 abortion cases (1–5 fetuses per abortion case) were investigated by polymerase chain reaction (PCR) methods for family Chlamydiaceae and selected Chlamydia-like organisms such as Parachlamydia acanthamoebae and Waddlia chondrophila. In 0.35% of the cases (1/286 fetuses), the Chlamydiaceae real-time PCR was positive. In the Chlamydiaceae-positive fetus, Chlamydia abortus was detected by a commercial microarray and 16S ribosomal RNA PCR followed by sequencing. The positive fetus had a Porcine circovirus-2 coinfection. By the Parachlamydia real-time PCR, 3.5% (10/286 fetuses of 9 abortion cases) were questionable positive (threshold cycle values: 35.0–45.0). In 2 of these 10 cases, a confirmation by Chlamydiales-specific real-time PCR was possible. All samples tested negative by the Waddlia real-time PCR. It seems unlikely that Chlamydiaceae, Parachlamydia, and Waddlia play an important role as abortigenic agents in Swiss sows.

A nested multiplex polymerase chain reaction assay for the differential identification of three zooanthroponotic chlamydial strains in porcine swab samples

Porcine chlamydial infection is an enzootic infectious disease caused by multiple members of the family Chlamydiaceae (e.g. Chlamydophila abortus, Chlamydia suis, and Chlamydophila pneumoniae). Rapid and accurate differentiation of these pathogens is critical in the control and prevention of disease. The aim of the current study was to develop a nested multiplex polymerase chain reaction (nmPCR) assay to simultaneously detect the 3 chlamydial pathogens in clinical samples. In the first round of the nmPCR, 1 pair of family-specific primers were used to amplify the 1,100 base pair (bp) fragment of chlamydial ompA gene. In the second round of the nmPCR, 4 inner primers were designed for Ch. abortus, C. suis, and Ch. pneumoniae. Each pathogen produced a specific amplicon with a size of 340 bp, 526 bp, and 267 bp respectively. The assay was sensitive and specific for detecting target pathogens in both cell cultures and clinical specimens. The results, incorporated with the improved rapid DNA extraction protocol, suggest that the nmPCR could be a promising assay for differential identification of different chlamydial strains in pigs.

Chlamydiaceae infections in pig

Chlamydiaceae are Gram-negative obligate intracellular bacteria. They are responsible for a broad range of diseases in animals and humans. In pigs, Chlamydia suis, Chlamydia abortus, Chlamydia pecorum and Chlamydia psittaci have been isolated. Chlamydiaceae infections in pigs are associated with different pathologies such as conjunctivitis, pneumonia, pericarditis, polyarthritis, polyserositis, pseudo-membranous or necrotizing enteritis, periparturient dysgalactiae syndrome, vaginal discharge, return to oestrus, abortion, mummification, delivery of weak piglets, increased perinatal and neonatal mortality and inferior semen quality, orchitis, epididymitis and urethritis in boars. However, Chlamydiaceae are still considered as non-important pathogens because reports of porcine chlamydiosis are rare. Furthermore, Chlamydiaceae infections are often unnoticed because tests for Chlamydiaceae are not routinely performed in all veterinary diagnostic laboratories and Chlamydiaceae are often found in association with other pathogens, which are sometimes more easily to detect. However, recent studies have demonstrated that Chlamydiaceae infections in breeding sows, boars and piglets occur more often than thought and are economically important. This paper presents an overview on: the taxonomy of Chlamydiaceae occurring in pigs, diagnostic considerations, epidemiology and pathology of infections with Chlamydiaceae in pigs, public health significance and finally on prevention and treatment of Chlamydiaceae infections in pigs.

Recent developments in the laboratory diagnosis of chlamydial infections

There are two main approaches to diagnosing infections by Chlamydia and Chlamydophila spp. in mammals and birds. The first involves the direct detection of the agent in tissue or swab samples, while the second involves the serological screening of blood samples for the presence of anti-chlamydial antibodies. Ultimately, the test that is used is dependent on the types of samples that are submitted to the diagnostic laboratory for analysis. The present paper gives an overview on methodologies and technologies used currently in diagnosis of chlamydial infections with emphasis on recently developed tests. The performance characteristics of individual methods, such as the detection of antigen in smears and in pathological samples, the isolation of the pathogen, various antibody detection tests and DNA-based methods utilising conventional and real-time PCR, as well as DNA microarray technology are assessed, and specific advantages and drawbacks are discussed. Further, a combination of a specific real-time PCR assay and a microarray test for chlamydiae is proposed as an alternative reference standard to isolation by cell culture.

Intensively kept pigs pre-disposed to chlamydial associated conjunctivitis

In the present study, ocular chlamydial infections in pigs that originate from two different farming systems were investigated. In particular, the aim was to test pigs with and without clinical ocular symptoms for the presence of Chlamydiaceae and for linked infections with Acanthamoebae spp. possibly acting as vectors for Chlamydia or Chlamydia-like organisms. In a total of 181 pigs, 102 from Germany (GER), representing the intensively kept animals and 79 from Switzerland (CH), which were kept extensively, were screened for the presence of different pathogens by PCR, including a new Chlamydiaceae-specific intergenic spacer rRNA gene PCR. Additionally, results of clinical examination and cytology were compared between the symptomatic and asymptomatic pigs of the two groups. Ocular symptomatic pigs showed a high prevalence of Chlamydia suis in both groups: CH 79%, GER 90%. Only 23% asymptomatic pigs from CH, but 88% asymptomatic pigs from GER were positive for C. suis by PCR. DNA of Chlamydia-like organisms were detected in 19% CH, but only in 2% GER pigs, whereas only 4% CH and 1% GER pigs were also positive for Acanthamoebae spp. A co-infection of Acanthamoebae spp. and C. suis was present in only 3% of the CH but 28% of the GER pigs. In general, the intensively kept pigs in our study seemed to be pre-disposed to ocular chlamydial infection and associated conjunctivitis. Infections with Chlamydia-like organisms alone and in combination with Acanthamoebae played no role for clinical findings within the tested pig groups, whereas a co-infection of Acanthamoebae and C. suis was able to cause serious ocular manifestations in half of the cases of intensively kept pigs being positive for these microorganisms.

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.

Chlamydiae in oviducts and uteri of repeat breeder pigs

Chlamydial infections of the genital organs cause reproductive failure in female pigs, and the uterus is recognized a target tissue for an infection. In contrast, information on the effect of chlamydiae on the porcine oviduct is patchily and inconclusive, although the bacteria are known to cause severe tubal defects in humans and laboratory animals. The aim of this study was to examine the segments ampulla (A), isthmus (I) and utero-tubal junction of the left (n=20) or both (n=22) oviducts, and uteri (U) from 42 culled repeat breeder pigs for chlamydiae using ompA-PCR, partial ompA gene sequencing, immunohistochemistry (IHC) and microscopy of tissue specimens for histopathology. As revealed by PCR, among a total of 26 chlamydia-positive females, 19 were tested positive in one or more segments of one or both oviducts, 14 were found positive in the uterus, and concomitant infections of both organs were observed in 7 of them. Sequencing of 33 PCR products revealed the following chlamydial species: Chlamydophila (Cp.) psittaci (n=18), Cp. abortus (n=2), Chlamydia (C.) suis (n=10), and C. trachomatis (n=3). Immunopositive staining was observed within the surface epithelium (in A, I, U), stromal tissue (in I, U) and muscular layer (in A, I, U). A total of 24 females had inflamed oviductal segments (in A and/or I) and 36 inflamed uteri. However, there was no relationship between histopathology and results of PCR or IHC. In conclusion, chlamydiae were found to infect oviducts and uteri of pigs. Further studies are required to clarify whether chlamydial infection causes specific histopathology and alters tubal function.

Prevalence of chlamydiae in boars and semen used for artificial insemination

Although there are indications for venereal transmission of chlamydiae in pigs, direct diagnostic evidence on the presence of these bacteria in boars and boar semen in particular is still incomplete. We investigated boars from two studs (A, B) in semen (A: n = 174; B: n = 100) and faeces (A: n = 174; B: n = 24) for chlamydiae using ompA-PCR and partial ompA gene sequencing. Additionally, blood serum was examined for chlamydial antibodies using an indirect ELISA (A: n = 171; B: n = 62). Chlamydiae were found in 9 (5.2%) and 24 (24.0%) semen specimens, and in 71 (40.1%) and 2 (8.3%) faecal samples from boars of stud A and B, respectively. Regarding individual chlamydial species, Chlamydophila psittaci and Chlamydia suis were identified most frequently, with the former predominating in semen (in 23 out of 33 positive samples) and the latter in faeces (68/73). In contrast, Chlamydophila pecorum was found only sporadically. Chlamydial antibodies were detected in 80 (46.8%) and 6 (9.7%) boars of stud A and B, respectively. No correlation was observed between the data from serology and PCR of semen or faeces in either of the studs. In conclusion, detection of chlamydiae in semen of boars suggests a potential for venereal transmission. Whether the high overall prevalence of chlamydial infections reflects a general situation in boars needs to be investigated. Serological testing failed to identify boars shedding chlamydiae in their semen.

Evaluation of lung function in pigs either experimentally or naturally infected with Chlamydiaceae

This study evaluated the influence of chlamydial infections on lung function in conventionally raised pigs. Eight pigs aged 39-44 days were included in an aerogeneous challenge model (4 were exposed to Chlamydia suis; 4 served as controls). Nineteen pigs aged 5-27 weeks without clinical symptoms (but partly PCR-positive for chlamydial species) were examined over 6 months. For lung function testing, impulse oscillometry was used. In total, all 27 pigs underwent 465 lung function tests. Variables of ventilation (respiratory rate, tidal volume, minute volume), respiratory impedance (expressed as resistance and reactance within the frequency range 3-15 Hz), and model derived resistance of proximal and distal airways were measured. Experimental exposure to C. suis significantly affected lung function. Early distal airway obstruction (3-5 days after infection) was followed by an obstruction of proximal airways (7 days after infection). The breathing pattern was significantly changed (decreased tidal volume; increased respiratory rate). In symptom-free pigs having a naturally acquired presence of different chlamydial species in the respiratory system, no deterioration in lung function could be determined up to the age of 6 months. In conclusion, the consequences of respiratory chlamydial infections appear to vary from clinical inapparence to severe respiratory distress.

Occurrence of Chlamydiaceae spp. in a wild boar (Sus scrofa L.) population in Thuringia (Germany)

Tissue samples from lungs, pulmonary lymph nodes, large intestine, and uteri of 14 wild boar bagged at a seasonal hunt were examined for the presence of chlamydiae, mycobacteria and mycoplasmas. Nested PCR detected chlamydial DNA in 57.1% of the animals, predominantly in the lung. DNA sequencing identified Chlamydophila psittaci as the predominant species, but Chlamydophila abortus and Chlamydia suis were also encountered. Immunohistochemical staining of tissue sections confirmed the presence of typical chlamydial inclusions in lungs and uteri. While the role of Chlamydiaceae as pathogens in wild boar has yet to be established, the present findings revealed a possible wildlife reservoir of these bacteria.

Immunoblotting, ELISA and culture evidence for Chlamydiaceae in sows on 258 Belgian farms

The prevalence of Chlamydiaceae infections on 258 closed pig breeding farms in Belgium was examined. For this purpose, 258 farms were randomly selected in the provinces West-Vlaanderen (44%), Oost-Vlaanderen (20%), Antwerpen (10%) and Vlaams-Brabant (6%). Of all farms examined, 96.5% were positive for Chlamydia-specific antibodies in ELISA and most were moderately to strongly positive. ELISA results revealed only 9 (3.5%) sero-negative farms. None of the ELISA negative sera reacted in immunoblotting. Only 212 of 249 ELISA positive sera reacted positive in immunoblotting. Additionally, 23 autopsy samples were examined by isolation in Vero cells. The major outer membrane sequence of the one isolate obtained showed 98.6% amino acid homology to the one of Chlamydophila psittaci strain CP3, formerly isolated from a pigeon. Present observations indicate that chlamydial infections are nearly endemic in the Belgian pig population and that Belgian pigs can become infected with C. psittaci. Nevertheless, the role and significance of Chlamydiaceae as pathogens in pigs remain unsolved and require further investigation.

Respiratory chlamydial infection based on experimental aerosol challenge of pigs with Chlamydia suis

An experimental study of aerogeneous challenge in pigs was conducted in order to reveal characteristic features of porcine respiratory chlamydiosis. Eight conventionally raised pigs were exposed to a pathogenic strain of Chlamydia (C.) suis, four controls were mock infected. Besides pathological changes, the acute-phase and humoral immune responses, as well as the dissemination and transmission of the challenge strain was monitored in the course of infection. The data from clinical investigations, LPS-binding protein assay, antibody ELISAs, confocal laser scanning and light microscopy, immunohistochemical staining and PCR provided extensive evidence of the pathogenic potential of C. suis for the porcine respiratory system. This model appears suitable for further pathophysiological and immunological investigations of chlamydial respiratory infections and can also be recommended for studies of Chlamydia-associated infections of the human lung.

Expression of the Major Outer Membrane Protein (MOMP) of Chlamydophila abortus, Chlamydophila pecorum, and Chlamydia suis in Escherichia coli using an Arabinose-inducible Plasmid Vector

The ompA genes encoding the 40 kDa major outer membrane protein (MOMP) of Chlamydophila (Ch.) abortus, Ch. pecorum, and Chlamydia (C.) suis were cloned into the arabinose-inducible plasmid vector pBADMycHis, and recombinant MOMPs (rMOMP) from the three chlamydial species were expressed at high levels in Escherichia (E.) coli. The proteins lacking the 22 aa N-terminal signal peptide were expressed as insoluble cytoplasmic inclusion bodies which were readily purified using immobilized metal-affinity chromatography. The rMOMPs including the N-terminal signal peptide were expressed and translocated as a surface-exposed immunoaccessible protein into the outer membrane of E. coli. Transformants expressing this full-length rMOMP were significantly reduced in viability. Purified native elementary bodies (EB) and rMOMPs of the three chlamydial species purified from the E. coli cytoplasm were used for immunization of rabbits. The resulting sera were analysed for their ability to recognize homologous and heterologous rMOMP and native EB. When testing rMOMP antisera against rMOMP and EB antigens, marked cross-reactivities were detected between the three species. Using EB antisera and rMOMPs as antigens, a significant species-specific reactivity was measured.

The effects of the periodical use of in-feed chlortetracycline on the reproductive performance of gilts and sows of a commercial pig farm with a history of clinical and subclinical viral and bacterial infections

The objective of this study was to assess the effects of in-feed chlortetracycline (CTC) as a measure of preventing or minimizing infectious problems of reproductive failure in gilts and sows. In a farm of 400 Large White x Landrace gilts and sows with a clinical history of porcine respiratory and reproductive syndrome (PRRS) virus, the animals were treated with CTC. Treatment consisted of 10 g CTC sow/day for 15 days every 3 months. It improved the health status of sows by decreasing post-farrowing clinical mastitis and vaginal discharges, abortions, return-to-oestrus and irregular return-to-oestrus rates. These beneficial effects had a positive impact on the performance of the litter. More piglets were born live and weaned. These positive effects improved with repeated use of CTC. The serological evidence of PRRS virus, Leptospira spp. and Chlamydia spp. and the subsequent beneficial use of the antimicrobial agent indicate that reproductive failure, possibly resulting from the bacterial agents can be controlled with in-feed use of broad spectrum antimicrobials.