Development of a new multiplex quantitative PCR for the detection of Glaesserella parasuis, Mycoplasma hyorhinis, and Mycoplasma hyosynoviae

Glaesserella parasuis, Mycoplasma hyorhinis, and Mycoplasma hyosynoviae are important porcine pathogens responsible for polyserositis, polyarthritis, meningitis, pneumonia, and septicemia causing significant economic losses in the swine industry. A new multiplex quantitative polymerase chain reaction (qPCR) was designed on one hand for the detection of G. parasuis and the virulence marker vtaA to distinguish between highly virulent and non-virulent strains. On the other hand, fluorescent probes were established for the detection and identification of both M. hyorhinis and M. hyosynoviae targeting 16S ribosomal RNA genes. The development of the qPCR was based on reference strains of 15 known serovars of G. parasuis, as well as on the type strains M. hyorhinis ATCC 17981T and M. hyosynoviae NCTC 10167T . The new qPCR was further evaluated using 21 G. parasuis, 26 M. hyorhinis, and 3 M. hyosynoviae field isolates. Moreover, a pilot study including different clinical specimens of 42 diseased pigs was performed. The specificity of the assay was 100% without cross-reactivity or detection of other bacterial swine pathogens. The sensitivity of the new qPCR was demonstrated to be between 11-180 genome equivalents (GE) of DNA for M. hyosynoviae and M. hyorhinis, and 140-1200 GE for G. parasuis and vtaA. The cut-off threshold cycle was found to be at 35. The developed sensitive and specific qPCR assay has the potential to become a useful molecular tool, which could be implemented in veterinary diagnostic laboratories for the detection and identification of G. parasuis, its virulence marker vtaA, M. hyorhinis, and M. hyosynoviae.

On-farm colorimetric detection of Pasteurella multocida, Mannheimia haemolytica, and Histophilus somni in crude bovine nasal samples

This work modifies a loop-mediated isothermal amplification (LAMP) assay to detect the bovine respiratory disease (BRD) bacterial pathogens Pasteurella multocida, Mannheimia haemolytica, and Histophilus somni in a colorimetric format on a farm. BRD causes a significant health and economic burden worldwide that partially stems from the challenges involved in determining the pathogens causing the disease. Methods such as polymerase chain reaction (PCR) have the potential to identify the causative pathogens but require lab equipment and extensive sample processing making the process lengthy and expensive. To combat this limitation, LAMP allows accurate pathogen detection in unprocessed samples by the naked eye allowing for potentially faster and more precise diagnostics on the farm. The assay developed here offers 66.7-100% analytical sensitivity, and 100% analytical specificity (using contrived samples) while providing 60-100% concordance with PCR results when tested on five steers in a feedlot. The use of a consumer-grade water bath enabled on-farm execution by collecting a nasal swab from cattle and provided a colorimetric result within 60 min. Such an assay holds the potential to provide rapid pen-side diagnostics to cattle producers and veterinarians.

On-farm colorimetric detection of Pasteurella multocida, Mannheimia haemolytica, and Histophilus somni in crude bovine nasal samples

This work modifies a loop-mediated isothermal amplification (LAMP) assay to detect the bovine respiratory disease (BRD) bacterial pathogens Pasteurella multocida, Mannheimia haemolytica, and Histophilus somni in a colorimetric format on a farm. BRD causes a significant health and economic burden worldwide that partially stems from the challenges involved in determining the pathogens causing the disease. Methods such as polymerase chain reaction (PCR) have the potential to identify the causative pathogens but require lab equipment and extensive sample processing making the process lengthy and expensive. To combat this limitation, LAMP allows accurate pathogen detection in unprocessed samples by the naked eye allowing for potentially faster and more precise diagnostics on the farm. The assay developed here offers 66.7-100% analytical sensitivity, and 100% analytical specificity (using contrived samples) while providing 60-100% concordance with PCR results when tested on five steers in a feedlot. The use of a consumer-grade water bath enabled on-farm execution by collecting a nasal swab from cattle and provided a colorimetric result within 60 min. Such an assay holds the potential to provide rapid pen-side diagnostics to cattle producers and veterinarians.

Severe pneumonia in a street rat (Rattus norvegicus) caused by Rodentibacter rarus strain RMC2

Background

Rodents are one of the most dangerous reservoirs and carriers of infectious diseases. Gradually, rats have become predominant in cities, sometimes staying in close vicinity to humans, pets, and other animals. Consequently, they tend to increase the transmission risk of pathogens.

Case Description

Here, we report an original case of bacterial pneumonia in a street rat (Rattus norvegicus). The rat was found dead on a street in the chief town of Marseille (France) after being run over by a car. The necropsy of the corpse revealed generalized granulomatous pneumonia in almost all the pulmonary lobes. Lung lesions and predominantly multiple fibro-inflammatory areas are presumably the witness of an infectious etiology. Bacterial isolation was carried out from lung tissues. Colonies were identified by MALDI-TOF MS and confirmed by 16S rRNA sequencing. The following bacteria were identified: Staphylococcus cohnii, Bordetella bronchiseptica, Bordetella parapertussi, Corynebacterium glucuronolyticum, Pelistega suis and Rodentibacter rarus. Based on the histopathological diagnosis and the avoidance approach, the most likely etiological agent of pneumonia is therefore R. rarus, a little-known Pasteurellales bacterium that is closely related to Rodentibacter pneumotropicus.

Conclusion

These data emphasize the severity of R. rarus infection in rodents. Thus, pointing out a potential risk for other animals (dogs, cats, and birds), as well as humans. The health monitoring program for rodents and rabbits pasteurellosis should now include R. rarus. Therefore, the pathological effect of the Rodentibacterspecies and/or strains needs to be better explored.

Aggregatibacter actinomycetemcomitans pneumonia mimicking lung cancer in a previously healthy 12-year-old child from Saudi Arabia: a case report

Aggregatibacter actinomycetemcomitans formely known as Actinobacillus actinomycetemcomitans is a known part of the normal oral flora. It can sometimes cause oral or rarely extra-oral infections secondary to hematogenous extension or aspiration. It is a rare cause of invasive pneumonia. It can resemble tuberculosis or lung cancer in its presentation. Making the diagnosis in such case is crucial for better management that usually require tissue biopsy. We report a case of Aggregatibacter actinomycetemcomitans invasive pneumonia in a 12-year-old previously healthy boy from Saudi Arabia. After a prolonged course of antibiotics, clinical and radiological follow up showed complete resolution of the infection.

Identification of Lonepinella sp. in Koala Bite Wound Infections, Queensland, Australia

We report 3 cases of koala bite wound infection with Lonepinella koalarum–like bacteria requiring antimicrobial and surgical management. The pathogens could not be identified by standard tests. Phylogenetic analysis of 16S rRNA and housekeeping genes identified the genus. Clinicians should isolate bacteria and determine antimicrobial susceptibilities when managing these infections.

Identification of Histophilus somni by a nanomaterial optical fiber biosensor assay

Histophilus somni is an opportunistic pathogen responsible for respiratory and systemic diseases of cattle and sheep. Rapid and accurate detection of H. somni is essential to distinguish H. somni from other potential pathogens for proper control and treatment of infections. Nanomaterial optical fiber biosensors (NOFS) recognize analyte interactions, such as DNA hybridization, with high specificity and sensitivity, and were applied to detect H. somni DNA in culture and clinical samples. An ionic self-assembled multilayer (ISAM) film was fabricated on a long-period grating optical fiber, and a biotinylated, nucleotide probe complementary to the H. somni 16S rDNA gene was coupled to the ISAM film. Exposure of the ISAM::probe to ⩾100 killed cells of H. somni strain 2336 without DNA amplification resulted in attenuation of light transmission of ⩾9.4%. Exposure of the complexed fiber to Escherichia coli or non- H. somni species of Pasteurellaceae reduced light transmission by ⩽3.4%. Exposure of the ISAM::probe to blood, bronchoalveolar fluid, or spleen from mice or calves infected with H. somni resulted in ⩾24.3% transmission attenuation. The assay correctly detected all 6 strains of H. somni tested from culture, or tissues from 3 separate mice and calves tested in duplicate. Six heterologous strains (representing 6 genera) reacted at below the cutoff value of 4.87% attenuation of light transmission. NOFS detected at least 100 H. somni cells without DNA amplification within 45 min with high specificity. Although different fibers could vary in signal sensitivity, this did not affect the sensitivity or specificity of the assay.

[Endocarditis of mitral and aortic prosthetic heart valves caused by Aggregatibacter aphrophilus]

We present the case of an acute endocarditis of mitral and aortic prosthetic heart valves caused by Aggregatibacter aphrophilus (Haemophilus aphrophilus-paraphrophilus). This third report in the literature emphasizes the diagnostic work-up and the role of positron emission tomography combined with computed tomography in this setting. The specificities of endocarditis due to the HACEK group (Haemophilus spp., Aggregatibacter, Cardiobacterium hominis, Eikenella corrodens and Kingella spp.) and the specific microbiological data and therapeutic options pertinent to this germ are discussed.

Potential Risk for Localized Aggressive Periodontitis in African American Preadolescent Children

PURPOSE

This study aimed to evaluate the potential risk for localized aggressive periodontitis (LAgP) in African American children by detection of the potential periodontal pathogen Aggregatibacter actinomycetemcomitans (Aa) using polymerase chain reaction (PCR) and microbiome analysis.

METHODS

Twenty-one pre-adolescents (age range equals 10.7 to 13.1 years old) were recruited, for this IRB-approved study. Oral examination included limited periodontal examination determining bleeding index (BOP) and periodontal probing (PD). An oral mucosa sample was used for analysis.

RESULTS

Nine of 21 children were Aa+ by PCR. The Aa+ group had a significantly higher proportion of teeth with BOP and PD greater than four mm than the Aa- group (P=0.014 and 0.006 for percent BOP and percent PD equal to or greater than four mm, respectively; Mann Whitney Test). No significant differences in microbe abundance or composition were found from comparison of Aa+ versus Aa- samples.

CONCLUSIONS

Detection of Aa from preadolescent African American children was associated with signs of periodontal inflammation. Although none of these children were diagnosed with LAgP, PCR targeting Aa could be a risk factor. Further study is indicated; however, the usefulness of PCR in dental practice setting to assess risk may be cost-effective for early diagnosis and prevention of LAgP.

Retroperitoneal, Psoas, and Scrotal Abscesses Due to an Uncommon Organism - Aggregatibacter aphrophilus: Case Report and Review of Literature

Aggregatibacter aphrophilus is an uncommon cause of vertebral infections and its complications are infrequently seen. We believe ours is the first reported case of scrotal abscess as a complication of vertebral osteomyelitis. We have also reviewed nine cases with complications similar to this report. Epidural abscess is the most commonly found complication, having been reported in six patients, followed closely by psoas abscess, which was seen in five patients. All except one patient underwent surgical drainage, with all patients showing complete resolution of infection.

Aggregatibacter aphrophilus misidentified as Brucella spp. in an immunocompetent patient with brain abscess

Aggregatibacter aphrophilus rarely causes brain abscesses. Here we report a case of the brain abscess caused by Aggregatibacter aphrophilus. Cultivated gram negative coccobacilli from cerebral abscess were initially misidentified as Brucella spp. because it gave false positive agglutination with anti-Brucella sera. Definite identification was made with MALDI-TOF assay. Right to left shunt through the pulmonary arteriovenous malformation was speculated to be the underlying cause for the brain abscess. The patient was treated successfully with ampicillin-sulbactam after failing ceftriaxone treatment.

Clinical Case of the Month:A 54 Year-Old Woman With Fever and Chills of Four-Days Duration

A 54 year-old woman with diabetes mellitus type two and end-stage renal disease on hemodialysis presented to the emergency department with a four day history of generalized malaise, fever, and chills. Her symptoms were also associated with occasional dyspnea without a cough. She reported intermittent chronic diarrhea with hemodialysis which was currently unchanged. On the day of admission, she could not tolerate hemodialysis due to her symptoms. Over the past year she admitted to night sweats and a 40 pound weight loss. She denied having palpitations, chest pain, hemoptysis, lymph node swelling, sick contacts, or recent travel. The remainder of the review of systems was negative.

Human Wound Infection with Mannheimia glucosida following Lamb Bite

Mannheimia spp. are veterinary pathogens that can cause mastitis and pneumonia in domestic cattle and sheep. While Mannheimia glucosida can be found as normal flora in oral and respiratory mucosa in sheep, there have been no reported cases of human infection with this organism.

[Cutaneous infection with Aggregatibacter actinomycetemcomitans]

BACKGROUND

Aggregatibacter actinomycetemcomitans is a small, gram-negative, non-motile, coccobacillus. Aggregatibacter actinomycetemcomitans is known to cause periodontal disease and to be associated with actinomycosis.

CASE REPORT

We report a patient developed a chronic wound following trauma about the right heel. The lesion resolved after oral antibiotic therapy with cefpodoxime und surgical debridement. Bacterial cultures grew abundant Aggregatibacter actinomycetemcomitans, but no actinomyces species.

OBJECTIVE

The importance of Aggregatibacter actinomycetemcomitans in chronic wounds needs to be explored.

Classification, identification, and clinical significance of Haemophilus and Aggregatibacter species with host specificity for humans

The aim of this review is to provide a comprehensive update on the current classification and identification of Haemophilus and Aggregatibacter species with exclusive or predominant host specificity for humans. Haemophilus influenzae and some of the other Haemophilus species are commonly encountered in the clinical microbiology laboratory and demonstrate a wide range of pathogenicity, from life-threatening invasive disease to respiratory infections to a nonpathogenic, commensal lifestyle. New species of Haemophilus have been described (Haemophilus pittmaniae and Haemophilus sputorum), and the new genus Aggregatibacter was created to accommodate some former Haemophilus and Actinobacillus species (Aggregatibacter aphrophilus, Aggregatibacter segnis, and Aggregatibacter actinomycetemcomitans). Aggregatibacter species are now a dominant etiology of infective endocarditis caused by fastidious organisms (HACEK endocarditis), and A. aphrophilus has emerged as an important cause of brain abscesses. Correct identification of Haemophilus and Aggregatibacter species based on phenotypic characterization can be challenging. It has become clear that 15 to 20% of presumptive H. influenzae isolates from the respiratory tracts of healthy individuals do not belong to this species but represent nonhemolytic variants of Haemophilus haemolyticus. Due to the limited pathogenicity of H. haemolyticus, the proportion of misidentified strains may be lower in clinical samples, but even among invasive strains, a misidentification rate of 0.5 to 2% can be found. Several methods have been investigated for differentiation of H. influenzae from its less pathogenic relatives, but a simple method for reliable discrimination is not available. With the implementation of identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry, the more rarely encountered species of Haemophilus and Aggregatibacter will increasingly be identified in clinical microbiology practice. However, identification of some strains will still be problematic, necessitating DNA sequencing of multiple housekeeping gene fragments or full-length 16S rRNA genes.

Intracranial abscess secondary to dental infection

We report a case of Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) bacteraemia and secondary brain abscess in a patient where periodontal disease was implicated as the probable source.

[Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis in aggressive periodontitis in Morocco -- preliminary study]

OBJECTIVE

The microbial eatiology of aggressive perodontitis is different worldwidly. The purpose of this study was to determine the presence or absence of two anaerobic, highly pathogenic bacteria, Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis (P.g) in aggressive periodontitis in a Moroccan population.

MATERIAL AND METHODS

Our study involved a sample of 32 subjects, 20 with aggressive periodontitis and 12 with a healthy periodontium. A pool of bacterial samples was performed in each patient looking for Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis by the method of bacterial culture.

RESULTS AND CONCLUSION

Microbiological analysis showed an association of the presence of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis with aggressive periodontitis in Morocco. Porphyromonas gingivalis would be less present than Aggregatibacter actinomycetemcomitans in aggressive periodontitis in Morocco (30% vs 83%)(p < or = 0.05%). However, given the small sample size other studies are necessary.

[Relevance and diagnostics of selected bacterial pathogens of poultry]

This paper provides an overview of diseases caused by Bordetella avium, Gallibacterium anatis, Ornithobacterium rhinotracheale, Riemerella anatipestifer and Enterococcus cecorum in poultry flocks. These bacterial species are almost exclusively found in birds. Their identification with biochemical methods is described and alternative molecular biological methods are discussed.

Fatal meningitis in a calf caused by Mannheimia varigena

Mannheimia varigena was identified as the etiologic agent of meningitis in a young Belgian White Blue heifer calf. Species identification of the bacterium was done by phenotyping and molecularly confirmed by tDNA-PCR. Standard bacteriological examination might fail to differentiate species belonging to the genus Mannheimia.

Bacterial meningitis and encephalitis in ruminants

The clinical aspects of bacterial meningitis in neonates are described in this article. Specific types of meningitis affecting adult cattle are also described. Other conditions occurring less frequently,such as frontal sinusitis and brain abscess, are discussed.

Detection of Gallibacterium spp. in chickens by fluorescent 16S rRNA in situ hybridization

Gallibacterium has recently been included as a new genus of the family Pasteurellaceae Pohl 1981, which encompasses bacteria previously reported as Pasteurella anatis, "Actinobacillus salpingitidis," and avian Pasteurella haemolytica-like organisms. So far, identification has exclusively relied on phenotypic characterization. We present a method based on a cyanine dye 3.18-labeled in situ hybridization probe targeting 16S rRNA to allow specific detection of bacteria belonging to the genus Gallibacterium. The probe, GAN850, showed no cross-reactivity to 25 other poultry-associated bacterial species, including members of the families Pasteurellaceae, Enterobacteriaceae, and Flavobacteriaceae, when cross-reactivities were evaluated by whole-cell hybridization. The probe was further evaluated by hybridization to formalin-fixed spleen and liver tissues from experimentally infected chickens, in which it proved to be useful for the detection of Gallibacterium. Additionally, determination of the spatial distribution and the host cell affiliation of Gallibacterium at various times during the infection process was possible. In conclusion, the in situ hybridization technique described may be of use as a diagnostic tool as well as for studies to elucidate the pathogenesis of Gallibacterium infections in chickens.

An enzyme-linked immunosorbent assay (ELISA) for monitoring rodent colonies for Pasteurella pneumotropica antibodies

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of Pasteurella pneumotropica antibodies in the sera of rats, mice, hamsters and Mastomys. P. pneumotropica from mice and rats showed cross-reactivity. The ELISA using P. pneumotropica NCTC 8284 detected more infected animals than selective culture in groups of rodents from which P. pneumotropica, Haemophilus sp and/or Actinobacillus sp were cultured. Cross reactivity between P. pneumotropica NCTC 8284 and haemophilus and actinobacillus isolates were not studied.

Development and evaluation of PCR test for detection of Taylorella equigenitalis

A PCR for the detection of Taylorella equigenitalis, the causative agent of contagious equine metritis, was developed and evaluated. A genus-specific primer-probe set was derived from the 16S ribosomal DNA sequences. The PCR was specific and amplified a 585-bp product from all 64 available T. equigenitalis isolates. This PCR product hybridized with a specific probe in a dot spot assay. A variety of microorganisms from the genital tracts of horses or with a close phylogenetic relationship to T. equigenitalis did not yield a visible PCR product and were all negative in the dot spot hybridization assay. The results of the PCR assay were compared with those of culture by using 191 genital swabs from horses of several breeds. We demonstrate that the sensitivity of the PCR assay is superior to that of culture. The assay is most sensitive when DNA from culture plates incubated for at least 2 days is used. Of the tested samples, 1.5% were positive in the culture assay, whereas 35% were positive in the culture PCR assay. PCR-positive samples were obtained from all breeds tested. This means that many T. equigenitalis-carrying horses go unidentified by the current culturing technique. This affects current views about the spread and control of T. equigenitalis.