Bacteraemia with Leptotrichia buccalis: report of a case and review of the literature

Microbiota populations in supragingival plaque, subgingival plaque, and saliva habitats of adult dogs

Background

Oral diseases are common in dogs, with microbiota playing a prominent role in the disease process. Oral cavity habitats harbor unique microbiota populations that have relevance to health and disease. Despite their importance, the canine oral cavity microbial habitats have been poorly studied. The objectives of this study were to (1) characterize the oral microbiota of different habitats of dogs and (2) correlate oral health scores with bacterial taxa and identify what sites may be good options for understanding the role of microbiota in oral diseases. We used next-generation sequencing to characterize the salivary (SAL), subgingival (SUB), and supragingival (SUP) microbial habitats of 26 healthy adult female Beagle dogs (4.0 ± 1.2 year old) and identify taxa associated with periodontal disease indices.

Results

Bacterial species richness was highest for SAL, moderate for SUB, and lowest for SUP samples (p < 0.001). Unweighted and weighted principal coordinates plots showed clustering by habitat, with SAL and SUP samples being the most different from one another. Bacteroidetes, Proteobacteria, Firmicutes, Fusobacteria, Actinobacteria, and Spirochaetes were the predominant phyla in all habitats. Paludibacter, Filifactor, Peptostreptococcus, Fusibacter, Anaerovorax, Fusobacterium, Leptotrichia, Desulfomicrobium, and TG5 were enriched in SUB samples, while Actinomyces, Corynebacterium, Leucobacter, Euzebya, Capnocytophaga, Bergeyella, Lautropia, Lampropedia, Desulfobulbus, Enhydrobacter, and Moraxella were enriched in SUP samples. Prevotella, SHD-231, Helcococcus, Treponema, and Acholeplasma were enriched in SAL samples. p-75-a5, Arcobacter, and Pasteurella were diminished in SUB samples. Porphyromonas, Peptococcus, Parvimonas, and Campylobacter were diminished in SUP samples, while Tannerella, Proteocalla, Schwartzia, and Neisseria were diminished in SAL samples. Actinomyces, Corynebacterium, Capnocytophaga, Leptotrichia, and Neisseria were associated with higher oral health scores (worsened health) in plaque samples.

Conclusions

Our results demonstrate the differences that exist among canine salivary, subgingival plaque and supragingival plaque habitats. Salivary samples do not require sedation and are easy to collect, but do not accurately represent the plaque populations that are most important to oral disease. Plaque Actinomyces, Corynebacterium, Capnocytophaga, Leptotrichia, and Neisseria were associated with higher (worse) oral health scores. Future studies analyzing samples from progressive disease stages are needed to validate these results and understand the role of bacteria in periodontal disease development.

A cavitary pneumonia caused by leptotrichia species in an immunocompetent patient

Leptotrichia species (LS) is an anaerobic Gram negative bacillus in the Bacteroidaceae family and part of the normal human oral flora. It is rarely pathogenic, but occasionally causes diseases in immunocompromised hosts. I am reporting a case of cavitary pneumonia caused by LS in an immunocompetent host.

Leptotrichia buccalis: A rare cause of bacteraemia in non-neutropenic patients

The anaerobic bacterium, Leptotrichia buccalis (Lb), belongs to the normal oral flora of humans and is seldom found in clinically significant specimens. However, on rare occasions, Lb has been isolated from blood cultures from patients with lesions of the oral mucosa, in particular from patients with neutropenia. Over a period of 6 months, Lb was isolated from blood cultures in our laboratory from 2 immunocompetent patients. The identification characteristics of Lb are described including the typical morphology at microscopy. Furthermore, we review the bacteraemic cases reported so far together with present knowledge of the pathogenicity and epidemiology of Lb.

Severe pneumonia with Leptotrichia sp. detected predominantly in bronchoalveolar lavage fluid by use of 16S rRNA gene sequencing analysis

We present the first case of severe pneumonia possibly caused by Leptotrichia species with oral bacteria. This was found in a healthy but elderly subject whose bronchoalveolar lavage fluid was analyzed by 16S rRNA gene sequencing analysis. The combination of this method and microscopic observation provided useful information for diagnosis and treatment.

Leptotrichia species in human infections

Leptotrichia species typically colonize the oral cavity and genitourinary tract. These anaerobic bacteria belong to the normal flora of humans and are seldom found in clinically significant specimens. However, on rare occasions, Leptotrichia has been isolated from blood cultures of patients with lesions in the oral mucosa, in particular from patients with neutropenia. These organisms should be considered potential pathogens in neutropenic patients, especially when breaks in the mucosal barriers are present through which they frequently spread to the bloodstream. Leptotrichia has also been recovered from immunocompetent persons, e.g. patients with endocarditis. Although their role in infections remains elusive and not much is known, they have been suggested as emerging pathogens. The present review deals with taxonomy, diagnosis, clinical importance, pathogenesis, host defence, infection control, and spectrum of Leptotrichia infections, and ends with a few typical case reports. Currently, six species have been validly published, but a number of yet uncultivable species exist. Molecular methods recovering uncultivable species should be used to get a real idea of their role as pathogens.

Leptotrichia buccalis bacteremia in two patients with acute myelogenous leukemia

Leptotrichia buccalis is rarely implicated in systemic disease. We report two patients with clinically significant L. buccalis bacteremia which developed during the neutropenia secondary to chemotherapy. Based upon our experience, L. buccalis bacteremia should be considered in certain high-risk immunocompromised patients with mucositis and/or gingivitis.

Peripartum bacteremias due to Leptotrichia amnionii and Sneathia sanguinegens, rare causes of fever during and after delivery

We report three cases of delivery and postpartum bacteremia due to unusual anaerobic bacteria in healthy young women. Leptotrichia amnionii bacteremia occurred during delivery in two mothers and was associated with fetal distress during labor. Conversely, Sneathia sanguinegens bacteremia occurred postpartum, 2 days after delivery, without consequence for the neonate.

Genetic diversity of Leptotrichia and description of Leptotrichia goodfellowii sp. nov., Leptotrichia hofstadii sp. nov., Leptotrichia shahii sp. nov. and Leptotrichia wadei sp. nov

Sixty strains of Gram-negative, anaerobic, rod-shaped bacteria from human sources initially assigned to Leptotrichia buccalis (n=58) and 'Leptotrichia pseudobuccalis' (n=2) have been subjected to polyphasic taxonomy. Full-length 16S rDNA sequencing, DNA-DNA hybridization, RAPD, SDS-PAGE of whole-cell proteins, cellular fatty acid analysis and enzymic/biochemical tests supported the establishment of four novel Leptotrichia species from this collection, Leptotrichia goodfellowii sp. nov. (type strain LB 57(T)=CCUG 32286(T)=CIP 107915(T)), Leptotrichia hofstadii sp. nov. (type strain LB 23(T)=CCUG 47504(T)=CIP 107917(T)), Leptotrichia shahii sp. nov. (type strain LB 37(T)=CCUG 47503(T)=CIP 107916(T)) and Leptotrichia wadei sp. nov. (type strain LB 16(T)=CCUG 47505(T)=CIP 107918(T)). Light and electron microscopy showed that the four novel species were Gram-negative, non-spore-forming and non-motile rods. L. goodfellowii produced arginine dihydrolase, beta-galactosidase, N-acetyl-beta-glucosaminidase, arginine arylamidase, leucine arylamidase and histidine arylamidase. L. shahii produced alpha-arabinosidase. L. buccalis and L. goodfellowii fermented mannose and were beta-galactosidase-6-phosphate positive. L. goodfellowii, L. hofstadii and L. wadei were beta-haemolytic. L. buccalis fermented raffinose. With L. buccalis, L. goodfellowii showed 3.8-5.5 % DNA-DNA relatedness, L. shahii showed 24.5-34.1 % relatedness, L. hofstadii showed 27.3-36.3 % relatedness and L. wadei showed 24.1-35.9 % relatedness. 16S rDNA sequencing demonstrated that L. hofstadii, L. shahii, L. wadei and L. goodfellowii each formed individual clusters with 97, 96, 94 and 92 % similarity, respectively, to L. buccalis.

Septic arthritis caused by a gram-negative bacterium representing a new species related to the Bordetella-Alcaligenes complex

A knee-joint exudate culture yielded on two occasions a gram-negative bacterium. Regular methods for speciation did not provide an identification. The infection was successfully treated with ciprofloxacin. The unknown isolate, CCUG 36768, was subjected to further investigation, including 16S rDNA sequencing, protein profiling, cellular fatty acid analysis, and various biochemical tests, in order to produce a species identification. The 1469 bp-long 16S rDNA sequence did not reveal identity with any known species sequence. CCUG 36768 clustered in a group of species, including Alcaligenes defragrans, Denitrobacter permanens, Taylorella equigenitalis, Alcaligenes faecalis, and four strains of Alcaligenes species without a specific species name. Bordetella species also showed a high degree of similarity with CCUG 36768. Protein profiling, cellular fatty acid analysis and computer-assisted analysis of biochemical profiles indicated similarity with Bordetella-Alcaligenes species, often close to B. holmesii and B. avium. API 20 NE indicated the profile of Moraxella species of poor identity. It is concluded that CCUG 36768 represents a new bacterial species of pathogenic potential in humans. It is related to the Bordetella-Alcaligenes group. Powerful new methods for speciation are available and it is recommended that unknown isolates from normally sterile sites be submitted for further analysis. Several isolates are required for the definition of new species.