Cervical spondylodiscitis with spinal epidural abscess caused by Aggregatibacter aphrophilus

The First Known Case of Liver Abscess Caused by Aggregatibacter aphrophilus in Japan

A 48-year-old man presented with a sustained fever. Abdominal computed tomography revealed multilocular liver abscesses. He underwent percutaneous needle aspiration, yielding straw-colored pus. Gram staining revealed Gram-negative coccobacilli. The organism grew only on chocolate II agar in a 7% carbon dioxide atmosphere. Identification of Aggregatibacter aphrophilus was confirmed using mass spectrometry and 16S rRNA gene sequencing. He was successfully treated with antibiotics. Liver abscess caused by A. aphrophilus is extremely rare. We herein report the first such case in Japan. Even fastidious organisms, such as A. aphrophilus, should be correctly identified using mass spectrometry or 16S rRNA gene sequencing for adequate treatment.

[A case of osteomyelitis caused by mixed infection by Aggregatibacter aphrophilus and Staphylococcus aureus]

A 46-year-old man presented with a 10-day history of progressive weakness and numbness in both his legs. The spinal MRI and abdominal CT revealed discitis of L4/L5 and multiple epidural abscesses. The blood culture tested positive for methicillin sensitive Staphylococcus aureus (MSSA). The Gram stain of sample from abscess drainage showed Gram-positive cocci in clusters and small Gram-negative rods. The Gram-positive cocci in clusters were identified as MSSA using a general culture method and the small Gram-negative rods were identified as Aggregatibacter aphrophilus using a 16s ribosomal RNA sequencing method. The patient was treated four times with surgical abscess drainages and a long course of intravenous antibiotics therapy following which he recovered. No case of mixed infection by A. aphrophilus and S. aureus has been reported in MEDLINE; therefore, our case should be the first case report. Since we confirmed not only Gram-positive cocci in clusters but also Gram-negative rods in the abscess sample, we did not stop the identification procedure at the point when MSSA was identified and finally identified A. aphrophilus with 16s ribosomal RNA sequencing. Especially, in a mixed infection with organisms whose growth speed is different, an organism with slow growth might be missed if the Gram stain of sample were skipped. This case implies the significance of Gram staining as the identification procedure for organisms.

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.

Microbiology and treatment of acute apical abscesses

Acute apical abscess is the most common form of dental abscess and is caused by infection of the root canal of the tooth. It is usually localized intraorally, but in some cases the apical abscess may spread and result in severe complications or even mortality. The reasons why dental root canal infections can become symptomatic and evolve to severe spreading and sometimes life-threatening abscesses remain elusive. Studies using culture and advanced molecular microbiology methods for microbial identification in apical abscesses have demonstrated a multispecies community conspicuously dominated by anaerobic bacteria. Species/phylotypes commonly found in these infections belong to the genera Fusobacterium, Parvimonas, Prevotella, Porphyromonas, Dialister, Streptococcus, and Treponema. Advances in DNA sequencing technologies and computational biology have substantially enhanced the knowledge of the microbiota associated with acute apical abscesses and shed some light on the etiopathogeny of this disease. Species richness and abundance and the resulting network of interactions among community members may affect the collective pathogenicity and contribute to the development of acute infections. Disease modifiers, including transient or permanent host-related factors, may also influence the development and severity of acute abscesses. This review focuses on the current evidence about the etiology and treatment of acute apical abscesses and how the process is influenced by host-related factors and proposes future directions in research, diagnosis, and therapeutic approaches to deal with this disease.

Insidious Onset of Tetraparesis due to Cervical Epidural Abscess from Enterococcus faecalis

We report a case of cervical epidural abscess from Enterococcus faecalis, which caused an insidious onset of tetraparesis. This 53-year-old female with a history of diabetes mellitus and chronic renal failure under hemodialysis presented with pain and progressive weakness of upper and lower extremities without fever. Although a recent MRI she did at the beginning of symptoms showed no significant pathologies, except for a cervical disc herniation and adjacent spinal degeneration, and stenosis that confused the diagnostic procedure, newer imaging with CT and MRI, which was performed due to progression of tetraparesis, revealed the formation of a cervical epidural abscess. Surgical drainage was done after a complete infection workup. The patient showed immediate neurological improvement after surgery. She received antibiotics intravenously for 3 weeks and orally for another 6 weeks. The patient was free from complications 24 months after surgery. A high index of suspicion is most important in making a rapid and correct diagnosis of spinal epidural abscess. The classic clinical triad (fever, local pain, and neurologic deficits) is not sensitive enough for early detection. Continuous clinical, laboratory, and imaging monitoring are of paramount importance. Early diagnosis and surgical intervention could optimize the final functional outcome.

Discitis and epidural abscess after dental extraction in a pediatric patient: a case report

Neck pain is a relatively common pediatric complaint. Most is of benign etiology. We present an unusual case of epidural abscess with associated discitis in the cervical spine of a 12-year-old after a dental extraction. This potentially dangerous complication was diagnosed before neurological complications developed and was successfully treated with antibiotics alone, preventing the need for surgery. An extensive search of the literature has revealed only 5 cases of epidural abscess secondary to dental sepsis, and to the author's knowledge, this is the first reported case in the pediatric population. We present the case and a brief review of the literature on this subject.

Microbiology of odontogenic bacteremia: beyond endocarditis

SUMMARY

The human gingival niche is a unique microbial habitat. In this habitat, biofilm organisms exist in harmony, attached to either enamel or cemental surfaces of the tooth as well as to the crevicular epithelium, subjacent to a rich vascular plexus underneath. Due to this extraordinary anatomical juxtaposition, plaque biofilm bacteria have a ready portal of ingress into the systemic circulation in both health and disease. Yet the frequency, magnitude, and etiology of bacteremias due to oral origin and the consequent end organ infections are not clear and have not recently been evaluated. In this comprehensive review, we address the available literature on triggering events, incidence, and diversity of odontogenic bacteremias. The nature of the infective agents and end organ infections (other than endocarditis) is also described, with an emphasis on the challenge of establishing the link between odontogenic infections and related systemic, focal infections.