Dialister pneumosintes Associated with Human Brain Abscesses

Abstract

In this report, we review two cases of brain infection due to Dialister pneumosintes in previously healthy patients. The bacterium was isolated from the first patient by blood culture and directly from a brain abscess in the second patient. In both cases, the infection was suspected to be of nasopharyngeal or dental origin. The patients had favorable outcomes following surgical debridement and antibiotic treatment. After in vitro amplification and partial sequencing of the 16S rRNA gene, two strains were classified as D. pneumosintes. However, traditional biochemical tests were not sufficient to identify the bacteria. In addition to causing periodontal and opportunistic infections, D. pneumosintes, contained in mixed flora, may behave as a clinically important pathogen, especially in the brain. In addition to phenotypic characterization, 16S rRNA partial sequencing was used to identify D. pneumosintes definitively. CASE REPORTSCase 1. A 17-year-old man was admitted to Strasbourg University Hospital for fever and dysphagia that had evolved over 1 week. Prior to admission, he had received amoxicillin and then clarithromycin. On physical examination, he presented with a high fever (40°C), right temporal headache, paralysis of the left arm, and swelling of the submandibular lymph nodes. Laboratory investigations revealed an inflammatory syndrome with a C-reactive protein level measuring 118 mg/liter and a leukocyte count of 13.3 ϫ 10 9 cells/liter. Standard cerebrospinal fluid analysis as well as aerobic and anaerobic cultures did not reveal any abnormalities. Two aerobic and anaerobic blood cultures (BACTEC Plus Aerobic/F and BACTEC Plus Anaerobic/F; BD, Pont-de-Claix, France) were performed upon admission.A brain computerized tomography (CT) scan revealed a subdural empyema compressing the right frontal lobe. Arteriography of the cerebral vessels revealed possible thrombophlebitis of the longitudinal median sinus. Antimicrobial treatment with cefotaxime at 12 g/day, metronidazole at 1.5 g/day, and acyclovir at 2.4 g/day was started. The general condition of the patient rapidly worsened, leading to sepsis and aggravation of his neurologic symptoms. On the second day after admission, a right frontal craniotomy was performed. A subdural empyema was evacuated and the frontal sinuses were drained. Thiamphenicol (750 mg) was injected into the operative cavity. Postsurgical treatment consisted of metronidazole, cefotaxime, ofloxacin, carbamazepine, and heparin.Gram staining of the empyema revealed numerous polymorphonuclear cells and small gram-negative rods. Rare colonies of Streptococcus anginosus grew on chocolate agar under aerobic conditions and also on blood agar supplemented with hemin and vitamin K 1 under anaerobic conditions. Rare colonies of S. anginosus and coagulase-negative Staphylococcus were isolated from the frontal sinus sample. On the fourth day of hospitalization, Dialister pneumosintes (IBS 708/99) was obtained from one of the blood cultures done on the day of admission. All other blood cultures done...

Microbiology of Odontogenic Bacteremia: beyond Endocarditis

“…Arguably, these lesions could serve as the primary infective focus for the dissemination and subsequent seeding of bacteria into an end organ site. For a majority of episodes, the absence of other detectable infective foci led researchers to conclude that the oral cavity, by default, is the primary source of infection (57,61,63,67,86,88,114,126,139). However, these studies, mainly case reports, suggest a relationship between pyogenic CNS infections and an oral origin of bacteria such as Abiotrophia spp., Dalister pneumosintes, Streptococcus intermedius, S. oralis, Streptococcus constellatus, Fusobacterium spp., F. nucleatum, Aggregatibacter actinomycetemcomitans, and Porphyromonas gingivalis (57,61,63,67,86,88,114,126,139).…”

Antimicrobial Susceptibilities and Clinical Sources ofDialisterSpecies

“…More rarely, D. pneumosintes has been isolated from bite wound infections, during respiratory tract and head and neck infections (7,9), from amniotic fluid and placenta samples (6), in human brain abscesses (18), and during bacteremia (12,18). D. invisus has also been identified in urinary tract specimens from renal transplant recipients (4).…”

“…has been greatly improved by culture-independent studies, mainly focused on oral flora (2,(15)(16)(17)19), comprehensive microbiological information on Dialister spp. remains relatively scarce and antimicrobial susceptibility data are available for only a few isolates (8,18).…”

<i>Dialister pneumosintes</i> Bacteremia Caused by Dental Caries and Sinusitis

“…Lepargneur et al reported D. pneumosintes bacteremia in a young woman with suppurative thrombosis of the ovarian veins. In addition, Rousee et al described two cases of central nervous system infection caused by D. pneumosintes (19). The first case involved a young man with a subdural abscess adjacent to the right frontal lobe in whom D. pneumosintes infection was diagnosed on a blood culture.…”