A Case Report of Trueperella bernardiae Pelvic Osteomyelitis and Sepsis: Literature Review of Trueperella bernardiae Infections

Trueperella bernardiae infections are rare. A handful of case reports mention T. bernardiae as the primary pathogen. Our case mentions its presentation as sepsis. Commonly reported cases include less acute presentation, including bone and joint infections, brain abscess, breast abscess, bacteremia, and urinary tract infection (UTI). None of these cases were presented as sepsis. Literature is limited when it comes to its treatment. We managed our case based on the literature review of the prior case reports. Most strains are susceptible to beta-lactams and vancomycin. It is associated with an excellent prognosis if treated with appropriate antibiotics. This article also provides a brief literature review of current case reports available for T. bernardiae infections.

A 76-year-old man with a medical history significant for prostate cancer status post-prostatectomy in 2018. He had chronic urinary retention with incontinence postoperatively and had chronic foley catheter with intermittent self-catheterization since 2018. Other medical conditions included sleep apnea and recurrent UTIs. He presented to the emergency department with progressive bilateral lower extremity weakness for 3 weeks and lethargy with chills. He reported pain in both lower extremity and pelvis. He specifically had pain during ambulation, especially while changing position. Due to symptoms, he was now unable to ambulate by himself. He denied any urinary or stool incontinence, had no new urinary symptoms, and no numbness in his legs. At baseline, he was an independent male, lived at home in Missouri with his wife, and had no recent trauma or travel. In the emergency department, he was found to be febrile at 39.5°C, tachycardic up to 156 bpm, and blood pressure documented as 80 systolic over 50 diastolic. He was on room air and had a respiratory rate of 12 bpm. On examination he was confused with Glasgow coma scale of 12. He met the sepsis criteria based on quick Sequential Organ Failure Assessment (qSOFA) scoring [21]. On neurological examination, he had a power of 4/5 on left hip flexion and left knee extension on manual muscle test. The rest of the neurological examination was unremarkable. There was pain on palpation of the inner thigh and groin area; perineal sensations were intact, and rectal tone was intact. Laboratory workup on presentation showed white blood count (WBC) of 6.57 × 10⁹/L (3.5–10.5 × 10⁹/L), with 92.6% neutrophils. General chemistry, including electrolytes, creatinine, and liver tests, was normal. Lactic acid was 1.1 mmol/L (0.5–2.2 mmol/L). He had procalcitonin 0.95 ng/mL (0–0.05 ng/mL). Erythrocyte sedimentation rate (ESR) was 112 mm/h (0–20 mm/h) and C-reactive protein (CRP) was 22 (<0.3 mg/dL). Urinalysis showed leukocytes small; nitrites were negative, and bacteria reported as trace, white blood count >30 hpf (0–3 hpf). He was started on intravenous piperacillin/tazobactam 4.5 g every 8 h and intravenous vancomycin 1 g every 12 h, with an initial working diagnosis of sepsis secondary to possible UTI. Two sets of blood cultures were taken from two different peripheral sites. After 48 h of incubation, both samples showed gram-positive rods in blood. Urine culture showed multiple organisms with a concern of contaminant sample. Magnetic resonance imaging (MRI) cervical, thoracic, and lumbar spine without contrast showed multilevel degenerative spine disease and no evidence of cord compression. Magnetic resonance imaging pelvis showed bilateral pelvic septic arthritis associated with adjacent micro-abscesses and bilateral pubic bone osteomyelitis, which explained his lower extremity and pelvic pain (Fig. 1). Later blood cultures were speciated as T. bernardiae with help of matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF). We were not able to obtain sensitivities for T. bernardiae. After blood cultures were reported, piperacillin/tazobactam was discontinued, and intravenous vancomycin was continued. Clinically his confusion improved, and he was neurologically back to baseline. He completed a 6-week course of intravenous vancomycin. He was seen in outpatient infectious disease clinic visit and was noted to have clinical improvement, and his erythrocyte sedimentation rate and CRP also showed significant improvement.

T. bernardiae is a facultative, non-spore-forming, non-motile, anaerobic, gram-positive coryneform coccobacilli. It is catalase and oxidase negative. It has variable hemolytic activity. It was initially named coryneform group 2, later labeled Arcanobacterium bernardiae in 1997, and now classified into the genus Trueperella in 2011 [1, 2]. It is a commensal of human skin flora and oropharynx. However, the literature has also reported the isolation of T. bernardiae in porcine stool [3]. One case report also mentions T. bernardiae infection after significant pig exposure [4]. Interestingly, it has not been considered pathogenic until recently, primarily because of initially being classified as coryneform bacteria, which led to its identification as non-pathogenic commensal. Additionally, because lack of detection or incorrect detection of T. bernardiae in usual culture media made its diagnosis difficult. With the advent of MALDI-TOF mass spectrometry, its identification has been made easier and more efficient [5]. Currently, T. bernardiae infections have been reported in the literature as causing UTIs [6, 7], prosthetic joint infections [8‒10], bacteremia [11‒14], breast abscess [15], brain abscess [16], skin and soft tissue infections/post-surgical infections [11, 14, 17, 18], bone infections excluding prosthetic joint infections [4, 19, 20], and septic thrombophlebitis [13]. Limited case reports are available. Table illustrating a literature review of T. bernardiae infections till date is attached to this case report (Table 1). Infections are more common in immunocompromised populations, especially with a previous history of gastrointestinal and genitourinary malignancy or diabetes mellites. However, infections in immunocompetent hosts have also been documented. There has been no age, gender, or race predilection found in the literature review. Polymicrobial infection with other bacteria is common. Listed coinfection with Staphylococcus aureus, Actinotignum sanguinis, Bacteroides fragilis, Enterococcus avium, Peptoniphilus lacrimalis, Morganella morganii, Peptostreptococcus, Fusobacterium gonidiaformans, and Escherichia coli has been reported [11, 15]. T. bernardiae infection outcomes are favorable and are associated with a cure in all the cases reported in the literature. Of note, this case presented with sepsis, bacteremia, and pelvic joint infection. We hypothesized that due to indwelling foley catheter he might have acquired a UTI and that let him have prostatitis and subsequent pelvis osteomyelitis and septic arthritis. His acute presentation was in the setting of bacteremia which was secondary to his osteomyelitis and pelvis septic arthritis. After the literature review, by searching Arcanobacterium bernardiae and T. bernardiae on PubMed, only six case reports have been found for bone and joint infections, and none of them were associated with sepsis or bacteremia, which makes it the first reported case of T. bernardiae bone and joint infection associated with bacteremia and sepsis. Given the paucity of available literature and case reports, the treatment choice has not been precise. Agents used for treatment have included quinolones, penicillin, cephalosporins, carbapenems, and clindamycin. We did not have susceptibilities for this case, but in view of susceptibility data in literature, vancomycin was chosen for this patient. In the future, with the advent of MALDI-TOF, more data are expected to be documented. The E-test method is the most frequently used method to determine minimum inhibitory concentration [5]. No clinical breakpoints have been determined for T. bernardiae; European Committee on Antimicrobial Susceptibility Testing (EUCAST) and pharmacokinetic and pharmacodynamic (non-species related) clinical breakpoints have been utilized. As per current susceptibility data, resistance has not been much of a concern for T. bernardiae. Resistance to metronidazole, aminoglycosides, and penicillin G, however, has been reported. To conclude, T. bernardiae infections are rare but are now known to have clinical significance. Infections are more commonly seen in immunocompromised hosts with a history of malignancy. Urinary tract remains a common site of primary infection. This case adds another case to the literature regarding T. bernardiae infections and especially highlights the point that they can present with a more serious presentation like sepsis. MALDI-TOF helps in the identification of these rare pathogens. Treatment is associated with a good prognosis. The CARE Checklist has been completed by the authors for this case report, attached as online supplementary material (for all online suppl. material, see https://doi.org/10.1159/000539826).

Ethical approval is not required for this study in accordance with local or national guidelines. Written informed consent was obtained from the patient’s next of kin for publication of the details of their medical case and any accompanying images.

The authors have no conflicts of interest to declare.

No funding required.

Saliha Saleem was directly involved in literature review and wrote the main body of the manuscript and discussion. William Roland did the final review and editing of the case. Abdullah Lodhi assisted in literature review.

All data generated or analyzed during this study are included in this article and its online supplementary material. Further enquiries can be directed to the corresponding author.