Veillonella species are rare causes of serious infections such as meningitis[
2], endocarditis[
3], obstructive pneumonitis[
4], prosthetic joint infection[
5], and bacteremia[
6]. Bacteremia has been reported almost always in association with an underlying infection such as osteomyelitis. There have been seven previous reports of vertebral osteomyelitis[
7‐
13] and one report of foot cellulitis and osteomyelitis in a middle-aged woman associated with sepsis caused by
V. parvula[
14] (Table
1). Our report is considered to be the second report of V
eillonella nonvertebral osteomyelitis associated with bacteremia. Borchardt[
14] reported the first case of nonvertebral osteomyelitis in which a 54-year-old Indian diabetic woman developed foot cellulitis and toe osteomyelitis after attempting to shave a callus on her right foot two months before presentation. The patient recovered completely after excision of the phalanx and metatarsal bones along with four weeks of intravenous penicillin treatment.
V parvula was isolated from the excised tissue and the blood culture. In five of the previously reported clinical infections, the patients were previously healthy and the portal of entry was not identified. Isner-Horobeti[
11] reported on a 27-year-old man with unknown risk factors for infection, who presented with an L4 to L5 spondylodiscitis. The patient was cured after a prolonged course (11 weeks) of intravenous followed by oral penicillin. In another report by Bongaerts[
9]
V. parvula was isolated from the spine (T12 to L1) of a previously healthy 74-year-old man who was treated with six weeks of intravenous penicillin. Similar cases were reported by Hidalgo[
10] and Kishen
et al.[
12] of
Veillonella spondylodiscitis in older patients without any risk factors. The outcome of the patients was favorable after antibiotic treatment alone or combined with surgical management. On the other hand, colonoscopy was considered by Marriott[
7] as a possible source of entry of
V. parvula causing bacteremia and lumbar discitis in a 55-year-old man who had undergone small intestinal and rectal biopsies eight weeks prior to presentation. In another report by Barnhart[
13], postoperative
Veillonella osteomyelitis of the cervical spine was reported from a 31-year-old man who had suffered a cervical fracture at the level of the fourth and fifth cervical vertebrae two months before presentation. The possible source of entry of the organism was thought to be the esophageal perforation that had occurred during surgery.
Veillonella was isolated repeatedly from a retropharyngeal soft tissue abscess, which was drained followed by parenteral penicillin administration for six weeks. The best method for identification of
Veillonella strains at the species level requires direct sequencing of the 16S rRNA gene[
15]. Conventional phenotypic and biochemical testing does not provide adequate discrimination between species. The pathogenic role of these anaerobes has not been established. However, previously published reports demonstrated their role as a true pathogen associated with fatal overwhelming septicemia[
6]. In our case, in which
Veillonella species was isolated in pure culture from blood in a patient with signs of severe diabetic wound infection illustrates the pathogenic role of this microorganism. The strictly anaerobic organism failed to grow from the wound probably due to improper sample collection and transport supportive of anaerobic culture. In addition, the presence of other rapidly growing aerobic organisms as part of the polymicrobial infection might interfere with their recovery from wound infection.
Veillonella is usually vancomycin, tetracycline, aminoglycosides, and ciprofloxacin resistant and infection typically responds well to therapy with penicillin. Other antimicrobial agents to which the organism is usually susceptible
in vitro include cephalosporins, clindamycin, metronidazole, and chloramphenicol. There are no clear treatment recommendations in the literature due to the scarce number of reports on
Veillonella as a pathogen associated with invasive infection. However, the previous few reports showed good response to antibiotics such as penicillin, cephalosporins, chloramphenicol, clindamycin and metronidazole[
16‐
20]. Metronidazole was suggested by Warner
et al.[
16] as an effective drug for the management of serious infections like bacteremia, brain abscess, and meningitis. The isolate from our case showed unusual high minimum inhibitory concentration (MIC) to penicillin (>32μg/ml). However, in a recent study
Veillonella species isolated from the oral cavities of humans demonstrated a high level of resistance to penicillin G (MIC, 2μg/ml)[
21] and reduced susceptibility to ampicillin or amoxicillin. Reports on the management of infections caused by
Veillonella isolates demonstrating high MIC to penicillin is lacking due to limited published studies on the susceptibility of
Veillonella species to different antimicrobial agents, particularly penicillin, and their clinical effectiveness.
Table 1
Previously reported cases of osteomyelitis caused by
Veillonella
1. (This study)
| 49/M |
Veillonella sp. | NR | Diabetes mellitus and diabetic foot | Foot bone (Calcenous) | Imipenem |
| 55/M |
V. parvula
|
V. parvula
| Colonoscopy | Lumbar spine discitis | Ceftriaxone |
| 61/F |
V. parvula
|
V. parvula
| Sjogren’s syndrome, xerostomia- | Thora columbar spine | Ceftriaxone |
| 74/M | NR |
V. parvula
| None | Spine | Penicillin |
| 70/M | NR |
V. parvula
| None | Spine | US |
| 27/M | NR |
Veillonella sp.
| None | Lumbar spondylodiscitis | Amoxicillin |
| 76/F |
Veillonella sp.
|
Veillonella sp.
| None | Lumbar spondylodiscitis and paraspinal space abscesses | Spinal surgery + Cefotaxime/metronidazole |
| 31/M | NR |
Veillonella sp.
| Cervical vertebral fracture/Post cervical spine fusion | Cervical spine and retropharyngeal abscess | Penicillin G + abscess drainage |
| 54/F |
V. parvula
|
V. parvula
| Diabetes mellitus and foot shaving injury | Phalanx and metatarsal bone and cellulitis | Excision of infected bone + penicillin |