Orthopedic infections caused by obligatory anaerobic Gram-negative rods: report of two cases

Abstract

Anaerobic bone and joint infections are uncommon, although the number of anaerobic infections is presumably underestimated because of difficulties with isolation and identification of obligate anaerobes. This study describes two cases of complicated Bacteroides fragilis peri-implant infection of the lumbar spine, infection of the hip and osteomyelitis. Bacteria were identified with the use of a mass spectrometer, VITEK MS system. Drug susceptibility was performed with the use of E-test. The EUCAST breakpoints were used for interpretation with B. fragilis ATCC 25285 as a control. In the two described cases clinical samples were collected for microbiological examination intraoperatively and simultaneously empirical treatment was applied. B. fragilis was isolated in monoculture or in a combination with other bacteria. The treatment was continued according to the susceptibility tests. In a case one clindamycin failure was observed and clindamycin resistance of the isolate was likely due to inadequate time of therapy. Difficulties in collecting an adequate samples and culturing anaerobic bacteria cause that not all infections are properly recognized. In a successful therapy, identification and determination of the susceptibility of the pathogen are essential as well as an appropriate surgical debridement.

A case of very delayed surgical site infection after instrumented spine surgery

“…In 80-90% of the cases there is a concomitant increases in ESR values at the same time of the low back pain's recurrence. 6 For diagnosis of delayed SSI, often the surgical wound swab is negative. Indeed, microorganisms tend to form an exopolysaccharide matrix (a glycosal matrix) close to the hardware, and they are present with low concentration into the host-matrix interface, where the wound swab is usually done.…”

“…7,8 however are described only few cases of delayed vertebral infections caused by this organism. 5,6 In the literature, the and Propionibacterium acnes. [1][2][3][4] The etiopathogenetic mechanism has not yet been clearly defined, but there are two possibilities: contamination of microorganisms during surgery or in the postoperative period and haematogenous spread.…”

“…The slow growth of bacteriodes may explains the delayed infection of the described case. 5,6 Finally, removal of the hardware in case of delayed SSI could be safe if there are signs of vertebral fusion, so this reduces the risk of pseudoarthrosis and deformity. [1][2][3][4]7,8 In all cases this is the last option after a prolonged target therapy.…”

“…Post-operative surgical site infections (SSI) are serious complications in instrumented spine surgery [1][2][3][4][5][6][7][8] despite the diffusion of minimally invasive techniques. 4 The treatment of delayed SSI remains controversial and, despite the earlyonset SSI, are less frequent.…”

What we actually know about the pathogenicity of Bacteroides pyogenes

“…Nevertheless, anaerobic infections are the most overlooked of all bacterial infections. Of all known anaerobes Bacteroides are the most often isolated from clinical specimens [1][2][3][4]. To date, Bacteroides fragilis is regarded as the most virulent.…”