Severe knee arthritis due to Eikenella corrodens following a human bite

Postoperative septic arthritis with Eikenella corrodens and Streptococcus mitis following arthroscopic anterior cruciate ligament reconstruction in an adolescent: A case report and review of the literature

We present a case of postoperative septic arthritis with Eikenella corrodens and Streptococcus mitis following an arthroscopic anterior cruciate ligament reconstruction in an adolescent male with no pertinent medical history. The patient presented to the emergency department nine days after the operation with fever, an elevated white blood cell count, knee pain, and effusion. Arthrocentesis of the knee yielded purulent fluid that tested positive for S. mitis. Repeat intraoperative cultures revealed E. corrodens. In addition to antibiotics, the patient's treatment course included arthroscopic irrigation and debridement in the operating room as well as removal of graft material and fixation devices. To our knowledge, this is the first case of a polymicrobial infection of E. corrodens and S. mitis causing septic arthritis in a teenager following arthroscopic anterior cruciate ligament reconstruction.

"Fight-bite": not just a hand problem

Human bite wounds around the knee are rarely seen, yet may require the same urgent attention as a fight bite to the hand. Two cases of polymicrobial septic arthritis of the knee secondary to a human bite wound are described. In both the cases, the diagnosis of the septic arthritis was delayed because the intra-articular wound was unrecognized. The injuries were initially deemed superficial and managed with local wound care. In each case, the knee was flexed at the time of injury and the quadriceps tendon was penetrated by a tooth which inoculated the knee joint. Septic arthritis of the knee presented, in both cases, 72 hours after the injury. These infections proved challenging to treat and required multiple surgeries and prolonged antibiotic therapy. The "fight bite" phenomenon of the hand is widely recognized and the same phenomenon can occur at the knee.

Antibiotic resistances of starter and probiotic strains of lactic acid bacteria

The antibiotic resistances of 45 lactic acid bacteria strains belonging to the genera Lactobacillus, Streptococcus, Lactococcus, Pediococcus, and Leuconostoc were investigated. The objective was to determine antibiotic resistances and to verify these at the genetic level, as is currently suggested by the European "qualified presumption of safety" safety evaluation system for industrial starter strains. In addition, we sought to pinpoint possible problems in resistance determinations. Primers were used to PCR amplify genes involved in beta-lactam antibiotic, chloramphenicol, tetracycline, and erythromycin resistance. The presence of ribosomal protection protein genes and the ermB gene was also determined by using a gene probe. Generally, the incidences of erythromycin, chloramphenicol, tetracycline, or beta-lactam resistances in this study were low (<7%). In contrast, aminoglycoside (gentamicin and streptomycin) and ciprofloxacin resistances were higher than 70%, indicating that these may constitute intrinsic resistances. The genetic basis for ciprofloxacin resistance could not be verified, since no mutations typical of quinolone resistances were detected in the quinolone determining regions of the parC and gyrA genes. Some starter strains showed low-level ampicillin, penicillin, chloramphenicol, and tetracycline resistances, but no known resistance genes could be detected. Although some strains possessed the cat gene, none of these were phenotypically resistant to chloramphenicol. Using reverse transcription-PCR, these cat genes were shown to be silent under both inducing and noninducing conditions. Only Lactobacillus salivarius BFE 7441 possessed an ermB gene, which was encoded on the chromosome and which could not be transferred in filter-mating experiments. This study clearly demonstrates problems encountered with resistance testing, in that the breakpoint values are often inadequately identified, resistance genes may be present but silent, and the genetic basis and associated resistance mechanisms toward some antibiotics are still unknown.

Virulence factors of Enterococcus faecalis: relationship to endodontic disease

Enterococcus faecalis is a micro-organism that can survive extreme challenges. Its pathogenicity ranges from life-threatening diseases in compromised individuals to less severe conditions, such as infection of obturated root canals with chronic apical periodontitis. In the latter situation, the infecting organisms are partly shielded from the defense mechanisms of the body. In this article, we review the virulence factors of E. faecalis that may be related to endodontic infection and the periradicular inflammatory response. The most-cited virulence factors are aggregation substance, surface adhesins, sex pheromones, lipoteichoic acid, extracellular superoxide production, the lytic enzymes gelatinase and hyaluronidase, and the toxin cytolysin. Each of them may be associated with various stages of an endodontic infection as well as with periapical inflammation. While some products of the bacterium may be directly linked to damage of the periradicular tissues, a large part of the tissue damage is probably mediated by the host response to the bacterium and its products.

Activity and diffusion of tigecycline (GAR-936) in experimental enterococcal endocarditis

The activity of tigecycline (GAR-936), a novel glycylcycline, was investigated in vitro and in experimental endocarditis due to the susceptible Enterococcus faecalis JH2-2 strain, its VanA type transconjugant BM4316, and a clinical VanA type strain, E. faecium HB217 resistant to tetracycline. MICs of GAR-936 were 0.06 micro g/ml for the three strains. In vitro pharmacodynamic studies demonstrated a bacteriostatic effect of GAR-936 that was not enhanced by increasing concentrations to more than 1 micro g/ml and a postantibiotic effect ranging from 1 to 4.5 h for concentrations of 1- to 20-fold the MIC. Intravenous injection of [(14)C]GAR-936 to five rabbits with enterococcal endocarditis sacrificed 30 min, 4 h, or 12 h after the end of the infusion evidenced a lower clearance of GAR-936 from aortic vegetations than from serum and a homogeneous diffusion of GAR-936 into the vegetations. In rabbits with endocarditis, GAR-936 (14 mg/kg of body weight twice a day [b.i.d.]) given intravenously for 5 days was bacteriostatic against both strains of E. faecalis. Against E. faecium HB217, bacterial counts in vegetations significantly decreased during therapy (P < 0.01), and the effect was similar with GAR-936 at 14 mg/kg b.i.d., 14 mg/kg once a day (o.d.), and 7 mg/kg o.d., which provided concentrations in serum constantly above the MIC. Mean serum elimination half-life ranged from 3.3 to 3.6 h. No GAR-936-resistant mutants were selected in vivo with any regimen. We concluded that the combination of prolonged half-life, significant postantibiotic effect, and good and homogeneous diffusion into the vegetations may account for the in vivo activity of GAR-936 against enterococci susceptible or resistant to glycopeptides and tetracyclines, even when using a o.d. regimen in rabbits.

Anomalous role of tumor necrosis factor alpha in experimental enterococcal infection

The murine D-galactosamine (D-gal) model of tumor necrosis factor alpha (TNF-alpha) hypersensitization was used as an initial tool to investigate the potential contribution of TNF-alpha to lethal intraperitoneal (i.p.) infection with Enterococcus faecalis. D-gal sensitized mice to lethal E. faecalis infection, whereas dexamethasone and neutralizing anti-TNF-alpha antibody protected D-gal-treated, E. faecalis-infected mice, implicating TNF-alpha in the lethal response to E. faecalis infection in D-gal-treated mice. Circulating TNF-alpha was undetectable for at least 8 h following i.p. E. faecalis infection, although low peritoneal levels of TNF-alpha were detected within 3 h, suggesting that localized TNF-alpha production contributed to the lethal response to E. faecalis infection in D-gal-treated mice. Although i.p. E. faecalis infection failed to induce a detectable systemic TNF-alpha response, circulating Interleukin-6 (IL-6) was detected within 3 h of infection. IL-6 was also detected in the peritoneum within an hour of infection, prior to the appearance of peritoneal TNF-alpha. In striking contrast to in vivo results, E. faecalis induced a potent and rapid TNF-alpha response from both mouse peritoneal macrophages and the RAW 264.7 cell line in vitro. This led us to hypothesize that TNF-alpha production in response to E. faecalis infection is suppressed by IL-6 in vivo. In vitro experiments demonstrated a statistically significant, but modest, inhibitory effect of IL-6 on TNF-alpha production by RAW cells stimulated with E. faecalis. Collectively, these data indicate that acute, lethal E. faecalis infection appears to induce an unusual cytokine response that differs in character from that previously described for most other gram-positive and gram-negative bacteria.

Intraspecies genomic groups in Enterococcus faecium and their correlation with origin and pathogenicity

Seventy-eight Enterococcus faecium strains from various sources were characterized by random amplified polymorphic DNA (RAPD)-PCR, amplified fragment length polymorphism (AFLP), and pulsed-field gel electrophoresis (PFGE) analysis of SmaI restriction patterns. Two main genomic groups (I and II) were obtained in both RAPD-PCR and AFLP analyses. DNA-DNA hybridization values between representative strains of both groups demonstrated a mean DNA-DNA reassociation level of 71%. PFGE analysis revealed high genetic strain diversity within the two genomic groups. Only group I contained strains originating from human clinical samples or strains that were vancomycin-resistant or beta-hemolytic. No differentiating phenotypic features between groups I and II were found using the rapid ID 32 STREP system. The two groups could be further subdivided into, respectively, four and three subclusters in both RAPD-PCR and AFLP analyses, and a high correlation was seen between the subclusters generated by these two methods. Subclusters of group I were to some extent correlated with origin, pathogenicity, and bacteriocinogeny of the strains. Host specificity of E. faecium strains was not confirmed.