Background. The association of the magA gene with the hypermucoviscosity phenotype relevant to the pathogenesis of Klebsiella pneumoniae liver absces

Residents in Taiwan are often exposed to marine microorganisms through seafood and occupational exposure. The number of reported cases of infection attributable to this organism has increased since the first case was reported in 1985. The increasing number of cases may be caused by greater disease activity or improved recognition by clinicians or laboratory workers. We analyze a clinical-case series of 84 patients with V. vulnificus infection from 1995 to 2000 and describe the molecular epidemiologic features of pathogens isolated from these patients. The spectrum of clinical manifestations and outcomes, options of antimicrobial therapy, and virulence mechanisms were investigated. Results of molecular typing of isolates from humans and marine environment in this country had a high genetic divergence among these isolates. Education and measures are needed to prevent this emerging disease.

Research from JAMA Internal Medicine — Prognostic Factors and Antibiotics in Vibrio vulnificus Septicemia

Vibrio vulnificus is a gram-negative, highly invasive bacterium responsible for human opportunistic infections. We studied the antibacterial effects of toluidine blue O (TBO)-mediated photodynamic therapy (PDT) for V. vulnificus wound infections in mice. Fifty-three percent (10 of 19) of mice treated with 100 μg of TBO per ml and exposed to broad-spectrum red light (150 J/cm ² at 80 mW/cm ² ) survived, even though systemic septicemia had been established with a bacterial inoculum 100 times the 50% lethal dose. In vitro, the bacteria were killed after exposure to a lower light dose (100 J/cm ² at 80 mW/cm ² ) in the presence of low-dose TBO (0.1 μg/ml). PDT severely damaged the cell wall and reduced cell motility and virulence. Cell-killing effects were dependent on the TBO concentration and light doses and were mediated partly through the reactive oxygen species generated during the photodynamic reaction. Our study has demonstrated that PDT can cure mice with otherwise fatal V. vulnificus wound infections. These promising results suggest the potential of this regimen as a possible alternative to antibiotics in future clinical applications.

The MICs of six fluoroquinolones as well as minocycline and cefotaxime for 46 clinical isolates of Vibrio vulnificus were determined by the agar dilution method. All the drugs tested had good activities against all isolates, with the MICs at which 90% of the isolates tested were inhibited (MIC ₉₀ s) by five of the fluoroquinolones ranging between 0.03 and 0.06 μg/ml. The MIC ₉₀ of lomefloxacin, on the other hand, was 0.12 μg/ml. Time-kill studies were conducted with these agents and a clinical strain of V. vulnificus , VV5823. When approximately 5 × 10 ⁵ CFU of V. vulnificus /ml was incubated with any one of the above-mentioned six fluoroquinolones at concentrations of two times the MIC, there was an inhibitory effect on V. vulnificus that persisted for more than 48 h with no noted regrowth. The efficacies of the fluoroquinolones were further evaluated in vivo in the mouse model of experimental V. vulnificus infection and compared to the efficacy of a combination therapy using cefotaxime plus minocycline. With an inoculum of 1.5 × 10 ⁷ CFU, 28 (87.5%) of 32 mice in the cefotaxime-minocycline-treated group survived and 29 (91%) of the 32 mice in the moxifloxacin-treated group survived while none of the 32 mice in the control group did. With an inoculum of 3.5 × 10 ⁷ CFU, the difference in survival rates among groups of 15 mice treated with levofloxacin (13 of 15), moxifloxacin (10 of 15), gatifloxacin (10 of 15), sparfloxacin (11 of 15), ciprofloxacin (12 of 15), or lomefloxacin (10 of 15) was not statistically significant while none of the 15 mice treated with saline survived. We concluded that the newer fluoroquinolones as single agents are as effective as the cefotaxime-minocycline combination in inhibiting V. vulnificus both in vitro and in vivo.