[Redo Mitral Valve Replacement for Prosthetic Valve Endocarditis in a Patient with End Stage Colon Cancer:Report of a Case].

Prosthetic valve endocarditis (PVE) is rare but devastating. A 69-year old man admitted for active endocarditis caused by Streptococcus pasteurianus. Antibiotic therapy was started, but the patient developed bowel obstruction owing to cancer with multiple liver metastases, and underwent transverse colectomy. Following colectomy, antibiotic agent was given continued for 4 weeks after and mitral valve replacement( MVR) using a bioprosthesis was performed. Oral antibiotic therapy was continued for six months after MVR to avoid infection recurrence. One year after MVR, the size of multiple liver metastases increased despite oral anticancer drugs administration. A totally implantable central venous access port( CV port) was placed and intravenous chemotherapy was started for progressive metastatic colorectal cancer. But the CV port was removed due to device infection caused by multiple drug resistant Staphyrococcus lugdunensis one month later, but the patient developed prosthetic valve endocarditits( PVE) due to the same bacterium, that caused valve stenosis. Redo MVR was indicated because of progressive dyspnea and uncontrollable fever. The patient was discharged one month after redo MVR, but suffered carcinomatous peritonitis, and eventually died eight months post-discharge. Chemotherapy needs caution because of potential risk of PVE in patients with prosthetic valves, especially for those with a history of infectious endocarditis.

Staphylococcus aureus MazG hydrolyzes oxidized guanine nucleotides and contributes to oxidative stress resistance.

We previously reported that knockout of the mazG (SA1292) gene decreases Staphylococcus aureus killing activity against silkworms. S. aureus MazG (SaMazG) has a nucleotide pyrophosphatase domain conserved among MazG family proteins, but its biochemical characteristics are unknown. In the present study, we purified recombinant N-terminal His-tagged SaMazG protein and examined its biochemical activity. SaMazG hydrolyzed GTP, UTP, dGTP, and TTP into nucleoside monophosphates. Hydrolytic activity of SaMazG against ATP, CTP, dATP, and dCTP was low or not detected. SaMazG exhibited high hydrolytic activity against 8-oxo-GTP and 8-oxo-dGTP, oxidized guanine nucleotides, with a Vmax/Km ratio more than 15-fold that of GTP. Furthermore, the S. aureus mazG knockout mutant was sensitive to hydrogen peroxide compared with the parent strain. These results suggest that SaMazG is a nucleotide pyrophosphatase hydrolyzing oxidized guanine nucleotides that contributes to the oxidative stress resistance of S. aureus.

Antibiotic-producing bacteria from stag beetle mycangia.

The search for new antibiotics or antifungal agents is crucial for the chemotherapies of infectious diseases. The limited resource of soil bacteria makes it difficult to discover such new drug candidate. We, therefore, focused on another bacterial resource than soil bacteria, the microbial flora of insect species. In the present study, we isolated 40 strains of bacteria and fungi from the mycangia of three species of stag beetle, Dorcus hopei binodulosus, Dorcus rectus, and Dorcus titanus pilifer. We identified those species with their ribosomal DNA sequences, and revealed that Klebsiella spp. are the most frequent symbiont in the stag beetle mycangia. We examined whether these microorganisms produce antibiotics against a Gram-negative bacterium, Escherichia coli, a Gram-positive bacterium, Staphylococcus aureus, or a fungus, Cryptococcus neoformans. Culture supernatants from 33, 29, or 18 strains showed antimicrobial activity against E. coli, S. aureus, or C. neoformans, respectively. These findings suggest that bacteria present in the mycangia of stag beetles are useful resources for screening novel antibiotics.

Open Reintervention for Aneurysmal Sac Enlargement after EVAR.

We performed a late open reintervention for aneurysmal sac enlargement due to persistent type 2 endoleak (PT2EL) after EVAR for 8 of 286 patients. Surgical techniques are as follows: (1) The entire aneurysmal body was exposed. (2) All the aortic branched vessels were ligated. (3) The aneurysmal sac was opened followed by the performance of complete hemostasis. (4) An equine pericardium was wrapped and sutured to the aneurysmal sac to for reinforcement. This method is considered to be one of the feasible options for the treatment of aneurysmal sac re-enlargement after EVAR.