Methicillin-Resistant Staphylococcus aureus: Comparison of Susceptibility Testing Methods and Analysis of mecA-Positive Susceptible Strains

Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for an increasing number of serious nosocomial and community-acquired infections. Phenotypic heterogeneous drug resistance (heteroresistance) to antistaphylococcal beta-lactams affects the results of susceptibility testing. The present study compared the MRSA-Screen latex agglutination test (Denka Seiken Co., Ltd., Tokyo, Japan) for detection of PBP 2a with agar dilution, the VITEK-1 and VITEK-2 systems (bioMérieux, St. Louis, Mo.), and the oxacillin agar screen test for detection of MRSA, with PCR for the mecA gene used as the "gold standard" assay. Analysis of 107 methicillin-susceptible S. aureus (MSSA) isolates and 203 MRSA isolates revealed that the MRSA-Screen latex agglutination test is superior to any single phenotype-based susceptibility testing method, with a sensitivity of 100% and a specificity of 99.1%. Only one isolate that lacked mecA was weakly positive by the MRSA-Screen latex agglutination test. This isolate was phenotypically susceptible to oxacillin and did not contain the mecA gene by Southern blot hybridization. The oxacillin agar screen test, the VITEK-1 system, the VITEK-2 system, and agar dilution showed sensitivities of 99.0, 99.0, 99.5, and 99%, respectively, and specificities of 98.1, 100, 97.2, and 100%, respectively. The differences in sensitivity or specificity were not statistically significant. Oxacillin bactericidal assays showed that mecA- and PBP 2a-positive S. aureus isolates that are susceptible to antistaphylococcal beta-lactams by conventional methods are functionally resistant to oxacillin. We conclude that the accuracy of the MRSA-Screen latex agglutination method for detection of PBP 2a approaches the accuracy of PCR and is more accurate than any susceptibility testing method used alone for the detection of MRSA.     

Mucosal bromodomain-containing protein 4 mediates aeroallergen-induced inflammation and remodeling

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Biodegradation study of crop residues as affected by exogenous inorganic nitrogen and fungal inoculants

The comparative decomposition of chickpea residue, and chopped and unchopped wheat straw was investigated in pits for 120 days. Microbial biomass, humus, C/N ratio, pH, Electrical conductivity (EC), dehydrogenase, alkaline phosphatase, cellulase, xylanase, total phenol and soluble protein were determined to assess their response to the addition of inorganic nitrogen and mixed fungal inoculum of Aspergillus nidulans, Phanerochaete chrysosporium and Trichoderma viride. The evaluation of physico-chemical parameters (organic matter, organic carbon, N, C/N, pH, EC, microbial biomass) revealed that by supplementing unchopped wheat straw with 1% urea and mixed fungal inoculum, a lowest C/N ratio of 10.7, lowest biomass of 9.54 and highest humus content of 13% can be achieved within 3 months. Germination of Lepidium sativum (cress seeds) showed a germination index >60%, in this treatment. The enzyme assay for dehydrogenase indicated highest microbial activity in uninoculated treatments compared to fungal inoculated counterparts, in the second month sampling (active phase of composting). However, cellulase and xylanase activity showed an upward trend during curing phase of composting. Chickpea residue compost, though resulted in a C/N ratio of 17.3, but its germination index was less than 60%. The rapid quality tests conducted for H2S, NH3, NO3 and starch confirmed the stability and maturity of finished compost prepared from wheat straw through microbial inoculants.     

Anticoagulation for coexisting bioprosthetic aortic valve thrombosis and anticoagulant-related bleeding: “A double edge sword”

The choice of anticoagulant agents for newly implanted bioprosthetic valve varies significantly, particularly in the presence of postoperative atrial fibrillation with increasing use of nonvitamin K oral anticoagulation (NOACs) in recent years. We reported a challenging case with a coexisting bioprosthetic aortic valve thrombosis and significant anticoagulant-related bleeding. Clinical management strategy and brief literature review were presented.     

Spontaneous bacterial peritonitis in the Czech Republic

The objective of the study was to assess the prevalence and more detailed data pertaining to the incidence of spontaneous bacterial peritonitis (SBP) in the Czech Republic. The authors examined 99 patients with cirrhosis of the liver and ascites. SBP was diagnosed in a high percentage--35 patients, i.e. 35.4%. It was found more frequently in patients with an alcoholic etiology of cirrhosis who had a history of subfebrile and febrile temperatures and increasing trend of ascites. For the diagnosis the increase of leucocytes in serum and C reactive protein levels may prove useful. Lower values of total protein and albumin in ascites predispose to the development of this infection. Reduction of the number of thrombocytes in the group of patients with SBP indicates the influence of portal hypertension in the etiology of this disease.     

Epidemiology of sporadic bloody diarrhea in rural Western Kenya

We conducted laboratory-based surveillance and a case-control study to characterize the epidemiology of bloody diarrhea in rural Western Kenya. From May 1997 through April 2001, we collected stool from 451 persons with bloody diarrhea presenting to four rural clinics. Cultures of 231 (51%) specimens yielded 247 bacterial pathogens: 198 Shigella (97 S. flexneri, 41 S. dysenteriae type 1, 39 S. dysenteriae type non-1, 13 S. boydii, 8 S. sonnei), 33 Campylobacter, 15 non-typhoidal Salmonella, and 1 Vibrio cholerae O1. More than 90% of the isolates (excluding Campylobacter) were resistant to trimethoprim-sulfamethoxazole and tetracycline, and more than 80% were resistant to ampicillin. Most (74%) ill persons received medication to which their isolate was resistant. Drinking Lake Victoria water and sharing latrines between multiple households increased risk of bloody diarrhea. Washing hands after defecating was protective. Providing safe drinking water and more latrines, and promoting hand washing could reduce the burden of illness from bloody diarrhea while limiting injudicious antimicrobial use.