COMPARISON OF ETEST AND AGAR DILUTION FOR DETERMINING MINIMUM INHIBITORY CONCENTRATION OF VANCOMYCIN TO HEALTHCARE-ASSOCIATED METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS

ABSTRACTObjectives: To compare agar dilution method and Etest in the determination of minimum inhibitory concentration (MIC) of vancomycin to healthcareassociatedmethicillin-resistantStaphylococcusaureus(HA-MRSA).Methods: A total of 98 non-duplicate strains of HA-MRSA isolated from different clinical specimens were tested for their antibiotic susceptibilitypattern by Kirby-Bauer disk diffusion method and vancomycin MIC by agar dilution method and Etest (BioMerieux, France).Results: Out of 98 strains of HA-MRSA, 94 (95.9%) were vancomycin susceptible (MIC ≤2 µg/ml and 4 (4.1%) were vancomycin intermediate (MIC4 µg/ml) by agar dilution method. By Etest, 53 (54.1%) were vancomycin susceptible, 4 (4.1%) were vancomycin intermediate, and the remaining 41isolates had vancomycin MIC between 2 µg/ml and 4 µg/ml.Conclusion: Etest allows the detection of HA-MRSA strains with intermediate MIC values in addition to traditional dilutions. These properties willhelp in detection of MIC creep and also decision-making in using vancomycin for the treatment of serious infections caused by HA-MRSA.Keyword: Vancomycin, Minimum inhibitory concentration, Etest, Agar dilution

VANCOMYCIN INTERMEDIATE AND VANCOMYCIN RESISTANT STAPHYLOCOCCUS AUREUS – MECHANISMS, CLINICAL SIGNIFICANCE AND DETECTION

Vancomycin is used as the antibiotic of choice for severe infection caused by methicillin resistant Staphylococcus aureus. Increased use of vancomycin and the selective pressure has resulted in the emergence of S.aureus with reduced susceptibility to vancomycin and vancomycin resistant S.aureus. This review summarizes the definition, mechanism, clinical significance and epidemiology of S.aureus with reduced susceptibility to vancomycin. It also discusses laboratory methods for detection and treatment options available for these pathogens

Simulating Root System Development of Short-duration Pigeonpea

Length and weight of pigeonpea roots were measured weekly in different soil layers and compared with estimates obtained from a root simulation model using daily climatic data, soil physico-chemical properties and dry matter allocation to roots. Daily moisture content and temperature at different soil depths were well simulated using sub-routines from the CERES-Maize model. Daily allocation of dry matter to roots was calculated from logistic functions fitted to the growth data for shoots and roots. Although root length and weight tended to be underestimated by the model, regressions between measured and simulated root growth were highly significant so that the model could, with a few modifications, be used to predict root system development

Melioidosis presenting with mediastinal lymphadenopathy masquerading as malignancy: a case report

<p>Abstract</p> <p>Introduction</p> <p>Melioidosis, endemic in Thailand and in the Northern Territory of Australia is an emerging infectious disease in India which can present with varied forms. A case of melioidosis, presenting as a rare anterior mediastinal mass which can masquerade as malignancy or tuberculosis, is described here. With treatment, our patient initially showed an increase in the size of mediastinal node and development of new submandibular node.. To the best of our knowledge, this phenomenon has not been documented in the literature and the same is highlighted in this case report. </p> <p>Case Presentation</p> <p>A 43-year-old Asian man with diabetes presented with fever, loss of appetite, weight loss for one month and painful swelling below his left mandible for five days. An examination revealed an enlarged left submandibular lymph node and bilateral axillary lymph nodes. A chest X-ray showed mediastinal widening. Computed tomography of his thorax showed a lobulated heterogeneously enhancing anterior mediastinal mass encasing the superior vena cava suggestive of malignancy. An excision biopsy of the lymph node showed granulomas suggestive of tuberculosis but bone marrow culture and lymph node aspirate culture grew <it>Burkholderia pseudomallei</it>. He was treated with parenteral ceftazidime and amoxicillin-clavulanic acid. During the course of treatment, he developed an enlargement of the submandibular lymph node on the opposite side. It gradually subsided with the continuation of therapy orally with a combination of cotrimoxazole and doxycycline for six months. A repeat computed tomography chest scan showed resolution of the mediastinal mass.</p> <p>Conclusion</p> <p>Melioidosis can present as a mediastinal mass that mimics tuberculosis or malignancy. During the initial phase of treatment of melioidosis, the appearance of new lymph nodes or an increase in the size of the existing lymph nodes does not mean treatment failure. Inexperienced clinicians may consider this as treatment failure and may switch treatment. To the best of our knowledge, this is the first report documenting this phenomenon in melioidosis cases.</p

Within-Host Evolution of Burkholderia pseudomallei in Four Cases of Acute Melioidosis

Little is currently known about bacterial pathogen evolution and adaptation within the host during acute infection. Previous studies of Burkholderia pseudomallei, the etiologic agent of melioidosis, have shown that this opportunistic pathogen mutates rapidly both in vitro and in vivo at tandemly repeated loci, making this organism a relevant model for studying short-term evolution. In the current study, B. pseudomallei isolates cultured from multiple body sites from four Thai patients with disseminated melioidosis were subjected to fine-scale genotyping using multilocus variable-number tandem repeat analysis (MLVA). In order to understand and model the in vivo variable-number tandem repeat (VNTR) mutational process, we characterized the patterns and rates of mutations in vitro through parallel serial passage experiments of B. pseudomallei. Despite the short period of infection, substantial divergence from the putative founder genotype was observed in all four melioidosis cases. This study presents a paradigm for examining bacterial evolution over the short timescale of an acute infection. Further studies are required to determine whether the mutational process leads to phenotypic alterations that impact upon bacterial fitness in vivo. Our findings have important implications for future sampling strategies, since colonies in a single clinical sample may be genetically heterogeneous, and organisms in a culture taken late in the infective process may have undergone considerable genetic change compared with the founder inoculum

An iridoid with anticancer activity from the sepals of <i style="">Mussaenda ‘dona aurora’</i>

1019-1022The sepals of Mussaenda ‘dona aurora’ afford three iridoid glycosides and four flavonoids. Among them, Sanshiside-D, a new iridoid glycoside has been found to suppress the growth of vero cell lines (IC 50 -1.99 μM/mL). Sanshiside methyl ester and lamalbide are inactive towards vero cell lines

Melioidosis: An under-diagnosed entity in western coastal India: A clinico-microbiological analysis

Clinico-microbiological analysis of a series of 25 patients with culture proven melioidosis was done. All patients came from the coastal regions of Kerala and Karnataka and presented between June 2005 to July 2006. They were analysed with respect to clinical presentation, occupation, epidemiology and microbiological features. No single presenting clinical feature was found to be typical of melioidosis. The disease was found to mimic a variety of conditions, including tuberculosis and malignancy. Burkholderia pseudomallei was isolated from blood, sputum, pus, urine, synovial, peritoneal and pericardial fluids. Diabetes mellitus was the most common predisposing factor and 80% of the cases presented during the Southwest monsoon (June to September). It is probable that melioidosis is highly prevalent in western coastal India and yet, greatly underestimated. Better awareness, both among clinicians and microbiologists, coupled with improved diagnostic methods to allow early diagnosis and hence early treatment, will significantly reduce the morbidity and mortality associated with this disease