Innovative Journal of Medical and Health Sciences

Background and Purpose: Preoperative evaluation and differentiation of intra-axial brain masses is essential for therapy and prognosis. The integrated Magnetic Resonance Imaging (MRI) techniques such as Diffusion Weighted Imaging (DWI), Magnetic Resonance Spectroscopy (MRS) and Dynamic Susceptibility Contrast (DSC) MRI allow insights into tumour anatomy and physiology. Our study was designed to find the sensitivity, specific and accuracy of a diagnostic algorithm comprising of these techniques.

Materials and Methods: Thirty consecutive immunocompetent patients with treatment naïve intra-axial brain masses underwent MRI from July 2016 to July 2017. Conventional and DWI, MRS and MR perfusion scans were performed using 1.5 T MR imaging system. The following cut-off values (ADC ?1.1 /100mm², intralesional Cho/NAA > 2.2, perilesional Cho/NAA >1 and rCBV >1.75) were applied to the diagnostic strategy algorithm. Histopathological analysis served as the gold standard. Sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV) and accuracy were obtained. 

Results: Twenty one of 30 cases were correctly classified using the diagnostic algorithm. One case of primary central nervous system lymphoma (PCNSL) was misdiagnosed as metastasis, 2 cases of high-grade neoplasm (HGN) as brain abscesses, 1 case of HGN as metastasis, 1 case of HGN as low-grade neoplasm (LGN), 1 case of LGN as HGN, 1 case of LGN as abscess / tumefactive demyelinating lesion (TDL), 1 case of brain abscess as HGN, and 1 case of metastasis (breast carcinoma) as HGN.

Conclusion: Diagnosing intra-axial brain masses using a combination of advanced imaging techniques (MRS, MR perfusion and ADC) is fairly accurate.

Context: Alpha-hemolysin (Hly) is a common exotoxin produced by Escherichia coli, which plays an important role as a virulence factor in a number of clinical infections. There exist other virulence properties exhibited by such strains whose role in pathogenesis have not yet been clearly elucidated.

Aims: Aim of present study was to characterize those alpha-hemolysin producing isolates on the basis of their virulence factors and phylogenetic background.

Settings and Design: This descriptive study was carried out in a multi-specialty tertiary care hospital.

Methods and Material: Three hundred non-repeat E. coli isolates from in-patients were studied. Isolates were differentiated as haemolytic and non-haemolytic on the basis of both phenotypic methods such as haemolysis on sheep blood agar and genotypic detection of the hly gene. Possession of virulence and drug resistance genes was determined by multiplex polymerase chain reaction (PCR). Phylogenetic analysis was performed by triplex PCR methods. Antibiotic sensitivity testing was performed by disk diffusion method.

Results: Of the 300 isolates, it was observed that by phenotypic (haemolysis on blood agar) method, 65(22%) were hemolytic whereas the genotypic method detected 70 (23.5%) isolates possessing alpha haemolysin (hlyA+) marker. B2 phylogroup isolates were found to harbour the hlyA+ marker at a significantly higher (P < 0.05) rate.  The possession of papC and cnf1 genes was significantly higher in hlyA+ isolates.

Conclusions: Alpha-haemolysin producing isolates demonstrated higher virulence properties. The microbiology laboratory may report haemolytic characteristics of the isolates as it may alert the physician of the higher pathogenic potential of the strain and to initiate appropriate treatment.