Browsing by Author "Naqvi, S. Ali"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Characteristics of Escherichia coli Isolated from Bovine Mastitis Exposed to Subminimum Inhibitory Concentrations of Cefalotin or Ceftazidime
    (2018-11-01) Liu, Gang; Ding, Laidi; Han, Bo; Piepers, Sofie; Naqvi, S. Ali; Barkema, Herman W.; Ali, Tariq; De Vliegher, Sarne; Xu, Siyu; Gao, Jian
    Escherichia coli is a major udder pathogen causing clinical mastitis in dairy cattle and its heat stable endotoxin in powdered infant formula milk is a potential risk factor in neonatal infections. Cephalosporins are frequently used for treatment of mastitis caused by mastitis; however, use of these antimicrobials may induce antimicrobial resistance in E. coli. The objective of this study was to explore the in vitro effect of subminimum inhibitory concentrations (sub-MIC) of cefalotin (CF) and ceftazidime (CAZ) on the morphology, antimicrobial resistance, and endotoxin releasing characteristics of 3 E. coli isolates recovered from bovine clinical mastitis. The parent E. coli isolates, which were susceptible to CF and CAZ, were exposed to CF or CAZ separately at sub-MIC levels to produce 9 generations of induced isolates. Colonies of the CAZ-induced isolates from all 3 parent E. coli were smaller on blood agar and the bacteria became filamentous, whereas the CF-induced isolates did not demonstrate prominent morphological changes. After induction by CF or CAZ, many induced isolates showed resistance to cefoxitin, CAZ, CF, kanamycin, ampicillin, and amoxicillin/clavulanic acid while their parent isolates were susceptible to these antimicrobials. Notably, 5 CAZ-induced isolates from the same parent isolate were found to produce extended-spectrum beta-lactamase (ESBL) though none of the tested ESBL related genes could be detected. All CAZ-induced isolates released more endotoxin with a higher release rate, whereas endotoxin release of CF-induced E. coli isolates was not different from parent isolates. The exposure of cephalosporins at sub-MIC levels induced resistant Escherichia coli. We inferred that cephalosporins, especially CAZ, should be used prudently for treatment of clinical E. coli mastitis.
  • Thumbnail Image
    ItemOpen Access
    Cytokines and Chemokines in Pediatric Appendicitis: A Multiplex Analysis of Inflammatory Protein Mediators
    (2019-02-21) Naqvi, S. Ali; Thompson, Graham C.; Joffe, Ari R.; Blackwood, Jaime; Martin, Dori-Ann; Brindle, Mary; Barkema, Herman W.; Jenne, Craig N.
    Objectives. We aimed to demonstrate the potential of precision medicine to describe the inflammatory landscape present in children with suspected appendicitis. Our primary objective was to determine levels of seven inflammatory protein mediators previously associated with intra-abdominal inflammation (C-reactive protein—CRP, procalcitonin—PCT, interleukin-6 (IL), IL-8, IL-10, monocyte chemoattractant protein-1—MCP-1, and serum amyloid A—SAA) in a cohort of children with suspected appendicitis. Subsequently, using a multiplex proteomics approach, we examined an expansive array of novel candidate cytokine and chemokines within this population. Methods. We performed a secondary analysis of targeted proteomics data from Alberta Sepsis Network studies. Plasma mediator levels, analyzed by Luminex multiplex assays, were evaluated in children aged 5-17 years with nonappendicitis abdominal pain (NAAP), acute appendicitis (AA), and nonappendicitis sepsis (NAS). We used multivariate regression analysis to evaluate the seven target proteins, followed by decision tree and heat mapping analyses for all proteins evaluated. Results. 185 children were included: 83 with NAAP, 79 AA, and 23 NAS. Plasma levels of IL-6, CRP, MCP-1, PCT, and SAA were significantly different in children with AA compared to those with NAAP (). Expansive proteomic analysis demonstrated 6 patterns in inflammatory mediator profiles based on severity of illness. A decision tree incorporating the proteins CRP, ferritin, SAA, regulated on activation normal T-cell expressed and secreted (RANTES), monokine induced by gamma interferon (MIG), and PCT demonstrated excellent specificity (0.920) and negative predictive value (0.882) for children with appendicitis. Conclusions. Multiplex proteomic analyses described the inflammatory landscape of children presenting to the ED with suspected appendicitis. We have demonstrated the feasibility of this approach to identify potential novel candidate cytokines/chemokine patterns associated with a specific illness (appendicitis) amongst those with a broad ED presentation (abdominal pain). This approach can be modelled for future research initiatives in pediatric emergency medicine.