Browsing by Author "Khan, Ayesha"

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    A Multicenter Study To Evaluate Ceftaroline Breakpoints : Performance in an Area with High Prevalence of Methicillin-Resistant Staphylococcus aureus Sequence Type 5 Lineage
    (2019) Khan, Ayesha; Rivas, Lina M.; Spencer, María; Martínez, Rodrigo; Lam, Marusella; Rojas, Pamela; Porte, Lorena; Silva, Francisco; Braun, Stephanie; García Cañete, Patricia; Valdivieso, Francisca; Mvlhauser, Margareta; Lafourcade, Mónica; Miller, William R.; Arias, César A.; Munita, José M.
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    High Burden of Intestinal Colonization With Antimicrobial-Resistant Bacteria in Chile: An Antibiotic Resistance in Communities and Hospitals (ARCH) Study
    (2023) Araos, Rafael; Smith, Rachel M.; Styczynski, Ashley; Sánchez Barría, Felipe Andrés; Acevedo, Johanna; Maureira, Lea; Paredes, Catalina; Gonzalez, Maite; Rivas, Lina; Spencer-Sandino, Maria; Peters, Anne; Khan, Ayesha; Sepulveda, Dino; Rojas Wettig, Loreto; Rioseco, Maria Luisa; Usedo, Pedro; Undurraga, Eduardo A.
    We report a high colonization burden resulting from antimicrobial-resistant Gram-negative bacteria in hospitals and a community in Chile. Strikingly, 29% (95% confidence interval, 24-34) of community-dwelling adults carried extended-spectrum cephalosporin-resistant Enterobacterales, highlighting the magnitude of the community reservoir of antimicrobial resistance., Background Antimicrobial resistance is a global threat, heavily impacting low- and middle-income countries. This study estimated antimicrobial-resistant gram-negative bacteria (GNB) fecal colonization prevalence in hospitalized and community-dwelling adults in Chile before the coronavirus disease 2019 pandemic. Methods From December 2018 to May 2019, we enrolled hospitalized adults in 4 public hospitals and community dwellers from central Chile, who provided fecal specimens and epidemiological information. Samples were plated onto MacConkey agar with ciprofloxacin or ceftazidime added. All recovered morphotypes were identified and characterized according to the following phenotypes: fluoroquinolone-resistant (FQR), extended-spectrum cephalosporin-resistant (ESCR), carbapenem-resistant (CR), or multidrug-resistant (MDR; as per Centers for Disease Control and Prevention criteria) GNB. Categories were not mutually exclusive. Results A total of 775 hospitalized adults and 357 community dwellers were enrolled. Among hospitalized subjects, the prevalence of colonization with FQR, ESCR, CR, or MDR-GNB was 46.4% (95% confidence interval [CI], 42.9-50.0), 41.2% (95% CI, 37.7-44.6), 14.5% (95% CI, 12.0-16.9), and 26.3% (95% CI, 23.2-29.4). In the community, the prevalence of FQR, ESCR, CR, and MDR-GNB colonization was 39.5% (95% CI, 34.4-44.6), 28.9% (95% CI, 24.2-33.6), 5.6% (95% CI, 3.2-8.0), and 4.8% (95% CI, 2.6-7.0), respectively. Conclusions A high burden of antimicrobial-resistant GNB colonization was observed in this sample of hospitalized and community-dwelling adults, suggesting that the community is a relevant source of antibiotic resistance. Efforts are needed to understand the relatedness between resistant strains circulating in the community and hospitals.
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    Real-World Performance of Susceptibility Testing for Ceftolozane/Tazobactam against Non-Carbapenemase- Producing Carbapenem-Resistant Pseudomonas aeruginosa
    (2022) Rivas, Lina; Martinez, José R.W.; Munita, José M.; Alcalde-Rico, Manuel; Olivares Pacheco, Jorge; García Cañete, Patricia; Olivares-Pacheco J.; Moreno, María Victoria; Rojas, Pamela; Wozniak Banchero, Aniela; Miller, William; Arias, Cesar A.; Khan, Ayesha
    Ceftolozane/tazbactam (C/T) is a potent anti-pseudomonal agent that has clinical utility against infections caused by non-carbapenemase, producing-carbapenemresistant Pseudomonas aeruginosa (non-CP-CR-PA). Accurate, precise, and reliable antimicrobial susceptibility testing (AST) is crucial to guide clinical decisions. However, studies assessing the performance of different AST methods against non-CP-CR-PA (the main clinical niche for C/T), are lacking. Here, we evaluated performance of gradient strips (Etest and MIC test strip [MTS], and disk diffusion [DD]) using CLSI breakpoints. Additionally, we assessed the performance of DD using EUCAST breakpoints. For all susceptibility tests, we used a collection of 97 non-CP-CR-PA clinical isolates recovered from 11 Chilean hospitals. Both gradient strips and DD had acceptable performance when using CLSI breakpoints, yielding a categorical agreement (CA) of .90% and 92%, respectively. In contrast, DD using EUCAST breakpoints performed suboptimally (CA 81%). MTS yielded a higher essential agreement (EA, .90%) than Etest (84%). Importantly, the performance of all methods varied significantly when the isolates were stratified by their degree of susceptibility to other anti-pseudomonal b-lactams. All methods had 100% CA when testing isolates that were pan-susceptible to all b-lactams (Pan-β-S). However, the CA markedly decreased when testing isolates resistant to all b-lactams (Pan-β-R). Indeed, the CA was 81% for Etest (six errors), 78% for MTS (seven errors), and 78% and 56% for DD when using CLSI (seven errors) or EUCAST breakpoints (14 errors), respectively. Our results suggest that all manual AST methods have strikingly decreased performance in the context of Pan-β-R P. aeruginosa with potentially major clinical implications.