[Source: Antimicrobial Agents and Chemotherapy, full page: (LINK). Abstract, edited.]
Changing of the Frequencies of β-Lactamase Genes Among Enterobacteriaceae in US Hospitals (2012-2014): Activity of Ceftazidime-Avibactam Tested against β-Lactamase-Producing Isolates
Mariana Castanheira1, Rodrigo E. Mendes1, Ronald N. Jones1 and Helio S. Sader1
Author Affiliations: 1JMI Laboratories, North Liberty, Iowa, US
Among 15,588 Enterobacteriaceae isolates collected in 63 United States (US) hospitals from 2012-2014, 2,129 (13.7%) displayed an extended spectrum β-lactamase (ESBL)-phenotype. These rates were similar over time (13.2-13.9%); however, differences among Escherichia coli (12.7/15.1% in 2012/2014; p=0.007) and Klebsiella pneumoniae (18.9/15.5%; p=0.006) were noted when comparing 2014 and 2012, respectively. Carbapenem-resistant Enterobacteriaceae (CRE; 2.3/1.8%) and carbapenem-resistant K. pneumoniae (6.8/5.1%; p=0.003) rates were lower in 2014 compared to prior years. Isolates carrying blaCTX-M-15-like were stable (42.1 to 42.4%), but a decrease among E. coli (59.1/49.7%; p=0.008) and an increase among K. pneumoniae (32.7/41.2%; p=0.022) in 2014 was observed. Isolates carrying blaKPC (304) decreased over the years (16.5/10.9%; p=0.008) mainly due to the decrease in K. pneumoniae harboring blaKPC (n=285; 35.6/28.4%; p=0.041) in hospitals of Mid-Atlantic and South Atlantic regions where these isolates were highly prevalent during 2012-2013. Isolates carrying blaCMY-2-like and blaCTX-M-14-like increased (8.2/11.9% and 9.1/12.9, respectively; p=0.04 for both), and those producing blaSHV ESBL decreased (24.9/12.7%; p<0.001) over the studied years, due to a decreased occurrence of these enzymes among K. pneumoniae. Other enzymes were detected in smaller numbers, including four K. pneumoniae isolates carrying blaNDM-1 metallo-β-lactamase (two in 2012 and two in 2014). Ceftazidime-avibactam, a recently approved β-lactamase inhibitor combination, was very active against the ESBL-phenotype isolates (MIC50/90, 0.12/1 μg/mL; 99.7% susceptible) and CRE strains (MIC50/90, 0.5/2 μg/mL; 98.5% susceptible) that displayed elevated MIC values for many comparator agents. In conclusion, significant changes were noted in the frequencies of isolates harbouring various β-lactamases among US hospitals between 2012-2014 that will require continued monitoring.
Contact Information: Mariana Castanheira, Ph.D., JMI Laboratories, 345 Beaver Kreek Ctr, Ste A, North Liberty, Iowa, 52317, US, Phone: 319-665-3370, Fax: 319-665-3371, Marianafirstname.lastname@example.org
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Keywords: Research; Abstracts; Antibiotics; Drugs Resistance; Carbapenem; Enterobacteriaceae; USA; Avibactam; Ceftazidime.