Regional Difference of Extended-spectrum β-lactamases (ESBLs) Susceptibility in USA Hospitals in 2015

Background:  We examined the regional differences in susceptibility of ESBLs producing E coli (EC), K pneumoniae (KP), and P mirabilis (PM) isolates in different settings.

Methods: We analyzed an electronic research dataset of Becton, Dickinson & Company from 346 USA hospitals in 2015. All non-duplicate EC, KP, and PM isolates (first isolate of a species per 30 day period) from all sources were categorized as ESBLs if confirmed as ESBL-positive per commercial panels or intermediate/resistant to either ceftriaxone, cefotaxime, ceftazidime or cefepime. Positive isolates were categorized into 3 settings by the specimen collection time: a) Admission: within 3 days of an inpatient admission and no previous admission within 14 days; b) Hospital-onset: 3 days post-admission or within 14 days of discharge; c) Ambulatory (neither a or b). Geographic regions were classified into NHSN categories (Sievert, 2013). Region 1, 7, & 8 were grouped into “Other” due to small number of hospitals. We conducted pairwise comparisons between regions using the region with the overall lowest ESBL rate as the reference group.

Results: The overall ESBL rate was 6.9% (56718/820017). The ESBL rates for ambulatory, admission, and hospital-onset settings were 5.7% (36086/631846), 9.2% (9693/105846), and 13.3% (10939/82325), respectively. Compared to Region 10, all regions, except for “Other”, had significantly higher ESBL rates, ranging from 4.4% to 7.9% (all P<0.05) for ambulatory; from 7.8% to 12.6% (all P<0.01) for admission; and 11.0% to 18.7% (all P<0.01) for hospital-onset settings.

NHSN Region	States	# of Hospitals	% ESBL
			Ambulatory	Admission	Hospital
2	NJ, NY, PR, VI	30	7.1	12.6	18.7
9	AZ, CA, HI, Pacific Islands	28	7.9	11.5	16.6
6	AR, LA, NM, OK, TX	59	6.9	9.6	13.4
4	AL, FL, GA, KY, MI, NC, SC, TN	98	6.2	9.2	13.2
5	IL, IN, MI, MN, OH, WI	85	4.4	8.2	11.5
3	DE, DC, MD, PA, VA, WV	13	5.2	7.8	11.0
10	AK, ID, OR, WA	22	4.0	5.5	8.6
1, 7, 8	Other	11	4.1	6.0	8.0
Overall		346	5.7	9.2	13.3

Conclusion: ESBL rates were highest in the hospital setting with significant regional differences. The highest ESBL region had a rate approximately twice that of the lowest region in all three settings. Regional and setting differences in ESBL epidemiology should be considered when making empiric antibiotic treatment decisions.