Measuring the Prevalence of Multidrug Resistant Acinetobacter (MDRA) Using OXA 23 and OXA 51 Gene Identification in Healthcare Facilities (HCF) in Washington DC

Background: Multidrug resistance among Acinetobacterinfections reported in healthcare-associated infections through the National Healthcare Safety Network (NHSN) decreased by 34% in the South Atlantic region between 2011 and 2014. NHSN data were largely from acute care hospitals and do not measure colonization rates, resistance in long term care facilities (LTCFs), nor infections that are not healthcare-associated. MDRA is classified as an urgent threat by the Centers for Disease Control and Prevention. A collaborative of HCFs conducted a point prevalence study to determine a baseline in Washington, DC.

Methods: The study was designed primarily to measure the prevalence of carbapenem-resistant Enterobacteriaceae in DC HCFs. Samples were also evaluated using the Acuitas® MDRO gene test (OpGen) that detects the OXA 23 and OXA 51 genes, commonly associated with MDRA. We assessed 2,216 patients from 16 HCFs (all 8 acute care hospitals (AH); 1 inpatient rehabilitation hospital (IRH), and 7 long term care facilities (LTCF). LTCFs included 5 skilled nursing facilities (SNF) and 2 long term acute care facilities (LTAC]). A total of 1021 patients met inclusion criteria and consented to participate.

Results: Overall MDRA point prevalence rate (PR) was 6.6%. The PR for AHs, IRH, and LTCFs were 3.7, 0.0, and 16.4, respectively [Table 1]. OXA 23, a gene associated with carbapenem-resistance in Acinetobacterwas detected in 0.8% of samples from AHs (0.0-2.0%), and from 4.9% of samples from LTCFs (0.0-15.4) [p<0.0001].

Table 1 Prevalence OXA-23 and OXA 51 Genes(MDRA) – Percent Positive Prevalence Ratio (PR) and Confidence Interval (CI) Comparing Location Type to Total
Location Type	n facilities	n patients targeted	n samples	% sampled	n MDRA	% MDRA	Range % MDRA	MDRA PR	MDRA PR CI
AH	8	1580	725	45.9	27	3.7	0.0-5.1	0.3	0.2-0.4 p<0.00001
LTCF	7	543	244	44.8	40	16.4	0.0-47.1	4.7	3.0-7.5 p<0.00001
IRH	1	93	52	55.9	0	0.0	-	-	-
Total	16	2216	1021	46.1	67	6.6	0.0-47.1

Conclusion: This study showed a significantly greater prevalence of MDRA in LTCFs in the setting of decreasing HAIs due to MDRA in AHs. Although the reason for the different PR is unknown, DC HCFs can use these data to collaborate for improved information on patients’ resistance profiles as they traverse the continuum of care.