Pseudomonas aeruginosa Non-susceptibility to Common Antibiotics by Source in USA Hospitals in 2015: A Multicenter Study

Background: We evaluated the non-susceptibility of commonly used antibiotics used to treat Pseudomonas aeruginosa (PSA) infections by source in the inpatient setting.

Methods: We analyzed a 2015 inpatient dataset in an electronic research database of Becton Dickinson & Company from 346 USA hospitals. All non-duplicate PSA isolates (first isolate of a species per 30 day period) from respiratory, blood, wound, or urine were identified as non-susceptible if intermediate or resistant to ciprofloxacin or levofloxacin, ceftazidime, cefepime, meropenem, or piperacillin/ tazobactam (PIP/TAZ).

Results: The non-susceptible rates across all 4 sources were 33.6% (14,169/42,207), 19.4% (5,673/29,310), 19.8% (7,611/38,424), 20.9% (5,759/27,514), and 14.0% (5,385/38,404) for ciprofloxacin/levofloxacin, ceftazidime, cefepime, meropenem, and PIP/TAZ, respectively. Respiratory source had significantly higher non-susceptible rates than other sources for each of the 5 antibiotics, ranging from 19.8% to 39.3% (all P<0.01) (see Table).

Source	Non-susceptibility Rate (%, n)
	Ciprofloxacin or Levofloxacin	Ceftazidime	Cefepime	Meropenem	PIP/TAZ
Respiratory	39.3 (5,916/15,071)	25.6 (2,723/10,649)	26.3 (3,667/13,926)	29.4 (3,050/10,377)	19.8 (2,747/13,862)
Blood	23.9 (472/1,976)	16.1 (218/1,355)	15.3 (279/1,827)	15.5 (205/1,320)	10.8 (197/1,822)
Wound	27.5 (3,036/11,050)	17.6 (1,339/7,597)	16.3 (1,639/10,025)	15.2 (1,097/7,238)	11.9 (1,190/10,039)
Urine	33.6 (4,745/14,110)	14.3 (1,393/9,709)	16.0 (2,026/12,646)	16.4 (1,407/8,579)	9.9 (1,251/12,681)
All 4 Sources	33.6 (14,169/42,207)	19.4 (5,673/29,310)	19.8 (7,611/38,424)	20.9 (5,759/27,514)	14.0 (5,385/38,404)

Conclusion: Across all 4 sources in the inpatient population, 1 in 3 PSA isolates was non-susceptible to ciprofloxacin or levofloxacin and 1 in 5 to ceftazidime, cefepime, or meropenem. Respiratory source had the highest rates of non-susceptibility for all of these common antibiotics which are considered the cornerstone of PSA therapy. These findings highlight the importance of antibiotic choice and source of infection when choosing anti-pseudomonal therapy.