The epidemiology of carbapenem resistance in Acinetobacter baumannii complex in Germany (2014-2018): an analysis of data from the national Antimicrobial Resistance Surveillance system

Abstract

Background: Carbapenem-resistant Acinetobacter baumannii complex (CRABC) has globally emerged as a serious public health challenge. This study aimed to describe epidemiological trends and risk factors of carbapenem resistance in A. baumannii complex isolates in Germany between 2014 and 2018.

Methods: We analysed 43,948 clinical A. baumannii complex isolates using 2014 to 2018 data from the German Antimicrobial Resistance Surveillance system. We applied descriptive statistics and uni- and multivariable regression analyses to investigate carbapenem resistance in A. baumannii complex isolates.

Results: The proportion of carbapenem resistance in clinical A. baumannii complex isolates declined from 7.6% (95% confidence interval [95% CI] 4.4-12.7%) in 2014 to 3.5% (95% CI 2.5-4.7%) in 2018 (adjusted OR [aOR] 0.85 [95% CI 0.79-0.93, p ≤ 0.001]). Higher mean CRABC proportions for 2014 to 2018 were observed in secondary care hospitals (4.9% [95% CI 3.2-7.5%], aOR 3.6 [95% CI 2.4-5.3, p ≤ 0.001]) and tertiary care hospitals (5.9% [95% CI 3.0-11.2%], aOR 5.4 [95% CI 2.9-10.0, p ≤ 0.001) compared to outpatient clinics (1.3% [95% CI 1.1-1.6%]). CRABC proportions in hospitals varied between German regions and ranged between 2.4% (95% CI 1.6-3.5%) in the Southeast and 8.8% (95% CI 4.2-17.3%) in the Northwest. Lower CRABC proportions were observed in younger patients (< 1 year: 0.6% [95% CI 0.2-1.3%]; 1-19 years: 1.3% [95% CI 0.7-2.5%]) than adults (20-39 years: 7.7% [95% CI 4.4-13.0%]; 40-59 years: 6.2% [4.2-8.9%]; 60-79 years: 5.8% [95% CI 4.0-8.3%]). In the 20-39 year old patient age group, CRABC proportions were significantly higher for men than for women (14.6% [95% CI 8.6-23.6%] vs. 2.5% [95% CI 1.3-4.5%]). A. baumannii complex isolates from lower respiratory infections were more likely to be carbapenem-resistant than isolates from upper respiratory infections (11.4% [95% CI 7.9-16.2%] vs. 4.0% [95% CI 2.7-6.0%]; adjusted OR: 1.5 [95% CI 1.2-1.9, p ≤ 0.001]).

Conclusions: In contrast to many other regions worldwide, carbapenem resistance proportions among clinical A. baumannii complex isolates are relatively low in Germany and have declined in the last few years. Ongoing efforts in antibiotic stewardship and infection prevention and control are needed to prevent the spread of carbapenem-resistant A. baumannii complex in Germany.

Keywords: ARS; Acinetobacter baumannii complex; Antimicrobial resistance; Carbapenem resistance; Epidemiology; Surveillance.

Fig. 1

Proportions of carbapenem resistance in A. baumannii complex isolates by care setting type. Mean proportions (%) with corresponding 95% confidence intervals of carbapenem-resistant A. baumannii complex among all A. baumannii complex isolates (n = 43,796*) in Germany by care setting type. Absolute numbers: Outpatient clinics (171/13,081), Secondary care hospitals (781/15,853), Tertiary care hospitals (769/13,022), Specialist care hospitals (96/1,335), Prevention and rehabilitation care centres (34/390), Other hospitals (1/115). *Isolates with unknown hospital type information were excluded in this analysis

Fig. 2

Time trend of carbapenem resistance proportions in A. baumannii complex isolates by care setting type. Time trend of mean proportions (%) with corresponding 95% confidence intervals of carbapenem-resistant A. baumannii complex among all A. baumannii complex isolates (n = 43,948) in Germany between 2014 and 2018, stratified by care setting type. Absolute numbers: Total: 2014 (261/3,437), 2015 (411/7,660), 2016 (334/10,139), 2017 (470/11,794), 2018 (380/10,918); Outpatient clinics: 2014 (22/950), 2015 (35/2,208), 2016 (32/3,187), 2017 (46/3,705), 2018 (36/3,031); Hospitals: 2014 (239/2,487), 2015 (376/5,452), 2016 (302/6,952), 2017 (424/8,089), 2018 (344/7,887)

Fig. 3

Regional distribution of carbapenem resistance proportions in A. baumannii complex isolates. Distribution of A. baumannii complex with carbapenem resistance in German regions, expressed as mean proportions (%) among all A. baumannii complex isolates (n = 43,270*) and with corresponding 95% confidence intervals. Absolute numbers: Northeast (116/4,689), Southeast (199/9,327), Southwest (245/8,819), West (959/14,945), Northwest (332/5,490). *Only isolates with complete information on regional origin were included in this analysis

Fig. 4

Age distribution of carbapenem resistance proportions in A. baumannii complex isolates by gender. Age distribution of mean proportions (%) with corresponding 95% confidence intervals of carbapenem-resistant A. baumannii complex among all A. baumannii complex isolates (n = 35,821*) stratified by gender, expressed as mean proportions. Absolute numbers: Total: < 1 year (8/1,390), 1–19 years (31/2,379), 20–39 years (196/2,560), 40–59 years (365/5,911), 60–79 years (873/15,054), 80 ≥ years (159/8,527); Female: < 1 year (3/587), 1–19 years (14/1,201), 20–39 years (36/1,463), 40–59 years (101/2,324), 60–79 years (225/5,812), 80 ≥ years (66/4,491); Male: < 1 year (5/803), 1–19 years (17/1,178), 20–39 years (160/1,097), 40–59 years (264/3,587), 60–79 years (648/9,242), 80 ≥ years (93/4,036). *Only isolates with complete information on gender and age were included in this analysis

Fig. 5

Proportions of carbapenem resistance in A. baumannii complex isolates by clinical specimen material. Mean proportions (%) with corresponding 95% confidence intervals of carbapenem-resistant A.baumannii complex among all A. baumannii complex isolates (n = 43,843*), stratified into clinical specimen materials. Absolute numbers: Urine (203/8,887), Wound (342/12,254), Upper respiratory (166/4,107), Blood (81/997), Lower respiratory (400/3,496), Other respiratory (41/443), Other (619/13,659). *Only isolates with complete information on clinical specimen material were included in this analysis