Carbapenem Resistant Pseudomonas aeruginosa Infections in Elderly Patients: Antimicrobial Resistance Profiles, Risk Factors and Impact on Clinical Outcomes

Figures & data

Figure 1 Department distribution of P. aeruginosa isolates.

Table 1 Susceptibility of P. aeruginosa to Antimicrobial Agents During the Period from 2018 Through 2020

Antimicrobial Agents	CRPA (N= 155)			CSPA (N= 445)			Overall (N= 600)
	Resistance n (%)	Intermediate n (%)	Susceptibility n (%)	Resistance n (%)	Intermediate n (%)	Susceptibility n (%)	Resistance n (%)	Intermediate n (%)	Susceptibility n (%)
Ciprofloxacin	79 (51.0)	15 (9.7)	61 (39.4)	87 (19.6)	23 (5.2)	335 (75.3)	166 (27.7)	38 (6.3)	396 (66.0)
Levofloxacin	75 (48.4)	10 (6.5)	70 (45.2)	74 (16.6)	27 (6.1)	344 (77.3)	149 (24.8)	37 (6.2)	414 (69.0)
Aztreonam	56 (36.1)	58 (37.4)	41 (26.5)	56 (12.6)	177 (39.8)	212 (47.6)	112 (18.7)	235 (39.2)	253 (42.2)
Cefoperazone	67 (43.2)	43 (27.7)	45 (29.0)	50 (11.2)	99 (22.3)	296 (66.5)	117 (19.5)	142 (23.7)	341 (56.8)
Gentamicin	44 (28.4)	8 (5.2)	103 (66.5)	43 (9.7)	21 (4.7)	381 (85.6)	87 (14.5)	29 (4.8)	484 (80.7)
Piperacillin	45 (29.0)	53 (34.2)	57 (36.8)	41 (6.8)	82 (18.4)	322 (72.4)	86 (14.3)	135 (22.5)	379 (63.2)
Ceftazidime	43 (27.7)	25 (16.1)	87 (56.1)	37 (8.3)	19 (4.3)	389 (87.4)	80 (13.3)	44 (7.3)	476 (79.3)
Tobramycin	42 (27.1)	12 (7.7)	101 (65.2)	31 (7.0)	7 (1.6)	407 (91.5)	73 (12.2)	19 (3.2)	508 (84.7)
Cefepime	36 (23.2)	15 (9.7)	104 (67.1)	21 (4.7)	34 (7.6)	390 (87.6)	57 (9.5)	49 (8.2)	494 (82.3)
Cefoperazone-sulbactam	34 (21.9)	40 (25.8)	81 (52.3)	15 (3.4)	45 (10.1)	385 (86.5)	49 (8.2)	85 (14.2)	466 (77.7)
Piperacillin-tazobactam	31 (20.0)	40 (25.8)	84 (54.2)	13 (2.9)	37 (8.3)	395 (88.8)	44 (7.3)	77 (12.8)	479 (79.8)
Amikacin	27 (17.4)	4 (2.6)	124 (80.0)	10 (2.3)	5 (1.1)	430 (96.6)	37 (6.2)	9 (1.5)	554 (92.3)
Meropenem	109 (70.3)	19 (12.3)	27 (17.4)	0 (0.0)	0 (0.0)	445 (100.0)	109 (18.2)	19 (3.2)	472 (78.7)
Imipenem	136 (87.7)	19 (12.3)	0 (0.0)	0 (0.0)	0 (0.0)	455 (100.0)	136 (22.7)	19 (3.2)	445 (74.2)

Abbreviations: CRPA, carbapenem-resistant Pseudomonas aeruginosa; CSPA, carbapenem-susceptible Pseudomonas aeruginosa.

Table 2 Univariate and Multivariate Analysis of Risk Factors for Inpatients with CRPA Infection

Variable	CRPA	CSPA	Univariate Analysis		Multivariate Analysis
	(N = 155)	(N = 445)	OR (95% CI)	P-value	OR (95% CI)	P-value
Age (Years), Median (IQR)	83 (74.0–89.0)	80 (71.0–86.0)	NA	0.013
Age in year, n (%)
65–74	24 (15.5)	17 (11.0)	0.672 (0.346–1.308)	0.241
75–84	72 (46.5)	103 (66.5)	2.283 (1.443–3.614)	0.001	0.458 (0.263–0.800)	0.006
≥85	59 (38.1)	35 (22.6)	0.475 (0.289–0.780)	0.003
Male sex, n (%)	99 (63.9)	89 (57.4)	0.763 (0.483–1.205)	0.245
Quarter, n (%)
January-March	50 (32.3)	61 (39.4)	1.363 (0.855–2.172)	0.193
April-June	33 (21.3)	28 (18.1)	0.815 (0.465–1.429)	0.475
July-September	38 (24.5)	34 (21.9)	0.865 (0.510–1.467)	0.591
October-December	34 (21.9)	32 (20.6)	0.926 (0.537–1.595)	0.781
Comorbidities, n (%)
Cerebrovascular disease	101 (65.2)	53 (34.2)	0.278 (0.174–0.444)	<0.001	3.517 (2.054–6.021)	<0.001
Hypertension	100 (64.5)	76 (49.0)	0.529 (0.336–0.834)	0.006
Diabetes mellitus	53 (34.2)	34 (21.9)	0.541 (0.326–0.896)	0.016
Coronary artery disease	49 (31.6)	27 (17.4)	0.456 (0.267–0.780)	0.004
Cardiac dysfunction	28 (18.1)	16 (10.3)	0.522 (0.270–1.010)	0.051
Renal dysfunction	23 (14.8)	20 (12.9)	0.850 (0.446–1.621)	0.622
Biliary tract disease	12 (7.7)	16 (10.3)	1.372 (0.626–3.004)	0.428
Bronchiectasis	15 (9.7)	19 (12.3)	1.304 (0.637–2.671)	0.467
Malignancy	8 (5.2)	14 (9.0)	1.824 (0.743–4.482)	0.184
Admitted to Intensive care unit, n (%)	26 (16.8)	12 (7.7)	0.416 (0.202–0.859)	0.015
Duration of (CR/CS) PA infection occurrence (days), median (IQR)	3.8 (2–4)	3.3 (2–4)	NA	0.190
Prior surgery (within 90 days), n (%)	10 (24.5)	7 (14.2)	0.686 (0.254–1.885)	0.619
Receiving invasive operation, n (%)
Nasogastric tube	78 (50.3)	48 (31.0)	0.443 (0.279–0.704)	0.001
Foley catheter	59 (38.1)	32 (20.6)	0.423 (0.255–0.702)	<0.001	2.073 (1.135–3.784)	0.018
Mechanical ventilation	35 (22.6)	18 (11.6)	0.450 (0.243–0.837)	0.010
Central venous catheter	23 (14.8)	16 (10.3)	0.661 (0.334–1.305)	0.231
Length of hospital stay (days), n (%)
< 7	4 (2.6)	8 (5.2)	2.054 (0.606–6.969)	0.239
7–13	54 (34.8)	74 (47.7)	1.709 (1.082–2.698)	0.021
≥ 14	97 (62.6)	66 (42.6)	0.443 (0.281–0.699)	<0.001	1.980 (1.154–3.399)	0.013
Laboratory findings, n (%)
C-reactive protein 10–30 mg/L	42 (27.1)	33 (21.3)	0.728 (0.431–1.228)	0.233
C-reactive protein > 30 mg/L	111 (71.6)	87 (56.1)	0.507 (0.316–0.813)	0.005
White blood cell count > 9.5 × 10^9/L	62 (40.0)	52 (33.5)	0.757 (0.477–1.203)	0.239
Mild anemia (hemoglobin 90–120 g/L)	124 (80.0)	98 (63.2)	0.430 (0.258–0.717)	0.001
Moderate anemia (hemoglobin 60~90 g/L)	4 (2.6)	2 (1.3)	0.493 (0.089–2.734)	0.684
Neutrophil percentage > 75%	87 (56.1)	81 (52.3)	0.856 (0.547–1.338)	0.494
Albumin < 35 g/L	100 (64.5)	67 (43.2)	0.419 (0.265–0.662)	<0.001	2.049 (1.121–3.746)	0.020
Co-carriage, n (%)
Klebsiella pneumoniae	28 (18.1)	12 (7.1)	0.381 (0.186–0.780)	0.007
Acinetobacter baumannii	27 (17.4)	18 (11.6)	0.623 (0.327–1.185)	0.147
Carbapenem resistant Enterobacteriaceae	17 (11.0)	10 (6.5)	0.560 (0.248–1.265)	0.159
Staphylococcus aureus	9 (5.8)	3 (1.9)	0.320 (0.085–1.206)	0.138
Escherichia coli	5 (3.2)	5 (3.2)	1.000 (0.284–3.526)	0.992
Previous antibiotic exposure (within 30 days), n (%)
Combination of antibiotics	52 (33.5)	36 (23.2)	0.599 (0.363–0.988)	0.044
Quinolones	26 (16.8)	21 (13.5)	0.778 (0.417–1.451)	0.428
Carbapenems	22 (14.2)	3 (1.9)	0.119 (0.035–0.408)	<0.001	7.022 (1.861–26.493)	0.004
Third- or fourth-generation cephalosporins	21 (13.5)	2 (1.3)	0.083 (0.019–0.362)	<0.001	12.649 (2.473–64.690)	0.002
Macrolides antibiotics	15 (9.7)	20 (12.9)	1.383 (0.680–2.812)	0.370
Glycopeptides	6 (3.9)	1 (0.6)	0.161 (0.019–1.356)	0.121
Aminoglycosides	4 (2.6)	2 (1.3)	0.493 (0.089–2.734)	0.684

Notes: Data are expressed as n (%) of patients for categorical variables and median for continuous as appropriate. Bold face indicates values that are significant (P<0.05).

Abbreviations: CRPA, carbapenem-resistant Pseudomonas aeruginosa; CSPA, carbapenem-susceptible Pseudomonas aeruginosa; OR, odds ratio; CI, confidence interval; IQR, interquartile range; NA, not available.

Table 3 Risk Factors for Mortality in Inpatients with CRPA Infection

Variable	CRPA	CSPA	Univariate Analysis		Multivariate Analysis
	(N = 26)	(N = 129)	OR (95% CI)	P-value	OR (95% CI)	P-value
Age (years), Median (IQR)	84 (77.0–90.0)	83 (74.0–88.0)	NA	0.450
Age in year, n (%)
65–74	1 (3.8)	23 (17.8)	0.184 (0.024–1.431)	0.072
≥ 75	25 (96.2)	106 (82.1)	5.425 (0.699–42.095)	0.072
Male, sex, n (%)	15 (57.7)	84 (65.1)	0.731 (0.310–1.723)	0.472
Quarter, n (%)
January-March	10 (38.5)	40 (31.0)	1.391 (0.580–3.332)	0.458
April-June	5 (19.2)	28 (21.7)	0.859 (0.297–2.482)	0.779
July-September	5 (19.2)	33 (25.6)	0.693 (0.242–1.984)	0.492
October-December	6 (23.1)	28 (21.7)	1.082 (0.397–2.953)	0.877
Comorbidities, n (%)
Cerebrovascular disease	14 (53.8)	87 (67.4)	0.563 (0.240–1.324)	0.184
Hypertension	18 (69.2)	82 (63.6)	1.290 (0.521–3.193)	0.582
Diabetes mellitus	12 (46.2)	41 (31.8)	1.840 (0.782–4.328)	0.159
Coronary artery disease	9 (34.6)	40 (31.0)	1.178 (0.484–2.868)	0.718
Cardiac dysfunction	6 (23.1)	22 (17.1)	1.459 (0.526–4.051)	0.466
Renal dysfunction	8 (30.8)	15 (11.6)	3.378 (1.253–9.106)	0.012
Biliary tract disease	3 (11.5)	9 (7.0)	1.739 (0.437–6.918)	0.427
Bronchiectasis	5 (19.2)	10 (7.8)	2.833 (0.880–9.124)	0.071
Malignancy	1 (3.8)	7 (5.4)	0.697 (0.082–5.919)	0.740
Admitted to ICU, n (%)	5 (19.2)	21 (16.3)	1.224 (0.415–3.611)	0.713
Prior surgery, n (%)	3 (26.9)	7 (24.0)	2.273 (0.547–9.443)	0.247
Invasive operation, n (%)
Nasogastric tube	15 (57.7)	63 (48.8)	1.429 (0.610–3.346)	0.410
Foley catheter	16 (61.5)	43 (33.3)	3.200 (1.340–7.644)	0.007
Mechanical ventilation	12 (46.2)	23 (17.8)	3.950 (1.617–9.650)	0.002	3.671 (1.424–9.467)	0.007
Central venous catheter	6 (23.1)	17 (13.2)	1.976 (0.695–5.621)	0.195
Length of hospital stay (days), n (%)
< 10	3 (11.5)	10 (7.8)	1.552 (0.396–6.079)	0.525
10–19	8 (30.8)	78 (60.5)	0.291 (0.118–0.718)	0.005
≥ 20	15 (57.7)	41 (31.8)	2.927 (1.236–6.929)	0.012
Laboratory findings, n (%)
C-reactive protein ≥ 10 mg/L	25 (96.2)	92 (71.3)	10.054 (1.314–76.928)	0.007
Hemoglobin:<130 g/L (Male), <115 g/L (Female)	22 (84.6)	108 (83.7)	1.069 (0.334–3.423)	0.071
Albumin < 35 g/L	17 (65.4)	83 (64.3)	1.047 (0.432–2.536)	0.919
Neutrophil percentage, n (%)
75–79	8 (30.8)	24 (18.6)	1.944 (0.757–4.995)	0.162
≥ 80	18 (69.2)	37 (28.7)	5.595 (2.238–13.983)	<0.001	2.908 (1.151–7.343)	0.024
White blood cell count > 9.5×10^9 /L	18 (69.2)	48 (37.2)	3.797 (1.534–9.396)	0.003
Co-carrage, n (%)
Klebsiella pneumoniae	8 (30.8)	20 (15.5)	2.422 (0.928–6.324)	0.065
Acinetobacter baumannii	5 (19.2)	22 (17.1)	1.158 (0.394–3.403)	0.790
Carbapenem resistant Enterobacteriaceae	3 (11.5)	14 (10.9)	1.071 (0.285–4.030)	1.000
Staphylococcus aureus	0 (0.0)	9 (7.0)	NA	0.226
Escherichia coli	3 (11.5)	2 (1.60)	8.283 (1.311–52.334)	0.034
Previous antibiotic exposure (within 30 days), n (%)
Combination of antibiotics	7 (26.9)	45 (34.9)	0.688 (0.269–1.759)	0.433
Quinolones	4 (15.4)	22 (17.1)	0.884 (0.277–2.821)	1.000
Carbapenems	1 (3.8)	21 (16.3)	0.206 (0.026–1.602)	0.127
Third- or fourth-generation cephalosporins	2 (7.7)	19 (14.7)	0.482 (0.105–2.211)	0.382
Glycopeptides	1 (3.8)	5 (3.9)	0.992 (0.111–8.860)	1.000
Aminoglycosides	0 (0.0)	4 (3.1)	NA	0.607

Notes: Data are expressed as n (%) of patients for categorical variables and median for continuous as appropriate. Bold face indicates values that are significant (P<0.05).

Abbreviations: CRPA, carbapenem-resistant Pseudomonas aeruginosa; CSPA, carbapenem-susceptible Pseudomonas aeruginosa; OR, odds ratio; CI, confidence interval; IQR, interquartile range; NA, not available.