Risk factors and clinical responses of pneumonia patients with colistin-resistant Acinetobacter baumannii-calcoaceticus

Table 1 Demographic data and clinical characteristics of patients with ventilator-associated pneumonia due to colistin-resistant and colistin-susceptible Acinetobacter baumannii- calcoaceticus complex

Variable	Total, n = 124	CRABC group, n = 16	CSABC group, n = 108	P-value
Male sex (%)	63 (50.8)	13 (81.3)	50 (46.3)	0.019
Age, med ± (min-max)	73.0 ± (18-91)	59.5 ± (18-86)	74.0 ± (18-91)	0.022
Comorbidity
Diabetes mellitus (%)	35 (28.2)	5 (31.5)	30 (27.8)	0.771
Chronic renal failure (%)	11 (8.9)	0 (0.0)	11 (10.2)	0.356
Chronic obstructive lung disease (%)	33 (26.6)	4 (25.0)	29 (26.9)	1.000
Hypertension (%)	57 (46.0)	8 (50.0)	49 (45.4)	0.938
Congestive heart failure (%)	25 (20.2)	4 (25.0)	21 (19.4)	0.738
Malignity (%)	30 (24.2)	2 (12.5)	28 (25.9)	0.353
Cerebrovascular disease (%)	24 (19.4)	1 (6.3)	23 (21.3)	0.305
Trauma (%)	8 (6.5)	3 (18.8)	5 (4.6)	0.066
Operation (%)	24 (19.4)	2 (12.5)	22 (20.4)	0.735
Immunosuppression (%)	9 (7.3)	1 (6.3)	8 (7.4)	1.000
Obesity (%)	12 (9.7)	3 (18.8)	9 (8.3)	0.186
Duration of mechanical ventilation before diagnosis, med ± min-max	11 ± (2-450)	12 ± (4-50)	11 ± (2-450)	0.872
Total length of ICU stays, med ± min-max	45.5 ± (5-540)	49.0 ± (11-305)	43.0 ± (5-540)	0.685
Central venous catheterization (%)	67 (54.0)	9 (56.3)	58 (53.7)	1.000
Urethral catheterization (%)	114 (91.9)	14 (87.5)	100 (92.6)	0.616
Total parenteral nutrition (%)	21 (16.9)	6 (37.5)	15 (13.9)	0.030
Prior receipt of colistin (%)	11 (8.9)	6 (37.5)	5 (4.6)	0.001
Prior receipt of carbapenems (%)	68 (54.8)	10 (62.5)	58 (53.7)	0.696
Prior receipt of linezolid (%)	6 (4.8)	1 (6.3)	5 (4.6)	0.571
Prior receipt of ampicillin/sulbactam (%)	19 (15.3)	1 (6.3)	18 (16.7)	0.462
Prior receipt of flouroquinolones (%)	51 (41.1)	5 (31.3)	46 (42.6)	0.556
Prior receipt of teicoplanin (%)	25 (20.2)	6 (37.5)	19 (17.6)	0.091
Prior receipt of piperacillin/tazobactam (%)	19 (15.3)	1 (6.3)	18 (16.7)	0.462
Prior receipt of ceftriaxone (%)	9 (7.3)	0 (0.0)	9 (8.3)	0.603
Presence of bacteremia (%)	3 (2.4)	2 (12.5)	1 (0.9)	0.044
APACHE II scores, med ± min-max	14. 0 ± (5-28)	22.5 ± (17-28)	12.0 ± (5-22)	< 0.001
SOFA scores, med ± min-max	9.0 ± (3-20)	9 ± (7-18)	9 ± (3-20)	0.546
Clinical response (%)	71 (61.3)	11 (68.8)	65 (60.2)	0.703
Laboratory response (%)	82 (66.1)	13 (81.3)	69 (63.9)	0.277
Radiological response (%)	65 (52.4)	10 (62.5)	55 (52.9)	0.551
Microbiological response (%)	67 (54.0)	9 (56.3)	58 (53.7)	1.000
Duration of microbiological cure, med ± (min-max)	4 ± (2-10)	6 ± (3-10)	3 ± (2-7)	<0.001
In-hospital mortality (%)	77 (62.1)	6 (37.5)	71 (65.7)	0.058
VAP-related mortality (%)	50 (40.3)	5 (31.3)	45 (41.7)	0.603

VAP: Ventilator associated pneumonia; CRABC: Colistin resistant Acinetobacter baumannii-calcoaceticus complex; CSABC: Colistin susceptible Acinetobacter baumannii-calcoaceticus complex; APACHE: High Acute Physiology and Chronic Health Evaluation; SOFA: Sequential Organ Failure Assessment.

Table 2 Clinical characteristics and antibiotic treatment combinations of patients with ventilator-associated pneumonia due to colistin-resistant Acinetobacter baumannii - calcoaceticus complex (part 1)

	Patients’ number with ventilator associated pneumonia due to colistin-resistant Acinetobacter baumannii-calcoaceticus complex
Isolate number of patients	1	2	3	4	5	6	7	8
Culture location	TA	BAL	TA	TA	TA	BAL	TA	BAL
Phenotype of isolate	1	1	1	1	1	1	1	2
MIC of isolate	8	> 256	4	6	4	> 256	> 256	> 256
Treatment	1	1	1	1	2	3	2	2
Clinical response	Yes	Yes	No	No	Yes	Yes	No	Yes
Laboratory response	Yes	Yes	No	Yes	Yes	Yes	Yes	Yes
Radiological response	Yes	Yes	No	No	Yes	Yes	No	Yes
Microbiological response	Yes	Yes	No	No	Yes	Yes	Yes	Yes
VAP-related mortality	No	No	Yes	No	No	No	Yes	No

Treatment 1: meropenem + colistin, Treatment 2: meropenem + ampicillin/sulbactam, Treatment 3: colistin + amikacin. MIC: Minimum inhibitory concentration; VAP: Ventilator-associated pneumonia; BAL: Bronchoalveolar lavage; TA: Tracheal aspirate.

Table 3 Clinical Characteristics and Antibiotic treatment combinations of patients with ventilator-associated pneumonia due to colistin-resistant Acinetobacter baumannii - calcoaceticus complex (part 2)

Variables	Patients’ number with ventilator associated pneumonia due to colistin-resistant Acinetobacter baumannii-calcoaceticus complex
Isolate number of patients	9	10	11	12	13	14	15	16
Culture location	TA	TA	TA	TA	TA	TA	BAL	TA
Phenotype of isolate	3	4	3	1	1	4	4	1
MIC of isolate	> 256	32	> 256	16	6	8	24	4
Treatment	4	5	1	1	2	7	6	1
Clinical response	Yes	Yes	No	Yes	Yes	Yes	Yes	No
Laboratory response	Yes	Yes	No	Yes	Yes	Yes	Yes	No
Radiological response	Yes	Yes	No	Yes	No	Yes	Yes	No
Microbiological response	Yes	Yes	No	No	No	No	Yes	No
VAP related mortality	No	No	Yes	No	Yes	No	No	Yes

Treatment 1: meropenem + colistin, Treatment 2: meropenem + ampicillin/sulbactam, Treatment 4: colistin + ampicillin/sulbactam + trimethoprim/sulfamethoxazole, Treatment 5: colistin + ampicillin/sulbactam, Treatment 6: meropenem + trimethoprim/sulfamethoxazole, Treatment 7: meropenem + sulbactam + trimethoprim/sulfamethoxazole. MIC: Minimum inhibitory concentration; VAP: Ventilator-associated pneumonia; BAL: Bronchoalveolar lavage; TA: Tracheal aspirate.

Table 4 Phenotypes of colistin-resistant Acinetobacter sp. isolates

Isolate number of patients	AN	CN	TOB	SAM	STX	IPM	MEM	CAZ	CIP	TZP
1	R	R	R	R	R	R	R	R	R	R
2	R	R	R	R	R	R	R	R	R	R
3	R	R	R	R	R	R	R	R	R	R
4	R	R	R	R	R	R	R	R	R	R
5	R	R	R	R	R	R	R	R	R	R
6	R	R	R	R	R	R	R	R	R	R
7	R	R	R	R	R	R	R	R	R	R
8	R	R	S	R	R	R	R	R	R	R
9	R	S	R	R	R	R	R	R	R	R
10	R	R	R	R	S	R	R	R	R	R
11	R	S	R	R	R	R	R	R	R	R
12	R	R	R	R	R	R	R	R	R	R
13	R	R	R	R	R	R	R	R	R	R
14	R	R	R	R	S	R	R	R	R	R
15	R	R	R	R	S	R	R	R	R	R
16	R	R	R	R	R	R	R	R	R	R

CO: Colistin; AN: Amikacin; CN: Gentamicin; TOB: Tobramycin; TE: Tetracycline; IPM: Imipenem; LEV: Levofloxacin; SXT: Trimetoprim-sulfamethoxazole; CIP: Ciprofloxacin; MEM: Meropenem; PIP: Piperacillin; TZP: Piperacillin-tazobactam; FEP: Sefepim; CAZ: Ceftazidim; SAM: Sulbactam-ampicillin; R: Resistant; S: Susceptible.