Severe postoperative infections following surgery for digestive system diseases

Table 1 Baseline demographic and clinical characteristics of patients, n (%)/mean ± SD

Variable	Infection group (n = 38)	Non-infection group (n = 118)	t/χ2	P value
Age (years)	63.2 ± 11.8	57.2 ± 12.1	2.70	0.008
Male sex	25 (65.8)	67 (56.8)	0.94	0.332
BMI (kg/m2)	24.8 ± 3.9	23.6 ± 3.5	1.78	0.077
Smoking	18 (47.4)	38 (32.2)	2.84	0.092
Diabetes mellitus	17 (44.7)	20 (16.9)	12.06	< 0.001
Hypertension	16 (42.1)	35 (29.7)	1.98	0.160
COPD	5 (13.2)	8 (6.8)	1.48	0.224
Chronic liver disease	8 (21.1)	14 (11.9)	1.98	0.160
Previous abdominal surgery	12 (31.6)	24 (20.3)	2.03	0.154
ASA classification
I-II	18 (47.4)	82 (69.5)	6.08	0.014
III-IV	20 (52.6)	36 (30.5)
NRS 2002 ≥ 3	22 (57.9)	40 (33.9)	6.85	0.009
Albumin (g/L)	32.8 ± 4.6	37.2 ± 4.1	5.62	< 0.001
Hemoglobin (g/L)	112.4 ± 18.6	124.8 ± 16.2	3.94	< 0.001
WBC (× 109/L)	7.8 ± 2.9	6.4 ± 2.1	3.17	0.002
CRP (mg/L, median, IQR)	12.4 (5.8-24.6)	4.2 (1.8-10.5)	3.861	< 0.001
HbA1c (%)	7.2 ± 1.8	5.9 ± 1.1	5.04	< 0.001
Fasting glucose (mmol/L)	7.6 ± 2.4	5.8 ± 1.6	5.20	< 0.001

¹Mann-Whitney U test.

BMI: Body mass index; COPD: Chronic obstructive pulmonary disease; ASA: American Society of Anesthesiologists; NRS: Nutritional Risk Screening; WBC: White blood cell; CRP: C-reactive protein; HbA1c: Glycosylated hemoglobin; IQR: Interquartile range.

Table 2 Operative characteristics of patients with and without severe postoperative infections, n (%)/mean ± SD

Variable	Infection group (n = 38)	Non-infection group (n = 118)	t/χ2	P value
Primary diagnosis			3.42	0.490
Colorectal cancer	15 (39.5)	40 (33.9)
Gastric cancer	10 (26.3)	28 (23.7)
Hepatocellular carcinoma	6 (15.8)	19 (16.1)
Pancreatic diseases	5 (13.2)	14 (11.9)
Other	2 (5.3)	17 (14.4)
Surgical approach			7.01	0.008
Open	27 (71.1)	55 (46.6)
Laparoscopic/MIS	11 (28.9)	63 (53.4)
Wound classification			9.27	0.002
Clean-contaminated	23 (60.5)	99 (83.9)
Contaminated/dirty	15 (39.5)	19 (16.1)
Emergency surgery	8 (21.1)	12 (10.2)	2.90	0.089
Operative duration (minute)	285.6 ± 98.4	198.3 ± 78.6	5.44	< 0.001
≥ 240 minutes	24 (63.2)	32 (27.1)	16.04	< 0.001
Blood loss (mL)	486.2 ± 312.5	268.4 ± 198.7	4.82	< 0.001
Blood transfusion	16 (42.1)	22 (18.6)	8.45	0.004
Drainage placement	30 (78.9)	72 (61.0)	3.98	0.046

MIS: Minimally invasive surgery.

Table 3 Distribution of severe postoperative infection sites and Clavien-Dindo grades (n = 38)

Infection site	n (%)	Grade IIIa/b	Grade IVa/b	Grade V
Intra-abdominal	20 (52.6)	14	5	1
Abscess	12 (31.6)	9	3	0
Anastomotic leak	5 (13.2)	2	2	1
Infected collection	3 (7.9)	3	0	0
Surgical site infection	11 (28.9)	9	2	0
Deep incisional	7 (18.4)	6	1	0
Organ/space	4 (10.5)	3	1	0
Pulmonary infection	7 (18.4)	5	2	0
Secondary bacteremia	6 (15.8)	-	-	-

Table 4 Distribution of pathogenic organisms isolated from severe postoperative infections (n = 44 isolates), n (%)

Pathogen	Isolates	%	ESBL+	MDR
Gram-negative bacteria	29	65.9
Escherichia coli	12	27.3	5 (41.7)	4 (33.3)
Klebsiella pneumoniae	8	18.2	2 (25.0)	2 (25.0)
Pseudomonas aeruginosa	5	11.4	-	2 (40.0)
Enterobacter cloacae	4	9.1	-	1 (25.0)
Gram-positive bacteria	11	25.0
Enterococcus faecalis	5	11.4	-	1 (20.0)
Staphylococcus aureus	4	9.1	-	1 (25.0)1
Other Gram-positive	2	4.5	-	0
Fungi	4	9.1
Candida albicans	3	6.8	-	-
Candida glabrata	1	2.3	-	-

¹Methicillin-resistant Staphylococcus aureus.

Percentages in the main % column are calculated using all 44 isolates as the denominator; multidrug-resistant percentages in parentheses are calculated using the number of isolates of each listed pathogen as the denominator. ESBL: Extended-spectrum beta-lactamase; MDR: Multidrug-resistant.

Table 5 Multivariate logistic regression analysis of risk factors for severe postoperative infection

Variable	β	SE	Wald	Adjusted OR	95%CI	P value
Diabetes mellitus	1.138	0.415	7.52	3.12	1.38-7.06	0.006
Albumin < 35 g/L	1.054	0.408	6.68	2.87	1.29-6.39	0.010
Operative time ≥ 240 minutes	0.971	0.412	5.56	2.64	1.18-5.92	0.018
Open approach	0.880	0.424	4.31	2.41	1.05-5.54	0.038

OR: Odds ratio; CI: Confidence interval.

Table 6 Comparison of clinical outcomes between infection and non-infection groups, n (%)/mean ± SD

Variable	Infection group (n = 38)	Non-infection group (n = 118)	t/χ2	P value
Total hospital stay (days)	24.3 ± 9.8	11.6 ± 5.2	10.46	< 0.001
Postoperative stay (days)	19.8 ± 8.6	8.4 ± 4.3	10.72	< 0.001
ICU admission	14 (36.8)	8 (6.8)	21.02	< 0.001
ICU stay (days, median, IQR)	4.5 (2-8)	2 (1-3)	2.861	0.004
Mechanical ventilation	6 (15.8)	3 (2.5)	8.94	0.003
Re-intervention	10 (26.3)	2 (1.7)	22.84	< 0.001
Percutaneous drainage	6 (15.8)	1 (0.8)
Reoperation	4 (10.5)	1 (0.8)
30-day mortality	4 (10.5)	1 (0.8)	8.14	0.004
30-day readmission	8 (21.1)	6 (5.1)	9.04	0.003

¹Mann-Whitney U test.

ICU: Intensive care unit; IQR: Interquartile range.