3.1 The general information
94 cases of the 2297 patients who underwent colorectal surgery and were included in the study have SSIs. 44 patients have MDRO infection, while 10 of these patients have drug-sensitive organism infection, and 40 of these patients do not have specific pathogens. As a result, the incidence of surgical site infection following colorectal surgery is 4.09%, while the incidence of infections caused by MDRO is 1.92%. Compared to the control group, the infection group has a heavier disease burden. The duration of hospital stays and overall costs are longer in the infection group than in the control group. The difference is statistically significant. Table 1 displays the patients’ demographics and clinical data.
Table 1. demographics and clinical data
|
Infection group (n=94)
|
Control group(n=93)
|
P value
|
Demographics data
|
|
|
|
Age
|
59.69±10.18
|
60.00±9.45
|
0.830
|
Gender (male/female)
|
68/26
|
67/26
|
0.964
|
Clinical data
|
|
|
|
Operation time(min)
|
225(185.00-271.25)
|
210(160.00-250.00)
|
0.084
|
Preoperative serum creatinine(mmol/L)
|
75.50(65.00-89.00)
|
78.00(68.75-86.55)
|
0.428
|
Preoperative total bilirubin (mmol/L)
|
9.25(6.78-14.75)
|
10.40(7.40-14.20)
|
0.771
|
Preoperative albumin level (g/L)
|
37.35(34.58-40.20)
|
38.50(36.50-40.40)
|
0.034
|
Preoperative fasting blood glucose (mmol/L)
|
5.19(4.77-5.86)
|
4.97(4.46-5.63)
|
0.093
|
History of Inpatient Visits
|
38/94
|
30/93
|
0.245
|
ICU admission to before infection
|
7/94
|
0/93
|
0.014
|
Ever multidrug resistant bacteria infections
|
0/94
|
0/93
|
/
|
Prior use of antibiotics
|
16/94
|
0/93
|
<0.001
|
Implants in the surgery
|
1/94
|
0/93
|
1.000
|
Mechanical ventilation
|
14/94
|
1/93
|
0.001
|
Trachea cannula
|
14/94
|
1/93
|
0.001
|
Tracheotomy
|
0/94
|
0/93
|
/
|
Retention catheterization
|
93/94
|
93/93
|
1.000
|
Central venous indwelling catheter
|
87/94
|
75/93
|
0.017
|
Use fiberoptic bronchoscope
|
0/94
|
0/93
|
/
|
Use of gastroscope
|
87/94
|
84/93
|
0.586
|
Blood purification treatment
|
1/94
|
0/93
|
1.000
|
Total parenteral nutrition
|
0/94
|
0/93
|
/
|
Blood transfusion
|
8/94
|
0/93
|
0.007
|
Other invasive procedures
|
0/94
|
0/93
|
/
|
Radiotherapy
|
4/94
|
1/93
|
0.386
|
Chemotherapy
|
19/94
|
21/93
|
0.693
|
Immunosuppressive agents
|
0/94
|
2/93
|
0.246
|
Long-term and heavy use of glucocorticoids
|
0/94
|
0/93
|
/
|
Unconscious before surgery
|
0/94
|
0/93
|
/
|
Unconscious after surgery
|
0/94
|
0/93
|
/
|
Chronic neonatal lung disease
|
7/94
|
1/93
|
0.065
|
Cardiovascular disease
|
18/94
|
28/93
|
0.092
|
Diabetes
|
9/94
|
13/93
|
0.374
|
Hematological malignancy
|
0/94
|
0/93
|
/
|
Traumatism
|
1/94
|
0/93
|
1.000
|
Fire burn
|
0/94
|
0/93
|
/
|
Liver cirrhosis
|
0/94
|
0/93
|
/
|
Chronic renal insufficiency
|
0/94
|
1/93
|
1.000
|
Disease burden
|
|
|
|
Hospitalization costs(yuan)
|
85716.96(72069.25-106707.84)
|
56318.06(49657.60-64092.41)
|
<0.001
|
Length of stay (day)
|
27.50(22-34)
|
15(12-18)
|
<0.001
|
*Quantitative data with a normal distribution and homogeneous variance are described by the mean ± standard deviation; otherwise, the median and interquartile range are used to depict the data.
3.2 Type of surgical site infection
SSIs include superficial incision infection, deep incision infection, and organ compartment infection. Table 2 displays this comprehensive data.
Table 2. sites of infection
|
All infection case
|
MDR group
|
NMDR group
|
Superficial incision infection
|
18(19.15%)
|
7(15.91%)
|
11(22.00%)
|
Deep incision infection
|
12(12.76%)
|
7(15.91%)
|
5(10.00%)
|
Organ/space infection
|
64(68.09%)
|
30(68.18%)
|
34(68.00%)
|
Total
|
94(100%)
|
44(100%)
|
50(100%)
|
3.3 Etiological distribution of patients with surgical site infection
The primary pathogens detected are Escherichia coli (n = 43,57.33%), Klebsiella pneumonia (n = 5,6.67%), Pseudomonas aeruginosa (n = 10,13.33%), Enterococcus faecalis (n = 5,6.67%), Enterococcus faecium (n = 1,1.33%), Enterococcus avium (n = 7,9.33%), other strains (n = 4,5.34%) in 54 patients who has unambiguous etiological examination results. Table 3 details this information.
Table 3. etiological distribution of patients with surgical site infection
pathogenic species
|
strain number(strain)
|
detection rate
|
Escherichia coli
|
43
|
57.33%
|
Klebsiella pneumoniae
|
5
|
6.67%
|
Pseudomonas aeruginosa
|
10
|
13.33%
|
Enterococcus faecalis
|
5
|
6.67%
|
Enterococcus faecium
|
1
|
1.33%
|
Enterococcus avium
|
7
|
9.33%
|
Other strains
|
4
|
5.34%
|
Total
|
75
|
100%
|
3.4 Susceptibility results of a pathogen in surgical site infection
3.4.1 Drug resistance rate of gram-negative bacteria to surgical site infection after colorectal surgery
In contrast to imipenem and piperacillin tazobactam, Escherichia coli had high resistance to ampicillin, cefazolin, cefuroxime, ceftriaxone, levofloxacin, ciprofloxacin, gentamicin, and ampicillin sulbactam. Ampicillin, cefazolin, cefoxitin, cefuroxime, and ceftriaxone had a high level of resistance against Klebsiella pneumonia, while imipenem, levofloxacin, ciprofloxacin, gentamicin, and piperacillin tazobactam had a low level of resistance. All antimicrobials were only moderately resistant to pseudomonas aeruginosa. Table 4 shows this specific information in detail.
Table 4. Drug resistance rate of gram-negative bacteria
antimicrobials
|
Escherichia coli
|
Klebsiella pneumoniae
|
Pseudomonas aeruginosa
|
ampicillin
|
90.70%
|
100%
|
/
|
cefazolin
|
72.09%
|
60.00%
|
/
|
cefoxitin
|
25.58%
|
40.00%
|
/
|
cefuroxime
|
67.44%
|
60.00%
|
/
|
ceftriaxone
|
62.79%
|
40.00%
|
/
|
imipenem
|
2.33%
|
0
|
0
|
levofloxacin
|
46.51%
|
0
|
10.00%
|
ciprofloxacin
|
51.16%
|
0
|
0
|
gentamicin
|
41.86%
|
0
|
0
|
Ampicillin sulbactam
|
44.19%
|
20.00%
|
10.00%
|
Piperacillin tazobactam
|
6.98%
|
0
|
10.00%
|
3.4.2 Drug resistance rate of gram-positive bacteria to surgical site infection after colorectal surgery
All antimicrobials were only moderately resistant to enterococcus faecalis. A high level of resistance to ampicillin, levofloxacin, ciprofloxacin, and tetracycline was present in Enterococcus faecium, but not to gentamicin, tigecycline, and vancomycin. A high level of gentamicin and tetracycline resistance was present in Enterococcus avium, whereas ampicillin, levofloxacin, ciprofloxacin, tigecycline, and vancomycin resistance were absent. Table 5 displays this comprehensive information.
Table 5. Drug resistance rate of gram-positive bacteria
antimicrobials
|
Enterococcus faecalis
|
Enterococcus faecium
|
Enterococcus avium
|
ampicillin
|
0
|
100%
|
28.57%
|
levofloxacin
|
0
|
100%
|
14.29%
|
ciprofloxacin
|
0
|
100%
|
14.29%
|
gentamicin
|
20.00%
|
0
|
71.43%
|
tigecycline
|
20.00%
|
0
|
0
|
tetracycline
|
40.00%
|
100%
|
100%
|
vancomycin
|
0
|
0
|
0
|
3.5 Risk factors for surgical sites infection
Low albumin levels before surgery, prior use of antibiotics, preoperative ICU stay, mechanical ventilation, trachea cannula, central venous indwelling catheter, and blood transfusion are all statistically significant risk factors between the case and control groups, according to a univariate analysis. The aforementioned statistically significant factors are examined using multi-factor logistic regression analysis. A multi-factor logistic regression analysis reveals that the only independent risk factor for SSIs is mechanical ventilation. The particular details are shown in Table 6.
Table 6. Risk factors for surgical sites infections
|
|
|
Univariate analysis
|
multi-factor logistic regression analysis
|
factors
|
Case group(n=94)
|
Control group(n=93)
|
OR(95%CI)
|
P
|
β
|
SE
|
Wald X2
|
P
|
OR(95%CI)
|
albumin before surgery
|
37.35,5.65
|
38.50,3.90
|
/
|
0.034
|
|
|
|
|
|
prior use of antibiotics
|
16
|
0
|
0.830(0.757~0.909)
|
<0.001
|
|
|
|
|
|
preoperative ICU admission
|
7
|
0
|
0.926(0.874~0.980)
|
0.014
|
|
|
|
|
|
mechanical ventilation
|
14
|
1
|
16.10(2.071~125.158)
|
0.001
|
2.309
|
1.081
|
4.559
|
0.033
|
10.063(1.208~83.785)
|
trachea cannula
|
14
|
1
|
16.10(2.071~125.158)
|
0.001
|
|
|
|
|
|
central venous indwelling catheter
|
87
|
75
|
2.983(1.182~7.530)
|
0.017
|
|
|
|
|
|
blood transfusion
|
8
|
0
|
0.915(0.860~0.973)
|
0.007
|
|
|
|
|
|
3.6 risk factors for multidrug-resistant organism of surgical site infection
ICU admission, mechanical ventilation, trachea cannula, and high preoperative venous blood glucose levels were statistically significantly different between the multi-resistant case group and the NMDR case group, according to a univariate analysis. The aforementioned statistically significant factors are examined using multi-factor logistic regression analysis. The only independent risk factor for multi-resistance organism infection at the surgical site infection is mechanical ventilation. Table 7 provides more information in detail.
Table 7. risk factors for multi-drug resistant organism
|
|
|
univariate analysis
|
multi-factor logistic regression analysis
|
factors
|
MDR group(n=44)
|
NMDR group(n=50)
|
OR (95%CI)
|
P
|
β
|
SE
|
Wald X2
|
P
|
OR(95%CI)
|
ICU admission
|
7
|
0
|
0.841(0.739~0.956)
|
0.004
|
|
|
|
|
|
mechanical ventilation
|
11
|
3
|
5.222(1.351~20.184)
|
0.018
|
1.836
|
0.814
|
5.084
|
0.024
|
6.273(1.271~30.948)
|
trachea cannula
|
11
|
3
|
5.222(1.351~20.184)
|
0.018
|
|
|
|
|
|
high preoperative venous blood glucose
|
5.34,1.33
|
5.03,1.03
|
/
|
0.042
|
|
|
|
|
|