Diabetes is a metabolic syndrome characterized by hyperglycemia, which has become a heavy burden to China [
There were several researches reported that acute DFI is usually caused by aerobic Gram-positive cocci, but deep or chronic wounds often harbor aerobic Gram-negative and obligate anaerobic bacteria, often polymicrobial flora [
On the other hand, to better provide optimal antimicrobial therapy, clinician should be familiar with the common microbial isolates and antibiotic resistance patterns in their own region of practice. Many studies from different regions showed different bacterial profiles in DFIs, especially in warm climate in Asia and Africa [
With the aim of understanding the bacterial profile and antibiotic resistance patterns in DFUs in Guangzhou, furthermore in different Wagner’s grades, IDSA/IWGDF grades, and different ulcer types, 117 DFI patients and 207 bacterial isolates were collected from Sun Yat-sen Memorial Hospital from Jan. 1, 2010, to Dec. 31, 2015. The clinical data and microbial information were compared among the different DFUs’ grades and types. This knowledge will provide more practical advice about antibiotic agent choice to the clinicians.
A hospital-based retrospect study of 405 inpatients (238 males and 167 females) with DF in the Department of Endocrinology and Metabolism in Sun Yat-sen Memorial Hospital between Jan. 1, 2010, and Dec. 31, 2015, was carried out, including 388 DFU (230 males and 158 females), among which 117 cases presented DFI (72 males and 45 females). Therefore, a total of 117 complete surveys were obtained.
All patients, parents, or guardians signed informed consent approving the use of their specimen samples for research purposes, and the Ethics Committee of Sun Yat-sen Memorial Hospital approved the study. Ethical committee’s Reference number: [2017] 伦备第(09)号. Clinical diagnosis of infection was defined by the presence of at least 2 of the following indicators: local swelling or indurations, >0.5 cm of erythema around the wound, local tenderness or pain, local warmth, and purulent discharge [
Characteristics of DFIs of varying Wagner’s grades, IDSA/IWGDF grades, and DFU types.
Clinical characteristic | Wagner’s grades | IDSA/IWGDF grades | DFU types | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
1 | 2 | 3 | 4 | 1 | 2 | 3 | 4 | IFU | NFU | N-IFU | |
Number of patients ( |
7 | 34 | 44 | 32 | 1 | 54 | 53 | 9 | 53 | 5 | 59 |
Mean age (years, y)a | 66.7 ± 14.8 | 64.7 ± 9.7 | 64.0 ± 11.0 | 66.1 ± 11.6 | 63.4 | 65.9 ± 11.2 | 65.0 ± 11.6 | 62.2 ± 11.5 | 64.8 ± 11.5 | 63.4 ± 14.0 | 65.5 ± 11.0 |
Male/female ( |
2/5 | 20/14 | 30/14 | 20/12 | 1/0 | 34/20 | 32/21 | 5/4 | 35/18 | 2/3 | 35/24 |
Duration of diabetes | 1.5 (59.0) | 2.5 (23.0) | 18.6 (24.5) | 4.2 (7.6) | 1.8 | 2.7 (23.9) | 6.5 (23.5) | 2.8 (13.6) | 4 (23.0) | 24 (31.3) | 6.8 (10.5) |
(months, m)b | |||||||||||
BMIa | 24.5 ± 6.0 | 24.5 ± 5.6 | 23.4 ± 2.7 | 27.0 ± 2.1 | 25.9 | 24.0 ± 4.4 | 27.7 ± 2.1 | 23.3 ± 2.2 | 28.3 ± 2.1 | 24.9 ± 3.9 | 23.4 ± 3.8 |
HbA1c (%)a | 6.5 ± 1.4 | 8.9 ± 2.0 | 8.0 ± 2.3 | 8.8 ± 2.9 | 7.9 | 8.6 ± 2.4 | 7.9 ± 2.1 | 9.9 ± 3.2 | 8.6 ± 2.2 | 9.6 ± 2.8 | 8.3 ± 2.6 |
CRP (mg/L)b |
19.7 (76.3) | 22 (46.5) | 25.5 (72.8) | 91.9 (226.9) | 11 | 21.8 (47.5) | 49.3 (117.9) | 197.6 (231.4) | 22.7 (69.5) | 10.9 (129.0) | 70 (82.7) |
PCT (mmol/L)b |
0.2 (0.1) | 0.2 (0.3) | 1.0 (0.3) | 2.5 (0.6) | 0 | 0.2 (0.2) | 0.7 (0.1) | 2.4 (0.4) | 0.2 (0.1) | 0.1 (0.0) | 0.7 (0.2) |
Newly diagnosedc |
1 (14.3) | 11 (32.4) | 7 (15.9) | 12 (37.5) | 0 (0.0) | 21 (38.8) | 8 (15.1) | 2 (22.2) | 11 (20.75) | 0 (0.0) | 20 (33.8) |
Polymicrobial infectionc | 4 (57.1) | 22 (64.7%) | 24 (54.5%) | 20 (62.5%) | 0 (0.0) | 38 (70.4%) | 27 (50.9%) | 6 (66.7%) | 28 (52.8%) | 1 (20.0%) | 41 (69.5%) |
aExpressed as mean ± SD; bexpressed as media (interquartile range); cexpressed as number (percentage); BMI: body mass index; CRP: C-reaction protein; PCT: procalcitonin.
All the specimens were sampled to the microbiology laboratory within 48 h after hospital admission. Swabbing were collected from each wound after the wound had been cleansed (using 0.9% sterile saline and gauze) and debrided (removal of necrotic tissue, foreign material, calluses, and undermined wound edges) [
In descriptive statistics, the frequency of isolate distribution and antibiotic resistance was treated as categorical variables. The chi-square or two-sided Fisher’s exact test was used to discriminate whether the distributions were significantly different between different groups. The distributed variables were expressed as the mean ± standard deviation and compared by one-way ANOVA. Variables without normal distribution were expressed as the media (interquartile range) and compared by Kruskal-Wallis
Totally, 95.8% DF patients suffered from DFU (388/405), 30.2% (117/388) of which were clinically infected. Additionally, the DFIs in this study were mainly classified in the moderate or severe grades (Wagner’s 2~4 grades and IDSA/IWGDF 2~3 grades), rarely in the mild stage, and only 5 patients were NFU (4.3%). All the patients enrolled were type 2 diabetes ones. The percentage of newly diagnosed DFUs was 26.4%, mainly in Wagner’s grades 2 and 4 (32.4% and 37.5%), IDSA/IWGDF grade 2 (38.8%), and N-IFUs (33.8%). With an increasing Wagner’s grades and IDSA/IWGDF grades, the serum C-reaction protein (CRP) and procalcitonin (PCT) level had an increased trend (
A total of 232 isolates were detected from the 117 specimens, including 207 (89.2%) bacteria and 25 (10.7%) funguses, totally 46 pathogens (Figure
Distribution of the 207 bacteria isolates.
With an increasing of Wagner’s grades and IDSA/IWGDF grades, the proportion of Gram-negative bacterial infection was obviously increased (Figure
Distribution of bacteria of DFIs of varying Wagner’s grades, IDSA/IWGDF grades, and DFU types. (a) The number of bacteria isolated in different DFU types; (b) the number of bacteria isolated in different IDSA/IWGDF grades; (c) the number of bacteria isolated in different Wagner’s grades.
Distribution of bacteria of DFIs of varying Wagner’s grades, IDSA/IWGDF grades, and DFU types.
Classification ( |
Gram-positive coccus |
Gram-negative bacilli | ||||||
---|---|---|---|---|---|---|---|---|
|
CNS |
|
|
Enterobacteriaceae |
|
|
Other non- |
|
DFU type | ||||||||
NFU (10) | 2 (20.0) | 2 (20.0) | 1 (10.0) | 1 (10.0) | 4 (40.0) | 0 | 0 | 0 |
IFU (94) | 21 (22.3) | 14 (14.9) | 6 (6.4) | 8 (8.5) | 30 (31.9) | 3 (3.0) | 9 (9.6) | 3 (3.2) |
N-IFU (103) | 16 (15.5) | 7 (6.8) | 7 (6.8) | 10 (9.7) | 48 (46.6) | 5 (4.9) | 7 (6.8) | 3 (2.9) |
Wagner’s grades | ||||||||
Grade 1 (11) | 5 (45.5) | 1 (9.1) | 0 | 1 (9.1) | 4 (36.4) | 0 | 0 | 0 |
Grade 2 (68) | 10 (14.7) | 12 (17.6) | 6 (8.8) | 8 (11.7) | 27 (39.4) | 0 | 4 (5.9) | 1 (1.4) |
Grade 3 (71) | 14 (19.7) | 7 (9.8) | 6 (8.5) | 6 (8.5) | 28 (39.4) | 3 (4.2) | 5 (7.0) | 2 (2.8) |
Grade 4 (57) | 10 (17.5) | 3 (5.3) | 2 (3.5) | 4 (7.0) | 23 (40.3) | 5 (8.7) | 7 (12.3) | 3 (5.3) |
IWGDF grades | ||||||||
Grade 1 (1) | 0 | 1 (100.0) | 0 | 0 | 0 | 0 | 0 | 0 |
Grade 2 (104) | 22 (21.2) | 15 (14.4) | 5 (4.8) | 10 (9.6) | 42 (40.4) | 3 (2.8) | 5 (4.8) | 2 (1.9) |
Grade 3 (87) | 14 (16.1) | 7 (8.0) | 8 (9.2) | 8 (9.2) | 35 (40.2) | 4 (4.6) | 8 (9.2) | 3 (3.4) |
Grade 4 (15) | 3 (20.0) | 0 | 1 (6.7) | 1 (6.7) | 5 (33.3) | 1 (6.7) | 3 (20.0) | 1 (6.7da) |
aThe numbers of the pathogens isolated; CNS: coagulase negative
More than a half of the DFIs in this study were polymicrobial (59.8%, 70/117), with aerobic Gram-positive cocci (GPC), and especially staphylococci, the most common causative organisms. Especially in the IWGDF grade 2, Wagner’s grade 2/4 DFUs, and N-IFU patients (Table
MDR (multiple-drug resistance) isolates were broadly distributed in the 207 bacteria isolated from different grades and DFU types (40.5%, 84/207). XDR (extensively drug resistant) isolates accounted for 9.7% in the bacteria (20/207), mainly isolated in Wager’s grade 3 (14.1%, 10/71) and IWGEF grade 3 (13.8%, 12/87), especially IFUs (12.8%, 12/94). The definition of MDR and XDR was according to the international expert proposal for interim standard definition for acquired resistance in 2012 [
As the main pathogens of DFI, the antibiotic sensitivity information of
As the representative of Gram-positive cocci,
Antibiotic resistance rates of Enterobacteriaceae isolated in DFI in different Wagner’s grades, IDSA/IWGDF grades, and DFU types. (a) Antibiotic resistance rates of Enterobacteriaceae isolated in different IDSA/IWGDF grades’ DFIs; (b) antibiotic resistance rates of Enterobacteriaceae isolated in different Wagner’s grades’ DFIs; (c) antibiotic resistance rates of Enterobacteriaceae isolated in different DFU types. AMP, ampicillin; SAM, ampicillin/sulbactam; ATM, aztreonam; IPM, imipenem; MEM, meropenem; CTT, cefotetan; CZO, cephazolin; CXM, cefuroxime; CRO, ceftriaxone; CAZ, ceftazidime; FEP, cefepime; CSL, cefoperazone/sulbactam; CIP, ciprofloxacin; LEV, levofloxacin; SXT, trimethoprim/sulfamethoxazole; AMK, amikacin; GEN, gentamicin; TOB, tobramycin; TZP, piperacillin/tazobactam.
Similarly, high resistance rates to the common antibiotics were detected in Enterobacteriaceae. Almost all the isolates were resistant to the ampicillin (85.4%, 70/82), followed by the first/second generation cephalosporin, including cefazolin (72.0%, 59/82) and cefuroxime (64.6%, 53/82), especially in the higher Wagner’s grades and IDSA/IWGDF grades. Low resistance rates were detected to carbapenem (1.2%, 1/82), cefoperazone-sulbactam (7.3%, 6/82), the fourth generation cephalosporin (8.5%, 7/82), and tobramycin (8.5%, 7/82). Generally, the resistance to antibiotic increased with the increasing of IDSA/IWGDF grades (Figure
Antibiotic resistance rates of
According to the resistance rates of 33 antibiotic agents of the two major pathogens above, we defined the regimens whose resistance rate was <30% as “potential empirical regimens” and the ones whose resistance rate > 70% as “alarming empirical regimens” in every grades and types. Details showed in Table
Potential and alarming empirical regimens for different Wagner’s grades, IDSA/IWGDF grades, and types of diabetic foot infections.
Classification | Usual pathogen(s)a | Potential empirical regimensb | Alarming empirical regimensc |
---|---|---|---|
Type | |||
NFU | Enterobacteriaceae | Aztreonam; cefotetan; 2nd~4th gen ceph; carbapenem; FQ; cipro; T/S; |
First gen ceph; ampicillin |
IFU | Enterobacteriaceae | Aztreonam; 3rd/4th gen ceph; carbapenem; FQ; cipro; T/S; |
Ampicillin |
|
|
Pen; second/third gen ceph; tetracycline | |
N-IFU | Enterobacteriaceae | Aztreonam; cefotetan; 3rd/4th gen ceph; carbapenem; |
First/second gen ceph; ampicillin |
|
|
Pen | |
Wagner’s grade | |||
1~2 |
|
|
Pen |
Enterobacteriaceae | Aztreonam; cefotetan; 3rd/4th gen ceph; carbapenem; FQ; cipro; T/S; |
First gen ceph; ampicillin | |
3 | Enterobacteriaceae | Aztreonam; cefotetan; 3rd/4th gen ceph; carbapenem; FQ; |
First/second gen ceph; ampicillin |
|
|
Pen; tetracycline | |
4 | Enterobacteriaceae | Same to Wanger grade 3 | First/second gen ceph; ampicillin |
|
Same to Wanger grade 3 | Pen; first~third gen ceph; tetracycline | |
IWGDF grade | |||
1~2 | Enterobacteriaceae | Aztreonam; cefotetan; 2nd~4th gen ceph; carbapenem; FQ; cipro; clindamycin; T/S; |
First gen ceph; ampicillin |
|
|
Pen | |
3 | Enterobacteriaceae | aztreonam; cefotetan; 2nd ~ 4th gen ceph; carbapenem; FQ; cipro; |
First/second gen ceph; ampicillin |
|
|
Pen; third gen ceph; tetracycline | |
4 | Enterobacteriaceae | Carbapenem; |
First/second gen ceph; ampicillin |
|
|
Pen; first~third gen ceph; tetracycline |
To our knowledge, this is the first prospective study on microbiological profile and antibiotic resistance pattern of the diabetic foot infection based on the different classification systems, in order to give the clinicians more suggestions in details for initial empirical antibiotic selection according to the comprehensive assessment of the patients.
DFU continues to be a major reason for lower extremity amputation worldwide [
To the DFIs, selection of an initial antibiotic regimen is usually empirical, so the likely pathogens and their antibiotic sensitivity often are “guessed” by the clinician before the microorganism cultivation and sensitivity tests. Therefore, a detailed bacterial profile and antibiotic resistance pattern associated with the different severity and types of DFIs is urgently needed for the clinicians. Actually, the severity of the DFU and infection is first determined by the clinical classification scheme. Various classification systems have been proposed to assess the severity of diabetic foot lesion that attempt to encompass different characteristics of ulcer including ulcer size, depth, ischemia, infection, and neuropathy [
In this study, different bacterial profiles and antibiotic sensitivity were found in different Wagner’s grade, IWGDF grade, and DFU types. With the aggravation of the wound and infection, the Gram-negative bacterial species harbored and increased, especially the proportion of
Selection of an initial antibiotic regimen is usually empirical, that is, the best guess at what agents will cover the likely pathogens. In details, this study gave the clinician suggestions about the most possible regimens as the “potential antibiotics,” and the regimens should not be used for their high resistance as the “alarming antibiotics” according to different wounds. When the patients were evaluated by Wagner-Meggit classification system and IWGDF/IDSA classification system, and the ulcers were typed as IFU, NFU, or N-IFU, clinicians can choose the overlapping of different systems according to Table
However, this paper only provided the empirical regimens selected suggestion about the predominant GNB and GPB, while did not cover all the pathogens. Actually, some other pathogens showed higher resistance rates to more antibiotics due to their natural resistance, for example, the
The major limitation of this study is the lack of anaerobic culturing. Further study is required to evaluate the anaerobic distribution and drug sensitivity in the different grades of DFUs. Another limitation is the small number of included patients, especially those with Wagner-Meggit grade 1 or IWGDF/IDSA grade 1 wound, and rarely neuropathic ulcerations. Tissue biopsy is known as the most standard method, and swab cultures are considered as not reliable since it generally includes the colonizers and not the causative pathogen [
Different bacterial profiles and antibiotic sensitivity were found in different Wagner’s grades, IWGDF grades, and DFU types. Clinician should try to stay updated in antibiotic resistance pattern of common pathogens in their area, especially when practice on the empirical antibiotic use. This paper provided the detailed practical information (potential empirical regimens and alarming empirical regimens) to the clinician based on the assessments to the DFIs from the different aspects in this region.
The funders played no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.
The authors declare that they have no competing interests.
Songyin Huang, Zhaofan Luo, and Xiaoying Xie contributed to the design of the study and the writing of the manuscript. Yunwen Bao, Lijia Ni, and Dan Liu performed the experiments. Shaona Niu, Haixiong Lin, Hongyu Li, Li Yan, and Chaohui Duan assisted in the quantitative data collection. All authors read and approved the final version of the manuscript. Xiaoying Xie and Yunwen Bao contributed equally to this work.
This work was supported by the grants from the Natural Science Foundation of Guangdong Province (2016A030313345) and the Sun Yat-sen Initiative Program for Scientific Research (YXQH201701). This work was supported by Grant [2013]163 from the Key Laboratory of Malignant Tumor Molecular Mechanism and Translational Medicine of Guangzhou Bureau of Science and Information Technology.