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Can Open Fracture Debridement Improve Postoperative Wound Infection?

Damaged soft tissues provide an ideal environment for bacterial growth and subsequent infections. This study was to evaluate the spectrum of bacterial contamination of predebridment and postdebridment measures in patients with open fractures and to study the best timing suitable for eradication of the micro-organism in a tertiary hospital. These studies was conducted over 112 patients open fracture wound episodes with or without overt signs of infection were included in this study. A patient is considered to have an open fracture wound infection when clinical signs and symptoms of infection were present. Four swabs were taken for each patient, the first was taken as pre debridement swab, the second was post debridement swab, the third swab was after 3 days after debridement and the fourth was 7 days after debridement. Specimens were examined aerobically and anaerobically. Of the 112 wound specimens examined by Gram stain, 66.96% were positive for the presence of bacteria. The Gram-positive and Gram-negative bacteria accounted for 58.66% and 41.33%, respectively. S. aureus (44.2%) was the dominant isolate. The most effective drugs against the tested Gram-positive were amoxicillin/clavulonic acid, erythromycin, vancomycin, cefuroxime and ampicillin. Whereas, the most effective drugs against the tested Gram-negative bacteria were gentamicin, ciprofloxacin, tazocin, imipenem and aztreonam. Postoperative bacterial infection can be decreased if debridement was done at optimum time.


INTRODUCTION
Damaged soft tissues provide suitable medium for bacterial growth. Bacterial growth is correlated to the severity of the soft tissue injury. It is favored by long tissue ischemia and poor perfusion of muscles and periosteum that lead to tissue necrosis [1].
Open fractures were classified by Gustilo and Anderson [2] into Grade I, Grade II and Grade III. Grade III was sub classified into a, b, c. Infections in Grade I and Grade II open fractures are quite infrequent which was demonstrated by Gustilo et al. [3] but in Grade III open fractures, the overall infection rate was about 50%.
The debridement of wounds was described first by Desault [4] in the 18th century. It has since evolved to include the thorough irrigation of the fracture site by a number of different means. Irrigation and debridement is believed to be the most important factor in reducing the prevalence of infection following an open fracture [5].
Lee [6] postulated that bacterial cultures were of no predictive value regarding later infection and even in positive post debridement bacterial cultures only 42% resulted in infections. However, Kreder and Armstrong [7] reported that predebridment bacterial culture were highly sensitive (88%) in identifying wounds developing infection but their specificity was as low as 42%.
Treatment for open fractures is controversy. It usually involves wound debridement with irrigation, intravenous antibiotics, good coverage for the bone and soft tissue, and adequate rigid stabilization [8][9][10].
This study aimed to evaluate the spectrum of bacterial contamination pre and post debridement in patients with open fractures in a tertiary hospital and to study the best timing suitable for eradication of the micro-organism and if it is effective to decrease the postoperative infections or of no value.

PATIENTS AND METHODS
A cross-sectional prospective study was conducted in the Medical Microbiology and Plain radiographs images were taken for each patient. Wound beds were prepared before specimen collection by using Levine's technique [15], where the wound surface is cleansed with moistened sterile gauze. Dressed wounds were cleansed with non-bacteriostatic sterile normal saline after removing the dressing. This technique is believed to be the best technique for swabbing open wounds and more reflective of tissue bioburden than swabs of exudates or swabs by other techniques [16 cotton-tipped applicator was rotated over a 1 cm 2 area for 5 seconds with sufficient pressure to express fluid and bacteria to surface from within the wound tissue. The applicators were applied deep into the wounds in order to avoid contaminants that are usually found on the surface of the wounds [15,16].
In this study, there were four swabs taken for each patient, the first swab was taken as pre debridement swab, the second was post debridement swab, the third swab was after 3 days from the debridement and the fourth swab was 7 days from the debridement. S were transported in Amies transport medium (Oxoid Ltd, UK) to the bacteriological laboratory within an hour. The specimens that were collected during night were kept at 4 until staining and culture. Gram staining was performed for the wound swabs according to standard procedures. All wound swabs were cultured aerobically, anaerobically and for mycological culture. For aerobic cultures, the swabs were cultured on the ordinary media (blood, chocolate and MacConkey's agars). Plates were incubated at 37°C for 48 hours. For anaerobic culture, the swabs were cultured on blood agar plate and incubated anaerobically at 37°C for 48 hours. Mycological analysis was done by direct examination and culture on Sabouraud Dextrose Agar with and without cyclohexamide and incubated at 37°C and 25°C. For positive bacterial isolates, routine biochemical reactions were done using the API system ( Fig. 1). The bacterial isolates were subjected to susceptibility testing by standard Kirby Bauer disc diffusion meth susceptibility patterns of the bacterial isolates were detected following the antimicrobial agents panel recommended by Clinical Laboratory Standard Institute (CLSI), 2010. The diameter of the inhibition zone was measured in millimeters and interpreted according to CLSI guidelines (Fig. 2).
Gram-positive bacteria were tested against amoxicillin (AML) (25 µg), amoxicillin Barakat et al.;BJMMR,16(4): [1][2][3][4][5][6][7][8][9][10][11]2016; Article no. 3 16]. A sterile tipped applicator was rotated over area for 5 seconds with t pressure to express fluid and bacteria to surface from within the wound tissue. The applicators were applied deep into the wounds in order to avoid contaminants that are usually found on the surface of the wounds In this study, there were four swabs taken for each patient, the first swab was taken as pre debridement swab, the second was post debridement swab, the third swab was after 3 days from the debridement and the fourth swab was 7 days from the debridement. Specimens were transported in Amies transport medium (Oxoid Ltd, UK) to the bacteriological laboratory within an hour. The specimens that were collected during night were kept at 4 o C overnight until staining and culture. Gram staining was wound swabs according to standard procedures. All wound swabs were cultured aerobically, anaerobically and for mycological culture. For aerobic cultures, the swabs were cultured on the ordinary media (blood, chocolate and MacConkey's agars). cubated at 37°C for 48 hours. For anaerobic culture, the swabs were cultured on blood agar plate and incubated anaerobically at 37°C for 48 hours. Mycological analysis was done by direct examination and culture on Sabouraud Dextrose Agar with and without yclohexamide and incubated at 37°C and 25°C. For positive bacterial isolates, routine biochemical reactions were done using the API 1). The bacterial isolates were subjected to susceptibility testing by standard Kirby Bauer disc diffusion methods. The susceptibility patterns of the bacterial isolates were detected following the antimicrobial agents panel recommended by Clinical Laboratory Standard Institute (CLSI), 2010. The diameter of the inhibition zone was measured in millimeters reted according to CLSI guidelines [17] positive bacteria were tested against g), amoxicillin-clavulonic

DATA ENTRY AND ANALYSIS
Data entry was done by using EpiInfo software and analysis was done using both EpiInfo-2002 software and SPSS version 13.0 for windows. Pearson chi-square and Fisher exact tests analysis were used to compare categorical variables. The level of significance was set at 0.05 in order to consider a p-value <0.05 as indicator of a statistically significant difference with 95% confidence.

RESULTS
One hundred and twelve patients were admitted into the Orthopedic Surgery Department at Mansoura University Hospital and Mansoura Emergency Hospital (MEH), Egypt. The relation between age, grade and the first and second swabs was revealed in Table 1. The s were sent to the Medical Microbiology and Diagnostics Unit at Medical Microbiology and Immunology Department. Direct Gram stained film and culture of the swabs revealed significant relation between patient age and bacterial growth in second swab but one ( Table 2).  of the swabs revealed significant relation between patient age and bacterial growth in second swab but not the first

Fig. 2. Antibiotic sensitivity test of Klebsiella pneumoniae
Of the 112 wound specimens cultured, 43 swabs (38.4%) were positive in the pre debridment swabs. Of these, 40 swabs (93.02%) were monomicrobial growth and 3 swabs (6.97%) were polymicrobial growth and no bacterial growth was detected in 69(61.6%) swabs. In the post debridment swabs; there was positive culture in 24 swabs (21.4%). Of these, 18 ones (75%) were mono-microbial growth and 6 swabs (25%) were polymicrobial growth and no bacterial growth in 88 swabs (78.6%). In the third swabs that were taken three days after trauma, positive growth was only in one sample (0.9%) and no growth in 111 samples (99.1%). In the fourth swabs, positive growth was in 4 swabs (3.6%) and no bacterial growth was detected in 108 samples (96.4%) (  Table 4. All of the 112 patients had been treated with ampicillin /sulbactam, metronidazole and ceftazidime from the first day of admission and changed the antibiotics according to culture and sensitivity results [11]. The antibiotic regimen was changed according to culture and sensitivity testing after the second swab in 29 (25.89%) cases (Table 5).
In general, the most effective drugs against Gram-positive bacteria were amoxicillin/ clavulonic acid, erythromycin, vancomycin, cefuroxime andampicillin. The most effective drugs against Gram-negative bacteria were gentamicin, ciprofloxacin, tazocin, imipenem and aztreonam. Cefaclor, ofloxacin, ceftazidime, cefotaxime, cefepime and amoxicillin antibiotics were completely resistant to different microorganisms.

DISCUSSION
Open fractures are always associated with softtissue injury [18,19]. Wound and bone infections mainly occur in higher G-A grades of open fractures [12,18,20]. The complications of open fractures increase with increasing age of the patient [19][20][21]. There is no previous published report concerning the bacteriology of open fracture wounds in Mansoura Emergency Hospital (MEH). To address the problem, this study was undertaken to isolate and identify the bacterial etiologic agents in compound fracture wounds and their antimicrobial susceptibility pattern from orthopedic patients admitted to MEH, Egypt. Also we purposed to study if debridement can reduce the probability of later infection.
In this study, patients aged between 9 and 83 years with a median age of 27 years. The males were 104 (92.9%) and the females were 8(7.1%). Studies by Ikem et al. [22] and Fakoor and Pipelzadeh [23], reported similar findings. In this study, 59 patients (52.7%) that were from 16-60 years gave no bacterial growth in the first swabs and 35 patients (31.54%) were with positive bacterial growth. This might be explained by the fact that traditionally, in this country, males mainly are involved in some occupations such as the transportation, industry and construction works. Farmers and daily laborers are mostly men with very few exceptions. Males are commonly involved in assault or interpersonal violence. Consequently, more than 40% of the injury caused by road traffic accident (RTA) and interpersonal violence affected mainly males particularly those involved in economically important occupations in agriculture, transport, construction and other industries.   ). This is similar to a study reported by Ikem et al. [22] in Nigeria.
In this study, wounds were simply washed with sterile normal saline and iodine or H 2 O 2 solutions and dressed during fracture stabilization. Meticulous wound management and irrigation with copious fluid were essential for the care of all patients with open fracture wounds. Necrotic tissue and other contaminating materials from the wound site were debrided. The aim was to reduce the bacterial load and to increase the chance of early wound closure [3].
The total bacterial isolation rate from the open fracture wounds was 38.4% in the first swabs. This is slightly lower than that reported in Chandigarh, India by Sen et al. [24] which was 45% and 45.8% was reported in Ile-ife, Nigeria by Ikem et al. [22]. Different factors related to wound bed preparation; sample collection, sample transportation and culturing technique might have an effect in the reduction of the bacterial isolation rate. The finding of small number of colonies in these organisms may be due to inadequate or recent antibiotic treatment and the presence of high level of inhibitory substance in the culture media [25,26].
In general, quantitative bacterial counts were useful in managing open fractures. If the quantitative bacterial count is greater than 10 at any one time, it should be taken as a predictor of infection. Then, further medical intervention should be considered prior to definitive fracture care and soft tissue coverage.
The predominant isolates (58.66%) of the open fracture wounds were Gram-positive bacteria compared to Gram-negative ones (41.33%). This is in agreement with a study done in USA [11]. The Gram-negative (41.33%) to Grampositive (58.66%) bacterial proportion in our findings agrees with reports from Minnesota, USA (40% vs. 60%) [2], Indian tertiary care hospital, India (47% vs. 53%) [41] and Gondar teaching hospital, Ethiopia (29% vs.71%) [33]. The observed difference can be mainly explained by the high proportion of G-A grade III open fracture wounds with some older or chronic ones due mainly to the unusually high number of bullet injury. It is also noted that bacterial prevalence differs in different environments [6].
In this study, 81.96% of culture-positive wounds showed mono-microbial growth and 10.71% showed polymicrobial growth. Similarly, Johnson et al. [46] reported that Gram-positive bacteria were less frequently recovered and 37% were polymicrobial infections. The profile of the bacterial isolates study comparatively agreed with findings that have been observed in Nigeria [39], India [41,47], Romania [44], and Iran [45].
All patients had been treated with ampicillin/ sulbactam, metronidazole and ceftazidime before collection of samples [48]. Of these, 38.4% had positive culture results in the first swabs. The possible explanation for high culture positivity rate could be mainly due to bacterial resistance for prophylactically administered antimicrobials [11,21]. In addition, this also shows the rational use of some antibiotics alone or in combination, requires periodic evaluation and the establishment of antimicrobial policy for prophylaxis and treatment in Mansoura Emergency Hospital. The study provided insights into the susceptibility profile of bacteria isolated from open fracture wounds. In our study, the most effective drugs against the Gram-positive bacteria were amoxicillin/ clavulonic acid, erythromycin, vancomycin, cefuroxime and ampicillin. In the other hand the most effective drugs against the Gram-negative bacteria were gentamicin, ciprofloxacin, tazocin, imipenem and aztreonam. This is in agreement with reports from Ile-Ife, Nigeria [22], Lagos, Nigeria [39], and Ahwaz University of Medical Sciences teaching hospitals, Iran [45]. In the study, the antibiotic regimen was changed in 29 patients according to the culture and sensitivity after second swabs.
Many factors have contributed to such level of bacterial resistance, including antimicrobial misuse by health professionals and unskilled practitioners. In Egypt, it is a common practice that antimicrobials can be purchased without prescription, which leads to misuse of antimicrobials by the public thus contributing to the emergence and spread of antimicrobial resistance. Other causal factors can be poor drug quality, poor hospital hygienic conditions accounting for the spread of resistant bacteria, and inadequate surveillance, i.e. lack of information from routine antimicrobial susceptibility testing of bacterial isolates and surveillance testing of bacterial isolates and surveillance of antibiotic resistance, all of which are crucial for good clinical practice and for rational policies against antibiotic resistance [49].
Serious infections caused by Gram-positive bacteria are increasingly difficult to treat because of pathogens such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin resistant enterococci (VRE) and penicillinresistant Streptococcus pneumoniae. The more recent emergence of vancomycin intermediate and resistant MRSA (VISA and VRSA) has further compromised treatment options [50]. The detection of multidrug resistant isolates may further limit therapeutic options.

COMPLIANCE WITH ETHICAL REQUIREMENTS
The protocol of the study was reviewed and approved by our institutional review board and a written informed consent was obtained from all studied patients.