Injury Characteristics, Infection and Resistance Pattern of Open Fracture Tibia in Tertiary Orthopaedic Centre in Dhaka

Background: Open fractures are a frequent occurrence in the in accident and emergency department that requires immediate care. As a pedal bone, the tibia is very prone to accidental injury, easily becomes bare following the trauma and very prone to infection. Updated knowledge about microbial aspects of open tibia fracture infection is essential for proper management. Objective: This study evaluated the injury characteristics and resistance patterns of microorganisms involved in the infection of open fracture tibia in a single-centred study. Methods: This was a cross-sectional study on a total of 384 patients presented at the emergency department with open fractures of the tibia (all Gustilo types) from January 2020 to July 2020 at the National Institute of Traumatology and Orthopedic Rehabilitation (NITOR), Bangladesh. Three successive culture sensitivity tests were carried out-one at the emergency room (surveillance culture), 2nd at the emergency theatre after debridement and third at ward after 1 week (7 to 10 days). Results: Average age of the patients was 36.2± 15.5 years, with motor vehicle accidents being the predominant cause (72.9%). Gustilo III fractures were most prevalent (54.4%). The maximum infection rate was in Gustilo IIIB Fractures (40.4%). There was a significant difference in contamination rate between on admission culture (37.0%) and post debridement culture ( 26.3% ). The infection rate from the ward samples was 44.5 %, where the postdebidement contamination was less only 26.3%. But from the ward sample, it again increased to 44.5%. Among the patient entering the ward after debridement with no contamination (73.7%) became infected in 34.62% cases, which indicates hospital-acquired infection. The bacterial resistance patterns from the ward samples were more virulent with multidrug resistance, predominantly Pseudomonas spp. and Kliebsiella spp. Conclusion: The present study provided insight into the injury characteristics and infection patterns of open fractures of the tibia. Early debridement reduced the contamination, but there was still hospital-acquired infection with more virulent multidrug resistance phenotypes.

as the indoor atmosphere at ward. [6][7][8] These infections lead to malunion, nonunion, chronic osteomyelitis and sometimes even ultimate amputation. 1,9 Tibial shaft fractures account for 2% of all fractures and 44,4% of all open long-bone fractures in adults. 10,11 Due to the specific anatomical features of the tibia (limited soft coverage) more than 15% of its' fractures are classified as open and have made most infectionprone bone of the body. 10 The Gustilo classification system is used widely to grade open fractures. The infection rate of open fractures varies with the fracture characteristic. Infection rates progressively increased from 0% to 2% for Gustilo type-I, 2% to 10% for type-II, and 10% to 50% for type-III. 9 Management of open fractures is based on the principles that include assessment of the patient, classification of the injury, antibiotic therapy, debridement and wound management, fracture stabilization, early bone grafting, and supplemental procedures to achieve healing. 8,9,12 Surgical debridement is considered the most critical step for open lower limb fracture management.
This infection complication and antibiotic resistance synergistically pose a significant threat to the health care system. It not only increases the risk for complications, but extended hospital stay and economic burden to the hospital resources put an unexpected load to the citizen as well as the Government. 6 Updated knowledge about all these aspects of open tibia fracture is essential for proper management. The present study has evaluated injury characteristics and resistance patterns of microorganisms involved in the infection of open fracture tibia in a single-centre cross-sectional study among the Bangladeshi population.

Materials and Methods
This was a cross-sectional study conducted between January 2020 to July 2020 at the National Institute of Traumatology and Orthopaedic Rehabilitation (NITOR), Sher-E-Bangla Nagar, Dhaka where patients of all ages and both the sexes presented with open fractures of tibia attending emergency, were studied. Sample size of this study was 384. Purposive sampling (non randomised) according to availability of the patients and strictly considering the inclusion and exclusion criteria were done. From Admission till discharge three successive culture sensitivity test were done. Cultures were initial culture/surveillance culture (culture sample from initial wound before prophylactic antibiotic), post debridement culture (last saline irrigation in emergency theater) and finally infection culture (7 to 10 days after admission).
Approval from the Institutional Review Board (IRB) of National Institute of Traumatology and Orthopaedic Rehabilitation (NITOR), Sher-E-Bangla Nagar, Dhaka was taken to conduct this study. Keeping compliance with Helsinki Declaration for medical research involving human subject 1964, the study subjects were informed verbally about the study design, the purpose of the study and right for withdrawing themselves from the project at any time, for any reason. Individual who gave informed written consent to participate voluntarily in the study were included as a study sample.
Data were collected in a structured data collection form filled up by the investigator containing all the variables of interest according to inclusion criteria after taking their permission regarding participation and this research work. At arrival of the patients, time of hospital admission, demographic variables, date and time of injury were noted along with mechanism of injury, Gustilo types and subtypes and fracture injury characteristics. During initial resuscitation at emergency room, surveillance culture sample (from wound before prophylactic antibiotic) was collected and sent to lab. Prophylactic antibiotics (intravenous Flucloxacillin and 3rd generation cephalosporin) was administered. Then patients were sent to emergency theatre for wound debridement, fracture stabilization and soft tissue care. Debridement was done following current practice at NITOR using chlorhexidine (Hexi scrub), normal saline, hydrogen peroxide and povidone-iodine solution. A second post debridement culture (last saline wash from the wound at emergency theatre) was sent. From the theatre after initial fracture stabilisation. Stable patients were sent to postoperative ward followed by to general ward. A third infection culture sample after admission in the ward at 7 to 10 days was sent for culture sensitivity and identification of organism. Results of all culture were noted in same structured data collection form.
The data were tabulated and quantitative parameters such as age of patient were summarized in terms of mean with standard deviation and percentage, F 2 -statistic was applied to see significant difference between variables. The significance of the results was determined in 95% confidence interval and a value of p<0.05 considered to be statistically significant.

Discussion
Open fracture tibia is one of the commonest emergency admissions in orthopaedic surgery. 13 Exposure and contamination of the open fracture with environmental microorganisms are widespread. 14 Tibia as a pedal bone, being mostly subcutaneous it is very prone to accidental injury and easily become bare following the trauma. An updated knowledge about injury characteristics and the resistance pattern of microorganisms involved in infection is the much required area of open fracture tibia management.
In this study, it was observed that the mean age of the patient was 36.2±15.5 years. An epidemiological study for 7 years on tibia fracture and another related study on Bangladeshi population also found similar mean age. 15,16 In another study conducted in Brazil, the mean age of the patients with open fractures was 36±12.60 years. 17 The results of all these studies are similar to our study. There were 345(89.8%) male and 39(10.2%) female patients in our study, which states of male predominance. Several related studies has reported male predominance. 18,15,19 Considering injury characteristics according to Gustilo and Anderson classification found Gustilo type III fracture were predominant (54.4%) followed by type II (31.3%) and among the Subtypes IIIA were predominant (27.3%) followed by IIIB (23.7%.). A quantitative descriptive study conducted at ULBRA university hospital in Canoas, Rio Grande do Sul, Brazil, found similar type injury characteristics, which is in agreement with this study. 17 A review article comprising 32 articles of 3036 patients of tibia also found same type Gustilo III predominance. Still, among the subtypes, IIIB was the highest subtype, while in our study, it is IIIA. 10 But this difference is minimum. In the present study, common gram-negative and gram-positive organisms alarmingly multidrugresistant. Pseudomonas and Klebsiella species are only sensitive to intravenous imipenem or meropenem only around 50-60%, which is the highest sensitivity of all used drugs for these two organisms in this study.   24 In another sample, 50% of the strains displayed an imipenem and meropenem sensitivity close to our sample. 22 There is positive correlation of bacterial contamination between times elapsed since injury and debridement. Further multicentred and randomised study required to evaluate the nosocomial infection addressed in this study.

Conclusion
The study found Gustilo type III tibia fractures are predominant injury with highest infection rate. Surgical debridement is effective in reducing contamination from the open fracture wound, but the hospital-acquired infection is common in orthopaedic admitted patients where Gram-negative pathogens were dominant, and the antibiograms showed alarming pattern of drug resistance.