Efficacy of Culture and Sensitivity in the Management of Open Tibial Fractures

Background: The pattern of organisms found in open fractures is important in the selection of antibiotics for prophylaxis and empirical treatment. An increasing antibiotic resistance is a challenge in treatment and prevention of infections.

Objectives: The objectives of this study were to identify the common microorganisms that infect open tibial fractures in our hospital ii) to determine the antibiotic sensitivity patterns during the course of treatment, and iii) to evaluate whether pre-debridement and post-debridement cultures are predictors of infection in open fracture wounds.

Material & Methods: This was a prospective study conducted at Me division Hospital, Jeedimatla, Hyderabad, India where 108 open tibial fractures were analyzed to determine the infective etiological agents and the antibiotic sensitivity pattern of the isolated organism. All patients who had open fractures of one or both limbs without other long bone fractures or open wounds in any other parts of the body, and no focus of infection were included in the study. Patients with open fractures which were treated outside with IV or oral antibiotics before coming to Emergency Department and patients who were undergone wound debridement or surgical procedure of the open tibial fracture outside of this hospital were excluded from this study. All patients underwent clinical examination and history noted. Demographic detail, date and time of injury, mechanism of injury and time elapsed since injury to presentation in Emergency Department was noted. Wounds were swabbed before and after debridement and fractures were classified based on Gustilo Anderson’s grading system. Appropriate treatment for bony as well as soft injury was carried out and patient was followed up in the ward to note the infections that developed from pre- as well as post-debridement cultures.

Results: Of the 108 pre and post debridement samples that were sent, it was found that 41% of pre debridement samples were positive for infective organisms and of these 59% grew the infective organisms in culture. In the post debridement series, only 20% of the cultures grew the infective organism, of which only 64% cases got infected. Hence pre debridement cultures were more accurate in predicting open fractures infections. However, of the cases that did become infected, the infective organism was isolated in 85% cases. The most common organism that was isolated to be non-fermentative Gram-negative bacilli followed by Pseudomonas aeruginosa in our study and the antibiotics recommended for treating these infections were cefeperazone sulbactum combination followed by amikacin.

Conclusion: The use of pre- and post-debridement bacterial culture samples have got a value in determining infections in open tibial fractures. The most common organism that was encountered in our study was non-fermentative Gram-negative bacilli followed by Pseudomonas aeruginosa and the antibiotic of choice was found to be cefeperazone sulbactum combination followed by amikacin.

The problem of open fracture management has plagued surgeons since the time of Hippocrates. The open fractures represent a therapeutic challenge to the Orthopedic surgeons. They are difficult to treat and the cost of inadequate treatment is high both financial terms and in continuing patient disability. In the past, open fractures of the tibia have been associated with infections, limb loss marked morbidity and high mortality rates owing to sepsis. Prevention of wound sepsis remains the prime objective in the management of open tibial fractures. There is universal agreement that open fractures require emergency treatment in the form of wound debridement and irrigation. Beyond this, use of cultures in the assessment and predictivity of infections is still controversial. It is universally accepted that antibiotics have an important role to play in the treatment of open tibial fractures but the duration and initiation of treatment still remain open to debate. 

• To identify the common bacterial agents that are encountered in open tibial fractures and their antibiotic sensitivity patterns during the course of treatment.
• To chalk out a treatment protocol that will guide all antibiotic regimes when planning initiation of antibiotics in open tibial fractures.
• To evaluate whether pre-debridement and post-debridement samples are predictors of subsequent wound infections.

This was a prospective study involving 107 patients and 108 limbs who presented with open tibial fractures at Medivision Super Specialty Hospital, Jeedimatla, Hyderabad, India, between December 2017 and November 2018. 

Inclusion criteria

All patients who had open fractures of one or both limbs without other long bone fractures or open wounds in any other parts of the body, or any other focus of infection detected clinically or laboratory wise.

Exclusion criteria

Patients with open fractures who have been treated by IV or antibiotic dressings before coming to Emergency Department, and patients who were undergone wound debridement or surgical procedure for the before coming to this hospital.

All patients with open tibial fractures underwent a detailed clinical examination and history noted and the details of the patient such as demographic details (Name, age, and sex), date and time of injury, mechanism of injury, and the time elapsed since injury to presentation in Emergency Department at Medivision Hospital, Hyderabad were noted.

All patients underwent trauma assessment and appropriate treatment; the affected limb(s) were splinted and the wounds were inspected for the size and extent of wound. Both soft tissue and bone status was assessed and the amount of contamination was noted. All wounds were tentatively classified based on Gustilo Anderson’s grading system of open fractures. All patients were given tetanus toxoid and the leg was splinted. The wound was covered by a sterile saline soaked gauge.

Under complete aseptic precautions the wound was first cleaned with sterile normal saline and then a wound swab was taken and sent to the Microbiology Laboratory. This was the pre-debridement sample. Then a thorough wound toileting was carried out in operation theatre using 6-10 liters of IV saline under complete asepsis. Following which another swab was taken deep within the wound (post-debridement sample). The wound was then debrided under anesthesia and the open fracture is classified depending on the findings. The soft tissue wounds are addressed as the need may be and the bone injury is stabilized depending on factors like soft tissue coverage, contamination, communition and periosteal stripping. Further management of open tibial fractures is carried as per the guidelines given in literature. All patients were started on antibiotics after pre-debrima culture samples were taken. Cefazolin, gentamycin and metronidazole for type 1 and 2, and type 3 fractures were started on cephaperazone sulbactum and amikacin. All patients were given antibiotics for three days and subsequent antibiotics depended on the growth of these pre and post debridement cultures. If no growth occurred the antibiotics were stopped by fifth day.

The patients during their hospital stay were assessed clinically for signs of infection and repeat cultures were sent if infection was found to be present. The clinical parameters that were considered suggestive of wound infection were local rise of temperature, tenderness, serosangunious discharge, frank pus abscess collection, foul smell and necrosis of graft of flap, fever with chills. The patient wound was inspected regularly and dressing using appropriate antibiotic was done. If there was evidence of infection the wound was cultured and antibiotics started later to be followed by any secondary definitive soft tissue and bony procedure so as to obtain complete coverage of the open fracture wound. Once soft tissue cover was established and patient had no evidence of infection, the patient was then discharged from the hospital. The organisms that were encountered and their sensitivity was noted and later tabulated for analysis.

The total no of patients was 107, and 108 cases of open tibial fractures underwent treatment at Medivision Hospital, Jeedimatla, Hyderabad, India, between December 2017 and November 2018. Out of 107 patients, 94 were males (88%) and 13 were females (12%). The age of the patients ranged from three years to 75 years, out of which 13 patients (12%) were in the age range of less than 13 years, 71 patients (66%) were in the age range of 21 - 40 years. These amounted to the maximum number of cases. Nineteen cases (18%) were in the age range of 41 - 60 years and four cases (4%) were in the range of greater than 61 years.

Table 1: Age range of the patients

There were various causes for open tibial fractures. However, the most common was road traffic accidents amounting to 79% of cases.

Table 2: Mode of injuries

Of the 107 patients who presented in the emergency department 59 patients (55%) were taken up for debridement after six hours of their injury and 48 patients (45%) within six hours of injury.

As per Gustilo Anderson’s classification, of the 108 open fractures that was encountered, the maximum number was type 2 which amounted to 34 cases (31%) and followed by type 3b which accounted for 27 (25%) cases. 

Table 3: Gustilo Anderson’s classification.

From all 108 cases a pre-debridement culture swab was taken and all patients underwent a wound debridement. Following wound debridement, a post-debridement culture swab was taken. For bony stabilization, the following fixation methods were used as shown in Table 4. Some patients underwent more than one bony as well as soft tissue procedures (Table 5).

Table 4: Bone stabilization procedures.

Table 5: Soft tissue procedures that were carried out following debridement

Pre-debridement cultures

A total of 108 wound debridement cultures were taken before wound debridement was carried out. Of these 44 cultures (41%) was found to be positive for growth of the organisms and 64 cultures (59%) did not yield the growth of any organisms.

Table 6: Positive pre-debrima cultures based on Gustilo Anderson’s Classification (GAC).

Of the 108 cultures, 44 positive pre-debridement cultures were obtained. Of these 16 were obtained in Grade 3b open tibial fractures (36%) and 14 were of Grade 2 open fractures (32%). Of the 44 cultures that had grown organisms, it was found that 26 cases were infected and 18 cases did not get infected. Of these 26 infected cases, the infective organism was grown from 22 cases (Culture positive), whereas four cases did not yield any growth (Culture negative). Of the negative pre-debridement cultures, 60 cases did not cause infections (non-infective fractures) whereas four cases did get infected (Infected fractures) even though the pre-debridement culture did not register any growth.

Post-debridement cultures

A total of 108 post-debridement samples were taken for culture. Of these 22 cultures were found to be positive for growth of the organisms and 86 cultures did not yield the growth of any organisms. As per Gustilo and Anderson’s classification, of the 22 cases that were positive for infection in the post-debridement samples the maximum cases (Eight out of 22) were seen to be present in type 3b open fractures and followed by type 2 open fractures (Seven out of 22).

Table 7: Positive post-debrima cultures based on Gustilo Anderson’s Classification (GAC).

Out of 108 post-debridement samples taken for culture, 22 cultures were found to be positive, out of which 14 cases were clinically found to be infected as compared with eight cases which did not have clinical infection (Not infected). Of these 14 infected cases, 13 cases did grow the organism (Culture positive) in the infected fracture wound whereas one case was negative for the organism (Culture negative) even though there was clinical evidence of infection. Out of 108 post-debridement samples taken for culture, 86 cultures were found to be negative. Of these 86 cultures, 13 cases did grow the organism (Culture positive) whereas 73 cases were negative for the organism (Culture negative). On analysis of the above variables of pre- and post-debridement cultures by using the Chi square test the P value was found to be less than 0.03 and the variables were significantly associated.

Analysis of Infective Organisms in Open Tibial Fractures

The following infective organisms were isolated in this study of open tibial fractures both on pre and post debridement cultures.

Table 8: The bacterial isolates from open tibial fractures both on pre- and post-debridement cultures.

The most common bacteria isolated in this study was non-fermenting Gram-negative bacilli followed in decreasing frequency by Pseudomonas aeruginosa, Entrococcus spp, Enterobacter spp, E. coli. methicillin resistant Staphylococcus aureus (MRSA), Klebsieilla pneumoniae, Staphylococcus aureus, Citrobacter spp, and Proteus mirabilis. On categorization of the bacterial isolates based on the number of times they were isolated in pre-debridement cultures the following results were obtained as shown in Table 9.

Table 9: Categorization of the organism based on the number of times they were isolated in pre-debridement cultures.

On categorization of the bacterial isolates based on the number of times it was isolated in the post-debridement cultures the following results were obtained as shown in Table 10.

Table 10: Categorization of the bacterial isolates based on the number of times they were isolated in post-debridement cultures.

Of the 108 cases that were analyzed, clinical infections were found in 26 cases. A categorization of the infective cases based on the type of fractures is enumerated in Table 11.

Table 11: Categorization of the infective cases based on the type of fractures.

Antibiotic sensitivity pattern of the bacterial isolates

The antibiotic sensitivity patterns of the bacterial isolates are enumerated in descending order of sensitivity to the antibiotic. Non-fermenting Gram-negative bacilli - the sensitive antibiotics were cefeperazone and sulbactum combination >gentamycin/ciprofloxacin > amikacin >ceftazidime.  Pseudomonas aeruginosa was found to be sensitive to amikacin > ceftazidime >ciprofloxacin > cefaperazone >gentamycin. Enterococcus spp was found to be sensitive to gentamycin >vancomycin >pencillin. Enterobacter spp was found to be sensitive to amikacin >gentamycin >ciprofloxacin >ceftazidime/cefotaxime. E. coli was found to be sensitive to amikacin >gentamycin/ciprofloxacin/ceftazidime> cefotaxime/cefuroxime. MRSA was found to be sensitive to vancomycin >chloramphenicol >teicoplanin >ciprofloxacin. Kleibseilla pneumoniae was found to be sensitive to cefeperazone and sulbactum combination >amikacin >gentamycin, zosyn and netilimycin. Staphylococcus aureus was found to be sensitive to cloxacillin / methicillin.

This study was undertaken at Medivision Hospital, Hyderabad, India to analyze the type of bacterial agents that most commonly infect open tibial fractures and the antibiotic sensitivity pattern of the isolates. In this study, out of 108 cases, males were found to be more affected than females and amounted to 88% of the cases seen. Most patients were in the age group of 21 to 40 years (66%). Road traffic accidents caused the maximum number of cases (79%).  The 55% of cases presented in the emergency after six hours of injury and were taken up for wound debridement as compared to 45% of cases who presented in the emergency within six hours of injury. On correlation with the number of infections that developed in open tibial fractures it was found that 65% of these patients got infected as compared with 35% of cases which did not develop infection. 

When these cases where classified based on Gustilo Anderson s classification it was found that 31

Gram negative bacilli were the most frequently isolated organism in the cultures of open tibial fractures. This was found to cause a significant number of infections in open tibial fractures. Type 3b was the maximum number of open fractures that were infected and those patients that presented in the emergency greater than six hours had an increased infection rate when compared to those who reached the emergency within six hours. The organism was found to be sensitive to cefeperazone sulbactum combination followed by Amikacin and then to ciprofloxacin. Pre debridement as well as post debridement cultures have got a role in detecting infections in open fractures and their association in predicting infection is notable.