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Incidence of Aerobic Bacterial Infection in Postoperative Closed and Open Fracture Wounds at Tertiary Care Hospital in Western Rajasthan, India

Infection is still noted to be one of the major complications in the treatment of fractures. Infections are associated with prolonged hospital stay, leading to higher treatment cost, morbidity and mortality, particularly when the infecting agents are multidrug resistant. To compare incidence of infective agents and their resistance pattern between post-operative closed and open fracture wounds. In this particular study 125 patients of all age group were enrolled with exclusion of patients with history of diabetes mellitus, chronic steroid therapy, chemotherapy and HIV positive patients. Patients were divided into closed fracture and open fracture patients. A total of 120 isolates were obtained from 110 patients. 15 patients were cultured sterile. Organisms obtained were Enterobacter spp. (19.17%), Klebsiella spp. (15.83%), Staphylococcus aureus (12.5%), Coagulase negative Staphylococcus spp. (11.67%), E. coli (10.83%), Pseudomonas (10.83%), Acinetobacter spp. (7.50%), Citrobacter spp. (5.0%), Burkholderia cepacia complex (2.5%), Aeromonas hydrophila (2.5%), Proteus mirabilis (0.83%) and Aerococcus viridans (0.83%). 100% isolates of Staphylococcus species were sensitive against vancomycin, followed by linezolid, gentamicin, tetracycline, ciprofloxacin and azithromycin. Ampicillin, amox-clav and ceftriaxone were most ineffective drugs. Enterobacteriaceae isolates were almost totally resistant against ampicillin followed by amoxy-clav. Levofloxacin and imipenem were found most effective antibiotics. Non-enterobacteriaceae gram negative strains were multidrug resistant, ciprofloxacin, levofloxacin and imipenem were found effective in 5063% patients. In our study there was no significant difference of antibiotic sensitivity pattern was noted between post-operative closed and open fracture wounds. K e y w o r d s

pathogenic organism in wound without local or systemic tissue or both involvement may not result in infection in patient (Badoe et al., 1986). Wound infection could be defined as presence of pus in a lesion, as well as other general or local features of sepsis including pyrexia, pain and induration (Shija, 1976). A recent prevalence study has found that post surgical infections now termed as Surgical Site Infections (SSI)] were most common health care associated infection, accounting for 31% of all health care associated infections (HAIs) among hospitalized patients (Mangram et al., 1999).
Open fractures are more commonly associated with the infection. The treatment of open fractures along with infection has been improved in recent years. Disruption of the tissue barrier makes underlying structure prone to infection due to contact with environment (Horan et al., 1992). Infections in closed fractures are Healthcare Associated Infection (HAI) received during operative procedures of Open Reduction and Internal Fixation (ORIF). Studies have found in Open Reduction and Internal Fixation (ORIF) procedures an over-all infection rate is more as compared to closed fractures (De Bakey et al., 1946). Anatomic site and the severity of soft-tissue trauma may cause varying degree of infection and that may lead to complications with the tibia being most often affected (Fischer et al., 2000).
Knowledge of the etiological agents and their antibiotic susceptibility enables in selection of most appropriate antibiotic, therefore reducing treatment cost and duration of hospital stay. ORIF of with implants and prosthesis has now become the predominant modality of treatment of fractures in most trauma centers. This is because of the better understanding of the bio-mechanics of implants, their material and thus resulting in better functional outcome in these patients (Kirk et al., 2004). Surgical site infections remain the third most common nosocomial infection after urinary tract infections and pneumonia, and are the most common nosocomial infection in the surgical population at 38% (Anderson & Sexton, 2007).
Besides advanced techniques, nosocomial infection also poses hurdles in treatment of patients. Discovery of superbugs in hospital settings are creating great challenge in the choice of antibiotics.

Subjects and Methods
Samples for the present study were obtained from post-operative patients who had undergone operative procedure for management of closed or open fractures. Surgical sites were considered infected according to the set of clinical criteria mentioned by CDC. The specimens were collected aseptically using sterile cotton wool swabs. Samples were obtained from surgical site from the depth of wound, without contaminating with skin commensals and immediately transported to laboratory.

Inclusion criteria
1. Closed fracture wound patients with post-operative infection.
2. Open fracture wound patients with postoperative infection.

Exclusion criteria
1. Patients with immunodeficient states like diabetes mellitus, obesity, carcinoma, HIV/AIDS patients and patients on drugs such as steroids or cytotoxics.

Patients with pathological fractures.
3. Refusal to give consent for participating in the study.

Patient data collection
Structured questionnaires were used to extract data from the patients' case notes and/or the patients directly. The information included were, demographic data, existing chronic disease, immunocompromised states, smoking, occupation and any significant family history.
Identification of organisms: Bacterial isolates were identified by conventional methods and also by Vitek 2 automated system.

Antimicrobial Susceptibility Testing
Antimicrobial susceptibility pattern of isolated bacterial pathogens was performed by Kirby Bauer Disc Diffusion method (Bauer et al., 1966) and results were interpreted using criteria mentioned in the CLSI guidelines M100-S25.
Quality control: Escherichia coli (ATCC-25922) and Staphylococcus aureus (ATCC-25923) were used as reference strains for identification and drug susceptibility testing.

Results and Discussion
In the present study 125 cases of open and closed fracture wounds were included who showed signs of post-operative infection at surgical site. In this study, gram negative non-Enterobacteriaceae group of isolates in closed fracture cases were found totally resistant for ampicillin, amoxy-clav, ceftazidime and cefepime. 85% of bacteria were resistant to gentamicin. 70% of isolates were resistant to piperacillin and amikacin. 40-50% of bacteria were resistant to imipenem levofloxacin and ciprofloxacin. In case of open wound fractures, only piperacillin, imipenem, ciprofloxacin and levofloxacin were found to be effective and incidence of resistance was 87.5%, 37.5%, 37.5% and 37.5% respectively Antibiotic resistance pattern of gram positive isolates, enterobacteriaceae and non-enterobacteriaceae gram negative isolates are shown in detail in [ Figure 3], [ Figure 4], [ Figure 5] respectively. Orthopedic fractures with intact overlying skin are not exposed to external environment thus they are protected from getting infected. Sometimes these closed fractures require operative correction and may acquire healthcare associated infection.
Unlike closed fractures open fractures come in contact with external environment and also suffer more tissue damage. This requires thorough cleaning of wound and operative procedures also. Thus open fractures get exposed to community as well as hospital flora. This particular study was conducted to find out difference between incidence and resistance pattern of etiological agents in closed and open fracture wounds.
The overall incidence of gram negative bacteria is more (75%) in comparison to gram positive bacteria (25%) in our study. Similar findings of GNB have also been reported in India by Lilani et al., 2005 (76 Some other authors from india Jain et al., 2015 andabroad Robinson et al., 1989;Onche and Adedeji, 2004;Lee et al., 2006;Akinyoola et al., 2006;Hidron et al., 2008;Madu et al., 2010;Guo-qing Li et al., 2013; have found gram positive organisms to be more common in post-operative orthopaedic wards. The present study findings support the theory of gradual increase in the emergence of antibiotic resistant micro-organisms in post surgical patients. Onche and Adedeji, 2004, in their study on Microbiology of post-operative wound infection in implant surgery, found gentamicin to be most effective drug followed by ofloxacin for gram negative isolates. In study done by Aloe Agrawal et al., 2008, Pseudomonas (12cases), E. coli (9 cases), Klebsiella (3 cases), Proteus (2 cases) and Streptococcus (1 case) were found to be resistant to all antibiotics. Ako-Nai et al., 2009, in their study, found 72% resistance to amoxicillin, 44% to amoxy-clav, 57% to tetracycline 23% to gentamicin, and 10% against ofloxacin. Hassan et al., 2010, in their study noted all isolates of staphylococci were susceptible to vancomycin. Resistance rates of ≥50% to ceftazidime and/or cefotaxime were detected especially in Klebsiella spp., Pseudomonas spp. and E. coli and Acinetobacter strains.
Noticeably, susceptibility to imipenem for gram negative bacilli was >80%. Multi-resistant strains represented 48.6% (35/72) of the isolated gram negative strains. 57.1% and 66.7% of Pseudomonas spp. and Acinetobacter spp. isolates (19.4% of gram negative isolates) were resistant to amikacin, ciprofloxacin and ceftazidime. Phillip Mulepo, 2014, in his study, found that the (>80%) isolated gram negative bacteria were sensitive to amikacin, piperacillin and imipenem but resistant (>80%) to, ampicillin, amoxy-clav, ceftriaxone, ceftazidime was noted. The isolated gram positive bacteria; Staphylococcus aureus were sensitive (>80%) to vancomycin. In our study there was no significant variation of antibiotic resistance found between closed fracture and open fracture isolates.