The present study was a cross-sectional study which was conducted in Departments of Microbiology and Orthopaedics at RL Jalappa Hospital and Research Centre, a tertiary hospital in Southern Karnataka, India from April 2016 to May 2016. Ethical clearance was obtained from the Institutional Ethical Committee before starting the study (DMC/KLR/IEC/88/2018-19). Informed consent was taken and the patient’s details were collected in a predesigned proforma.

Inclusion criteria: Patients who underwent external fixation with AO external fixators, Ilizarov rings, Jess fixators and K-wires for fracture stabilisation or for limb lengthening were included in the study.

Exclusion criteria: Patients in whom the external fixator was applied in a different hospital or fractures which were fixed internally were not included in this study.

Sample size calculation: A sample size of 30 was calculated using free EPI software with 95% confidence interval, 5% type 1 error and 50% prevalence based on pilot study which was conducted in the hospital.

All patients included in the study were monitored for signs and symptoms of infection such as erythema, pain, tenderness and/or discharge from the contact site. If there was clinical suspicion of infection, discharge from the infection site was collected on two swabs and immediately transported to the microbiology laboratory. On receipt in the microbiology laboratory, one swab was used to prepare direct smears followed by Gram staining and the second swab was inoculated on 5% sheep blood agar and MacConkey agar and incubated at 37⁰C. The following morning, the plates were examined for growth. If there was no growth, the plates were incubated for another 24 hours. If any growth was seen, it was identified based on colony morphology, bacterial morphology on gram stain and biochemical reactions as per standard laboratory methods [6,7].

Antibiotic susceptibility testing was done as per Clinical Laboratory Standards Institute (CLSI 2016) guidelines with modified Kirby Bauer’s disc diffusion method using Mueller Hinton medium. The antibiotic tested were ampicillin (10 μg), amikacin (30 μg), amoxycillin-clavulanic acid (20 μg/10 μg), ceftazidime (30 μg), cefotaxime (30 μg), ceftriaxone (30 μg), chloramphenicol (30 μg), ciprofloxacin (5 μg), ertapenem (10 μg), gentamycin (10 μg), imipenem (10 μg), levofloxacin (5 μg), piperacillin (100 μg), piperacillin-tazobactam (100 μg/30 μg), tetracycline (30 μg), tobramycin (10 μg), and trimethoprim-sulfamethoxazole (1.25 μg/23.75 μg) [8]. The antibiotic discs were procured from Himedia, Mumbai, Maharashtra, India.

All the data was entered and analysed in Microsoft Excel 2010 and expressed as percentages.

A total of 30 patients who had external fixators within the study period of two months were reviewed. There were 27 (90%) male and 3 (10%) female patients. Male to female ratio was 9:1. Age of patients ranged from 16 to 60 years with a mean of 37 years. Age and gender distribution of patients is depicted in [Table/Fig-1]. The symptoms observed in the patients were pain, discharge and fever [Table/Fig-2]. The external fixators used included AO external fixators, Ilizarov rings, Jess fixators and K-wires. The bone more frequently requiring external fixation in the present study were the tibia (2), femur (1), humerus (1), ulna (1) and pelvis (1). The most common risk factor associated was increased thickness of soft tissue over the bone (4) and increased soft tissue motion (2).

Among the 30 patients included in the study, 6 (20%) patients showed clinical evidence of pin tract infections [Table/Fig-2]. The frequency of infection was more among the males (17%) compared to females (3%). Positive cultures were obtained from all the six samples. Acinetobacter baumanii was the most common causative agent followed by Pseudomonas aeruginosa, Citrobacterkoseri, Enterobacter species and Klebsiella pneumoniae. The isolated organisms exhibited varied pattern of antimicrobial susceptibility as shown in [Table/Fig-3]. Among the isolates of Acinetobacterbaumanii, one isolate was sensitive to amikacin, gentamycin, tobramycin, ciprofloxacin, levofloxacin, tetracycline and cotrimoxazole. Both the isolates were resistant to β-lactam group and β-lactam-β-lactamase inhibitor drugs like piperacillin, ceftazidime, imipenem and piperacillin/tazobactam. Pseudomonasaeruginosa was sensitive to all the drugs tested. Enterobacter species and Citrobacterkoseri were sensitive to tetracycline, imipenem and ertapenem as shown in [Table/Fig-3].

Out of six infected patients, one patient had osteomyelitis. In this case, the pin was removed and antibiotic therapy was followed. The patient responded to the treatment. The remaining five were simple infections involving the soft tissues. All these cases were treated with antibiotics as per sensitivity pattern and responded to the treatment [Table/Fig-2].

Pin tract infection is the most common complication of external fixation method of fracture treatment [9]. This complication can be catastrophic if not diagnosed and treated early. The complications can vary from decrease in stability of the pin–bone interface to severe osteomyelitis. There is no consensus on the precise definition of a pin site infection, but this frequent complication of external fixation is a cause of considerable cost and patient morbidity. In the present study, an attempt was made to study the common microorganisms responsible for pin tract infections and their antibiotic sensitivity pattern in a tertiary care hospital.

A total of 30 patients who had external fixators during the study period were followed-up. The incidence of pin tract infections was (20%) in the present study. Other studies have reported incidence ranging from (11%), and (87.7%) [10,11].

The commonest organism isolated in a similar study was Staphylococcusaureus followed by E. coli. Mahan J et al., reported 74.8% of screw tips culture positive at removal, with a higher rate of gram-positive bacteria which includes Staphylococusaureus and Staphylococcusepidermidis [12]. The organisms isolated in present study were Acinetobacter baumanii, Pseudomonas aeruginosa, Klebsiella pneumoniae, Citrobacter koseri and Enterobacter species which probably are hospital acquired. These isolates were found to be multidrug resistant strains.

The literature is limited with regard to prevention of pin site infection and there is no valid evidence to guide choice of dressing type, cleansing regimen, or other aspects of pin site infections and its care. Similar studies were done regarding the same. The rate of inflammation was (41.6%) and pin loosening was (22.9%) at the pin tract as reported by Mahan J et al., [12]. In the present study, the commonest complication was discharge from the site of infection which required frequent cleaning and antibiotics. Pin tract infection rate was (11.2%) in a study conducted by Parameswaran AD et al., [13].

Data on antibiotic susceptibility testing from isolates of pin tract infection is minimal. In the present study multidrug resistant pathogens were isolate which accounts for hospital acquired infections.

As the sample size was less, these findings should be extrapolated with caution. Further studies of similar kind with a larger sample size are necessary to establish diagnostic and therapeutic protocols for pin tract infections in our hospital.

Pin tract infection occurred in (20%) of the patients. In view of increased emergence of drug resistance there is a need for diagnosing pin tract infections. Early detection and treatment reduce the economic burden on the patient and decreased hospital stay. Further improving the prognosis and outcome.