Evaluation of Reliability of Tissue Specimens over Wound Swabs in Diagnosis of Orthopaedic Implant Related InfectionsCorrespondence Address :
Dr. Kanne Padmaja,
Nizam's Institute of Medical Sciences, Hyderabad, Telangana, India.
Introduction: Postoperative infections in orthopaedic implants is a major concerning factor. It can lead to the failure of implants and in severe cases can even lead to amputation and mortality. Total joint replacements and fracture fixations do help by reducing the agony of many patients but postoperative infections are a detrimental complication. It is an economic disaster for hospitals that treat large number of these patients therefore identification of risk factors, common pathogens involved, early initiation and prompt use of empirical therapy is necessary to prevent implant failures and also collection of deep tissue samples improves the diagnostic reliability and microbiological yield of implant related infections. Hence, appropriate collection of specimens is a key factor for early diagnosis and differentiating colonisers from true pathogens.
Aim: To evaluate the rate of implant related infections, sensitivity of Gramâ€™s stain and its accuracy in tissue samples over wound swabs and also to determine the trends in the antibiogram. Materials and Methods: A retrospective analysis was performed from the samples (tissues and wound swabs) received to the Department of Microbiology from October 1st 2017-October 30th 2018 (a period of one year) in patients with orthopaedic implants. Identification and susceptibility patterns of the bacterial pathogens were identified by the automated Vitek 2 compact system (biomeriux). The data was analysed in terms of frequency and percentage.
Results: A total of 141 cases were analysed out of which 45.3% (64/141) were tissue samples and 54.6% (77/141) were wound swabs. Culture positivity observed in tissues was 43.7% (28/64), in wound swabs 50.6% (39/77) and mixed infections were observed in 7.14% (2/28) of tissues and 5.12% (2/39) of wound swabs. Colonisers were observed in 14.2% (11/77) of wound swabs. Specificity of Gramâ€™s stain in comparison with tissue cultures was found to be 83.3% and sensitivity was 50%. Methicillin Sensitive Staphylococcus aureus (MSSA) 17.8% (05/28) and Escherichia coli 21.4% (6/28) were the major pathogens isolated from tissue cultures. Methicillin Resistant Staphylococcus aureus (MRSA) was isolated from 33.3% (13/39) of wound swabs followed by Escherichia coli (28.2%) (11/39). In the present study 25% (7/28) of tissue isolates showed Multidrug Resistance (MDR) and 3.5% (1/28) were Extended Spectrum Beta Lactamase (ESBL) producers. Among wound swabs 23% (9/39) isolates were MDR and 10.2% (4/39) were ESBL producers.
Conclusion: In the present study it was observed that tissue samples were found to be better specimens in comparison with wound swabs for the diagnosis of implant infections. Hence, appropriate collection of sample helps in accurate isolation of pathogens in implant infections.
Antimicrobial susceptibility, Extended spectrum beta lactamase producers, Methicillin resistant Staphylococcus aureus, Multidrug resistant organisms, Prosthetic joint infections
Date of Submission: Dec 22, 2019
Date of Peer Review: Jan 22, 2020
Date of Acceptance: Feb 08, 2020
Date of Publishing: Mar 01, 2020
• Financial or Other Competing Interests: None
• Was Ethics Committee Approval obtained for this study? No
• Was informed consent obtained from the subjects involved in the study? No
• For any images presented appropriate consent has been obtained from the subjects. NA
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