Is a Drain Tip Culture Required After Spinal Surgery? ↔ Drain Tip Culture: Would it Help us Predict and Prevent Surgical Site Infection after Orthopaedic Surgery?

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Jadav et al. International Journal of Pharmaceutical and Clinical Research 1057 Original Research Article Drain Tip Culture: Would it Help us Predict and Prevent Surgical Site Infection after Orthopaedic Surgery? Kirit L. Jadav1, Himanshu Ladani2 1Assistant Professor, Department of Orthopedics, GMERS Medical College and Hospital, Junagadh, Gujarat, India 2Associate Professor, Department of Orthopedics, GMERS Medical College and Hospital, Junagadh, Gujarat, India Received: 25-01-2024 / Revised: 23-02-2024 / Accepted: 26-03-2024 Corresponding Author: Dr. Himanshu Ladani Conflict of interest: Nil Abstract: Background and Objective: Systematic cultures of drain tips or drainage fluids are commonly used by surgical teams for the early detection of SSI, even in the absence of clinical suspicion of infection. However, their prognostic values are controversial. Objective of the study was to evaluate the diagnostic value of drain tip culture in predicting surgical site infection. Material and Methods: This study prospectively included 183 patients who undergoing into spine surgery at Central Orthocare Hospital, Junagadh. Patients with active infection in body excluded from study. Prophylactic antibiotic will be administered intra-operatively and postoperatively as per institute’s protocol. Drains from surgical site will be removed when the volume of postoperative fluid drainage was less than 50 ml in the preceding 24 hours and drain tip will be sent for culture. Surgical site infection (SSI) will be defined according to Centers for Disease Control and Prevention criteria. Results: Surgical Site Infection rate is 2.73 % in our study and out of 5 positive SSI one patient having MRSA while others having only clinical evidence of infection. Drain tip positive rate is 2.18 %. Association of DTC with SSI having high specificity and NPV of 98.31 % & 97.76 % respectively and low sensitivity & PPV of 20 % & 25 % respectively with p value less than 0.05. Conclusion: We are unable to conclude that the result of a drain tip culture always indicates the presence or absence of an SSI. But with p value of less than 0.05 drain tip culture is significantly associated with surgical site infection with high specificity, high negative predictive value and low sensitivity & low positive predictive value. Keywords: Drain tip culture, Orthopaedic Surgery, Surgical site infection. This is an Open Access article that uses a funding model which does not charge readers or their institutions for access and distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0) and the Budapest Open Access Initiative (http://www.budapestopenaccessinitiative.org/read), which permit unrestricted use, distribution, and reproduction in any medium, provided original work is properly credited. Introduction Surgical site infection (SSI) is an important operative complication with significant morbidity and represents an economic burden [1]. The reported incidence of SSI following spine surgery is in the range of 0.2% to 7.2% [2-6]. Given the elevated morbidity and neurologic dysfunction associated with delayed treatment, early detection and initiation of appropriate management is vital. The contamination of the surgical site may occur during pre-operative, per-operative or postoperative periods. Surgical drainage can be used to prevent hematoma formation, and thus SSI, but can also be a risk factor for SSI [7]. Indeed, many studies have found an association between the presence of surgical drainage and SSI or between the drainage duration and the proportion of SSI [7,8,9]. Systematic cultures of drain tips or drainage fluids are commonly used by surgical

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1058 the study are included in study. Patient not fulfilling inclusion criteria, patient not willing to participate in the study or not willing to sign the consent form, any active infection in the body and patients diagnosed with any infection of spineare excluded from study. Informed consent will be taken from patients undergoing study. Prophylactic antibiotics will be administered intraoperatively and postoperatively as per institute’s protocol. A close suction drainage system will apply in all the operations. A 12 Fr drain tube will placed subfascially and bring out through separate skin incision. Drains from surgical site will be removed under sterile precaution when the volume of postoperative fluid drainage was less than 50 ml in the preceding 24 hours and drain tip will be sent for culture. Data from culture studies using the distal tip of the wound drain will be used for analysis. Even if the drain tip culture is positive, we will not administer additional antimicrobial agents without other signs suggestive of surgical site infection. All patients will be treated with antimicrobial prophylaxis based on evidence-based guidelines and will be followed for at least 6 months after surgery. Post-operative visits will be at 15 days for stich removal, at 6 weeks, at 3 months and at 6 months to look for clinical sign of surgical site infection besides routine check-up. In case of suspected surgical site infection, wound swab would be collected and sent for microbiological analysis. Culture report to be recorded and treatment as per sensitivity report. Surgical site infection (SSI) will be defined according to Centers for Disease Control and Prevention criteria. Statistical analysis The recorded data was compiled and entered in a spreadsheet computer program (Microsoft Excel 2007) and then exported to data editor page of SPSS version 15 (SPSS Inc., Chicago, Illinois, USA). Quantitative variables were described as means and standard deviations or median and

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Results SSIs were identified in 05 of the 183 patients (2.73 %). Bacteria are isolated from the surgical site in 01 cases (20 %) in which MRSA is isolated while other 4 cases of SSIs there is clinical evidence of infection but no any organisms are isolated. Table 1 shows the relationship between DTCs and SSI group. Table 2 shows the demographic characteristics of patients. Mean age of surgery is 54.64 ± 14.24 years. Male/Female ratio is 85/98. Out of 183 patients 85 having Hypertension, 50 having Diabetes mellitus, 13 having thyroid problems, 13 having dyslipedemia and 07 having other comorbidities. In total, 29 patients underwent cervical surgery, 19 patients underwent thoracic surgery, and 150 patients underwent lumbosacral surgery. Estimated operative time is 104.42 ± 57.69 minutes. Estimated blood loss is 199.69 ± 160.27 ml. There is total 74 cases of multilevel surgeries and 109 cases of single level surgery. Instrumentation done in 127 cases while 56 cases are uninstumented. Prediction of SSIs was possible based on a positive drain culture (Table 3). Out of 04 DTC positive patient 01 patient develop SSI while Total of 4 patients develops SSI with negative DTC. Drain tip cultures had a sensitivity of 20%, specificity of 98.31 %, positive predictive value (PPV) of 25 %, and negative predictive value (NPV) of 97.76 % and p value of 0.005741 for detecting a wound infection. Out of 05 SSI positive patients 03 undergoing multilevel surgery while 02 undergoing single level surgery, 02 patients undergoing instrumentation while 03 patients undergoing uninstrumentation. Table 1: Association between Drain Tip culture and Surgical Site Infection SSI Positive SSI Negative Total DTC Positive 01 03 04 DTC Negative 04 175 179 Total 05 178 183 P Value 0.005741

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1059 Dorsal 19 Lumbosacral 150 Co-morbidities* Diabetes Mellitus 50 Hypertension 85 Thyroid 13 Dyslipedemia 13 Others 07 Surgery Operative Time (min) 104.42 ± 57.69 Estimated Blood Loss (ml) 199.69 ± 160.27 Multilevel 74 Single level 109 Insrumentation 127 Uninstrumentation 56 *There is some overlap Table 3: Prediction of SSIs Using Positive Drain Culture Prediction of SSI Percentile (%) Sensitivity 20 Specificity 98.31 PPV 25 NPV 97.76 Table 4 : Relation of SSI with level of surgery and use of instrumentation Single Level Multilevel Instrumented Uninstrumented SSI Positive 02 03 02 03 SSI Negative 107 71 125 53 Discussion Closed suction drainage is an established method that has the aim of preventing wound hematoma. A drain tip culture is a convenient and noninvasive method [11,12], but may not be appropriate as a routine test because the evaluation of infection may be unreliable [13]. It has also been suggested that bacteria identified in the SSI and in drain tip culture results may not necessarily match [14]. In addition, routine culture of all suction drain tips is expensive and hence may not be cost effective [15]. Thus, the appropriate strategy for use of drain tip cultures is unclear. Bacterial detection rates of 0%– 10.8% have been reported in drain tip cultures in orthopedic surgery [12,14,16,17]. In our study bacterial detection rate in drain tip culture is 2.18 %. Previously, Sørensen and Sørensen [12] reported that early removal of the drain decreases the risk of retrograde migration of bacteria from the skin, and the frequency of positive drain tip cultures and the risk of infection are substantially increased if the drainage time is >6 days; thus, early removal of drains seems to be appropriate. Weinrauch [14] suggested that the low rate of culture-positive drain tips may partly be due to early removal, as well as to postoperative antibiotic prophylaxis while drains remain in place. In orthopedic surgery, Sankar et al [18] found that suction tip cultures had a sensitivity of 75%, specificity of 97%, PPV of 50%, and NPV of 99% for prediction of SSIs. In spinal surgery with instrumentation, Nakayama et al [19] found a sensitivity of 60%, specificity of 98%, PPV of 60%, and NPV of 98% for prediction of deep SSIs using suction tip cultures. In our study has Sensitivity of 20 %, Specificity of 98.31 %, PPV of 25 % and NPV of 97.76 %. Thus only Specificity and NPV value match with previous studies. Infections after spinal surgery are most commonly caused by Gram-positive organisms found on skin flora, most notably Staphylococcus aureus and Staphylococcus epidermidis (MSSE). [20] However, the incidence of infection with methicillin-resistant bacteria (including MRSA) is increasing, [21] and MRSA has also increased in postsurgical infection. [22] In our study organism isolated in SSI in only one patient and that organism is MRSA. There is no significant difference between use of instrumentation and uninsrumentation, no significant difference in level of surgery.

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1059 Dorsal 19 Lumbosacral 150 Co-morbidities* Diabetes Mellitus 50 Hypertension 85 Thyroid 13 Dyslipedemia 13 Others 07 Surgery Operative Time (min) 104.42 ± 57.69 Estimated Blood Loss (ml) 199.69 ± 160.27 Multilevel 74 Single level 109 Insrumentation 127 Uninstrumentation 56 *There is some overlap Table 3: Prediction of SSIs Using Positive Drain Culture Prediction of SSI Percentile (%) Sensitivity 20 Specificity 98.31 PPV 25 NPV 97.76 Table 4 : Relation of SSI with level of surgery and use of instrumentation Single Level Multilevel Instrumented Uninstrumented SSI Positive 02 03 02 03 SSI Negative 107 71 125 53 Discussion Closed suction drainage is an established method that has the aim of preventing wound hematoma. A drain tip culture is a convenient and noninvasive method [11,12], but may not be appropriate as a routine test because the evaluation of infection may be unreliable [13]. It has also been suggested that bacteria identified in the SSI and in drain tip culture results may not necessarily match [14]. In addition, routine culture of all suction drain tips is expensive and hence may not be cost effective [15]. Thus, the appropriate strategy for use of drain tip cultures is unclear. Bacterial detection rates of 0%– 10.8% have been reported in drain tip cultures in orthopedic surgery [12,14,16,17]. In our study bacterial detection rate in drain tip culture is 2.18 %. Previously, Sørensen and Sørensen [12] reported that early removal of the drain decreases the risk of retrograde migration of bacteria from the skin, and the frequency of positive drain tip cultures and the risk of infection are substantially increased if the drainage time is >6 days; thus, early removal of drains seems to be appropriate. Weinrauch [14] suggested that the low rate of culture-positive drain tips may partly be due to early removal, as well as to postoperative antibiotic prophylaxis while drains remain in place. In orthopedic surgery, Sankar et al [18] found that suction tip cultures had a sensitivity of 75%, specificity of 97%, PPV of 50%, and NPV of 99% for prediction of SSIs. In spinal surgery with instrumentation, Nakayama et al [19] found a sensitivity of 60%, specificity of 98%, PPV of 60%, and NPV of 98% for prediction of deep SSIs using suction tip cultures. In our study has Sensitivity of 20 %, Specificity of 98.31 %, PPV of 25 % and NPV of 97.76 %. Thus only Specificity and NPV value match with previous studies. Infections after spinal surgery are most commonly caused by Gram-positive organisms found on skin flora, most notably Staphylococcus aureus and Staphylococcus epidermidis (MSSE). [20] However, the incidence of infection with methicillin-resistant bacteria (including MRSA) is increasing, [21] and MRSA has also increased in postsurgical infection. [22] In our study organism isolated in SSI in only one patient and that organism is MRSA. There is no significant difference between use of instrumentation and uninsrumentation, no significant difference in level of surgery.

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Table 3: Prediction of SSIs Using Positive Drain Culture Prediction of SSI Percentile (%) Sensitivity 20 Specificity 98.31 PPV 25 NPV 97.76 Table 4 : Relation of SSI with level of surgery and use of instrumentation Single Level Multilevel Instrumented Uninstrumented SSI Positive 02 03 02 03 SSI Negative 107 71 125 53 Discussion Closed suction drainage is an established method that has the aim of preventing wound hematoma. A drain tip culture is a convenient and noninvasive method [11,12], but may not be appropriate as a routine test because the evaluation of infection may be unreliable [13]. It has also been suggested that bacteria identified in the SSI and in drain tip culture results may not necessarily match [14]. In addition, routine culture of all suction drain tips is expensive and hence may not be cost effective [15]. Thus, the appropriate strategy for use of drain tip cultures is unclear. Bacterial detection rates of 0%– 10.8% have been reported in drain tip cultures in orthopedic surgery [12,14,16,17]. In our study bacterial detection rate in drain tip culture is 2.18 %. Previously, Sørensen and Sørensen [12] reported that early removal of the drain decreases the risk of retrograde migration of bacteria from the skin, and the frequency of positive drain tip cultures and the risk of infection are substantially increased if the drainage time is >6 days; thus, early removal of drains seems to be appropriate. Weinrauch [14] suggested that the low rate of culture-positive drain tips may partly be due to early removal, as well as to postoperative antibiotic prophylaxis while drains remain in place. In orthopedic surgery, Sankar et al [18] found that suction tip cultures had a sensitivity of 75%, specificity of 97%, PPV of 50%, and NPV of 99% for prediction of SSIs. In spinal surgery with instrumentation, Nakayama et al [19] found a sensitivity of 60%, specificity of 98%, PPV of 60%, and NPV of 98% for prediction of deep SSIs using suction tip cultures. In our study has Sensitivity of 20 %, Specificity of 98.31 %, PPV of 25 % and NPV of 97.76 %. Thus only Specificity and NPV value match with previous studies. Infections after spinal surgery are most commonly caused by Gram-positive organisms found on skin flora, most notably Staphylococcus aureus and Staphylococcus epidermidis (MSSE). [20] However, the incidence of infection with methicillin-resistant bacteria (including MRSA) is increasing, [21] and MRSA has also increased in postsurgical infection. [22] In our study organism isolated in SSI in only one patient and that organism is MRSA. There is no significant difference between use of instrumentation and uninsrumentation, no significant difference in level of surgery. There are several limitations in this study, including the modest sample size, and different types of surgery included and inclusion of too many young patients.. We also only used a cultured drain tip, and the drain fluid was not cultured. In addition, it was difficult to determine whether contamination had occurred in a case with a

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Single Level Multilevel Instrumented Uninstrumented SSI Positive 02 03 02 03 SSI Negative 107 71 125 53 Discussion Closed suction drainage is an established method that has the aim of preventing wound hematoma. A drain tip culture is a convenient and noninvasive method [11,12], but may not be appropriate as a routine test because the evaluation of infection may be unreliable [13]. It has also been suggested that bacteria identified in the SSI and in drain tip culture results may not necessarily match [14]. In addition, routine culture of all suction drain tips is expensive and hence may not be cost effective [15]. Thus, the appropriate strategy for use of drain tip cultures is unclear. Bacterial detection rates of 0%– 10.8% have been reported in drain tip cultures in orthopedic surgery [12,14,16,17]. In our study bacterial detection rate in drain tip culture is 2.18 %. Previously, Sørensen and Sørensen [12] reported that early removal of the drain decreases the risk of retrograde migration of bacteria from the skin, and the frequency of positive drain tip cultures and the risk of infection are substantially increased if the drainage time is >6 days; thus, early removal of drains seems to be appropriate. Weinrauch [14] suggested that the low rate of culture-positive drain tips may partly be due to early removal, as well as to postoperative antibiotic prophylaxis while drains remain in place. In orthopedic surgery, Sankar et al [18] found that suction tip cultures had a sensitivity of 75%, specificity of 97%, PPV of 50%, and NPV of 99% for prediction of SSIs. In spinal surgery with instrumentation, Nakayama et al [19] found a sensitivity of 60%, specificity of 98%, PPV of 60%, and NPV of 98% for prediction of deep SSIs using suction tip cultures. In our study has Sensitivity of 20 %, Specificity of 98.31 %, PPV of 25 % and NPV of 97.76 %. Thus only Specificity and NPV value match with previous studies. Infections after spinal surgery are most commonly caused by Gram-positive organisms found on skin flora, most notably Staphylococcus aureus and Staphylococcus epidermidis (MSSE). [20] However, the incidence of infection with methicillin-resistant bacteria (including MRSA) is increasing, [21] and MRSA has also increased in postsurgical infection. [22] In our study organism isolated in SSI in only one patient and that organism is MRSA. There is no significant difference between use of instrumentation and uninsrumentation, no significant difference in level of surgery. There are several limitations in this study, including the modest sample size, and different types of surgery included and inclusion of too many young patients.. We also only used a cultured drain tip, and the drain fluid was not cultured. In addition, it was difficult to determine whether contamination had occurred in a case with a 1060 positive drain culture but no SSI. Regardless, if bacteria are detected on the drain tip, infection should be suspected and wound puncture and a bacterial culture test should be performed. Cases with detection of the same bacteria in the drain tip and bacterial culture test have a higher possibility of SSI and contamination of the drain tip is unlikely. We are unable to conclude that the result of a drain tip culture always indicates the presence or absence of an SSI. But with p value of less than 0.05 drain tip culture is significantly associated with surgical site infection with high specificity and high negative predicted value.

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In orthopedic surgery, Sankar et al [18] found that suction tip cultures had a sensitivity of 75%, specificity of 97%, PPV of 50%, and NPV of 99% for prediction of SSIs. In spinal surgery with instrumentation, Nakayama et al [19] found a sensitivity of 60%, specificity of 98%, PPV of 60%, and NPV of 98% for prediction of deep SSIs using suction tip cultures. In our study has Sensitivity of 20 %, Specificity of 98.31 %, PPV of 25 % and NPV of 97.76 %. Thus only Specificity and NPV value match with previous studies. Infections after spinal surgery are most commonly caused by Gram-positive organisms found on skin flora, most notably Staphylococcus aureus and Staphylococcus epidermidis (MSSE). [20] However, the incidence of infection with methicillin-resistant bacteria (including MRSA) is increasing, [21] and MRSA has also increased in postsurgical infection. [22] In our study organism isolated in SSI in only one patient and that organism is MRSA. There is no significant difference between use of instrumentation and uninsrumentation, no significant difference in level of surgery. There are several limitations in this study, including the modest sample size, and different types of surgery included and inclusion of too many young patients.. We also only used a cultured drain tip, and the drain fluid was not cultured. In addition, it was difficult to determine whether contamination had occurred in a case with a 1060 positive drain culture but no SSI. Regardless, if bacteria are detected on the drain tip, infection should be suspected and wound puncture and a bacterial culture test should be performed. Cases with detection of the same bacteria in the drain tip and bacterial culture test have a higher possibility of SSI and contamination of the drain tip is unlikely. We are unable to conclude that the result of a drain tip culture always indicates the presence or absence of an SSI. But with p value of less than 0.05 drain tip culture is significantly associated with surgical site infection with high specificity and high negative predicted value.

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Infections after spinal surgery are most commonly caused by Gram-positive organisms found on skin flora, most notably Staphylococcus aureus and Staphylococcus epidermidis (MSSE). [20] However, the incidence of infection with methicillin-resistant bacteria (including MRSA) is increasing, [21] and MRSA has also increased in postsurgical infection. [22] In our study organism isolated in SSI in only one patient and that organism is MRSA. There is no significant difference between use of instrumentation and uninsrumentation, no significant difference in level of surgery. There are several limitations in this study, including the modest sample size, and different types of surgery included and inclusion of too many young patients.. We also only used a cultured drain tip, and the drain fluid was not cultured. In addition, it was difficult to determine whether contamination had occurred in a case with a 1060 positive drain culture but no SSI. Regardless, if bacteria are detected on the drain tip, infection should be suspected and wound puncture and a bacterial culture test should be performed. Cases with detection of the same bacteria in the drain tip and bacterial culture test have a higher possibility of SSI and contamination of the drain tip is unlikely. We are unable to conclude that the result of a drain tip culture always indicates the presence or absence of an SSI. But with p value of less than 0.05 drain tip culture is significantly associated with surgical site infection with high specificity and high negative predicted value.