Bacteria in hip surgery. A study of routine aerobic and anaerobic cultivation from skin and closed suction wound drains

Prediction of surgical site infection in spine surgery from tests of nasal MRSA colonization and drain tip culture

PURPOSE

MRSA is an organism that is a possible risk factor for postoperative SSI. The purpose of the study was to examine relationships among surgical site infection (SSI) after spinal surgery, nasal methicillin-resistant staphylococcus aureus (MRSA) colonization, and wound drain culture results.

METHODS

The subjects were 132 patients who underwent spinal instrumentation surgery. A preoperative nasal swab was used to check for the presence of MRSA colonization, and a wound drain tip culture was performed for detection of SSI. Data from culture studies using nasal samples and those from the distal tip of the wound drain were used for analysis.

RESULTS

Five patients (3.8%) had nasal MRSA, 17 (13%) had positive drain tip cultures, 15 (11%) had SSIs, and 10 (8%) had SSIs with MRSA. Patients with nasal MRSA had a higher rate of detection of bacteria in the drain tip culture (40 vs. 19%, p = 0.065), and the SSI rate was significantly higher in patients with a positive drain tip culture (33 vs. 10%, p = 0.012). The total SSI rate differed significantly between patients with and without nasal MRSA (40 vs. 10%, p = 0.039); however, the SSI with MRSA rate did not differ significantly between these groups.

CONCLUSION

MRSA carriers were not necessarily associated with MRSA infection, but were related to a positive drain tip culture and SSI, which might be due to endogenous skin bacteria. Therefore, possible SSI should be considered in patients with nasal MRSA colonization or bacteria detected in a drain tip culture.

Is a Drain Tip Culture Required After Spinal Surgery?

STUDY DESIGN

The efficacy of use of a drain tip culture for early detection of surgical-site infection (SSI) was investigated in 329 patients after spinal surgery.

OBJECTIVE

To examine the efficacy of a wound drain tip culture for detection of SSI in spinal surgery.

SUMMARY OF BACKGROUND DATA

A complication of SSI after spinal surgery has high associated morbidity and mortality, and is often difficult to treat.

MATERIALS AND METHODS

The subjects were patients who underwent spinal surgery at our institution between January 2010 and March 2013. All subjects were treated with antimicrobial prophylaxis based on evidence-based guidelines and were followed for at least 6 months after surgery. Data from culture studies using the distal tip of the wound drain were used for analysis.

RESULTS

Drain tip cultures were positive in 34 cases and there were 19 SSIs. Ten of the 34-tip culture-positive wounds developed SSI. Drain tip cultures had a sensitivity of 52%, specificity of 92%, positive predictive value (PPV) of 29%, and negative predictive value of 97% for predicting a wound infection. The association between a positive suction tip culture and wound infection was significant (P<0.05). The PPV for SSI was 60% in cases in which methicillin-resistant bacteria were detected in a drain tip, and the SSI rate in these cases differed significantly compared with those with non-methicillin-resistant bacteria (P=0.01).

CONCLUSIONS

A drain tip culture is useful for early detection of SSI caused by methicillin-resistant bacteria.

Suction Drain Tip Culture after Spine Surgery: Can It Predict a Surgical Site Infection?

Study Design

Retrospective clinical study.

Purpose

To assess the diagnostic value of suction drain tip culture in patients undergoing primary posterior spine surgery.

Overview of Literature

To date, the diagnostic value of suction drain tip culture for predicting surgical site infection (SSI) has not been firmly established in orthopedic or spinal surgery.

Methods

In total, 133 patients who underwent primary posterior spine surgery from January 2013 to April 2015 were included in this retrospective study. Patients diagnosed with infective disease or condition was excluded. The suction drain tip was cut off approximately 5 cm from its far end. The sample was sent to the microbiological laboratory of the hospital for culture analysis. Any signs of infection, such as wound discharge or dehiscence, fever, chills, or chronic pain, were recorded. The culture outcome, identification of bacteria, and postoperative transition of the serum C-reactive protein level were also recorded in all patients. The wounds were followed up for a minimum of 3 months.

Results

A positive drain tip culture was found in 48 patients (36.1%), of whom, 6 developed SSI. The sensitivity of drain tip culture for SSI after primary posterior spine surgery was 60.0%, and the specificity was 65.9%. The association between the incidence of positive suction tip culture and SSI was not statistically significant. Among the 48 positive drain tip cultures, there was no significant association between the occurrence of SSI and virulence of isolated bacteria. There was no significant association between drain tip culture positivity and the duration of drainage, or between the rate of SSI and duration of drainage.

Conclusions

Suction drain tip culture analysis is a poor predictor of SSI after primary posterior spine surgery. Routine use of a drain tip culture is not supported by the results of this study.

Bacteriology swabs in primary total knee arthroplasty

Objective: An early detection of possible periprosthetic infection may lead to an earlier and potentially less invasive treatment of infected total knee arthroplasty TKA). The purpose of the present study was to evaluate retrospectively our current, affordable clinical practice of intra-operative swab taking during primary TKA.

Methods: A total of 206 primary TKA were analysed retrospectively for intra-operative bacteriology swabs and subsequent periprosthetic infection. All bacteriology swabs were obtained in a standardized manner including a tissue sample. Data was statistically evaluated concerning standard descriptive statistics and using the chi-square test.

Results: Bacteria were identified in 43.4% with coagulase-negative staphylococci being the most frequently isolated pathogens (52.2%). Regarding the contingency tables and chi-squared tests, generally no association was found between positive intra-operative swabs and subsequent periprosthetic infection as well as all other parameters investigated (timing of the antibiotic prophylaxis and pre-operative laboratory results).

Conclusions: Bacteriology swabs during primary total knee arthroplasty are no adequate measure to predict subsequent periprosthetic infections, even if augmented with a tissue sample.

Prognostic value of suction drain tip culture in determining joint infection in primary and non-infected revision total hip arthroplasty: a prospective comparative study and review of the literature

INTRODUCTION

Closed suction drainage in joint replacement surgery has been considered to carry an obvious risk of bacteria invasion. Previous studies have shown controversial results regarding the role of suction drain culture in predicting artificial joint infection. Furthermore, the efficacy of the method has not been established in revision total hip or knee arthroplasty.

MATERIALS AND METHODS

Suction drain tips from 110 patients who underwent 73 primary and 37 revision non-infected total hip arthroplasties were prospectively cultured. The drains removed at 48 h postoperatively. The patients had an average age of 64.3 years (range 25-81 years) and followed up for 2-4 years (average 2.8 years).

RESULTS

Positive cultures were identified in two primary (2.74%) and six revision (16.22%) total hip replacements (p = 0.017). The most frequently isolated microorganisms were Staphylococcus aureus (3 cases) and S. epidermidis (2 cases). Resistance to perioperative antibiotics was found in three out of eight isolated pathogens. However, no infection was recorded in any of the eight patients whose cultures found positive.

CONCLUSION

Although suction drains are more often contaminated in revision total hip arthroplasty, the prognostic value of the method in determining joint infection is very limited and its routine use is not supported from the clinical data.

Suction drainage culture as a guide to effectively treat musculoskeletal infection

Following surgery for musculoskeletal infection, a positive suction drainage culture (SDC) is consistent with persistent sepsis. Our objective was to determine the effect of a negative SDC obtained in subsequent operations on the outcome of a musculoskeletal infection. 99 patients were prospectively enrolled, all treated surgically for musculoskeletal infection utilizing suction drainage and appropriate antimicrobial therapy. Surgery consisted of irrigation, debridement, and prosthetic exchange or implant removal. SDC was considered negative if all bottles resulted in negative cultures. Following SDC results, patients were placed into 1 of 2 treatment groups: 1) Negative SDC, and no new operation; or 2) Positive SDC, and new operation(s) until SDC was negative. Antibiotic therapy ranged from 6-12 weeks (osteomyelitis) to 10-21 d (soft tissue). Both groups were similar with regard to baseline characteristics. Cure was obtained in 91.8% of patients (56/61) in group 1 and 91.6% of patients (22/24) in group 2. Similar results were obtained in patients with an infection in the presence of an implant. In conclusion, a negative SDC following surgery for a musculoskeletal infection is a strong indication of eventual outcome.

Myths and legends in orthopaedic practice: are we all guilty?

Over years of practice, many beliefs and practices become entrenched as tried and tested, and we subconsciously believe they are based on scientific evidence. We identified nine such beliefs by interviewing orthopaedic surgeons in which studies (or lack thereof) apparently do not support such practices. These are: changing the scalpel blade after the skin incision to limit contamination; bending the patient's knee when applying a thigh tourniquet; bed rest for treatment of deep vein thrombosis; antibiotics in irrigation solution; routine use of hip precautions; routine use of antibiotics for the duration of wound drains; routine removal of hardware in children; correlation between operative time and infection; and not changing dressings on the floor before scrubbing. A survey of 186 practicing orthopaedic surgeons in academic and community settings was performed to assess their routine practice patterns. We present the results of the survey along with an in-depth literature review of these topics. Most surgeon practices are based on a combination of knowledge gained during training, reading the literature, and personal experience. The results of this survey hopefully will raise the awareness of the selected literature for common practices.

The value of bacterial culture during clean orthopedic surgery: a prospective study of 1,036 patients

OBJECTIVE

To determine whether bacterial cultures of the wounds of patients undergoing clean orthopedic surgery would help predict infection.

METHODS

During 1 year, 1,256 cultures were performed for 1,102 patients who underwent clean orthopedic surgery. Results were analyzed to evaluate their ability to predict postoperative infection.

RESULTS

The sensitivity, specificity, positive predictive value, and negative predictive value of the cultures were 38%, 92%, 7%, and 99%, respectively.

CONCLUSIONS

Cultures performed during clean orthopedic surgery were not useful for predicting postoperative infection.

Suction drain tip culture in orthopaedic surgery: a prospective study of 214 clean operations

We conducted a prospective cohort study in order to determine whether suction drain specimen cultures from orthopaedic surgery predicted an early wound infection. We included 218 consecutive clean orthopaedic operations requiring drains in one unit over a period of 1 year. The suction drain tip, drain fluid and wound discharge specimens were cultured, and the surgical wound was followed up for 3 months. There were six deep and two superficial wound infections. Wound infection was significantly related to positive suction tip culture but not to positive drain fluid culture. Following our methodology for culture, a positive drain tip culture predicts wound infection in 50% and a negative culture virtually excludes the possibility of a deep infection.

The value of suction drainage fluid culture during aseptic and septic orthopedic surgery: a prospective study of 901 patients

There are no guidelines on the value of suction drainage fluid culture (SDC), and it is difficult to determine whether the organisms cultured from suction drainage fluid samples are pathogenic or simply contaminants. We performed 2989 cultures of suction drainage fluid samples obtained, during a 1-year period, from 901 patients who underwent aseptic or septic orthopedic surgery (946 operations). The culture results were analyzed to evaluate their ability to detect postoperative infection after aseptic operations or to detect either a persistent or new episode of sepsis in patients known to have infection. For aseptic operations, the sensitivity of SDC was 25%, the specificity was 99%, the positive predictive value was 25%, and the negative predictive value was 99%. For septic operations, the sensitivity of SDC was 81%, the specificity was 96%, the positive predictive value was 87%, and the negative predictive value was 94%. We conclude that, for aseptic orthopedic surgery, SDC is not useful in detecting postoperative infection. However, for septic orthopedic surgery, it is of clinical importance.

Closed suction drainage after hip arthroplasty. Prospective study of bacterial contamination in 81 cases

In a prospective study we analyzed the volume of drainage, the contamination of the drain track, and drain tip in 81 primary total hip arthroplasties in 78 patients. The drain was removed when the drainage from midnight to the following morning was 20 mL or less. The drainage in the first 12 h and in total was reduced in cases with a drain period of 24 h, compared to cases with a drain period of 48 and 72 h. 4 cases had a positive culture from the wound before closure. 5 cases had a positive culture from the tip of the drain, and 6 from the drain track. The most frequently isolated microorganism was coagulase-negative Staphylococcus. The positive cultures from the drain track and tip were not correlated to the duration of drainage. 68 drains were removed within 48 h with no risk of developing wound complications.

Bacterial growth on suction drain tips. Prospective study of 489 clean orthopedic operations

The study included 489 clean orthopedic operations with implantation of major foreign materials (joint replacements and internal fixations of fractures). Specimens for culture were taken from the suction drainage system, either from the drain fluid or from the drain-tube tip or from both. Six superficial and five deep infections were seen following the operations. Only two cultures of drain fluid were positive, and neither of these became infected. Positive drain-tip cultures were seen after 56 operations, and of these, five were followed by infection. The risk of infection was increased if Staphylococcus aureus, Enterobacteriaceae, or Streptococcus faecalis was cultured from drain tips. Drain-tip cultures growing only coagulase-negative staphylococci, nonhemolytic streptococci, and corynebacteria were not correlated with increased risk of infection. There was a not significant tendency towards fewer infections if positive drain-tip cultures with virulent bacteria were treated with specific antibiotics.

Non-sporeforming anaerobic bacteria in clean surgical wounds--air and skin contamination

The contamination of clean surgical wounds with anaerobic and aerobic bacteria was studied in 52 hip operations. In addition to wound samples, samples from air and the patients' skin were taken. The median of the total number of bacteria isolated from the wounds was 26 colony-forming units (cfu). The median percentage of anaerobic bacteria in the wound counts was 30. Propionibacterium spp. were found in 71 per cent of the wounds and anaerobic or microaerophilic cocci, most often Peptococcus spp., were found in 23 per cent. In six of 43 patients the same bacterial flora was seen in the skin samples and wounds. The geometric mean of the total number of bacteria in the air was 70.3 cfu/m3. Of these the median percentage of anaerobic bacteria was 30.3. When operating clothing of a disposable fabric (Barrier 450, Johnson & Johnson) was used, the counts of airborne bacteria were a little less than half those found when conventional cotton clothing was worn. Probably because of the overall low air counts in the operating theatre and the great variability in the individual bacterial counts from the operation wounds, a significant decrease in wound contamination was not observed. A positive correlation was found between the duration of operation and wound contamination.