Bacterial colonization and resistance patterns in 133 patients undergoing a primary hip- or knee replacement in Southern Sweden

High Risk for Persistent Peri-Prosthetic Infection and Amputation in Mega-Prosthesis Reconstruction

A peri-prosthetic joint infection is a feared complication after mega-prosthesis reconstruction of large bone defects. The current study investigates how patients operated with a mega-prosthesis due to sarcoma, metastasis, or trauma, are affected by a deep infection focusing on re-operations, risk for persistent infection, arthrodesis, or subsequent amputation. Time to infection, causative bacterial strains, mode of treatment and length of hospital stay are also reported. A total of 114 patients with 116 prostheses were evaluated, a median of 7.6 years (range 3.8-13.7) after surgery, of which 35 (30%) were re-operated due to a peri-prosthetic infection. Of the infected patients, the prosthesis was still in place in 51%, 37% were amputated, and 9% had an arthrodesis. The infection was persistent in 26% of the infected patients at follow-up. The mean total length of hospital stay was 68 (median 60) days and the mean number of reoperations was 8.9 (median 6.0). The mean length of antibiotic treatment was 340 days (median 183). Coagulase-negative staphylococci and Staphylococcus aureus were the most frequent bacterial agents isolated in deep cultures. No MRSA- or ESBL-producing Enterobacterales were found but vancomycin-resistant Enterococcus faecium was isolated in one patient. In summary, there is a high risk for peri-prosthetic infection in mega-prostheses, resulting in persistent infection or amputation relatively often.

Recommendations on diagnosis and antimicrobial treatment of infections after anterior cruciate ligament reconstruction (ACL-R) endorsed by ESSKA and EBJIS

Infection after anterior-cruciate ligament reconstruction (ACL-R) is a rare but devastating complication affecting predominantly young and sportive individuals. A timely and correct diagnosis as well as an optimized management are paramount to circumvent serious sequelae and compromise in life quality. These recommendations are primarily intended for use by infectious disease specialists and microbiologists, but also orthopedic surgeons and other healthcare professionals who care for patients with infections after ACL-R. They are based on evidence mainly originating from observational studies and opinions of experts in the field and cover the management of infections after ACL-R with a special focus on etiology, diagnosis, antimicrobial treatment and prevention. Comprehensive recommendations on prevention, surgical treatment and rehabilitation are presented separately in a document primarily addressing orthopedics professionals.

Assessment of antimicrobial mismatches in empirical treatment in early PJI after aseptic revision arthroplasty

Background

In early periprosthetic joint infection (PJI), 'debridement, antibiotics and implant retention' (DAIR) is a widely accepted form of treatment. Empirical antimicrobial treatment is started while culture results of tissue samples taken during debridement are pending.

Objectives

In this retrospective study we assessed the antimicrobial mismatch rate between empirical treatment and the susceptibility of the causative microorganisms of PJI after aseptic revision arthroplasty. We analysed risk factors for antimicrobial mismatches and the impact of mismatches on the outcome of PJI treatment.

Results

A total of 119 patients were included in the analysis. In 72% (86/119) of the cases there was an antimicrobial mismatch in empirical treatment. Most of the antimicrobial mismatches were caused by multidrug-resistant (MDR) Staphylococcus spp. (77%, 66/86). In multivariable analysis, polymicrobial PJI was significantly associated with antimicrobial mismatch (OR: 6.89; 95% CI: 2.38-19.53; P < 0.001), and antimicrobial mismatch was significantly associated with reduced success rate of PJI treatment (OR: 0.20; 95% CI: 0.05 ± 0.82; P = 0.026). There was no difference in successful outcome between PJI caused by Gram-negative bacilli (61%) and Gram-positive bacteria (69%, P = 0.516).

Conclusions

Mismatching empirical antimicrobial treatment after DAIR following aseptic revision arthroplasty was significantly associated with failure of PJI treatment. Polymicrobial PJI is a risk factor for antimicrobial mismatch of the empirical treatment of PJI. Antimicrobial mismatch and delay in targeted treatment should be integrated in the approach to optimize antibiotic treatment to improve clinical outcomes, while minimizing unintended side effects of antimicrobial use (antimicrobial stewardship).

Methicillin-Resistant Staphylococcus epidermidis Lineages in the Nasal and Skin Microbiota of Patients Planned for Arthroplasty Surgery

Staphylococcus epidermidis, ubiquitous in the human nasal and skin microbiota, is a common causative microorganism in prosthetic joint infections (PJIs). A high proportion of PJI isolates have been shown to harbor genetic traits associated with resistance to/tolerance of agents used for antimicrobial prophylaxis in joint arthroplasties. These traits were found within multidrug-resistant S. epidermidis (MDRSE) lineages of multiple genetic backgrounds. In this study, the aim was to study whether MDRSE lineages previously associated with PJIs are present in the nasal and skin microbiota of patients planned for arthroplasty surgery but before hospitalization. We cultured samples from nares, inguinal creases, and skin over the hip or knee (dependent on the planned procedure) taken two weeks (median) prior to admittance to the hospital for total joint arthroplasty from 66 patients on agar plates selecting for methicillin resistance. S. epidermidis colonies were identified and tested for the presence of mecA. Methicillin-resistant S. epidermidis (MRSE) were characterized by Illumina-based whole-genome sequencing. Using this method, we found that 30/66 (45%) of patients were colonized with MRSE at 1–3 body sites. A subset of patients, 10/66 (15%), were colonized with MDRSE lineages associated with PJIs. The qacA gene was identified in MRSE isolates from 19/30 (63%) of MRSE colonized patients, whereas genes associated with aminoglycoside resistance were less common, found in 11/30 (37%). We found that MDRSE lineages previously associated with PJIs were present in a subset of patients’ pre-admission microbiota, plausibly in low relative abundance, and may be selected for by the current prophylaxis regimen comprising whole-body cleansing with chlorhexidine-gluconate containing soap. To further lower the rate of S. epidermidis PJIs, the current prophylaxis may need to be modified, but it is important for possible perioperative MDRSE transmission events and specific risk factors for MDRSE PJIs to be investigated before reevaluating antimicrobial prophylaxis.

Relationship between skin and urine colonization and surgical site infection in the proximal femur fracture: a prospective study

PURPOSE

Antibiotic prophylaxis is routinely used in the surgical management of proximal femur fractures. The role of bacterial colonization of the skin and urine in the development of deep surgical site infections (SSI) is yet to be elucidated. This study aimed to evaluate the role of previous skin and urine colonization in the development of deep SSI after a proximal femoral fracture surgery.

METHODS

We conducted a prospective observational study in 326 patients > 64 years old, who were scheduled to surgery. Cultures from skin samples of the surgical site and from urine were performed prior to the procedure, and cefazoline was administered as prophylaxis.

RESULTS

Skin microbiota was isolated in 233 (71.5%) cases; 8 (2.5%) samples were positive for other bacteria, and 85 (26%) were negative. Of 236 urine samples, 168 were negative or contaminated (71.2%), and 68 (28.8%) were positive, being 58/236 for Enterobacterales (24.6%). Acute deep SSI were diagnosed in nine out of 326 patients (2.7%), and two (22%) were infected by Gram-negative bacilli. Of the 9 cases, normal skin microbiota was isolated in 7 (78%), and the remaining two were negative. Seven cases had negative or contaminated urine cultures, and the one with E. coli did not correlate with SSI bacteria.

CONCLUSION

In our elderly hip fracture population, most patients harbored normal skin microbiota, and Enterobacterales urine cultures were positive in one-quarter of cases. There was no relationship between skin colonization, urine culture, and deep SSI. We therefore do not believe that our patients would benefit from modifying the current antibiotic prophylaxis.

Antibiotic Prophylaxis With Trimethoprim/Sulfamethoxazole Instead of Cloxacillin/Cefotaxime Increases Inguinal Surgical Site Infection Rate After Lower Extremity Revascularization

Due to the consistently high proportion of surgical site infections (SSI) after vascular surgery, a change of prophylactic antibiotic therapy from cloxacillin/cefotaxime to trimethoprim/sulfamethoxazole (TMP-SMX) was conducted in 2016. The study included consecutive patients undergoing lower extremity revascularization due to acute or chronic lower extremity arterial disease. The antibiotic regime was changed in between the two sampling periods (2014 -2016 versus 2016 -2017). The diagnosis of SSI was based on clinical examination and microbiological results, and severity was classified according to the Szilagyi classification. One hundred and twenty-two patients in the cloxacillin/cefotaxime and 67 patients in the TMP-SMX group were included. The SSI rates were 32.0% and 40.3%, respectively (p=0.25). The proportion of women were higher in the TMP-SMX group (32.8% versus 47.8%, respectively, p=0.043). No other differences between the two groups were found regarding patient, vascular surgery procedure characteristics or severity of SSI. Groin infection rate was higher in the TMP-SMX group (15.4% versus 30.5%, respectively, p=0.022). When adjusting for gender, groin infection was more common in the TMP-SMX group (Odds Ratio 2.5, 95% CI 1.1 -5.4). The groin SSI rate was higher after elective surgery in the TMP-SMX group (13.0% versus 27.8%, respectively, p=0.027), and also after adjusting for gender (Odds Ratio 2.6, 95% CI 1.1 -6.2). The change in antibiotic prophylaxis from Cloxacillin/Cefotaxime to TMP-SMX was associated with an increased rate of inguinal SSI in patients undergoing lower extremity revascularization, despite a possible Hawthorne effect.

The effect of preoperative oral antibiotic use on the risk of periprosthetic joint infection after primary knee or hip replacement: a retrospective study with a 1-year follow-up

OBJECTIVES

Antibiotics are used for various reasons before elective joint replacement surgery. The aim of this study was to investigate patients' use of oral antibiotics before joint replacement surgery and how this affects the risk for periprosthetic joint infection (PJI).

METHODS

Patients having a primary hip or knee replacement in a tertiary care hospital between September 2002 and December 2013 were identified (n = 23 171). Information on oral antibiotic courses purchased 90 days preoperatively and patients' chronic diseases was gathered. Patients with a PJI in a 1-year follow-up period were identified. The association between antibiotic use and PJI was examined using a multivariable logistic regression model and propensity score matching.

RESULTS

One hundred and fifty-eight (0.68%) cases of PJI were identified. In total, 4106 (18%) joint replacement operations were preceded by at least one course of antibiotics. The incidence of PJI for patients with preoperative use of oral antibiotics was 0.29% (12/4106), whereas for patients without antibiotic use it was 0.77% (146/19 065). A preoperative antibiotic course was associated with a reduced risk for subsequent PJI in the multivariable model (OR 0.40, 95% CI 0.22-0.73). Similar results were found in the propensity score matched material (OR 0.34, 95% CI 0.18-0.65).

CONCLUSIONS

The use of oral antibiotics before elective joint replacement surgery is common and has a potential effect on the subsequent risk for PJI. Nevertheless, indiscriminate use of antibiotics before elective joint replacement surgery cannot be recommended, even though treatment of active infections remains an important way to prevent surgical site infections.

A Prospective Comparative Study in Skin Antiseptic Solutions for Posterior Spine Surgeries: Chlorhexidine-Gluconate Ethanol Versus Povidone-Iodine

STUDY DESIGN

This is a prospective comparative study.

OBJECTIVE

We evaluated the efficacy of 2 standard antiseptic solutions, chlorhexidine-gluconate (CHG) and povidone-iodine (PD-I), in eliminating bacterial pathogens from surgical sites in posterior spine surgeries.

SUMMARY OF BACKGROUND DATA

Previous studies have shown that CHG is more effective for skin antisepsis than PD-I in joint surgeries. However, few studies have investigated the preoperative use of antiseptic solutions in spine surgery.

MATERIALS AND METHODS

A total of 190 patients who received posterior spine surgeries were included in this study. The patients were allocated to the group treated with 0.5% CHG in ethanol (N=98) or 10% PV-I (N=92). Sterile culture swabs were used to obtain samples from the skin area adjacent to the planned incision site before preparation, after preparation, and after wound closure.

RESULTS

No differences were found between the CHG-treated and the PD-I-treated groups in the patients' age, sex, disease status, surgical site, operating time, and intraoperative blood loss. Before surgical skin preparation, bacteria grew in the cultures of specimens of 83.7% of the patients; no significant difference was found between the 2 groups. The common organisms isolated from both the cervical and lumbar spine surgical sites were Staphylococcus sp., Corynebacterium sp., and Bacillus sp. After the skin preparation, there were no significant differences observed in the culture positive rate between the CHG (3.1%) and PD-I (5.1%) (P=0.49) solutions. The culture positive rates became higher after wound closure (preop=4.2%, postop=8.4%; P=0.07). The positive rate after wound closure in the CHG-treated group (5.1%) was smaller than in the PD-I-treated group (14.1%) (P=0.046). However, no difference was found in infection rates between the 2 groups.

CONCLUSIONS

While CHG-ethanol and PD-I were equally effective at eliminating the bacterial flora from the surgical site, CHG-ethanol showed a more favorable long-lasting effect for skin antisepsis in posterior spine surgeries.

Increased Resistance of Skin Flora to Antimicrobial Prophylaxis in Patients Undergoing Hip Revision Arthroplasty

BACKGROUND/AIM

Prosthetic joint infection (PJI) remains a major complication after total joint replacement and is the primary indication for revision arthroplasty. Specifically, coagulase-negative Staphylococci (CNS) can cause low-grade infections. Despite the use of cephalosporin-based antimicrobial prophylaxis (AMP) and antiseptic treatment at the surgical site, evidence suggests that a significant number of cases of dermal CNS results in low-grade PJI. Thus, this study examined the bacterial colonization and resistance patterns at the surgical site. We hypothesized that the bacteria developed resistance to antibiotics that are frequently used in primary and revision total hip arthroplasty (THA) procedures.

PATIENTS AND METHODS

Ninety patients, including 63 primary and 27 revision THA patients, were enrolled in this study. For each patient, a single swab of the skin at the surgical site was subjected to clinical microbiology to assess bacterial colonization. Furthermore, resistance to a sentinel panel of antibiotics (benzylpenicillin, erythromycin, tetracycline, oxacillin, fusidic acid, clindamycin, gentamicin, levofloxacin/moxifloxacin, rifampicin, linezolid and vancomycin) was tested.

RESULTS

In 96.7% of the patients, at least one bacterial strain was identified at the surgical site, with CNS strains comprising 93.1% of the total. The sentinel panel showed that 30.7% of the CNS strains exhibited maximal resistance to oxacillin, a commonly used cephalosporin. Additionally, oxacillin resistance increased 1.9-fold (p=0.042) between primary and revision THA. Notably, 8.1% of the CNS stains found on patients undergoing primary THA were resistant to gentamicin, an aminoglycoside, and this rate increased 4.7-fold (p=0.001) for patients undergoing revision THA.

CONCLUSION

CNS strains have significant resistance to standard AMP, particularly in individuals undergoing revision THA.

One-year incidence of prosthetic joint infection in total hip arthroplasty: a cohort study with linkage of the Danish Hip Arthroplasty Register and Danish Microbiology Databases

OBJECTIVE

To examine the trend of Prosthetic Joint Infections (PJI) following primary total hip arthroplasty (THA) and the antimicrobial resistance of the bacteria causing these infections.

MATERIALS AND METHODS

We identified a population-based cohort of patients in the Danish Hip Arthroplasty Register (DHR) who had primary THA and received their surgery in Jutland or Funen between 2005 and 2014. We followed the patients until revision, emigration, death, or up to 1-year of follow-up. Data from the DHR were combined with those from microbiology databases, the National Register of Patients, and the Civil Registration System. We estimated the cumulative 1-year incidence of PJI for two 5-year periods; 2005-2009 and 2010-2014. The hazard ratio of PJI as a measure of relative risk after adjusting for multiple risk factors was calculated.

RESULTS

Of 48,867 primary THAs identified, 1120 underwent revision within 1 year. Of these, 271 were due to PJI. The incidence of PJI was 0.53% (95% confidence interval (CI): 0.44; 0.63) during 2005-2009 and 0.57% (95% CI: 0.49; 0.67) during 2010-2014. The adjusted relative risk was 1.05 (95% CI: 0.82; 1.34) for the 2010-2014 period vs the 2005-2009 period. The most common micro-organisms identified in the 271 PJI were Staphylococcus aureus (36%) and coagulase-negative staphylococci (CoNS) (33%); others commonly identified included Enterobacteriaceae, enterococci, and streptococci. Antimicrobial resistance to beta-lactams and gentamicin did not change during the study period.

CONCLUSION

The risk of PJI within 1-year after primary THA and the antimicrobial resistance of the most prevalent bacteria remained unchanged during the 2005-2014 study period.

Wound Hygiene Practices After Total Knee Arthroplasty: Does It Matter?

BACKGROUND

Current literature is limited with regard to standardized postoperative surgical site hygiene after total knee arthroplasty (TKA). With little guidance from the literature, the timing of permissible postoperative cleaning is a decision made by the individual surgeon using anecdotal evidence. A standardized wound care regimen is of particular interest to minimize the risk of infection.

METHODS

To examine what species of bacteria recolonize the surgical site postoperatively, a randomized controlled trial was performed of 16 TKA patients who were allowed to shower at 2 days postoperatively and of 16 patients who were asked to wait until 2 weeks postoperatively before showering after TKA. Culture swabs of skin adjacent to the incision were performed preoperatively, just after incision closure, at dressing removal, and at 2 weeks postoperatively. Bacteria were speciated and compared between groups. A swab of the contralateral knee was performed at 2 weeks as a control. A survey of patient's preference regarding early and late showering was also carried out.

RESULTS

No difference was found between the groups in rate of colonization or bacterial type, and no patients developed infection. Patients overwhelmingly preferred early showering rather than late (P = .28-.99).

CONCLUSION

There is no difference in surgical site bacterial recolonization between early and delayed showering after primary TKA.

Antimicrobial susceptibility and body site distribution of community isolates of coagulase-negative staphylococci

The primary aim of this study was to determine antimicrobial resistance in coagulase-negative staphylococci (CoNS) from healthy adults in the community. Healthy adults (n = 114) were swabbed on six body sites; both armpits, both knee pits and both sides of the groin. Species determination was performed using Matrix Assisted Laser Desorption Ionization - Time of Flight (MALDI-TOF) and susceptibility testing for 11 relevant antimicrobials was performed by the disc diffusion method and minimal inhibitory concentration gradient test. In total, 693 CoNS isolates were identified. Susceptibility testing was done on 386 isolates; one CoNS from each species found on each participant from the different body sites. The prevalence of antimicrobial resistance in the CoNS isolates were; erythromycin (24.6%), fusidic acid (19.9%), tetracycline (11.4%), clindamycin (7.8%), gentamicin (6.2%) and cefoxitin (4.1%). Multidrug resistance was observed in 5.2% of the isolates. Staphylococcus epidermidis and S. hominis were the first and second most prevalent species on all three body sites. We conclude that CoNS isolates from healthy adults in the community have a much lower prevalence of antimicrobial resistance than reported in nosocomial CoNS isolates. Still, we believe that levels of resistance in community CoNS should be monitored as the consumption of antimicrobials in primary care in Norway is increasing.

Iodine-impregnated incision drape and bacterial recolonization in simulated total knee arthroplasty

Background and purpose - Iodine-impregnated incision drapes (IIIDs) are used to prevent surgical site infection (SSI). However, there is some evidence to suggest a potential increase in SSI risk as a result of IIID use, possibly from promotion of skin recolonization. A greater number of viable bacteria in the surgical field of an arthroplasty, and surgery in general, may increase the infection risk. We investigated whether IIID use increases bacterial recolonization compared to no drape use under conditions of simulated total knee arthroplasty (TKA). Methods - 20 patients scheduled for TKA were recruited. Each patient had 1 knee randomized for draping with IIID, while the contralateral knee was left bare. The patients thus served as their own control. The operating room conditions and perioperative procedures of a TKA were simulated. Cylinder samples were collected from the skin of each knee prior to disinfection, and again on 2 occasions after skin preparation-75 min apart. Quantities of bacteria were estimated using a spread plate technique under aerobic conditions. Results - We found similar quantities of bacteria on the intervention and control knees immediately after skin disinfection and after 75 min of simulated surgery. These quantities had not increased at the end of surgery when compared to baseline, so no recolonization was detected on the draped knees or on the bare knees. Interpretation - The use of IIIDs did not increase bacterial recolonization in simulated TKA. This study does not support the hypothesis that IIIDs promote bacterial recolonization and postoperative infection risk.

Microbiologic Safety of the Transareolar Approach in Breast Augmentation

BACKGROUND

In aesthetic breast augmentation, especially by the transareolar approach, there is increasing concern regarding the occurrence of capsular contracture and its potential correlation with intraoperative implant contamination from putative endogenous breast flora of the nipple and lactiferous ducts. However, detectable bacteria cannot be considered synonymous with established resident microflora.

OBJECTIVES

The authors sought to elucidate the existence of endogenous breast flora and assess the microbiologic safety of transareolar breast augmentation.

METHODS

In this prospective study (BREAST-MF), the authors collected microbiologic samples from the breast skin, ductal tissue, and parenchyma of 39 consecutive female patients who underwent breast procedures in a plastic surgery clinic. Swabs collected pre-, intra-, and postoperatively were processed for bacterial and fungal growth. Positive cultures underwent identification through VITEK and MALDI-TOF, as well as antimicrobial susceptibility testing.

RESULTS

Staphylococcus species accounted for 95 of 106 (89.6%) positive results from native breast skin, 15 of 18 (83.3%) positive results from decontaminated breast skin, and 4 of 4 (100%) positive results from the breast parenchyma. Methicillin resistance was present in 26.4% of S. epidermidis, 25.3% of S. hominis, and 71.4% of S. haemolyticus strains.

CONCLUSIONS

During transareolar breast augmentation, in the nipple-areola region it is more likely to find bacteria populating the skin, rather than endogenous breast flora, as previously considered. Appropriate preoperative decontamination is essential for minimizing the risk of postoperative infections. LEVEL OF EVIDENCE 3: Risk.

Burden of Surgical Site Infections Associated with Arthroplasty and the Contribution of Staphylococcus aureus

BACKGROUND

Patients undergoing arthroplasty are at considerable risk of experiencing post-operative complications, including surgical site infections (SSIs). In addition to potential economic consequences, SSIs can have a negative impact on patient outcomes and may potentially be life-threatening. Staphylococcus aureus has been consistently shown as the leading cause of SSIs associated with orthopedic surgery, with an important contribution from methicillin-resistant S. aureus (MRSA). This study evaluated the global burden of SSIs among patients undergoing orthopedic surgical procedures, and specifically those undergoing knee and hip arthroplasties.

METHODS

An extensive search of PubMed and recent conference proceedings was conducted. English articles published between 2003 and 2013 pertaining to SSI epidemiology, patient outcomes, and healthcare resource utilization and costs were reviewed.

RESULTS

Overall, 81 studies were included, mainly from North America and Europe. Median SSI and S. aureus SSI rates, calculated as percentage of all arthroplasty procedures, were 1.7% (range: 0.25%-4.4%; 15 studies) and 0.6% (range: 0.1%-23%), respectively. Median SSI rates were 1.3% (range: 0.05%-19%; 22 studies) after knee arthroplasty, and 2.1% (range: 0.05%-28%; 24 studies) after hip arthroplasty. S. aureus SSI rates ranged from 0.2%-2.4% and 0.18%-3.8% for patients undergoing knee and hip arthroplasty, respectively. The percentage of S. aureus SSIs because of MRSA varied widely within each patient category. SSI-related mortality data (14 studies) showed that in-hospital mortality rates were low (1.2%-2.5%), but increased with time after index arthroplasty procedure (up to 56% over 1 y). Studies assessing healthcare resource utilization (n = 21) revealed that developing post-orthopedic SSIs resulted in a two- to three-fold increase in length of hospital stay (LOS) compared with non-infected patients (median LOS: 18.9 d vs. 6 d for non-SSI patients). Patients with SSIs because of methicillin-resistant staphylococci incurred greater mean LOS compared with SSIs because of methicillin-sensitive organisms. Readmission rates reported in 11 studies indicate a greater likelihood in the presence of SSIs; comparison across studies was not feasible because of differences in data reporting. Consistent with increased healthcare resource utilization (LOS and readmission) associated with SSIs, cost studies (n = 23) revealed that the presence of SSIs was associated with up to three-fold cost increase compared with the absence of SSI across all orthopedic patient categories assessed.

CONCLUSIONS

SSIs are associated with increased morbidity, mortality rates, healthcare resource utilization, and costs. Despite the relatively low SSI incidence following orthopedic surgery and specifically arthroplasty, preventive methods, specifically those targeting S. aureus, would serve to minimize costs and improve patient outcomes.

Antibiotic Prophylaxis With Trimethoprim/Sulfamethoxazole Instead of Cloxacillin Fails to Improve Inguinal Surgical Site Infection Rate After Vascular Surgery

Background:

Surgical site infections (SSIs) and their prevention continue to be a major point of focus in all surgical specialties today. Antibiotic prophylaxis is one of the mainstays in their prevention. Due to the consistently high proportion of infections caused by intestinal flora from the start of our wound surveillance registry in 2005, we conducted a change in prophylactic antibiotic therapy from cloxacillin in 2012 to trimethoprim/sulfamethoxazole (TMP-SMX) in 2013.

Methods:

The study included all patients undergoing vascular surgery with groin incisions between March 1 and June 30 in 2012 and 2013, respectively, whereby the antibiotic regime was changed in between the 2 sampling periods. The diagnosis of SSI was based on clinical examination and microbiological results.

Results:

Two hundred nineteen patients with inguinal incisions were included in the analysis: 105 in the cloxacillin group of which 19% had SSI and 114 in the TMP-SMX group with an SSI rate of 18% ( P = .77), without differences between the 2 groups regarding age, gender, proportion of emergency surgery, type of surgery, or frequency of concomitant foot ulcers. The high proportion of infections caused by intestinal flora between time periods was unchanged (67% vs 81%, P = .34).

Conclusion:

There was no difference between the 2 groups, suggesting that the choice of antibiotic prophylaxis had a limited role in preventing SSI at our center. Despite this, the lower cost and ease of the administration of TMP-SMX can be seen as convincing advantages.

Sequence types of Staphylococcus epidermidis associated with prosthetic joint infections are not present in the laminar airflow during prosthetic joint surgery

Molecular characterization of Staphylococcus epidermidis isolates from prosthetic joint infections (PJIs) has demonstrated a predominance of healthcare-associated multi-drug resistant sequence types (ST2 and ST215). How, and when, patients acquire these nosocomial STs is not known. The aim was to investigate if sequence types of S. epidermidis associated with PJIs are found in the air during prosthetic joint surgery. Air sampling was undertaken during 17 hip/knee arthroplasties performed in operating theaters equipped with mobile laminar airflow units in a 500-bed hospital in central Sweden. Species identification was performed using MALDI-TOF MS and 16S rRNA gene analysis. Isolates identified as S. epidermidis were further characterized by MLST and antibiotic susceptibility testing. Seven hundred and thirty-five isolates were available for species identification. Micrococcus spp. (n = 303) and coagulase-negative staphylococci (n = 217) constituted the majority of the isolates. Thirty-two isolates of S. epidermidis were found. S. epidermidis isolates demonstrated a high level of allelic diversity with 18 different sequence types, but neither ST2 nor ST215 was found. Commensals with low pathogenic potential dominated among the airborne microorganisms in the operating field during prosthetic joint surgery. Nosocomial sequence types of S. epidermidis associated with PJIs were not found, and other routes of inoculation are therefore of interest in future studies.

Lack of efficacy of prophylactic application of antibiotic-loaded bone cement for prevention of infection in primary total knee arthroplasty: results of a meta-analysis

BACKGROUND

Deep incisional surgical site infection (SSI) is a devastating and costly complication of primary total knee arthroplasty (TKA). The effectiveness of antibiotic-loaded bone cement (ALBC) in preventing these infections remains controversial.

METHODS

A meta-analysis was conducted to assess the efficacy of ALBC in preventing deep infection in primary TKA after a detailed and systematic search of the PubMed, Embase, CNKI, and Cochrane databases had been performed to identify appropriate comparative trials on the prophylactic use of ALBC in primary TKA.

RESULTS

Five comparative trials were included. In total, 3,461 patients (ALBC group) received ALBC, whereas 3,176 patients (non-antibiotic-loaded cement; NALBC group) did not. The incidence of deep incisional SSI in the ALBC group was 1.32% (n=46) whereas the incidence in the NALBC group was 1.89% (n=60), figures which are not significantly different. No adverse events associated with ALBC were reported in any studies.

CONCLUSION

Statistical analysis did not reveal a significantly different incidence of deep or superficial SSI in patients receiving and not receiving antibiotic-loaded cement. The prophylactic application of ALBC thus did not show efficacy in primary TKA. More large-sample studies are required to confirm this finding.

Increasing Resistance of Coagulase-Negative Staphylococci in Total Hip Arthroplasty Infections: 278 THA-Revisions due to Infection Reported to the Norwegian Arthroplasty Register from 1993 to 2007

We investigated bacterial findings from intraoperative tissue samples taken during revision due to infection after total hip arthroplasty (THA). The aim was to investigate whether the susceptibility patterns changed during the period from 1993 through 2007. Reported revisions due to infection in the Norwegian Arthroplasty Register (NAR) were identified, and 10 representative hospitals in Norway were visited. All relevant information on patients reported to the NAR for a revision due to infection, including bacteriological findings, was collected from the medical records. A total of 278 revision surgeries with bacterial growth in more than 2 samples were identified and included. Differences between three 5-year time periods were tested by the chi-square test for linear trend. The most frequent isolates were coagulase-negative staphylococci (CoNS) (41%, 113/278) and Staphylococcus aureus (19%, 53/278). The proportion of CoNS resistant to the methicillin-group increased from 57% (16/28) in the first period, 1993-1997, to 84% (52/62) in the last period, 2003-2007 (P = 0.003). There was also significant increase in resistance for CoNS to cotrimoxazole, quinolones, clindamycin, and macrolides. All S. aureus isolates were sensitive to both the methicillin-group and the aminoglycosides. For the other bacteria identified no changes in susceptibility patterns were found.

A review of the biomaterials technologies for infection-resistant surfaces

Anti-infective biomaterials need to be tailored according to the specific clinical application. All their properties have to be tuned to achieve the best anti-infective performance together with safe biocompatibility and appropriate tissue interactions. Innovative technologies are developing new biomaterials and surfaces endowed with anti-infective properties, relying either on antifouling, or bactericidal, or antibiofilm activities. This review aims at thoroughly surveying the numerous classes of antibacterial biomaterials and the underlying strategies behind them. Bacteria repelling and antiadhesive surfaces, materials with intrinsic antibacterial properties, antibacterial coatings, nanostructured materials, and molecules interfering with bacterial biofilm are considered. Among the new strategies, the use of phages or of antisense peptide nucleic acids are discussed, as well as the possibility to modulate the local immune response by active cytokines. Overall, there is a wealth of technical solutions to contrast the establishment of an implant infection. Many of them exhibit a great potential in preclinical models. The lack of well-structured prospective multicenter clinical trials hinders the achievement of conclusive data on the efficacy and comparative performance of anti-infective biomaterials.