Meticillin resistance in orthopaedic coagulase-negative staphylococcal infections

General skin and nasal decolonization with octenisan® set before and after elective orthopedic surgery in selected patients at elevated risk for revision surgery and surgical site infections-a single-center, unblinded, superiority, randomized controlled trial (BALGDEC trial)

BACKGROUND

The preoperative body surface and nasal decolonization may reduce the risk of surgical site infections (SSI) but yields conflicting results in the current orthopedic literature.

METHODS

We perform a single-center, randomized-controlled, superiority trial in favor of the preoperative decolonization using a commercial product (octenidine® set). We will randomize a total number of 1000 adult elective orthopedic patients with a high risk for SSI and/or wound complications (age ≥ 80 years, chronic immune-suppression, American Society of Anesthesiologists score 3-4 points) between a decolonization (octenisan® wash lotion 1 × per day and octenisan® md nasal gel 2-3 × per day; during 5 days) and no decolonization. Decolonized patients will additionally fill a questionnaire regarding the practical difficulties, the completeness, and the adverse events of decolonization. The primary outcomes are SSI and revision surgeries for postoperative wound problems until 6 weeks postoperatively (or 1 year for surgeries with implants or bone). Secondary outcomes are unplanned revision surgeries for non-infectious problems and all adverse events. With 95% event-free surgeries in the decolonization arm versus 90% in the control arm, we formally need 2 × 474 elective orthopedic surgeries included during 2 years.

DISCUSSION

In selected adult orthopedic patients with a high risk for SSI, the presurgical decolonization may reduce postoperative wound problems, including SSI.

TRIAL REGISTRATION

ClinicalTrial.gov NCT05647252. Registered on 9 December 2022.

PROTOCOL VERSION

2 (5 December 2022).

Broad-spectrum antibiotic prophylaxis in tumor and infected orthopedic surgery-the prospective-randomized, microbiologist-blinded, stratified, superiority trials: BAPTIST Trials

BACKGROUND

The perioperative antibiotic prophylaxis with 1st or 2nd generation cephalosporins is evidence-based in orthopedic surgery. There are, however, situations with a high risk of prophylaxis-resistant surgical site infections (SSI).

METHODS

We perform a superiority randomized controlled trial with a 10% margin and a power of 90% in favor of the broad-spectrum prophylaxis. We will randomize orthopedic interventions with a high risk for SSI due to selection of resistant pathogens (open fractures, surgery under therapeutic antibiotics, orthopedic tumor surgery, spine surgery with American Society of Anesthesiologists (ASA) score ≥ 3 points) in a prospective-alternating scheme (1:1, standard prophylaxis with cefuroxime versus a broad-spectrum prophylaxis of a combined single-shot of vancomycin 1 g and gentamicin 5 mg/kg parenterally). The primary outcome is "remission" at 6 weeks for most orthopedic surgeries or at 1 year for surgeries with implant. Secondary outcomes are the risk for prophylaxis-resistant SSI pathogens, revision surgery for any reason, change of antibiotic therapy during the treatment of infection, adverse events, and the postoperative healthcare-associated infections other than SSI within 6 weeks (e.g., urine infections or pneumonia). With event-free surgeries to 95% in the broad-spectrum versus 85% in the standard prophylaxis arm, we need 2 × 207 orthopedic surgeries.

DISCUSSION

In selected patients with a high risk for infections due to selection of prophylaxis-resistant SSI, a broad-spectrum combination with vancomycin and gentamycin might prevent SSIs (and other postoperative infections) better than the prophylaxis with cefuroxime.

TRIAL REGISTRATION

ClinicalTrial.gov NCT05502380. Registered on 12 August 2022. Protocol version: 2 (3 June 2022).

Influence of Skin Commensals on Therapeutic Outcomes of Surgically Debrided Diabetic Foot Infections-A Large Retrospective Comparative Study

In diabetic foot infections (DFI), the clinical virulence of skin commensals are generally presumed to be low. In this single-center study, we divided the wound isolates into two groups: skin commensals (coagulase-negative staphylococci, micrococci, corynebacteria, cutibacteria) and pathogenic pathogens, and followed the patients for ≥ 6 months. In this retrospective study among 1018 DFI episodes (392 [39%] with osteomyelitis), we identified skin commensals as the sole culture isolates (without accompanying pathogenic pathogens) in 54 cases (5%). After treatment (antibiotic therapy [median of 20 days], hyperbaric oxygen in 98 cases [10%]), 251 episodes (25%) were clinical failures. Group comparisons between those growing only skin commensals and controls found no difference in clinical failure (17% vs. 24 %, p = 0.23) or microbiological recurrence (11% vs. 17 %, p = 0.23). The skin commensals were mostly treated with non-beta-lactam oral antibiotics. In multivariate logistic regression analysis, the isolation of only skin commensals was not associated with failure (odds ratio 0.4, 95% confidence interval 0.1-3.8). Clinicians might wish to consider these isolates as potential pathogens when selecting a targeted antibiotic regimen, which may also be based on oral non-beta-lactam antibiotic agents effective against the corresponding skin pathogens.

Higher Tissue Concentrations of Vancomycin Achieved With Low-Dose Intraosseous Injection Versus Intravenous Despite Limited Tourniquet Duration in Primary Total Knee Arthroplasty: A Randomized Trial

BACKGROUND

Vancomycin use has been suggested in high risk patients undergoing total knee arthroplasty (TKA). Previous literature has shown that a lower dose (500 mg) of vancomycin given by intraosseous regional administration (IORA) achieves tissue concentrations 4-10 times higher than intravenous (IV) administration. There is increasing interest in performing TKA with limited tourniquet inflation time. The purpose of this study is to evaluate whether IORA of vancomycin can achieve effective tissue concentrations with limited tourniquet inflation time.

METHODS

Based on prior power calculations, 24 patients undergoing primary TKA were randomized into 2 groups. Group IV-Systemic received weight-based (15 mg/kg) vancomycin with the tourniquet inflated for cementation only. Group IORA received 500 mg vancomycin via IORA after tourniquet inflation which remained inflated for 10 minutes, then reinflated for cementation only. Vancomycin concentrations from tissue, serum, and drain fluid were compared between the 2 groups.

RESULTS

Median vancomycin concentrations in tissue were significantly higher (5-15 times) at all time points in the IORA group. Concentrations in fat at the time of wound closure, after the tourniquet had been deflated for most of the procedure, were 5.2 μg/g in Group IV-Systemic and 33.1 μg/g in Group IORA (P < .001). Median bone concentrations taken just prior to cementation were 7.9 μg/g in Group IV-Systemic and 21.8 μg/g in Group IORA (P = .006). There were no complications related to IORA.

CONCLUSION

For surgeons who wish to limit tourniquet time and when indicated to use vancomycin, low-dose vancomycin IORA achieves tissue concentrations 5-15 times higher than those achieved by IV administration.

LEVEL OF EVIDENCE

Level 1 therapeutic randomized trial.

Impact of Healthcare-Associated Infections Connected to Medical Devices-An Update

Healthcare-associated infections (HAIs) are caused by nosocomial pathogens. HAIs have an immense impact not only on developing countries but also on highly developed parts of world. They are predominantly device-associated infections that are caused by the planktonic form of microorganisms as well as those organized in biofilms. This review elucidates the impact of HAIs, focusing on device-associated infections such as central line-associated bloodstream infection including catheter infection, catheter-associated urinary tract infection, ventilator-associated pneumonia, and surgical site infections. The most relevant microorganisms are mentioned in terms of their frequency of infection on medical devices. Standard care bundles, conventional therapy, and novel approaches against device-associated infections are briefly mentioned as well. This review concisely summarizes relevant and up-to-date information on HAIs and HAI-associated microorganisms and also provides a description of several useful approaches for tackling HAIs.

Capsicumicine, a New Bioinspired Peptide from Red Peppers Prevents Staphylococcal Biofilm In Vitro and In Vivo via a Matrix Anti-Assembly Mechanism of Action

Staphylococci are pathogenic biofilm-forming bacteria and a source of multidrug resistance and/or tolerance causing a broad spectrum of infections. These bacteria are enclosed in a matrix that allows them to colonize medical devices, such as catheters and tissues, and that protects against antibiotics and immune systems. Advances in antibiofilm strategies for targeting this matrix are therefore extremely relevant. Here, we describe the development of the Capsicum pepper bioinspired peptide "capsicumicine." By using microbiological, microscopic, and nuclear magnetic resonance (NMR) approaches, we demonstrate that capsicumicine strongly prevents methicillin-resistant Staphylococcus epidermidis biofilm via an extracellular "matrix anti-assembly" mechanism of action. The results were confirmed in vivo in a translational preclinical model that mimics medical device-related infection. Since capsicumicine is not cytotoxic, it is a promising candidate for complementary treatment of infectious diseases. IMPORTANCE Pathogenic biofilms are a global health care concern, as they can cause extensive antibiotic resistance, morbidity, mortality, and thereby substantial economic loss. So far, no effective treatments targeting the bacteria in biofilms have been developed. Plants are constantly attacked by a wide range of pathogens and have protective factors, such as peptides, to defend themselves. These peptides are common components in Capsicum baccatum (red pepper). Here, we provide insights into an antibiofilm strategy based on the development of capsicumicine, a natural peptide that strongly controls biofilm formation by Staphylococcus epidermidis, the most prevalent pathogen in device-related infections.

Deep surgical site infections following double-dose perioperative antibiotic prophylaxis in adult obese orthopedic patients

BACKGROUND

Obesity is a risk factor for surgical site infections (SSI). Based on retrospective comparisons and pharmacology, many orthopedic centers have adopted weight- or body mass index (BMI)-related antibiotic prophylaxis.

METHODS

Double-dose prophylaxis was introduced in March 2017 for patients weighting >80 kg. The period April 2014 to March 2017 ('before') was compared to the period March 2017 to June 2019 ('after') regarding the impact on deep SSIs.

RESULTS

A total of 9318 surgeries 'before' were compared to 7455 interventions 'after' the introduction of double-dose prophylaxis. Baseline demographic characteristics (age, sex, BMI, American Society of Anesthesiologists score, and duration of surgery) were similar. In the period 'after', 3088 cases (3088/16 773; 18%) received double-dose prophylaxis. Overall, 82 deep SSIs were observed (0.5%). The pathogens were resistant to the standard cefuroxime prophylaxis in 30 cases (30/82; 37%). Excluding these prophylaxis-resistant cases and all of the five hematogenous SSIs, the remaining 47 SSIs (57%) could have been prevented by the preceding prophylaxis. Double-dosing of parenteral cefuroxime from 1.5 g to 3.0 g in obese patients did not reduce deep SSIs (hazard ratio 0.7, 95% confidence interval 0.3-1.6). In the direct group comparison among obese patients >80 kg, the double-dose prophylaxis equally failed to alter the SSI risk (3088/16 726 non-infections vs 8/47 SSI despite double-dose prophylaxis; Chi-square test, P = 0.78).

CONCLUSIONS

In this single-center before-and-after study with almost 17 000 orthopedic surgeries in adult patients, systemic doubling of the perioperative antibiotic prophylaxis in obese patients clinically failed to reduce the overall deep SSI risk.

Efficacy of 16S rRNA variable regions high-resolution melt analysis for bacterial pathogens identification in periprosthetic joint infections

BACKGROUND

Accurate and rapid identification of microorganisms causing periprosthetic joint infections (PJIs) are necessary for choosing an appropriate antibiotic therapy. Therefore, molecular techniques are suggested for diagnosis in suspected PJIs. The Broad-range PCR and High-Resolution Melt Analysis (HRMA) were evaluated for the identification of causative organisms of PJIs in this study.

RESULTS

For 47 of 63 specimens, both the culture and broad-range PCR were positive. The culture was found to be able of organism's detection in 74.6% (47/63) of patients. Of 47 positive cultures, 11 (23.4%) were polymicrobial and 36 (76.59%) were monomicrobial cultures, in which 34 (91.89%) cases were detected by HRM assay. The sensitivity, specificity of HRMA vs monomicrobial culture were 91.89, 93.75%, respectively. The sensitivity, specificity of total HRMA (mono + poly) vs culture were 82.92, 93.75%.

CONCLUSIONS

HRM assay coupled with broad-range PCR are effective screening, rapid, and relatively cost-effective methods for discrimination of PJIs especially in aiding culture method. Using computer programs such as the Matlab-2018b program for HRM data analysis is also valuable and helpful in diagnosis.

Osteoarticular infections: a specific program for older patients?

BACKGROUND

With the increasing number of elderly patients, arthroplasties, fractures and diabetic foot infections, the worldwide number of osteoarticular infections (OAI) among the elderly is concomitantly expected to rise.

AIMS

We explore existing scientific knowledge about OAI in the frail elderly population.

METHODS

We performed a literature search linking OAIs to geriatric patients and comparing elderly patients (> 65 years) with average adults (range 18-65 years).

RESULTS

In this literature, financial aspects, comparison of diverse therapies on quality of life, reimbursement policies, or specific guidelines or nursing recommendations are missing. Age itself was not an independent factor related to particular pathogens, prevention of OAI, nursing care, and outcomes of OAI. However, geriatric patients were significantly more exposed to adverse events of therapy. They had more co-morbidities and more conservative surgery for OAI.

CONCLUSION

Available literature regarding OAI management among elderly patients is sparse. In recent evaluations, age itself does not seem an independent factor related to particular epidemiology, pathogens, prevention, nursing care, rehabilitation and therapeutic outcomes of OAI. Future clinical research will concern more conservative surgical indications, but certainly reduce inappropriate antibiotic use.

Four versus six weeks of antibiotic therapy for osteoarticular infections after implant removal: a randomized trial

BACKGROUND

The optimal duration of antibiotic therapy for treating orthopaedic implant infections after surgical drainage and complete implant removal is unknown.

METHODS

This was a single-centre, unblinded, prospective trial randomizing (1:1) eligible patients to either 4 or 6 weeks of systemic, pathogen-targeted antibiotic therapy. Clinical trial registration number: ClinicalTrials.gov (NCT0362209).

RESULTS

We analysed 123 eligible patients (62 in the 4 week antibiotic arm and 61 in the 6 week arm) in the ITT analysis. The patients' median age was 64 years, 75 (61%) were men and 38 (31%) were immunocompromised. The most common types of infection treated included: two-stage exchange procedure for prosthetic joint infection (n = 38); orthopaedic plate infection (44) and infected nail implants (11). The median duration of post-explant intravenous antibiotic therapy was 4 days. Overall, 120 episodes (98%) were cured microbiologically and 116 (94%) clinically after a median follow-up period of 2.2 years. During follow-up, four patients had a clinical recurrence with a pathogen other than the initial causative agent. We noted recurrence of clinical infection in four patients in the 4 week arm and three patients in the 6 week arm (4/62 versus 3/61; χ2 test; P = 0.74); in all cases, this occurred at around 2 months following the end of antibiotic treatment.

CONCLUSIONS

We found no statistically significant difference in the rates of clinical or microbiological remission between patients randomized to only 4 compared with 6 weeks of systemic antibiotic therapy after removal of an infected osteoarticular implant.

Coagulase-negative staphylococci (CoNS) as a significant etiological factor of laryngological infections: a review

This review article shows that coagulase-negative staphylococci (CoNS) are widely responsible for laryngological diseases. General characteristics of CoNS infections are shown in the introduction, and the pathogenicity in terms of virulence determinants, biofilm formation and genetic regulation mechanisms of these bacteria is presented in the first part of the paper to better display the virulence potential of staphylococci. The PubMed search keywords were as follows: CoNS and: nares infections, nasal polyps, rhinosinusitis, necrosing sinusitis, periprosthetic joint infection, pharyngitis, osteomyelitis of skull and neck bones, tonsillitis and recurrent tonsillitis. A list of laryngological infections and those related to skull and neck bones was presented with descriptions of the following diseases: rhinosinusitis, necrotizing sinusitis, nasal polyps, nares and nasal skin infections, periprosthetic joint infections, osteomyelitis, pharyngitis, and tonsillitis. Species identification and diagnostic problems challenging for diagnosticians are presented. Concluding remarks regarding the presence of CoNS in humans and their distribution, particularly under the effect of facilitating factors, are mentioned.

Changing perioperative prophylaxis during antibiotic therapy and iterative debridement for orthopedic infections?

Background

Perioperative antibiotic prophylaxis in non-infected orthopedic surgery is evident, in contrast to prophylaxis during surgery for infection. Epidemiological data are lacking for this particular situation.

Methods and findings

It is a single-center cohort on iterative surgical site infections (SSIs) in infected orthopedic patients. We included 2480 first episodes of orthopedic infections (median age 56 years and 833 immune-suppressed): implant-related infections (n = 648), osteoarticular infections (1153), and 1327 soft tissue infections. The median number of debridement was 1 (range, 1–15 interventions). Overall, 1617 infections (65%) were debrided once compared to 862 cases that were operated multiple times (35%). Upon iterative intraoperative tissue sampling, we detected pathogens in 507 cases (507/862; 59%), of which 241 (242/507; 48%) corresponded to the initial species at the first debridement. We witnessed 265 new SSIs (11% of the cohort) that were resistant to current antibiotic therapy in 174 cases (7% of the cohort). In multivariate analysis, iterative surgical debridements that were performed under current antibiotic administration were associated with new SSIs (odds ratio 1.6, 95%CI 1.2–2.2); mostly occurring after the 2^nd debridement. However, we failed to define an ideal hypothetic prophylaxis during antibiotic therapy to prevent further SSIs.

Conclusions

Selection of new pathogens resistant to ongoing antibiotic therapy occurs frequently during iterative debridement in orthopedic infections, especially after the 2^nd debridement. The new pathogens are however unpredictable. The prevention, if feasible, probably relies on surgical performance and wise indications for re-debridement instead of new maximal prophylactic antibiotic coverage in addition to current therapeutic regimens.

Effectiveness of Efflux Pump Inhibitors as Biofilm Disruptors and Resistance Breakers in Gram-Negative (ESKAPEE) Bacteria

Antibiotic resistance represents a significant threat to the modern healthcare provision. The ESKAPEE pathogens (Enterococcus faecium., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp. and Escherichia coli), in particular, have proven to be especially challenging to treat, due to their intrinsic and acquired ability to rapidly develop resistance mechanisms in response to environmental threats. The development of biofilm has been characterised as an essential contributing factor towards antimicrobial-resistance and tolerance. Several studies have implicated the involvement of efflux pumps in antibiotic resistance, both directly, via drug extrusion and indirectly, through the formation of biofilm. As a result, the underlying mechanism of these pumps has attracted considerable interest due to the potential of targeting these protein structures and developing novel adjunct therapies. Subsequent investigations have revealed the ability of efflux pump-inhibitors (EPIs) to block drug-extrusion and disrupt biofilm formation, thereby, potentiating antibiotics and reversing resistance of pathogen towards them. This review will discuss the potential of EPIs as a possible solution to antimicrobial resistance, examining different challenges to the design of these compounds, with an emphasis on Gram-negative ESKAPEE pathogens.

Antimicrobial Prophylaxis for the Prevention of Surgical Site Infections in Orthopaedic Oncology - A Narrative Review of Current Concepts

The incidence of surgical site infections (SSIs) after elective tumour orthopaedic surgery in adults is higher than non-oncologic orthopaedic surgery. Their causative microorganisms and antibiotic susceptibilities are also different from the non-oncologic cases; with no apparent predictable microbiological patterns. Clinicians continue to struggle to tailor the optimal prophylactic regimen for the very heterogeneous group of tumour patients. Many clinicians thus prolong the first-and second-generation cephalosporin agents, while a minority chooses to broaden the antimicrobial spectrum by combination prophylaxis. The variability in current practices and surgical techniques is enormous, even within the same setting. The scientific literature lacks adequate retrospective case-studies and there is currently only one prospective randomized trial. In this narrative review, we discuss various perioperative antibiotic concepts in oncologic orthopaedic surgery, including a summary of the state-to-the-art, opinions and difficulties related to the different prophylactic strategies.

Should antibiotic prophylaxis before orthopedic implant surgery depend on the duration of pre-surgical hospital stay?

Background

Prolonged hospital stay before surgery is a risk for colonization with antibiotic-resistant microorganisms and possible antibiotic-resistant surgical site infections (SSI), which lacks acknowledgement in international guidelines for perioperative antibiotic prophylaxis.

Method

Retrospective cohort study focusing on prophylaxis-resistant SSI in adult orthopedic implant patients; with emphasis on length of hospital stay prior to the index surgery.

Results

We enrolled 611 cases of SSI (median age, 65 years; 241 females and 161 immune-suppressed) in four large implant groups: arthroplasties (n = 309), plates (n = 127), spondylodeses (n = 31), and nails (n = 46). The causative pathogen was resistant to the perioperative antibiotic prophylaxis regimen in 307 cases (307/611; 50%), but the length of pre-surgical hospitalization did not influence the incidences of prophylaxis-resistant SSIs. These incidences were (107/211;51%) for the admission day, (170/345;49%) within 10 days of delay, (19/35;54%) between 10 and 20 days, and (11/20; 55%) beyond 20 days of hospital stay before surgery. The corresponding incidences of methicillin-resistant staphylococci were 13%, 14%, 17%, and 5%, respectively. In adjusted group comparisons, the length of prior hospital stay was equally unrelated to future prophylaxis-resistant SSI (odds ratio 1.0, 95% confidence interval 0.99-1.01).

Conclusions

In our retrospective cohort of orthopedic implant SSI, the length of pre-surgical hospital stay was unrelated to the incidence of prophylaxis-resistant pathogens.

Epidemiology and Antibiotic Resistance of Late Prosthetic Knee and Hip Infections

BACKGROUND

Prosthetic joint infections (PJI) are still a major complication of hip and knee arthroplasties. Identification of the causative pathogens and knowledge of their antibiotic susceptibilities are essential for the management of these infections. The main purpose of the study was to identify and compare the causative bacteria of prosthetic knee and hip joint infections in a reference Italian orthopedic center and to characterize antibiotic resistance profiles of bacteria involved.

METHODS

Data from 429 patients with diagnosis of PJI were collected from January 2013 to June 2015: 229 presented a hip and 200 a knee prosthesis infection. Prostheses and periprosthetic tissues were treated with dithiothreitol before plating onto different media and broths. Identification and antimicrobial susceptibility testing were carried out by VITEK2 Compact (bioMerieux).

RESULTS

There was not a substantial difference in the etiology of hip and knee PJI: staphylococci were the most frequently isolated bacteria in both groups, followed by Enterobacteriaceae and Propionibacterium acnes. Staphylococci showed a high rate of methicillin resistance (144 of 341) and a worrying frequency of isolates were resistant to teicoplanin (9%). Only 8.3% of Enterobacteriaceae produced extended-spectrum beta-lactamases, whereas the rate of carbapenemase-producing bacteria was not significant.

CONCLUSION

We observed similar etiology of hip and knee PJIs. Nevertheless, bacteria isolated from knee showed higher resistance rates to glycopeptides and fluoroquinolones when compared with those isolated from the hip. The reason for this difference remains to be elucidated in future studies.

Role and antimicrobial resistance of staphylococci involved in prosthetic joint infections

PURPOSE

Staphylococci are responsible for approximately half of all prosthetic joint infections (PJIs) and they are often multi-drug resistant. The main purpose of this study was to evaluate the incidence of PJIs caused by staphylococci in our hospital from March 2010 to February 2012, with particular reference to antibiotic resistance in relation to their classification as contaminant or infecting isolates.

METHODS

We analyzed samples recovered from 124 patients: most of them were male (55.8%) and the mean age was 66 ± 14 years. Prostheses derived from hip (54.8%) or knee (45.2%) replacement and they were processed by sonication. Isolates were identified using conventional biochemical methodologies. Antimicrobial susceptibility testing was carried out using the disk diffusion method as described by the European Committee on Antimicrobial Susceptibility Testing.

RESULTS

A total of 135 staphylococci were isolated: the prevalent species was Staphylococcus aureus, but, on the whole, coagulase-negative staphylococci represented 57% of cases. Fifty-one isolates were recovered from a single sample and were therefore defined as contaminant. Linezolid and glycopeptides showed excellent activity versus all the tested isolates, while penicillin, levofloxacin, and erythromycin offered reduced activity against staphylococci. Interestingly, high resistance rates were observed for coagulase-negative staphylococci other than S. epidermidis classified as contaminant strains.

CONCLUSIONS

We observed a remarkable spread of coagulase-negative staphylococci as causative agents of PJIs; but most of them were classified as contaminants. However, because of their low susceptibility to the antibiotics tested, further studies are necessary to evaluate their role as pathogens or as true contaminants.

Epidemiology and outcomes of surgical site infections following orthopedic surgery

BACKGROUND

Surgical site infections (SSIs) are common complications after surgeries, usually leading to increased health care costs. Therefore, we evaluated the efficiency of current preoperative antibiotic prophylaxis and risk factors of SSIs in the orthopedic wards in a major teaching hospital in China.

METHODS

We retrospectively reviewed a population of 2,061 patients who underwent orthopedic surgeries between January 2010 and January 2012 and examined the bacterial isolates and their resistance patterns associated with orthopedic infections. Moreover, a multivariate logistic regression was used to identify independent risk factors for SSIs.

RESULTS

Thirty-three out of the 45 clinical SSIs were culture positive, and a total of 35 bacterial strains was isolated, among which, 65.72% (n= 23) were gram-positive isolates, and 34.28% (n = 12) were gram-negative bacteria. Significantly, 68.6% of all bacterial isolates were resistant to cefuroxime. Additionally, this study found that diabetes mellitus (odds ratio [OR], 7.539), smoking (OR, 2.378), duration of surgeries longer than 3 hours (OR, 3.633), absence of antibiotic prophylaxis (OR, 6.562), and previous operations (OR, 2.190) were crucial independent risk factors associated with a significant increase in the development rate of SSIs following orthopedic incisional operations.

CONCLUSION

Our data suggested that appropriate modifications to antibiotic prophylaxis regimens should be considered. Furthermore, tightening glucose control, stopping smoking, providing proper antibiotic prophylaxis, and shortening surgery time are promising approaches to reduce the SSIs rate.

No need for broad-spectrum empirical antibiotic coverage after surgical drainage of orthopaedic implant infections

PURPOSE

Empirical broad-spectrum antibiotic treatment for orthopaedic implant infections after surgical lavage is common practice while awaiting microbiological results, but lacks evidence.

METHODS

This was a single-centre cohort study from 1996 to 2010 with a follow-up of two years.

RESULTS

We retrieved 342 implant infections and followed them up for a median of 3.5 years (61 recurred, 18%). Infected implants were arthroplasties (n = 186), different plates, nails or other osteosyntheses. The main pathogens were S. aureus (163, 49 methicillin-resistant) and coagulase-negative staphylococci (60, 45 methicillin-resistant). Median duration of empirical antibiotic coverage after surgical drainage was three days before switching to targeted therapy. Vancomycin was the most frequent initial empirical agent (147), followed by intravenous co-amoxiclav (44). Most empirical antibiotic regimens (269, 79%) proved sensitive to the causative pathogen, but were too broad in 111 episodes (32%). Cephalosporins and penicillins were used only in 44 and ten cases, respectively, although they would have covered 59% of causative pathogens identified later. Multivariate Cox regression analysis showed that neither susceptible antibiotic coverage (compared to non-susceptible; hazard ratio 0.7, 95% confidence interval 0.4-1.2) nor broad-spectrum use (hazard ratio 1.1, 0.8-1.5) changed remission rates.

CONCLUSIONS

Provided that surgical drainage is performed, broad-spectrum antibiotic coverage does not enhance remission of orthopaedic implant infections during the first three days. If empirical agents are prescribed from the first day of infection, narrow-spectrum penicillins or cephalosporins can be considered to avoid unnecessary broad-spectrum antibiotic use.

Staphylococcal cassette chromosome mec (SCCmec) and arginine catabolic mobile element (ACME) in Staphylococcus epidermidis isolated from prosthetic joint infections

The aim of the present study was to characterise the staphylococcal cassette chromosome mec (SCCmec) in Staphylococcus epidermidis isolated from prosthetic joint infections (PJIs) and, if possible, assign them to any of the presently known SCCmec types. In addition, the isolates were examined for the presence of the arginine catabolic mobile element (ACME). Sixty-one S. epidermidis isolates obtained from PJIs and 24 commensal S. epidermidis isolates were analysed. The mecA gene was detected in 49 of the 61 (80 %) PJI isolates and in four of the 24 (17 %) commensal isolates, and the composition of the SCCmec was further analysed. SCCmec types I and IV were the most common types among the PJI isolates. However, for over half (57 %) of the isolates, it was not possible to assign an SCCmec type. ACME was detected in eight (13 %) of the PJI isolates and in 14 (58 %) of the commensal isolates. The characterisation of the SCCmec elements revealed a large heterogeneity, with a high frequency of isolates carrying more than one type of the ccr gene complex. ACME was more common among the commensal isolates and may represent a survival benefit for S. epidermidis colonising healthy individuals in the community.