Aim. Currently, gram-negative bacteria (GNB), including multidrug-resistant (MDR-GNB) pathogens, are gaining importance in the aetiology of prosthetic joint infection (PJI). To characterize the antimicrobial resistance patterns of Gram-negative bacteria (GNB) causing hip prosthetic joint infections in elderly patients treated at a Brazilian tertiary academic hospital. Method. This is a retrospective, cross-sectional study of patients over 60 years of age undergoing hip arthroplasty from 2018 to 2023 at a tertiary academic trauma, which were diagnosed with hip prosthetic joint infection. PJI diagnosed was based on EBJIS criteria, in which intraoperative tissue cultures identified the pathogens. Demographics, reason for arthroplasty, type of implant and susceptibility patterns using disk diffusion method were analysed. Results. Overall, among 17 elderly patients diagnosed with hip infected arthroplasty, 45 bacterial isolated were identified. Debridement, irrigation, antibiotic and implant retention (DAIR) procedures due to uncontrolled infection occurred in 47.0% (n=8/17), and five patients underwent more than two DAIR surgeries. Tissue cultures yielded eleven different bacterial species, with GNB accounted for 64.4% (n=29/45) of pathogens. Klebsiella pneumoniae, Acinetobacter baumannii, Escherichia coli, and Pseudomonas aeruginosa were identified in 34.5% (n=10/29), 17.25% (n=5/29), 13.8% (n=4/29), and 13.8% (n=4/29), respectively. In the resistance profile analysis, E. coli was most sensitive to antibiotics, whereas K. pneumoniae showed resistance rates higher than 70% for cephalosporins, carbapenems, and quinolones. All A. baumannii isolates were resistant to meropenem, and 80% of these isolates were resistant to amikacin. Conclusions. This study emphasizes the role of GNB in the microbiological profile of PJI among elderly patients at a tertiary hospital in a Brazilian centre. The present study portrays a worryingly higher rates of MDR-GNB, mainly to quinolones and cephalosporins resistance which have been the cornerstone of PJI antibiotic treatment. In addition, higher rates carbapenems and aminoglycosides resistance shows a threat to antibiotic treatment of PJI. More global studies need to be carried out to show a likely change in the microbial epidemiology of PJI

Aim. Orthopedic implant related surgical site infection (SSI) is a severe complication which represents an important challenge concerning to its treatment. Therefore, gram-negative orthopedic infections have recently become a global concern. Method. Retrospective study through searching of the SCIH (infection control service) database, concerning to the year 2016 and 2017. Cases selected were those of implant placement clean surgeries (osteosynthesis or prosthetic placement) which evolved with SSI and Gram-negative bacterial growth in bone tissue or periprosthetic cultures. Results. During 2016 and 2017, 6150 clean surgeries with orthopedic implant placement were performed; 140 fulfilled SSI criteria (83 cases of open fracture reduction, 44 of hip arthroplasty, 13 of knee arthroplasty). Main agent of infections was Staphylococcus aureus (32,47%) mostly of them methicillin-sensitive (69,20%). However, Gram-negative bacteria were responsible for 64,95% of infections. (Klebsiella pneumoniae 12.8%; Acinetobacter baumannii and Enterobacter ssp 11.96%; Pseudomonas aeruginosa 9.40%) Among them, 100% Enterobacter ssp. were sensitive to carbapenems and 75% to ciprofloxacin. Klebsiella pneumoniae showed sensitivity to carbapenems in 85.7%, Pseudomonas aeruginosa showed sensitivity in 85.7% to carbapenems and 100% to ciprofloxacin. Acinetobacter baumannii showed the least favorable profile amongst Gram-negatives since only 12.5% of strains were sensitive to carbapenems, 28.6% to Ampicilin-sulbactam, 22.2% to ciprofloxacin, while showing 100% sensitivity to polymyxins. 14 patients in whom Acinetobacter baumannii was isolated were predominantly elderly (median 70 years), most of them have underlying/chronic diseases (71.42%) such as diabetes, arterial hypertension, alcoholism, smoking and heart failure. None presented sepsis related to this infection, but four of them died as result of hospitalization related complications (28,60% mortality rate). Among these deaths, 3 were related to total hip arthroplasty, and one to knee arthroplasty. One patient died as result of external causes. Among the survivors, five showed remission/cure. The follow up was lost in 4 patients. Conclusions. SSI caused by carbepenem-resistant Acinetobacter baumannii represents considerable impact on morbi-mortality in patients who undergo surgery with placement of orthopedic implants

Aim. Antibiotic loaded spacers are often used during a two-stage exchange for periprosthetic joint infections (PJI) both for its mechanical properties and as a means for local antibiotic delivery. The main goal of this study is to compare the rate of positive cultures during reimplantation with the use of different antibiotic loaded spacers: aminoglycoside only vs. combined glycopeptide/aminoglycoside vs. combined glycopeptide/carbapenem/aminoglycoside. Method. We retrospectively evaluated every two-stage exchange procedures for infected hip/knee arthroplasty between 2012–2018. Microbiological findings in the first and second stage were registered as well as the type of spacer and antibiotic(s) used. Cases in whom no cultures were obtained during reimplantation and cases without sufficient data on antibiotic(s) used in cement spacers were excluded. Results. Fifty-four cases were included (20THA and 34TKA), with an overall rate of positive cultures during reimplantation of 18.5% (10/54). The rate of positive cultures was statistically significant higher among spacers with monotherapy with aminoglycoside compared to spacers with combined antibiotic therapy- 35.7% (5/14) vs. 12.5% (5/40) respectively(p<0.05). Comparing those with combined glycopeptide/aminoglycoside (2/19) with triple glycopeptide/carbapenem/aminoglycoside therapy (3/21) there was no significant difference. Microorganisms present during the second stage were mostly staphylococci (coagulase-negative in four cases, S.aureus in three), Corynebacterium striatum, Enterococcus faecalis, C.albicans in one case each. In most cases (8/10), the isolated microorganism was the same as the first stage and was resistant to the antibiotic(s) used in the spacer in seven cases. Failure rate with the need for subsequent surgery was significantly higher at 60% (6/10) in cases with positive cultures at reimplantation compared to 4.5% (2/44) for those with negative cultures during reimplantation(p=0.0005). Conclusions. It has recently been suggested that adding a glycopeptide to the spacer may be advantageous when compared to spacers with aminoglycoside monotherapy, as it will produce significantly lower rates of positive cultures during reimplantation which have been shown to increase the risk of subsequent failure as is the case in our study. Local unavailability of obtaining powder aminoglycosides has driven us to manually add high doses of vancomycin and meropenem to commercially available low-dose gentamicin cement in many of our spacers and they seem to to perform just as well as commercially available vancomycin/gentamicin combination. Although many other variables not considered in this study may influence the rate of positive cultures during the second stage (quality of initial debridement, systemic antibiotic therapy, etc.), we believe these results portrait a sufficiently accurate picture of clinical results with the use of different spacers

Aim. Empiric antibiotic therapy for suspected pyogenic spondylodiscitis (SD) should be initiated immediately with severely ill patients and may also be necessary for culture-negative SD. The aim of this study was to infer an appropriate empiric antibiotic regimen by analyzing the antimicrobial susceptibility of isolated pathogens from microbiologically proven pyogenic spondylodiscitis. Method. We performed a retrospective review of adult patients with clinically proven SD treated at our level 1 trauma center between 2013 and 2020. Demographic data, radiologic findings, and treatment modalities were evaluated. The appropriateness of empiric antibiotic regimens was assessed based on the antibiograms of the isolated pathogens. Anamneses were used to distinguish between community-acquired (CA) and healthcare-associated (HA) pathogens, which included cases that had a hospital stay or invasive intervention in the past 6 months. Results. A total of 155 patients (male: N=88; female: N=67; mean age 66.1 ± 12.4 years) with SD were identified. In n= 74 (47.7%) cases, the infections were associated with the healthcare system (HA). N=34 (21.9%) patients suffered from sepsis. The lumbar spine was involved in 47.1% of the cases, the thoracic spine in 37.3%, and the cervical spine in 7.8%. In 7.8% of the cases, SD occurred in multiple spinal segments. N=96 (62.0%) patients were treated surgically. The mean hospital stay was 36.4 ± 36.3 days. Antibiograms of n=45 patients (HA: N=22; CA: N=23) could be retrospectively evaluated: The most frequently identified pathogens were Staphylococcus aureus (46.7%), Coagulase-negative Staphylococci (17.8%), Enterobacteriaceae (15.6%) and Streptococcus species (15.6%). Overall, 82.2% (HA: 68.2%; CA: 95.5%) of the isolated pathogens were sensitive to piperacillin/tazobactam, 77.8% (HA: 81.8%; CA: 72.2%) to vancomycin, 64.4% (HA: 68.2%; CA: 59.1%) to clindamycin, and 55.6% (HA: 36.4%; CA: 72.7%) to ceftriaxone. To a combination of vancomycin plus meropenem 97.8% of pathogens were sensitive (HA: 95.5%; CA: 100.0%), to vancomycin plus ciprofloxacin 91.1% (HA: 86.4%; CA: 95.7%), and to vancomycin plus cefotaxime 93.3% (HA: 90.9%; CA: 95.7%). In 14 cases, empiric antibiosis was adjusted based on the results of the antibiogram. Conclusions. Antibiotic resistance of CA SD pathogens differed significantly from HA SD. The identification of the pathogen and the analysis of its susceptibility guides the antibiotic therapy. Vancomycin in combination with a carbapenem, broad-spectrum cephalosporin, or fluoroquinolone may be appropriate for empiric treatment of HA SD

Aim. Gram negative bacteria (GNB) are emerging pathogens in chronic post-traumatic osteomyelitis. However, data on multi-drug (MDR) and extensively drug resistant (XDR) GNB are sparse. Methods. A multi-centre epidemiological study was performed in 10 countries by members of the ESGIAI (ESCMID Study Group on Implant Associated Infections). Osteosynthesis-associated osteomyelitis (OAO) of the lower extremities and MDR/XDR GNB were defined according to international guidelines. Data from 2000 to 2015 on demographics, clinical features, microbiology, surgical treatment and antimicrobial therapy were retrospectively analyzed. Cure was assessed after the end of treatment as the absence of any sign relevant to OAO. Factors associated with cure were evaluated by regression analysis. Results. A total of 53 infections of OAO of the lower extremities (hip, femur, tibia) were evaluated. Patients were female (n=32, 60.4%), with a mean age (SD) 57(3) years, history of trauma (83%), comorbidities (26.4%). The most frequent GNB were: E.coli (n=15), P.aeruginosa (n=14), Klebsiella spp (n=8), Enterobacter spp (n=8) and Acinetobacter spp (n=5). P.aeruginosa predominated the XDR group than the MDR one (n=6/10 vs n=8/43, p=0.01). Antibiotics were given mostly in combinations (64%) for a median duration of 117 days (SD:31.5). Carbapenems were the most frequently used agents (54.7%), followed by colistin (18.8%) and fluoroquinolones (15%). Surgical treatment included debridement with implant retention (n=22), implant explantation (n=22), new osteosynthesis (n=3), others(n=6). Only failure of the surgical treatment for OAO was associated with lack of cure [OR 8.924 (CI95%: 3.006–26.495), p<0.001] at the end of treatment, for a 12-month follow-up period. Patients' age, gender, comorbidities, history of trauma and surgery, clinical presentation of OAO, type of antimicrobial treatment (use of fluoroquinolones, carbapenems or colistin as monotherapy or in combination) as well as type of surgical intervention (explantation vs implant retention) were not found to significantly influence the patients' outcome. Overall, cure was assessed in 31 patients (58.5%). Death occurred in 7 patients, all older than 60, with failure of surgical treatment (p=0.016). These patients presented with many comorbidities (57%) and without difference in treatment outcome between XDR and MDR infection (p=0.114). Conclusion. Osteosynthesis-associated infections of the lower extremities caused by MDR/XDR GNB are a severe complication in orthopaedic surgery. The role of surgical treatment is independently associated with outcome regardless of the type of intervention (explantation or implant retention) and the type of antimicrobial treatment

Aim. Prosthetic joint infections (PJI) due to Enterobacter cloacae are rare and often severe. The aim of this study is to describe cases with E. cloacae PJI. Method. We conducted a retrospective and a monocentric study in an orthopedic unit where complex bone and joint infections are managed. From 2012 to 2016, we included patients with PJI which perioperative samples were positive with E. cloacae. We collected background, clinical, biological and microbiological data of the current infection, surgical and medical treatment, and the outcome of these patients. Results. A total of twenty patients were included which 8 were male. Location was hip in 14 cases, knee in 5 cases and ankle in one case. The median time between arthroplasty and revision for infection was 3 years. Fourteen patients had at least two surgeries for previous PJI. The median time between the last surgery and the revision for E. cloacae infection was 31 days. Eleven patients were infected by extended-spectrum beta-lactamases (ESBL) strains. Most frequently, the antibiotics used were carbapenem in 9 cases, cefepim in 7 cases, a quinolone in 7 cases and fosfomycin in 4 cases. Infection was cured in 10 cases (50%) with a median time of follow-up of 24 months. Five patients had a recurrent infection, three due to Staphylococcus epidermidis, one to Staphylococcus epidermidis and Propionibacterium acnes and one to Escherichia coli. Four patients had a relapse of E. cloacae infection. One patient died from non-infectious cause (stroke). Conclusions. PJI infections due to E.cloacae usually occur early after the last prosthetic surgery, typically in patients with complex surgical history. A poor outcome, observed in nearly half of the patients could be explained in part by an association of factors: multiple risks factors, complex infectious history, a high rate of multiple resistance to antibiotics, unfavorable skin conditions

Aim. A two-stage surgical strategy (debridement-negative pressure therapy (NPT) and flap coverage) with prolonged antimicrobial therapy is usually proposed in pressure ulcer-related pelvic osteomyelitis but has not been widely evaluated. Method. Adult patients with pressure ulcer-related pelvic osteomyelitis treated by a two-stage surgical strategy were included in a retrospective cohort study. Determinants of superinfection (i.e., additional microbiological findings at reconstruction) and treatment failure were assessed using binary logistic regression and Kaplan-Meier curve analysis. Results. Sixty-four pressure ulcer-related pelvic osteomyelitis in 61 patients (age, 47 (IQR, 36–63)) were included. Osteomyelitis was mostly plurimicrobial (73%), with a predominance of S. aureus (47%), Enterobacteriaceae (44%) and anaerobes (44%). Flap coverage was performed after 7 (IQR, 5–10) weeks of NPT, with 43 (68%) positive bone samples among which 39 (91%) were superinfections, associated with a high ASA score (OR, 5.8; p=0.022). An increased prevalence of coagulase negative Staphylococci (p=0.017) and Candida (p=0.003) was observed at time of flap coverage. An ESBL Enterobacteriaceae was found in 5 (12%) patients, associated with fluoroquinolone consumption (OR, 32.4; p=0.005). Treatment duration was as 20 (IQR, 14–27) weeks, including 11 (IQR, 8–15) after reconstruction. After a follow-up of 54 (IQR, 27–102) weeks, 15 (23%) failures were observed, associated with previous pressure ulcer (OR, 5.7; p=0.025) and Actinomyces infection (OR, 9.5; p=0.027). Conclusions. Pressure ulcer-related pelvic osteomyelitis is a difficult-to-treat clinical condition, generating an important consumption of broad-spectrum antibiotics. Carbapenem should be reserved for ESBL at-risk patients only, including those with previous fluoroquinolone use. The uncorrelation between outcome and the debridement-to-reconstruction interval argue for a short sequence to limit the total duration of treatment

PJI du to Enterobacter cloacae are rare and often severe. The aim of our study is to define the history of patients with such infections and their outcome. We conducted a retrospective monocentric study in an orthopedic unit where complex bone and joint infections are supported. From 2011 to 214 we selected patients with E. cloacae PJI based on data from the microbiology laboratory. In their files we collected information on their background, their medical and surgical history, antibiotics they received in the year before infection, the suspected portal of entry, the management and the outcome. Twelve patients were included, 7 male and 5 female. PJI was located to the hip in 8 cases, the knee in 3 cases and the ankle in one case. The average time between the placing of the first prosthesis and infection was 3 years. Eleven patients had one or more surgery for previous PJI. The average time elapsed since the last surgery was 30 days. Eleven patients had been treated with antibiotic combinations for at least 6 weeks, in the year before E cloacae infection. A portal of entry was identified only two times: urinary tract infection in one patient and catheter-related infection in one patient. Antibiotics the more often prescribed were carbapenems (n = 5) and cefepime (n = 4), each combined with quinolones (n =4) or fosfomycin (n = 3). Two patients required an additional debridement within an average of 18 days. Infectious outcome was favorable in 8 cases (67%) with a median duration of follow-up of 26 months. Two patients had a recurrent infection, one due to Streptococcus oralis and one to Candida albicans. One patient had a relapse of E cloacae infection. One patient died from unknown cause. PJI infections due to E.cloacae usually occur early after prosthetic surgery, typically in patients with complex surgical history. Despite a high rate of multi-resistance to antibiotics, outcome may be favorable in a large majority of patients

Little information is available about several important aspects of the treatment of melioidosis osteomyelitis and septic arthritis.

We undertook a retrospective review of 50 patients with these conditions in an attempt to determine the effect of location of the disease, type of surgical intervention and duration of antibiotic treatment on outcome, particularly complications and relapse.

We found that there was a 27.5% risk of osteomyelitis of the adjacent bone in patients with septic arthritis in the lower limb. Patients with septic arthritis and osteomyelitis of an adjacent bone were in hospital significantly longer (p = 0.001), needed more operations (p = 0.031) and had a significantly higher rate of complications and re-presentation (p = 0.048).

More than half the patients (61%), most particularly those with multifocal bone and joint involvement, and those with septic arthritis and osteomyelitis of an adjacent bone who were treated operatively, needed more visits to theatre.

Cite this article: Bone Joint J 2015;97-B:277–82.