Role of joint aspiration before re-implantation in patients with a cement spacer in place

BACKGROUND

The usefulness of a mandatory joint aspiration before re-implantation in patients with a cement spacer already in place is unclear.

AIM

To evaluate the role of culturing synovial fluid obtained by joint aspiration before re-implantation in patients who underwent a two-stage septic revision.

METHODS

A retrospective observational study was conducted, including patients that underwent a two-stage septic revision (hip or knee) from 2010 to 2017. After the first stage revision and according to intraoperative culture results, all patients were treated with an antibiotic protocol for 6-8 wk. Following 2 wk without antibiotics, a culture of synovial fluid was obtained. The results of these cultures were recorded and compared with cultures obtained during re-implantation surgery.

RESULTS

Forty-one patients (20 hip and 21 knee spacers) were included in the final analysis. In 39 cases, the culture of synovial fluid was negative, while in the remaining 2 cases (knee spacers) no analysis was possible due to dry tap. In 5 of the patients, two or more intraoperative cultures taken during the re-implantation surgery were positive.

CONCLUSION

We found no evidence to support mandatory joint aspiration before re-implantation in patients with a cement spacer in place.

Role of bacterial colonisation of vancomycin-gentamicin spacers in two-stage arthroplasty revision surgery: the usefulness of spacer sonication

PURPOSE

In two-stage replacements for septic loosening, some studies have suggested an association between bacterial colonisation of spacers and a higher number of complications after implantation of the definitive prosthesis. Our study aimed to determine the reoperation rate of patients undergoing two-stage revision surgery according to the culture results of spacer sonication.

METHODS

A retrospective observational study was conducted in which hip or knee spacers implanted at our institution with a diagnosis of periprosthetic joint infection from 2010 to 2018 were analysed. Patients were grouped into three categories: A. Patients with positive spacer sonication fluid culture, with or without positive cultures of the rest of the samples. B. Patients with negative spacer sonication culture and negative cultures of the rest of intraoperative samples. C. Patients with negative spacer sonication culture but positive cultures of the rest of intraoperative samples.

RESULTS

A total of 45 spacers were analysed: 10 were included in group A, 24 in group B and 11 in group C. The reoperation rate during the first year after the 2-stage revision surgery was 20%, 29.2% and 54.5% for each group, respectively, due to an infection in 10%, 20.8% and 45.5%. Spacers were colonised in all cases by low virulent micro-organisms.

CONCLUSION

In our study, bacterial colonisation of the spacer is not associated with a higher rate of reoperation. The group of patients with positive intraoperative cultures during the second-stage had the highest reoperation rate.

Higher accuracy of genotypic identification compared to phenotyping in the diagnosis of coagulase-negative staphylococcus infection in orthopedic surgery

PURPOSE

To determine whether Repetitive Extragenic Palindromic PCR (rep-PCR) genotyping can improve the diagnosis of coagulase-negative staphylococcal (CoNS) orthopaedic infections in comparison to phenotyping.

METHODS

Prospective study comparing the results of phenotypic/genotypic (rep-PCR) testing in patients with suspected CoNS infection. Each strain was analysed using both methods. Strains identified as identical in ≥2 samples were considered as pathogenic.

RESULTS

255 CoNS strains from 52 surgical episodes were included. Infection was diagnosed by phenotyping in 38(73%) cases and by genotyping in 40(77%). The Kappa index was 0.59. Sensitivity, Specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) for phenotyping (vs. rep-PCR) were: 88%, 75%, 92%, and 64%. 5/14(36%) of cases not considered as true infections by phenotyping were diagnosed as infections with genotyping. In a subgroup of 203 strains from 41 surgical procedures with orthopaedic implants, the kappa index was 0.68. Sensitivity, Specificity, PPV, and NPV for phenotyping were: 93%, 73%, 90% and 80%. Again, 2/10 episodes in which CoNS were considered non-infective by phenotyping were diagnosed as infected by genotyping.

CONCLUSIONS

Rep-PCR genotyping can identify identical CoNS strains that differ in their phenotype and should be used as a complementary technique. One-third of infected cases may be misdiagnosed without genotypic analysis.

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.

Impact of amoxicillin, associated or not with clavulanic acid, on pharyngeal colonization and selection of Streptococcus pneumoniae resistance in children under 5 years of age

Among young children, pneumococcal nasopharyngeal colonization (NPC) rates of >90% have been described. The aim of our study was to assess the effect of amoxicillin exposure on the NPC. From Dec 2001 to Feb 2004, less than 5 years old children with respiratory symptoms and fever who were prescribed amoxicillin were eligible. Three nasopharyngeal swabs were taken: at the time of the initial visit (IV), 60 hours after amoxicillin discontinuation (end of treatment visit, ETV), and 4 weeks later (follow-up visit, FUV). One hundred and thirty four children were included. NPC was detected in 58.5%, 42.9% and 51% of <1, 1-2 and >2 years-old children respectively (NS). Vaccine serotypes (VS) or vaccine-related serotypes (VRS) were identified in 80%, 40% and 55% of <1-year-old, 1-2 year-old and >2-year-old children respectively (NS). The proportion of PNSSP was 60% in <1-year-old children, 43% in 1-2 year-old children and 40% in >2-year-old children (NS). 49 out of 134 (36.5%) children completed the three study visits. 51%, 22.4% and 46.9% of those were colonized at IV, ETV and FUV, respectively (p=0.007). The percentage of resistant SP was 28%, 45.5% and 8.7% (p=0.05) for penicillin. In children <1 year of age, a higher proportion of SP colonization, presence of VS and PNSSP was found. A downfall of NPC at the end of therapy was observed. NPC returned to baseline levels thanks to "de novo" colonization in half of the cases, a few weeks after.

[Cotrimoxazole plus rifampicin in the treatment of staphylococcal osteoarticular infection]

OBJECTIVE

To evaluate the efficacy and safety of cotrimoxazol plus rifampicin in staphylococcal osteoarticular infection.

METHOD

Open, non-comparative study of adult hospitalized patients with documented staphylococcal bone infection.

RESULTS

From Feb 1989 to Dec 1993 28 episodes of staphylococcal bone infection were treated in 14 men and 13 women; the mean age was 48 +/- 21 years (range, 11-84). They received cotrimoxazol (7 mg/kg/day of trimethoprim) plus rifampicin (600-1200 mg/day), both orally, every 8 to 12 h with a mean duration of treatment of 34.2 +/- 8.2 days (range, 21 to 55 days). This antibiotic regimen was initiated at the same time that appropriate surgery for each specific condition was undertaken. Diagnoses were postsurgical osteomyelitis (10 cases), infected total hip prostheses (4 cases, one with 2 episodes), osteomyelitis secondary to external pin fixation (5 cases), soft tissue infections linked to orthopedic implants (3 cases), two cases of metatarsal osteomyelitis (one diabetic foot and one patient with polineuropathy), and one case each of chronic osteomyelitis of femur, hematogenous lumbar spondylitis and posttraumatic osteomyelitis. Four patients had bacteremia. The duration of the infection, prior to surgery was less than one month in 12 episodes, 1 month to 2 years in 14, and in 2 cases, of 10 and 13 years, respectively. In 23 episodes the causal agent was Staphylococcus aureus and in 5 cases it was coagulase-negative staphylococci. Patients had received previous parenteral therapy with other antimicrobials during 2-40 days (X: 18.6 +/- 10.2 days). All patients but one had resolution of the infection and are currently asymptomatic 6 months to 5 years posttreatment in the 21 evaluable cases (X: 38 +/- 13.1 months). Five patients had adverse effects secondary to the antibiotic combination and in three these were severe enough to discontinue the antimicrobials. In no case of the 11 patients with post-treatment control cultures were staphylococci recovered from the wound.

CONCLUSIONS

The combination of cotrimoxazole plus rifampicin, both given orally, was highly effective in this selected group of patients. This combination should be considered as a useful alternative therapy of staphylococcal bone infection and deserves further study.

[Fluoroquinolone and aminoglycoside resistance in chromosomal cephalosporinase-overproducing gram-negative bacilli strains with inducible beta-lactamase]

INTRODUCTION

The increasing prevalence of stable derepressed mutants over-producers of type I chromosomal cephalosporinase in inducible Enterobacteriaceae and Pseudomonas aeruginosa challenges the adequacy of third generation cephalosporins in the empirical treatment of certain nosocomial infections. We sought to determine the frequency of stable over-producers of type I enzyme and their associated resistance to fluoroquinolones and aminoglycosides.

METHODS

Disc-diffusion and MIC determinations to extended-spectrum beta-lactams, imipenem, ciprofloxacin and gentamicin were performed in all cell isolates of inducible enteric bacteria (Enterobacter spp., Citrobacter spp., Serratia spp., Morganella morganii, Providencia spp.) and P. aeruginosa collected during the period of study (1992-1993).

RESULTS

A total of 1,426 isolates of inducible enteric bacteria and P. aeruginosa were studied. Each one represented a single patient. Among the 511 isolates of enteric bacteria 15.1% of strains were found to be stable derepressed mutants (Serratia 2.2%; Morganella spp., 3%; Providencia and Proteus 3%; Citrobacter spp., 10%; Enterobacter spp., 23.6%); among the 916 P. aeruginosa isolates studied, 9.2% were stable over-producers. Among Citrobacter, Providencia and Proteus spp., 53.1% of stable over-producers were resistant to ciprofloxacin versus 20.2% of non-over-producers (p < 0.01); in P. aeruginosa, 35.3% of over-producers were resistant to gentamicin versus 25.0% in non-over-producers (p < 0.01).

CONCLUSION

The prevalence of stable derepressed mutants is high among enteric bacteria and P. aeruginosa with type I inducible beta-lactamase. These strains frequently exhibit resistance to fluoroquinolones and aminoglycosides, reducing considerably the available therapeutic options.

[Hip prosthesis infection: diagnostic approach and treatment of 27 cases]

BACKGROUND

Preoperative diagnosis of hip prosthesis infection (HPI) is difficult. There is no therapeutic option which is completely effective and without risk. The aim of this study was to evaluate a diagnostic approach and therapeutic strategy in a group of patients with HPI.

PATIENTS AND METHODS

A retrospective study of 27 episodes of HPI diagnosed by anatomopathologic and/or microbiologic examination of surgical samples was performed.

RESULTS

Twenty-three patients with 27 episodes of HPI out of a total of 24 hip prosthesis (HP) were treated. The infection was early in 15 episodes. The etiologic agents were plasmocoagulase negative staphylococcus (NSP) in 11 cases, P. aeruginosa in 8, S. aureus in 5, Enterococcus sp. in 2 and miscellaneous in the remaining cases. In 2 cases the infection was polymycrobial. Following a mean follow period of 22.6 +/- 15.2 months, 13 out of the 14 patients in whom the prosthesis was withdrawn were cured (in 4 a second prosthesis was implanted), one out of 6 in those in whom the prosthesis remained in situ following debridement, and 2 out of 3 episodes in whom reimplantation was performed over time. The withdrawal of the prosthesis was significantly greater than debridement in the treatment of early infection (p < 0.001). The total mean length of postoperative antibiotherapy was 48.2 +/- 17 days. No differences were observed in the oral versus parenteral treatment (p = 0.22), and nor was prognosis worse in those treated for less than 42 days.

CONCLUSIONS

The authors' experience suggests that attempts to save a hip prosthesis in early infection usually fail. In addition to prosthesis withdrawal or implantation of another prosthesis, six weeks of postoperative antibiotic therapy, which may be oral route, appear to be sufficient.