Comparative Efficacy of Continuous Ceftazidime Infusion vs. Intermittent Bolus against In Vitro Ceftazidime-Susceptible and -Resistant Pseudomonas aeruginosa Biofilm

Background: As the anti-biofilm pharmacokinetic/pharmacodynamic (PK/PD) properties of antibiotics are not well-defined, we have evaluated the PK/PD indices for different regimens of ceftazidime (CAZ; with/without colistin) against Pseudomonas aeruginosa biofilm. Methods: We have used the Center for Disease Control and Prevention Biofilm Reactor with two susceptible (PAO1 and HUB-PAS) and one resistant (HUB-XDR) strains of P. aeruginosa. The regimens were CAZ monotherapies (mimicking a human dose of 2 g/8 h, CAZ-IB; 6 g/daily as continuous infusion at 50 mg/L, CAZ-CI50; and 9 g/daily at 70 mg/L, CAZ-CI70) and CAZ-colistin combinations. Efficacy was correlated with the CAZ PK/PD parameters. Results: CAZ-CI70 was the most effective monotherapy against CAZ-susceptible strains (Δlog CFU/mL 54-0 h = -4.15 ± 0.59 and -3.05 ± 0.5 for HUB-PAS and PAO1, respectively; p ≤ 0.007 vs. other monotherapies), and adding colistin improved the efficacy over CAZ monotherapy. CAZ monotherapies were ineffective against the HUB-XDR strain, and CAZ-CI50 plus colistin achieved higher efficacy than CAZ-IB with colistin. The PK/PD index that correlated best with anti-biofilm efficacy was fAUC0-24h/MIC (r2 = 0.78). Conclusions: CAZ exhibited dose-dependent anti-biofilm killing against P. aeruginosa, which was better explained by the fAUC0-24h/MIC index. CAZ-CI provided benefits compared to CAZ-IB, particularly when using higher doses and together with colistin. CAZ monotherapies were ineffective against the CAZ-resistant strain, independently of the optimized strategy and only CAZ-CI plus colistin appeared useful for clinical practice.

Vertebral osteomyelitis after spine instrumentation surgery: risk factors and management

BACKGROUND

Vertebral osteomyelitis after spine instrumentation surgery (pVOM) is a rare complication. Most cases of infection occur early after surgery that involve skin and soft tissue and can be managed with debridement, antibiotics, and implant retention (DAIR).

AIM

To identify pVOM risk factors and evaluate management strategies.

METHODS

From a multicentre cohort of deep infection after spine instrumentation (IASI) cases (2010-2016), pVOM cases were compared with those without vertebral involvement. Early and late infections were defined (<60 days and >60 days after surgery, respectively). Multivariate analysis was used to explore risk factors.

FINDINGS

Among 410 IASI cases, 19 (4.6%) presented with pVOM, ranging from 2% (7/347) in early to 19.1% (12/63) in late IASIs. After multivariate analysis, age (adjusted odds ratio (aOR): 1.10; 95% confidence interval (CI): 1.03-1.18), interbody fusion (aOR: 6.96; 95% CI: 2-24.18) and coagulase-negative staphylococci (CoNS) infection (aOR: 3.83; 95% CI: 1.01-14.53) remained independent risk factors for pVOM. Cases with pVOM had worse prognoses than those without (failure rate; 26.3% vs 10.8%; P = 0.038). Material removal was the preferred strategy (57.9%), mainly in early cases, without better outcomes (failure rate; 33.3% vs 50% compared with DAIR). Late cases managed with removal had greater success compared with DAIR (failure rate; 0% vs 40%; P = 0.067).

CONCLUSION

Risk factors for pVOM are old age, use of interbody fusion devices and CoNS aetiology. Although the diagnosis leads to a worse prognosis, material withdrawn should be reserved for late cases or when spinal fusion is achieved.

Efficacy of meropenem extended infusion vs. intermittent bolus monotherapy and its combinations with colistin against Pseudomonas aeruginosa biofilm

INTRODUCTION

Device-related infections are difficult-to-treat due to biofilms. In this setting, optimizing the antibiotic efficacy is difficult since most PK/PD studies have been performed on planktonic cells, and therapies are limited when multidrug-resistant bacteria are involved. We aimed to analyze the PK/PD indices of meropenem predicting anti-biofilm efficacy against meropenem-susceptible and -resistant P. aeruginosa strains.

MATERIAL AND METHODS

Pharmacodynamics of meropenem dosages mimicking those of clinical practice (intermittent bolus of 2g every 8h; extended infusion of 2g over 4h every 8h), with and without colistin, were evaluated with the CDC Biofilm Reactor in vitro model for susceptible (PAO1) and extensively drug resistant (XDR-HUB3) P. aeruginosa. Efficacy was correlated with the pharmacokinetic/pharmacodynamic indices for meropenem.

RESULTS

Concerning PAO1, both meropenem regimens were bactericidal, with higher killing for the extended infusion (∆log₁₀ CFU/mL 54-0h=-4.66±0.93 and ∆log₁₀ CFU/mL 54-0h=-3.4±0.41 for intermittent bolus; p<0.001). Concerning XDR-HUB3, meropenem by intermittent bolus was non-active whereas it showed bactericidal effect by extended infusion (∆log₁₀ CFU/mL 54-0h=-3.65±0.29; p<0.001). Time above minimum inhibitory concentration (f%T_>MIC) had the best correlation with efficacy for both strains. Adding colistin always improved meropenem activity and resistant-strains did not emerge.

CONCLUSION

The f%T_>MIC was the PK/PD index that best correlated with the anti-biofilm efficacy of meropenem; it was better optimized when using extended infusion, allowing to recover bactericidal activity in monotherapy also against meropenem-resistant P. aeruginosa. Combining meropenem by extended infusion with colistin offered the most effective therapy for both strains. Optimizing meropenem dosing by extended infusion should be encouraged when treating biofilm-related infections.

Cutibacterium spp. Infections after Instrumented Spine Surgery Have a Good Prognosis Regardless of Rifampin Use: A Cross-Sectional Study

Infection after spinal instrumentation (IASI) by Cutibacterium spp. is being more frequently reported. The aim of this study was to analyse the incidence, risk factors, clinical characteristics, and outcome of a Cutibacterium spp. IASI (CG) compared with non-Cutibacterium IASI (NCG) infections, with an additional focus on the role of rifampin in the treatment. All patients from a multicentre, retrospective, observational study with a confirmed IASI between January 2010 and December 2016 were divided into two groups: (CG and NCG) IASI. Baseline, medical, surgical, infection treatment, and follow-up data were compared for both groups. In total, 411 patients were included: 27 CG and 384 NCG. The CG patients were significantly younger. They had a longer median time to diagnosis (23 vs. 13 days) (p = 0.025), although 55.6% debuted within the first month after surgery. Cutibacterium patients were more likely to have the implant removed (29.6% vs. 12.8%; p = 0.014) and received shorter antibiotic regimens (p = 0.014). In 33% of Cutibacterium cases, rifampin was added to the baseline therapy. None of the 27 infections resulted in treatment failure during follow-up regardless of rifampin use. Cutibacterium spp. is associated with a younger age and may cause both early and late IASIs. In our experience, the use of rifampin to improve the outcome in the treatment of a Cutibacterium spp. IASI is not relevant since, in our series, none of the cases had therapeutic failure regardless of the use of rifampin.

Comparative efficacy of dalbavancin alone and with rifampicin against in vitro biofilms in a pharmacodynamic model with methicillin-resistant Staphylococcus aureus

BACKGROUND

The anti-biofilm efficacy of dalbavancin has been evaluated in static models. Using an in vitro pharmacokinetic/pharmacodynamic model, we evaluated the comparative activity of dalbavancin alone and with rifampicin against biofilm-embedded methicillin-resistant S. aureus (MRSA).

METHODS

Two MRSA strains (HUB-4/HUB-5) were evaluated with the Calgary Device System and the dynamic CDC-Biofilm Reactor over 144 h. Dosage regimens simulated the human pharmacokinetics of dalbavancin (1500mg, single dose), vancomycin (1000mg/12 h) and linezolid (600mg/12 h), alone and with rifampicin (600mg/24 h). Efficacy was evaluated by assessing log10 CFU/mL changes (ΔlogCFU/mL) and we screened for resistance.

RESULTS

The minimal biofilm inhibitory/eradication concentrations of dalbavancin were 0.25/16 mg/L (HUB-4) and 0.25/8mg/L (HUB-5), respectively. In the pharmacokinetic/pharmacodynamic analysis, dalbavancin alone showed limited efficacy, but without resistance developing. Adding rifampicin improved the activities of dalbavancin, vancomycin, and linezolid, but rifampicin-resistant strains appeared over time in all cases. Dalbavancin-rifampicin was bactericidal against HUB-4 in the absence of resistance at 72 h and 144 h (ΔlogCFU/mL: -3.54±0.83, -4.32±0.12, respectively), an effect that was only achieved by linezolid-rifampicin at 144h (-3.33 ± 0.66). Against HUB-5, dalbavancin-rifampicin activity was impaired by rifampicin resistance to a greater extent than other combinations and had no bactericidal effect.

CONCLUSIONS

The anti-biofilm efficacy of dalbavancin was improved significantly by adding rifampicin. Although no dalbavancin resistance occurred, rifampicin resistance appeared in all combination therapies and decreased their efficacy over time. Dalbavancin-rifampicin in vitro treatment appears as promising anti-biofilm therapy, but further studies should evaluate the in vivo efficacy and the risk of resistance.

Infections after spine instrumentation: effectiveness of short antibiotic treatment in a large multicentre cohort

BACKGROUND AND OBJECTIVES

Available information about infection after spine instrumentation (IASI) and its management are scarce. We aimed to analyse DAIR (debridement, antibiotics and implant retention) prognosis and evaluate effectiveness of short antibiotic courses on early forms.

METHODS

Multicentre retrospective study of patients with IASI managed surgically (January 2010-December 2016). Risk factors for failure were analysed by multivariate Cox regression and differences between short and long antibiotic treatment were evaluated with a propensity score-matched analysis.

RESULTS

Of the 411 IASI cases, 300 (73%) presented in the first month after surgery, 48 in the second month, 22 in the third and 41 thereafter. Infections within the first 2 months (early cases) occurred mainly to older patients, with local inflammatory signs and predominance of Enterobacteriaceae, unlike those in the later periods. When managed with DAIR, prognosis of early cases was better than later ones (failure rate 10.4% versus 26.1%, respectively; P = 0.02). Risk factors for DAIR failure in early cases were female sex, Charlson Score, large fusions (>6 levels) and polymicrobial infections (adjusted HRs of 2.4, 1.3, 2.6 and 2.26, respectively). Propensity score matching proved shorter courses of antibiotics (4-6 weeks) as effective as longer courses (failure rates 11.4% and 10.5%, respectively; P = 0.870).

CONCLUSIONS

IASIs within the first 2 months could be managed effectively with DAIR and shorter antibiotic courses. Clinicians should be cautious when faced with patients with comorbidities, large fusions and/or polymicrobial infections.

Efficacy and Therapeutic Drug Monitoring of Continuous Beta-Lactam Infusion for Osteoarticular Infections Caused by Fluoroquinolone-Resistant Pseudomonas aeruginosa: A Prospective Cohort Study

BACKGROUND AND OBJECTIVES

Osteoarticular infections (OIs) caused by fluoroquinolone-resistant Pseudomonas aeruginosa, including multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains, have poor outcomes. We evaluated the outcomes of an optimized strategy of continuous beta-lactam infusion (BL-CI) guided by therapeutic drug monitoring (TDM) for OIs caused by fluoroquinolone-resistant P. aeruginosa.

METHODS

A prospective observational study of patients with P. aeruginosa OIs in a hospital-based BL-CI program (2016-2018) was carried out. TDM targeting free BL concentrations in plasma (fCss) of at least 3-4 × MIC was performed. We compared failure rates between patients with OIs caused by fluoroquinolone-resistant strains who were treated with BL-CI, with or without colistin, and patients with OIs caused by fluoroquinolone-susceptible strains who were treated with ciprofloxacin.

RESULTS

Fifty-two patients were included in the study, 19 (36.5%) of whom had OIs caused by fluoroquinolone-resistant P. aeruginosa (13 (68.4%) MDR/XDR strains; 11 (57.9%) device-related infections). The median duration of BL-CI was 36 days; ten patients (52.6%) received BL-colistin combinations. Eighty-two samples were utilized in the TDM, and most patients were found to have a median fCss of 3-10 × MIC; 17 dose adjustments were performed and eight patients needed dose decreases, five of which were due to chronic kidney disease or acute kidney injury (AKI). BL-CI was well tolerated, with the most frequent adverse event being AKI. Failure occurred to 4 patients (21.1%), which was similar to the failure rate of patients with OIs caused by fluoroquinolone-susceptible P. aeruginosa treated with ciprofloxacin (5/30 [16.7%]) (p = 0.699). TDM was also used in the initial BL treatment of patients with OIs caused by susceptible strains before those patients were switched to treatment with ciprofloxacin alone (33 patients, 110 samples, 19 dose adjustments).

CONCLUSIONS

BL-CI used with/without colistin and supported by TDM may be an alternative and effective treatment option for OIs caused by fluoroquinolone-resistant P. aeruginosa, where limited available therapeutic options exist, especially in the setting of multidrug resistance. Future research should elucidate whether this strategy can produce outcomes similar to those of patients treated for OIs caused by fluoroquinolone-susceptible strains.

Risk Factors of Daptomycin-Induced Eosinophilic Pneumonia in a Population with Osteoarticular Infection

BACKGROUND

Daptomycin-induced eosinophilic pneumonia (DEP) is a rare but severe adverse effect and the risk factors are unknown. The aim of this study was to determine risk factors for DEP.

METHODS

A retrospective cohort study was performed at the Bone and Joint Infection Unit of the Hospital Universitari Bellvitge (January 2014-December 2018). To identify risk factors for DEP, cases were divided into two groups: those who developed DEP and those without DEP.

RESULTS

Among the whole cohort (n = 229) we identified 11 DEP cases (4.8%) and this percentage almost doubled in the subgroup of patients ≥70 years (8.1%). The risk factors for DEP were age ≥70 years (HR 10.19, 95%CI 1.28-80.93), therapy >14 days (7.71, 1.98-30.09) and total cumulative dose of daptomycin ≥10 g (5.30, 1.14-24.66).

CONCLUSIONS

Clinicians should monitor cumulative daptomycin dosage to minimize DEP risk, and be cautious particularly in older patients when the total dose of daptomycin exceeds 10 g.

Measurement uncertainty of β-lactam antibiotics results: estimation and clinical impact on therapeutic drug monitoring

Background Despite that measurement uncertainty data should facilitate an appropriate interpretation of measured values, there are actually few reported by clinical laboratories. We aimed to estimate the measurement uncertainty of some β-lactam antibiotics (β-LA), and to evaluate the impact of reporting the measurement uncertainty on clinicians' decisions while guiding antibiotic therapy. Methods Measurement uncertainty of β-LA (aztreonam [ATM], cefepime [FEP], ceftazidime [CAZ], and piperacillin [PIP]) values, obtained by an UHPLC-MS/MS based-method, was estimated using the top-down approach called the single laboratory validation approach (EUROLAB guidelines). Main uncertainty sources considered were related to calibrators' assigned values, the intermediate precision, and the bias. As part of an institutional program, patients with osteoarticular infections are treated with β-LA in continuous infusion and monitored to assure values at least 4 times over the minimal inhibitory concentration (4×MIC). We retrospectively evaluated the impact of two scenarios of laboratory reports on clinicians' expected decisions while monitoring the treatment: reports containing only the β-LA values, or including the β-LA coverage intervals (β-LA values and their expanded measurement uncertainties). Results The relative expanded uncertainties for ATM, FEP, CAZ and PIP were lower than 26.7%, 26.4%, 28.8%, and 25.5%, respectively. Reporting the measurement uncertainty, we identified that clinicians may modify their decision especially in cases where 4×MIC values were within the β-LA coverage intervals. Conclusions This study provides a simple method to estimate the measurement uncertainty of β-LA values that can be easily applied in clinical laboratories. Further studies should confirm the potential impact of reporting measurement uncertainty on clinicians' decision-making while guiding antibiotic therapy.

In vitro pharmacokinetics/pharmacodynamics of continuous ceftazidime infusion alone and in combination with colistin against Pseudomonas aeruginosa biofilm

OBJECTIVES

The pharmacokinetics/pharmacodynamics of continuous infusion (CI) beta-lactams for Pseudomonas aeruginosa biofilm infections has not been defined. This study evaluated the efficacy of several dosage regimens of CI ceftazidime, with or without colistin, an antibiotic with a potential antibiofilm effect, against biofilm-embedded P. aeruginosa.

METHODS

Mature biofilms of the reference strain PAO1 and the clinical isolate HUB8 (both ceftazidime- and colistin-susceptible) were investigated over 54h using a dynamic CDC biofilm reactor. CI dosage regimens were ceftazidime monotherapy (4, 10, 20 and 40 mg/L), colistin monotherapy (3.50 mg/L), and combinations of colistin and ceftazidime (4 or 40 mg/L). Efficacy was evaluated by changes in log₁₀colony-forming units (cfu)/mL and confocal microscopy.

RESULTS

At 54 h, the antibiofilm activity of ceftazidime monotherapies was slightly higher for ceftazidime 20 mg/L (-2.84 log₁₀cfu/mL) and 40 mg/L (-3.05) against PAO1, but no differences were seen against HUB8. Ceftazidime-resistant colonies emerged with 4 mg/L regimens in both strains and with other regimens in PAO1. Colistin monotherapy had significant antibiofilm activity against HUB8 (-3.07), but lower activity against PAO1 (-1.12), and colistin-resistant strains emerged. Combinations of ceftazidime and colistin had higher antibiofilm activity at 54 h compared with each monotherapy, and prevented the emergence of resistance to both antibiotics; higher antibiofilm activity was observed with ceftazidime 40 mg/L plus colistin compared with ceftazidime 4 mg/L plus colistin (-4.19 vs. -3.10 PAO1; -4.71 vs. -3.44 HUB8).

CONCLUSIONS

This study demonstrated that, with %T>MIC=100%, CI ceftazidime displayed concentration-dependent antibiofilm activity against P. aeruginosa biofilm, particularly in combination with colistin. These results support the use of high-dosage regimens of CI ceftazidime with colistin against biofilm-associated infections with ceftazidime-susceptible P. aeruginosa.

Lower Success Rate of Débridement and Implant Retention in Late Acute versus Early Acute Periprosthetic Joint Infection Caused by Staphylococcus spp. Results from a Matched Cohort Study

BACKGROUND

Surgical débridement, antibiotics and implant retention (DAIR) is currently recommended by international guidelines for both early acute (postsurgical) and late acute (hematogenous) periprosthetic joint infections (PJIs). However, due to a different pathogenesis of infection, a different treatment strategy may be needed.

QUESTIONS/PURPOSES

(1) Compared with early acute PJIs, are late acute PJIs associated with a higher risk of DAIR failure? (2) When stratified by microorganism, is the higher risk of failure in late acute PJI associated with Staphylocococcus aureus infection? (3) When analyzing patients with S. aureus infection, what factors are independently associated with DAIR failure?

METHODS

In this multicenter observational study, early acute and late acute PJIs treated with DAIR were retrospectively evaluated and matched according to treating center, year of diagnosis, and infection-causing microorganism. If multiple matches were available, the early acute PJI diagnosed closest to the late acute PJI was selected. A total of 132 pairs were included. Treatment success was defined as a retained implant during follow-up without the need for antibiotic suppressive therapy.

RESULTS

Late acute PJIs had a lower treatment success (46% [60 of 132]) compared with early acute PJIs (76% [100 of 132]), OR 3.9 [95% CI 2.3 to 6.6]; p < 0.001), but the lower treatment success of late acute PJIs was only observed when caused by Staphylococcus spp (S. aureus: 34% versus 75%; p < 0.001; coagulase-negative staphylococci: 46% versus 88%; p = 0.013, respectively). On multivariable analysis, late acute PJI was the only independent factor associated with an unsuccessful DAIR when caused by S. aureus (OR 4.52 [95% CI 1.79 to 11.41]; p < 0.001).

CONCLUSIONS

Although DAIR seems to be a successful therapeutic strategy in the management of early acute PJI, its use in late acute PJI should be reconsidered when caused by Staphylococcus spp. Our results advocate the importance of isolating the causative microorganism before surgery.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Invasive Meningococcal Disease: What We Should Know, Before It Comes Back

Background

Invasive meningococcal disease (IMD), sepsis and/or meningitis continues to be a public health problem, with mortality rates ranging from 5% to 16%. The aim of our study was to further knowledge about IMD with a large series of cases occurring over a long period of time, in a cohort with a high percentage of adult patients.

Methods

Observational cohort study of patients with IMD between 1977 hand 2013 at our hospital, comparing patients with only sepsis and those with meningitis and several degrees of sepsis. The impact of dexamethasone and prophylactic phenytoin was determined, and an analysis of cutaneous and neurological sequelae was performed.

Results

A total of 527 episodes of IMD were recorded, comprising 57 cases of sepsis (11%) and 470 of meningitis with or without sepsis (89%). The number of episodes of IMD decreased from 352 of 527 (67%) in the first to 20 of 527 (4%) in the last quarter (P < .001). Thirty-three patients died (6%): 8 with sepsis (14%) and 25 with meningitis (5%) (P = .02). Cutaneous and neurological sequelae were present in 3% and 5% of survivors of sepsis and meningitis, respectively. The use of dexamethasone was safe and resulted in less arthritis, and patients given prophylactic phenytoin avoided seizures.

Conclusions

The frequency of IMD has decreased sharply since 1977. Patients with sepsis only have the highest mortality and complication rates, dexamethasone use is safe and can prevent some arthritis episodes, and prophylactic phenytoin might be useful in a selected population. A rapid response and antibiotic therapy may help improve the prognosis.

Measurement of ceftolozane and tazobactam concentrations in plasma by UHPLC-MS/MS. Clinical application in the management of difficult-to-treat osteoarticular infections

BACKGROUND

Ceftolozane, in combination with the β-lactamase inhibitor tazobactam, is a new option in the pipeline against multidrug-resistant Gram-negative bacilli. As for other β-lactam antibiotics, optimizing the use of ceftolozane-tazobactam is advisable, especially in difficult-to-treat infections. In this regard, therapeutic drug monitoring would be required to guide the treatment of ceftolozane-tazobactam. Thus, we aimed to develop and validate procedures based on UHPLC-MS/MS for measurement of ceftolozane and tazobactam plasma concentrations in clinical practice.

MATERIAL AND METHODS

Analyses were conducted using an Acquity® UPLC® integrated system coupled to an Acquity® TQD® tandem-quadrupole mass spectrometer. Ceftolozane, tazobactam and their internal standards (ceftazidime-D₅ and sulbactam) were detected by electrospray ionization mass spectrometry in positive and negative ion multiple reaction monitoring modes, using transitions of 667.2 → 199.3/139.0 and 551.9 → 467.9 for ceftolozane and ceftazidime-D₅, and 299.0 → 138/254.9 and 232.0 → 140.0 for tazobactam and sulbactam. Measurement procedures developed were used for guiding the treatment and adjusting daily dose of ceftolozane-tazobactam in patients with osteoarticular infections.

RESULTS

Coefficients of variation and absolute relative biases were <7.9% and 6.5% in all cases. The lower limit of quantification, linearity, normalized-recoveries, normalized-matrix effects and measurement uncertainties for ceftolozane were: 0.97 mg/L, (0.97-125) mg/L, ≤113.6%, ≤108.7%, and ≤ 18.7%, respectively; and for tazobactam: 1.04 mg/L, (1.04-125) mg/L, ≤103.6%, ≤101.9%, and ≤ 20.0%. No interferences and carry-over were observed. Patients plasma concentrations were higher than the recommended 3-4 times the minimal inhibitory concentrations.

CONCLUSIONS

Our measurement procedures are suitable for therapeutic drug monitoring of ceftolozane-tazobactam in patients with osteoarticular infections.

Analysis of mortality in a cohort of 650 cases of bacteremic osteoarticular infections

OBJECTIVES

The mortality of patients with bacteremic osteoarticular infections (B-OAIs) is poorly understood. Whether certain types of OAIs carry higher mortality or interventions like surgical debridement can improve prognosis, are unclarified questions.

METHODS

Retrospective analysis of a prospective cohort of patients with B-OAIs treated at a teaching hospital in Barcelona (1985-2014), analyzing mortality (30-day case-fatality rate). B-OAIs were categorized as peripheral septic arthritis or other OAIs. Factors influencing mortality were analyzed using logistic regression models. The association of surgical debridement with mortality in patients with peripheral septic arthritis was evaluated with a multivariate logistic regression model and a propensity score matching analysis.

RESULTS

Among 650 cases of B-OAIs, mortality was 12.2% (41.8% of deaths within 7 days). Compared with other B-OAI, cases of peripheral septic arthritis were associated with higher mortality (18.6% vs 8.3%, p < 0.001). In a multiple logistic regression model, peripheral septic arthritis was an independent predictor of mortality (adjusted odds ratio [OR] 2.12; 95% CI: 1.22-3.69; p = 0.008). Cases with peripheral septic arthritis managed with surgical debridement had lower mortality than those managed without surgery (14.7% vs 33.3%; p = 0.003). Surgical debridement was associated with reduced mortality after adjusting for covariates (adjusted OR 0.23; 95% CI: 0.09-0.57; p = 0.002) and in the propensity score matching analysis (OR 0.81; 95% CI: 0.68-0.96; p = 0.014).

CONCLUSIONS

Among patients with B-OAIs, mortality was greater in those with peripheral septic arthritis. Surgical debridement was associated with decreased mortality in cases of peripheral septic arthritis.

Invasive meningococcal disease: Impact of short course therapy. A DOOR/RADAR study

BACKGROUND

Invasive meningococcal disease is a severe infection. The appropriate duration of antibiotic therapy is not well established.

METHODS

Two hundred and sixty-three consecutive patients with invasive meningococcal disease treated with 4 days' antibiotic therapy were compared with 264 consecutive patients treated previously at the same center with 7 days' antibiotic therapy. A Desirability of Outcome Ranking (DOOR) and Response Adjusted for Duration of Antibiotic Risk (RADAR) study was also performed.

RESULTS

No relapses were recorded in any patient. Patients on the 4-day course were 63% female, with a median age of 23 years old (IQR 16-54) and patients on the 7-day course were 61% female, with a median age of 17 years old (IQR 12-43). Case fatality rate was 7% in the 4-d patients and 6% in the 7-d patients (p = 0.582). Neurological sequelae were recorded in 6% of the 4-d group and in 7% of the 7-d group ((p = 0.509) and cutaneous sequelae in 3% in both groups. There were no statistical significant differences between the groups in terms of clinical characteristics, laboratory findings or complications. The probability that a patient had a randomly chosen DOOR better with the 4-day regimen than with the 7-day regimen was 80.4% [95% CI 80.1-80.7%].

CONCLUSION

Invasive meningococcal disease may be successfully treated with a four-day course of antibiotic therapy without relapses.

Osteoarticular infection caused by MDR Pseudomonas aeruginosa: the benefits of combination therapy with colistin plus β-lactams

OBJECTIVES

In the era of emergence of MDR Pseudomonas aeruginosa, osteoarticular infections (OIs) add more difficulties to its treatment. The role of β-lactams (BLs) is questioned and older drugs need to be reconsidered. The objective of this study was to describe our experience in the management of OIs caused by MDR P. aeruginosa and evaluate different therapeutic options.

METHODS

This was a retrospective analysis of a prospectively collected cohort (2004-13) of patients with OI caused by MDR P. aeruginosa. We created two groups: (i) Group A (more difficult to treat), prosthetic joint infections (PJIs) and osteoarthritis (OA) managed with device retention; and (ii) Group B (less difficult to treat), OA managed without device retention. Antibiotic treatment was administered according to clinician criteria: monotherapy/combined therapy; and BL used by intermittent bolus (IB)/continuous infusion.

RESULTS

Of 34 patients, 15 (44.1%) had PJI and 19 (55.9%) had OA (8 related to an orthopaedic device). Twenty-three cases (68%) were caused by XDR P. aeruginosa. The initial management included removal of an orthopaedic device in 14 cases, together with antibiotic [alone, 19 (55.9%; 4 colistin, 14 BL-IB and 1 BL continuous infusion); and in combination, 15 (44.1%; 5 BL-IB and 10 BL continuous infusion)]. The overall cure rate was 50% (39% and 63% in Groups A and B, respectively), ranging from 31.6% with monotherapy to 73.3% with combined therapy (P = 0.016), with special interest within Group A (cure rate with combined therapy 71.4%, P = 0.049). After rescue therapy, which included removal of remaining devices, the cure rate reached 85.3%.

CONCLUSIONS

We suggest that the BL/colistin combination is an optimized therapy for OI caused by MDR P. aeruginosa, together with an appropriate surgical treatment.