Antibiotic guidelines coupled with selective reporting of antibiograms.

OBJECTIVES: We reported the impact of internal guidelines coupled with selective reporting of antibiotic susceptibility tests (srAST) on antibiotic adequacy in healthcare facilities. METHODS: This prospective study involved clinicians from three clinics with medical and surgical activities employing a full-time infectious disease (ID) specialist. Internal guidelines were updated in 2016. The clinics were working with the same laboratory, which delivered the srAST introduced in March 2017. Two weeks per month over a 6-month period, all isolated bacterial specimens, empirical antibiotic therapies (EAT) and the documented ones were analyzed. An EAT listed in the guidelines and a documented therapy mentioned in the srAST defined their adequacy. RESULTS: A total of 257 positive bacterial samples were analyzed in 199 patients, for which 106 infections were studied. Of these, 32% were urinary tract infections, 15% were primary bloodstream infections, 11% were bone infections, and 42% were other types of infection. The three main bacteria were Escherichia coli (27%), Staphylococcus aureus (24%), and Enterococcus faecalis (14%). The total number of antibiotic prescriptions was 168, with 75 (45%) EATs and 93 (55%) documented therapies. There were 35/75 (47%) adequate EATs and 86/93 (92%) adequate documented therapies. The ID specialist was not involved in 90/168 (53.5%) prescriptions, of which 43/90 (48%) were adequate, with 21/35 (60%) EATs and 22/86 (25%) documented therapies. There was a statistical correlation between compliance of the EATs with guidelines and of the documented therapy with srAST (p=0.02). CONCLUSION: Combining internal guidelines and srAST led to a high rate of antibiotic adequacy.

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.

Measurement uncertainty of ß-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 ß-lactam antibiotics (ß-LA), and to evaluate the impact of reporting the measurement uncertainty on clinicians' decisions while guiding antibiotic therapy. Methods Measurement uncertainty of ß-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 ß-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 ß-LA values, or including the ß-LA coverage intervals (ß-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 ß-LA coverage intervals. Conclusions This study provides a simple method to estimate the measurement uncertainty of ß-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.

Clinical Use of Colistin in Biofilm-Associated Infections.

Biofilm is an adaptive bacterial strategy whereby microorganisms become encased in a complex glycoproteic matrix. The low concentration of oxygen and nutrients in this environment leads to heterogeneous phenotypic changes in the bacteria, with antimicrobial tolerance being of paramount importance. As with other antibiotics, the activity of colistin is impaired by biofilm-embedded bacteria. Therefore, the recommendation for administering high doses in combination with a second drug, indicated for planktonic infections, remains valid in this setting. Notably, colistin has activity against metabolically inactive biofilm-embedded cells located in the inner layers of the biofilm structure. This is opposite and complementary to the activity of other antimicrobials that are able to kill metabolically active cells in the outer layers of the biofilm. Several experimental models have shown a higher activity of colistin when used in combination with other agents, and have reported that this can avoid the emergence of colistin-resistant subpopulations. Most experience of colistin in biofilm-associated infections comes from patients with cystic fibrosis, where the use of nebulized colistin allows high concentrations to reach the site of the infection. However, limited clinical experience is available in other scenarios, such as osteoarticular infections or device-related central nervous system infections caused by multi-drug resistant microorganisms. In the latter scenario, the use of intraventricular or intrathecal colistin also permits high local concentrations and good clinical results. Overall, the efficacy of intravenous colistin seems to be poor, but its association with a second antimicrobial significantly increases the response rate. Given its activity against inner bioflm-embedded cells, its possible role in combination with other antibiotics, beyond last-line therapy situations, should be further explored.

Encapsulation of green tea polyphenol by pH responsive, antibacterial, alginate microgels used for minimally invasive treatment of bone infection.

The treatment of bone infection requires drug carriers take large number of cargo, be antibacterial, promote proliferation and differentiation of osteoblasts. Herein, we proposed a strategy of preparing pH responsive, antibacterial, multistage structured microspheres encapsulated with green tea polyphenol used for minimally invasive treatment of bone infection. Tea polyphenol (TP) were encapsulated by porous silica nanospheres (SiO2 NSs). Then, sodium alginate (SA) microgel spheres (MSs) were prepared to encapsulate a lot of TP loaded SiO2 NSs. The outer layer of obtained TP@SiO2@SA microgel spheres were further wrapped by pH sensitive CaCO3. Mineral out-layer of the composite microspheres is used to neutralize the acidic environment caused by bacterial infection. At the same time, encapsulated TP is released pH sensitively to resist oxidative stress. Our results exhibited excellent drug delivery properties including drug loading efficiency (DLE) of 92.96% and drug loading content (DLC) of 19.62%. Besides, results demonstrated that TP@SiO2@SA@CaCO3 MSs can effectively kill Staphylococcus aureus and promote proliferation and differentiation of osteoblasts under stimulation of H2O2 at pH = 5.5.

Association of Vancomycin MIC and Molecular Characteristics with Clinical Outcomes in Methicillin-Susceptible Staphylococcus aureus Acute Hematogenous Osteoarticular Infections in Children.

Strains of methicillin-resistant Staphylococcus aureus (MRSA), particularly those belonging to the USA300 pulsotype, have been well described to cause severe osteoarticular infections (OAIs). A vancomycin MIC of ≥1.5 µg/ml has been demonstrated to contribute to disease severity in adults with MRSA and even methicillin-susceptible S. aureus (MSSA) bacteremia. Little data exist describing the outcomes of MSSA OAIs in terms of molecular characteristics and vancomycin MIC. All patients/isolates were chosen from a surveillance study at Texas Children's Hospital (TCH). S. aureus OAI isolates were identified from 2011 to 2016 and subjected to vancomycin Etests, pulsed-field gel electrophoresis (PFGE), and PCR to determine Panton-Valentine leucocidin (PVL) production and agr group. Two hundred fifty-two cases of S. aureus OAI were identified; 183 cases were MSSA (72.6%). During the study period, a decrease in the proportion of cases secondary to MRSA was observed, declining from 37.8% to 15.9% (P = 0.02). Of the MSSA isolates, 26.2% and 23.5% were USA300 and PVL positive, respectively. An increase in the proportion of MSSA isolates with a vancomycin MIC of ≥1.5 µg/ml occurred in the study period (P = 0.004). In MSSA, an elevated vancomycin MIC was associated with multiple surgical procedures and venous thromboses, even when adjusting for empirical ß-lactam use. An increase in vancomycin MIC was noted among isolates belonging to agr group 4 during the study period. Methicillin resistance is declining among S. aureus OAI isolates at TCH. Simultaneously, vancomycin Etest MICs are increasing among MSSA isolates. Vancomycin MICs of ≥2 µg/ml are associated with adverse clinical outcomes in MSSA irrespective of antibiotic choice, suggesting that this may be a surrogate for organism virulence.

Beta-lactams in continuous infusion for Gram-negative bacilli osteoarticular infections: an easy method for clinical use.

Continuous infusion (CI) of beta-lactams could optimize their pharmacokinetic/pharmacodynamic indices, especially in difficult-to-treat infections. PURPOSE: To validate an easy-to-use method to guide beta-lactams dosage in CI (formula). METHODS: A retrospective analysis was conducted of a prospectively collected cohort (n = 24 patients) with osteoarticular infections caused by Gram-negative bacilli (GNB) managed with beta-lactams in CI. Beta-lactams dose was calculated using a described formula (daily dose = 24 h × beta-lactam clearance × target "steady-state" concentration) to achieve concentrations above the MIC. We correlated the predicted concentration (Cpred = daily dose/24 h × beta-lactam clearance) with the patient's observed concentration (Cobs) measured by UPLC-MS/MS (Spearman's coefficient). RESULTS: The most frequent microorganism treated was P. aeruginosa (21 cases; 9 MDR). Beta-lactams in CI were ceftazidime (n = 14), aztreonam (7), and piperacillin/tazobactam (3), mainly used in combination (12 with colistin, 5 with ciprofloxacin) and administered without notable side effects. The plasma Cobs was higher overall than Cpred; the Spearman correlation between both concentrations was rho = 0.6 (IC 95%: 0.2-0.8) for all beta-lactams, and rho = 0.8 (IC 95%: 0.4-1) for those treated with ceftazidime. CONCLUSIONS: The formula may be useful in clinical practice for planning the initial dosage of beta-lactams in CI, while we await a systematic therapeutic drug monitoring. The use of beta-lactams in CI was safe.

A short artificial antimicrobial peptide shows potential to prevent or treat bone infections.

Infection of bone is a severe complication due to the variety of bacteria causing it, their resistance against classical antibiotics, the formation of a biofilm and the difficulty to eradicate it. Antimicrobial peptides (AMPs) are naturally occurring peptides and promising candidates for treatment of joint infections. This study aimed to analyze the effect of short artificial peptides derived from an optimized library regarding (1) antimicrobial effect on different bacterial species, (2) efficacy on biofilms, and (3) effect on osteoblast­like cells. Culturing the AMP-modifications with Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa, Staphylococcus aureus (including clinical isolates of MRSA and MSSA) and Staphylococcus epidermidis identified one candidate that was most effective against all bacteria. This AMP was also able to reduce biofilm as demonstrated by FISH and microcalorimetry. Osteoblast viability and differentiation were not negatively affected by the AMP. A cation concentration comparable to that physiologically occurring in blood had almost no negative effect on AMP activity and even with 10% serum bacterial growth was inhibited. Bacteria internalized into osteoblasts were reduced by the AMP. Taken together the results demonstrate a high antimicrobial activity of the AMP even against bacteria incorporated in a biofilm or internalized into cells without harming human osteoblasts.

A biodegradable antibiotic-eluting PLGA nanofiber-loaded deproteinized bone for treatment of infected rabbit bone defects.

We fabricated a biodegradable antibiotic-eluting poly(d,l)-lactide-co-glycolide nanofiber-loaded deproteinized bone (ANDB) scaffold that provided sustained delivery of vancomycin to repair methicillin-resistant Staphylococcus aureus bone defects. To fabricate the biodegradable ANDB, poly(d,l)-lactide-co-glycolide and vancomycin were first dissolved in 1,1,1,3,3,3-hexafluoro-2-propano. The solution was then electrospun to produce biodegradable antibiotic-eluting membranes that were deposited on the surface of bovine deproteinized cancellous bone. We used scanning electron microscopy to determine the properties of the scaffold. Both elution and high-performance liquid chromatography assays were used to evaluate the in vitro vancomycin release rate from the ANDB scaffold. Three types of scaffolds were co-cultured with bacteria to confirm the in vitro antibacterial activity. The infected bone defect rabbit model was induced by injecting 10(7) colony forming units of a methicillin-resistant Staphylococcus aureus strain into the radial defect of rabbits. Animals were then separated into treatment groups and implanted according to the following scheme: ANDB scaffold in group A, poly(d,l)-lactide-co-glycolide nanofiber-loaded deproteinized bone (NDB) scaffold with intravenous (i.v.) vancomycin in group B, and NDB scaffold alone in group C. Treatment efficacy was evaluated after eight weeks using radiological, microbiological, and histological examinations. In vitro results revealed that biodegradable ANDB scaffolds released concentrations of vancomycin that were greater than the minimum inhibitory concentration for more than four weeks. Bacterial inhibition tests also confirmed antibacterial efficacy lasted for approximately four weeks. Radiological and histological scores obtained in vivo revealed significant differences between groups A, B and C. Importantly, group A had significantly lower bacterial load and better bone regeneration when compared to either group B or C. Collectively, these results show that our fabricated ANDB scaffolds possess: (1) effective bactericidal activity against methicillin-resistant Staphylococcus aureus, (2) the ability to promote site-specific bone regeneration, and (3) the potential for use in the treatment of infected bone defects.

Measurement of ceftazidime concentration in human plasma by ultra-performance liquid chromatography-tandem mass spectrometry. Application to critically ill patients and patients with osteoarticular infections.

Ceftazidime is an antibiotic belonging to the third generation of the cephalosporin family. It is indicated in the treatment of serious, simple or mixed bacterial infections, and its administration in continuous or intermittent infusion allows optimization of the concentration of antibiotic to keep it above the minimum inhibitory concentration. We developed and validated a chromatographic method by ultra-performance liquid chromatography-tandem mass spectrometry to measure ceftazidime concentration in human plasma. Following extraction with acetonitrile and 1,2-dichloroethane, the chromatographic separation was achieved using an Acquity ® UPLC ® BEH(TM) (2.1 × 100 mm i.d., 1.7 µm) reverse-phase C18 column, with a water-acetonitrile linear gradient containing 0.1% formic acid at a 0.4 mL/min flow rate. Ceftazidime and its internal standard (cefotaxime) were detected by electrospray ionization mass spectrometry in positive ion multiple reaction monitoring mode using mass-to-charge transitions of 547.0 → 467.9/396.1 and 456.0 → 395.8/324.1, respectively. The limit of quantification was 0.58 mg/L and linearity was observed in the range 0.58-160 mg/L. Coefficients of variation and absolute relative biases were <9.8 and 8.4%. The mean recovery for ceftazidime was 74.4 ± 8.1%. Evaluation of the matrix effect showed ion enhancement, and no carry-over was observed. The validated method could be applied to daily clinical laboratory practice to measure the concentration of ceftazidime in plasma.

Treatment principles for Candida and Cryptococcus.

The yeasts Candida and Cryptococcus spp. are important human opportunistic pathogens. Candida spp. rely on skin or mucosal breach to cause bloodstream infection, whereas Cryptococcus spp. exploit depressed cell-mediated immunity characteristic of advanced HIV infection. The treatment for both organisms relies on the administration of rapidly fungicidal agents. In candidaemia, source control is important, with removal of prosthetic material and drainage of collections, as well as hunting for and tailoring therapy to disseminated sites of infection, particularly the eyes and heart. For cryptococcal meningitis, restoration of immune function through antiretroviral therapy (ART) is key, together with careful management of the complications of raised intracranial pressure and relapsed infection, both pre- and post-ART.

[Potential utility of ceftaroline fosamil in osteoarticular infections]. / Utilidad potencial de ceftarolina fosamil en las infecciones osteoarticulares.

Osteoarticular infections (OAI) include a wide-usually complex-spectrum of clinical scenarios. The approach is usually medical-surgical. In addition to this complexity, there is a low grade of evidence in the medical literature on these infections. Nevertheless, it is possible-and necessary-to integrate microbiological, pharmacological, experimental and clinical information to achieve the best possible clinical results. The most appropriate choice of antibiotic therapy largely depends on the clinical scenario and, obviously, on the microorganisms involved. Given the protagonism of staphylococci in OAI, it is appropriate to elucidate the role that could be played by a new antistaphylococcic agent in these infections. For clinicians who manage OAI, the incorporation of ceftaroline represents the recovery of a beta-lactam to treat methicillin-resistant staphylococci. This perspective can be used to guide the potential role of this new antibiotic for the management of OAI in various scenarios and the clinical research required for its introduction in clinical practice.

Fusidic acid for the treatment of bone and joint infections caused by meticillin-resistant Staphylococcus aureus.

There is a lack of surveillance data on resistance to fusidic acid (FA) in Asia, and no reviews of FA usage for the treatment of orthopaedic infections have been conducted since the year 2000. In this study, we present a systemic literature review of FA resistance in Asia and the clinical use of FA for the treatment of bone and joint infections (BJIs). The in vitro activity of FA against meticillin-resistant Staphylococcus aureus (MRSA) isolates remains good, with low (<10%) resistance rates in most Asian countries. FA in Asia appears to be a better oral anti-MRSA agent than trimethoprim/sulfamethoxazole and clindamycin. More than 80 cases of FA use for BJI have been reported since 2000 and the recurrence or failure rate is <10%. There is much evidence supporting the use of FA in combination with other antibiotics (e.g. rifampicin) as an oral treatment following intravenous glycopeptide treatment for BJIs.

Systemic exposure to tobramycin after local antibiotic treatment with calcium sulphate as carrier material.

INTRODUCTION: Osteoset(®) T is a calcium sulphate void filler containing 4% tobramycin sulphate, used to treat bone and soft tissue infections. Despite systemic exposure to the antibiotic, there are no pharmacokinetic studies in humans published so far. Based on the observations made in our patients, a model predicting tobramycin serum levels and evaluating their toxicity potential is presented. METHODS: Following implantation of Osteoset(®) T, tobramycin serum concentrations were monitored systematically. A pharmacokinetic analysis was performed using a non-linear mixed effects model based on a one compartment model with first-degree absorption. RESULTS: Data from 12 patients treated between October 2006 and March 2008 were analysed. Concentration profiles were consistent with the first-order slow release and single-compartment kinetics, whilst showing important variability. Predicted tobramycin serum concentrations depended clearly on both implanted drug amount and renal function. DISCUSSION AND CONCLUSION: Despite the popularity of aminoglycosides for local antibiotic therapy, pharmacokinetic data for this indication are scarce, and not available for calcium sulphate as carrier material. Systemic exposure to tobramycin after implantation of Osteoset(®) T appears reassuring regarding toxicity potential, except in case of markedly impaired renal function. We recommend in adapting the dosage to the estimated creatinine clearance rather than solely to the patient's weight.

Treatment of bone and joint infections caused by Gram-negative bacilli with a cefepime-fluoroquinolone combination.

A 3-year retrospective study evaluated the effectiveness and safety of cefepime plus a fluoroquinolone for treating bone and joint infections caused by Gram-negative bacilli (GNB) in 28 patients. Intra-operative cultures yielded primarily Pseudomonas spp. and Enterobacter cloacae. Full recovery (cure) was observed in 79% of patients. There were no serious adverse effects and no resistant organisms were isolated. The results of the study confirmed the safety and effectiveness of cefepime combined with a fluoroquinolone for the treatment of bone and joint infections caused by Gram-negative bacilli.

[Linezolid--novel antibiotic for the treatment of gram-positive bacterial infections]. / Linezolid--nowy antybiotyk w leczeniu zakazenwywolalych bakteriami gram-dodatnimi.

Linezolid, the first of a new class of antibiotics, the oxazolidinones, is approved for the treatment of Gram-positive bacterial infections, including resistant strains. Linezolid possesses bacteriostatic activity against both antibiotic-susceptible and resistant strains of staphylococci, enterococci and streptococci of relevance to human infection. Clinical trials have confirmed its effectiveness in the treatment of serious infections of skin and soft tissue and the lower respiratory tract. Linezolid has also provided improved outcomes in the treatment of serious vancomycin-resistant entrococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) infections. It is well absorbed with high bioavailability after oral administration and generally well tolerated.

[The bone reaction to the implantation of the corundum-vancomycin composite]. / Reakcja tkanki kostnej po implantacji ceramiki korundowej z Wankomycyna.

Polymethacrylate methylene (PMMA) used as the carrier for antibiotic gentamycin (Septopal) shows today very limited effectiveness. Only 24% of the staphylococcus strains is still susceptible for it. In 1982 this factor was as high as 97%! Because of the growing resistance of different strains of staphylococcus, enterococcus and G(-) bacillus for antibiotics in present use, came into being the necessity for evaluation of the state-of-the-art antibiotic carrier of the new generation, which should be effective to destroy the resistant strains of bacteria. The porous corundum ceramics proved to be good material for this purpose, specially in use for bone surgery. During the laboratory tests it was confirmed that corundum ceramics could be soaked with the different antibiotics of the new generations. The bacteriological tests proved that corundum ceramics soaked with the Vancomycin show the highest possibly antibacterial activity. On the basis of those results we undertook the implantation test on animals. The implantation was carried out on 10 rabbits in which the samples of tested ceramic with Vancomycin were implanted into femoral bone. The investigation periods were set up for 1, 3, 6 and 9 months. On the basis of received results of macroscopic, microscopic and radiological findings we can stated that corundum ceramic with Vancomycin can be used in the treatment of bone infections.