Azithromycin regulates bacterial virulence and immune response in a murine model of ceftazidime-treated Pseudomonas aeruginosa acute pneumonia.

Pseudomonas aeruginosa (PA) remains one of the leading causes of nosocomial acute pneumonia. The array of virulence factors expressed by PA and the intense immune response associated with PA pneumonia play a major role in the severity of these infections. New therapeutic approaches are needed to overcome the high resistance of PA to antibiotics and to reduce the direct damage to host tissues. Through its immunomodulatory and anti-virulence effects, azithromycin (AZM) has demonstrated clinical benefits in patients with chronic PA respiratory infections. However, there is relatively little evidence in PA acute pneumonia. We investigated the effects of AZM, as an adjunctive therapy combined with ceftazidime (CAZ), in a murine model of PA acute pneumonia. We observed that the combined therapy (i) reduces the weight loss of mice 24 h post-infection (hpi), (ii) decreases neutrophil influx into the lungs at 6 and 24 hpi, while this effect is absent in a LPS-induced pneumonia or when PA is pretreated with antibiotics and mice do not receive any antibiotics, and that (iii) AZM, alone or with CAZ, modulates the expression of PA quorum sensing regulators and virulence factors (LasI, LasA, PqsE, PhzM, ExoS). Our findings support beneficial effects of AZM with CAZ on PA acute pneumonia by both bacterial virulence and immune response modulations. Further investigations are needed to clarify the exact underlying mechanisms responsible for the reduction of the neutrophils influx and to better discriminate between direct immunomodulatory properties of AZM, and indirect effects on neutrophilia resulting from bacterial virulence modulation.

Effectiveness of At-Risk Gamblers' Temporary Self-Exclusion from Internet Gambling Sites.

To prevent risks associated with online gambling, many jurisdictions propose self-exclusion strategies as a part of a responsible gambling policy. To protect online gamblers, French law provides for a 7-day temporary non-reducible and voluntary self-exclusion measure that applies only to select websites. The objective of our study was to evaluate the effectiveness of this self-exclusion measure for at-risk online gamblers. It was an experimental randomized controlled trial targeted at risk prevention. The main outcomes were the money wagered and time spent gambling assessed 15 days (short-term) and 2 months (medium-term) after the implementation of the self-exclusion measure. The effectiveness of self-exclusion was also compared according to the gambling type (pure chance games, such as lottery or scratch tickets, skill and chance bank games such as sports betting or horserace betting, and skill and chance games such as poker). Sixty participants were randomly assigned to the experimental condition (n = 30; with the implementation of a self-exclusion measure) or control condition (n = 30). The randomization was stratified according to their favorite game [pure chance games (n = 20), skill and chance bank games (n = 20), and skill and chance social games (n = 20)]. The results revealed that self-exclusion had no short-term impact-but did have a medium-term impact-on gambling habits. After 2 months, the gambling-related cognitions ("illusion of control" and "the perceived inability to stop gambling") and the subscale "desire" of the Gambling Craving Scale (GACS) have decreased. Participants' opinions about the impact and effectiveness of self-exclusion were discussed. To conclude, it appeared that temporary self-exclusion is an interesting tool to protect online gamblers from excessive practices, but several modifications have to be made to improve its effectiveness and use.

Tetracycline use in the community may promote decreased susceptibility to quinolones in Escherichia coli isolates.

We previously found that the hospital use of tetracyclines is associated with quinolone resistance in hospital isolates of Enterobacteriaceae. Tetracyclines are heavily used in the community. Our aim was to assess whether their use in the community favors quinolone resistance in community isolates of Escherichia coli. Monthly data of community antibiotics use and E. coli quinolone resistance in a 1.3 million inhabitant French area were obtained from 2009 to 2014, and were analyzed with autoregressive integrated moving average (ARIMA) models. Quinolone use decreased from 10.1% of the total antibiotic use in 2009 to 9.3% in 2014 (trend, - 0.016; p-value < 0.0001), while tetracycline use increased from 16.5% in 2009 to 17.1% in 2014 (trend, 0.016; p < 0.0001). The mean (95% confidence interval) monthly proportions of isolates that were non-susceptible to nalidixic acid and ciprofloxacin were 14.8% (14.2%-15.5%) and 9.5% (8.8%-10.1%), respectively, with no significant temporal trend. After adjusting on quinolone use, tetracycline use in the preceding month was significantly associated with nalidixic acid non-susceptibility (estimate [SD], 0.01 [0.007]; p-value, 0.04), but not with ciprofloxacin non-susceptibility (estimate [SD], 0.01 [0.009]; p-value, 0.23). Tetracycline use in the community may promote quinolone non-susceptibility in E. coli. Decreasing both tetracycline and quinolone use may be necessary to fight against the worldwide growth of quinolone resistance.

Is there an association between prior anti-inflammatory drug exposure and occurrence of peritonsillar abscess (PTA)? A national multicenter prospective observational case-control study.

The aim of this study was to evaluate whether recent systemic anti-inflammatory agents (AIAs) exposure in patients with sore throat managed with or without antibiotic therapy influenced the risk of peritonsillar abscess (PTA). We conducted a multicenter case-control study in 13 French university hospitals in 2009-2012 comparing patients admitted with PTA to matched controls: patients with sore throat but without PTA who were followed up for 10 days after visiting their primary-care physician. In the multivariate stepwise logistic regression model comparing 120 cases with PTA to 143 controls, factors significantly associated with PTA were male gender (odds ratio [OR], 2.0; p = 0.03), smoking (OR, 2.0; p = 0.03), and prior self-medication with systemic AIAs (OR, 3.5; p = 0.01). Topical treatment was associated with significant protection against PTA (OR, 0.3; p < 0.001). In conclusion, self-medication with systemic AIAs appears to be an independent factor associated with the occurrence of PTA. This is an important message as non-steroidal AIAs access is favored by their over-counter availability in pharmacies. This finding must be interpreted with caution due to the study design and a prospective, randomized study is needed to substantiate these possible causal risk factors.

New in vitro and in vivo models to evaluate antibiotic efficacy in Staphylococcus aureus prosthetic vascular graft infection.

OBJECTIVE: Prosthetic vascular graft infection (PVGI) is an emerging disease, mostly caused by staphylococci, with limited data regarding efficacy of current antistaphylococcal agents. We aimed to assess the efficacy of different antibiotic regimens. METHODS: Six different strains of MSSA and MRSA were used. We compared results of minimal biofilm inhibitory and eradicating concentrations (MBICs and MBECs) obtained with a Calgary Biofilm Pin Lid Device (CBPD) with those yielded by an original Dacron(®)-related minimal inhibitory and eradicating concentration measure model. We then used a murine model of Staphylococcus aureus vascular prosthetic material infection to evaluate efficacy of different antibiotic regimens: vancomycin and daptomycin combined or not with rifampicin for MRSA and the same groups with cloxacillin and cloxacillin combined with rifampicin for MSSA. RESULTS: We demonstrated that classical measures of MBICs and MBECs obtained with a CPBD could overestimate the decrease in antibiotic susceptibility in material-related infections and that the nature of the support used might influence the measure of biofilm susceptibility, since results yielded by our Dacron(®)-related minimal eradicating assay were lower than those found with a plastic device. In our in vivo model, we showed that daptomycin was significantly more bactericidal than comparators for some strains of MRSA or MSSA but not for all. For the majority of strains, it was as efficient as comparators. The addition of rifampicin to daptomycin did not enhance daptomycin efficacy. CONCLUSIONS: Despite the heterogeneity of results according to bacterial strains, these innovative models represent an option to better evaluate the in vitro efficacy of antibiotics on Dacron(®)-related biofilm S. aureus infections, and to screen different antibiotic regimens in a mouse model of PVGIs.

Peritonsillar abscess (PTA): clinical characteristics, microbiology, drug exposures and outcomes of a large multicenter cohort survey of 412 patients hospitalized in 13 French university hospitals.

The aim of this study was to describe the epidemiology of hospitalized patients with peritonsillar abscess (PTA). We conducted a multicenter survey in 13 French university hospitals in 2009-2012 describing 412 patients. Median age was 29 year (range, 2-84) and current smoking habit was reported by 177 (43 %) patients. Most of the patients (92 %) had consulted a physician for sore throat within 10 days before admission for PTA diagnosis. Additional symptoms such as visible tonsil abnormalities (83 %), tender cervical adenopathy (57 %) and fever ≥ 38.5 °C (53 %) were also reported. A total of 65 % patients (269/412) reported recent systemic anti-inflammatory agents (AIAs) exposure by medical prescription (70 %), self-medication (22 %), or both (8 %); 61 % and 27 % reported recent exposure to antibiotic and topical treatments for sore throat, respectively. Non-steroidal AIAs were used most often (45 %), particularly arylpropionic derivatives. A rapid diagnosis antigen test (RDT) for Streptococcus pyogenes was performed in 70 (17 %) patients and was positive in 17 (24 %), of whom 9 (53 %) were exposed to AIAs and 14 (82 %) to antibiotics. To treat PTA, antibiotic therapy was given to 392 (95 %) patients. Of 333 antibiotic prescriptions, amoxicillin-clavulanic acid and metronidazole were the most prescribed antibiotics (42 and 17 %, respectively). Surgical drainage of the abscess was performed in 119 (29 %) cases and tonsillectomy in 75 (18 %) cases. The clinical outcome was favorable during the hospital stay in 404 (98 %) patients. In conclusion, patients with sore throat are often exposed to AIAs before PTA diagnosis, and antibiotic prescription was not often based on the RDT positivity.

Escherichia coli antibiotic resistance in emergency departments. Do local resistance rates matter?

Ciprofloxacin and cotrimoxazole are recommended to treat uncomplicated pyelonephritis and uncomplicated cystitis, respectively, provided that local resistance rates of uropathogens do not exceed specified thresholds (10 and 20 %, respectively). However, Escherichia coli resistance rates in Emergency Departments (ED) remain poorly described. Our objectives were to assess E. coli ciprofloxacin and cotrimoxazole resistance rates in EDs of a French administrative region, and to determine if resistance rates differ between EDs. This was a retrospective study of E. coli urine isolates sampled in ten EDs between 2007 and 2012. The following risk factors for resistance were tested using logistic regression: ED, sex, age, sampling year, sampling month. A total of 17,527 isolates were included. Ciprofloxacin local resistance rates (range, 5.3 % [95 % CI, 4.0-7.1 %] to 11.7 % [95 % CI, 5.2-23.2 %]) were ≤10 % in nine EDs in 2012. Five EDs were risk factors for ciprofloxacin resistance, as were male sex, age and sampling in April or October. Cotrimoxazole local resistance rates (range, 13.3 % [95 % CI, 6.3-25.1 %] to 20.4 % [95 % CI, 18.9-22.0 %]) were ≤20 % in seven EDs in 2012. Five EDs were risk factors for cotrimoxazole resistance, as were age, sampling between October and December, and sampling in 2011 and 2012. We found a significant variability of E. coli ciprofloxacin and cotrimoxazole resistance rates among EDs of a small region. These differences impact on the feasibility of empirical treatment of urinary tract infections with ciprofloxacin or cotrimoxazole in a given ED. Continuous local survey of antibacterial resistance in ED urinary isolates is warranted to guide antibacterial therapy of urinary tract infections.

Risk factors and pathogens involved in early ventilator-acquired pneumonia in patients with severe subarachnoid hemorrhage.

Ventilator-acquired pneumonia (VAP) is a common burden in intensive care unit (ICU) patients, but, to date, specific data are not available in patients with severe aneurysmal subarachnoid hemorrhage (SAH). A single neuro-ICU retrospective analysis of 193 patients with SAH requiring mechanical ventilation (MV) ≥48 h admitted from January 2005 to May 2010 was undertaken. The diagnosis of early VAP was prospectively upheld during a multidisciplinary staff meeting, according to the American Thoracic Society (ATS) 2005 guidelines with a threshold of 7 days after the onset of MV. Patients had a median age of 53 (44-62) years and 70 (36 %) were male. The median Glasgow coma scale (GCS) score before MV was 9 (5-14). 142 (74 %) patients had a World Federation of Neurosurgeons (WFNS) score ≥III. Aneurysm was secured with an endovascular coiling procedure in 162 (84 %) patients. 81 (48.7 %) patients declared an early VAP. On multivariate analysis, male sex (odds ratio [OR] 2.26, 95 % confidence interval [CI] [1.14-4.46]), use of mannitol before day 7 (OR 3.03, 95 % CI [1.54-5.95]), and achieving enteral nutrition ≥20 kcal kg(-1) day(-1) after day 7 (OR 2.91, 95 % CI [1.27-6.67]) remained independent risk factors of VAP. The main pathogens involved were methicillin-susceptible Staphylococcus aureus (MSSA) (34.9 %), Haemophilus influenzae (28.1 %), Streptococcus pneumoniae (15.5 %), and Enterobacteriaceae (10.7 %). Early VAP was associated with a longer duration of MV and ICU stay, but not with an excess of mortality. Early VAP bears significant morbidity in patients with severe SAH. Pathogens involved in early VAP are susceptible to antibiotics. Among modifiable risk factors of VAP, early enteral nutrition could be an easy and effective target.

A new procalcitonin cord-based algorithm in early-onset neonatal infection: for a change of paradigm.

Diagnostic of early-onset neonatal infection (EONI) remains an emergency. Recent studies underline the potential benefit of using Procalcitonin (PCT) in early diagnosis of bacterial infections in neonates. The aim of this study was to evaluate the diagnostic value of an umbilical blood cord PCT based algorithm in newborns suspected of EONI. The diagnostic value of the PCT based algorithm was compared to the French one currently in use by analyzing an 18-months database of newborns suspected of EONI in University Hospital of Nantes from March 2011 to September 2012. Among the 2,408 (40.8 %) newborns suspected of infection during this period, 2,366 were included in the study. The incidence of EONI was 3.4‰ (n = 20). There was no significant difference between the sensibilities of the PCT based algorithm and the current algorithm (90 %, respectively, 95%CI 76.9-100 versus 85.4-100; p = 0.90) and between their specificities (respectively 91.7 % (90.6-92.8) versus 87.4 % (86-88.7); p = 0.25). The antibiotic treatment rate would be significantly reduced with the PCT based algorithm [211 i.e. 8.9 % (7.8-10) versus 314 i.e. 13.3 % (11.9-14.7) in the current algorithm; p < 0.005] and less biological analysis would be performed [301 i.e. 12.7 % (11.4-14) versus 937 i.e. 39.6 % (37.6-41.6); p < 0.005]. Blood cord PCT seems to be a new and efficient marker to guide neonatologists taking care of newborns suspected of EONI. The PCT algorithm seems to be a safe alternative in diagnosis of EONI, allowing detection of EONI significantly as well as the current algorithm, without resulting in a substantially higher number of missed infections. These results have to be confirmed by a multicentric validation study.

Pseudomonas aeruginosa in French hospitals between 2001 and 2011: back to susceptibility.

The European Antimicrobial Resistance Surveillance Network (EARS-Net) reported an increase in the rates of resistance of Pseudomonas aeruginosa to antimicrobials between 2008 and 2011 in France. This alarming report was based on data collected during the harmonisation of breakpoints by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) committee. However, these data were not supported by the findings of other national surveillance networks. In this study, we assessed the trends in P. aeruginosa antimicrobial drug resistance at six French hospitals over a longer period of time (2001-2011) and with a constant definition of resistance. After the exclusion of incomplete data and duplicates, we sorted 34,065 isolates into the antimicrobial resistance patterns defined by the European Centre for Disease Prevention and Control (ECDC). The proportion of isolates with a resistant pattern (non-susceptible to one or two antimicrobial categories), a multidrug-resistant pattern (non-susceptible to three or four antimicrobial categories) or an extensively drug-resistant pattern (non-susceptible to five or six antimicrobial categories) decreased significantly over time. Logically, the proportion of isolates with a wild-type resistance pattern has increased significantly over the same period. No significant changes in the rates of resistance to cephalosporins and penicillins were observed, whereas carbapenem resistance rates increased. By contrast, the proportion of isolates resistant to fluoroquinolones, aminoglycosides and monobactams decreased significantly over time. In conclusion, our data do not confirm the EARS-net data, suggesting instead that antimicrobial drug resistance in P. aeruginosa might not have increased in French hospitals over the last decade.

A delivery system of linezolid to enhance the MRSA osteomyelitis prognosis: in vivo experimental assessment.

Staphylococcus aureus, a major responsible microorganism of osteomyelitis, represents a challenge to treat because of the poor penetration of antibiotics in bone and increasing minimum inhibitory concentrations (MICs) to glycopeptides. The calcium-deficient apatites (CDA), closer to the biological components found in bone and other calcified tissues, have osteoconductive properties. So, to process severe osseous infections, CDA can be used to deliver in the infectious site antibiotics like linezolid. The acute experimental osteomyelitis due to methicillin-resistant Staphylococcus aureus (MRSA) was induced in rabbit's femurs and surgery mimicking human procedures was performed at day three after inoculation. Animals were randomly assigned to treatment groups: L((IV)) [4-day linezolid IV infusion, human-equivalent dose of 10 mg/kg/12 h], L((CDA50%)) (100 mg CDA with linezolid 500 µg/mg) and L((CDA50%)) + L((IV)). Surviving bacteria were counted in bone marrow (BM) and bone (Bo) at day 3 (before treatment), day 7 (4-day treatment) or day 17 (14-day treatment). L(iv) was effective after a 4-day treatment with a log(10)CFU/g decrease of -2.63 ± 1.92 and -2.17 ± 1.58 in bone marrow and bone, respectively. CDA loaded with linezolid enhance the efficacy of the IV linezolid regimen by more than one log(10)CFU/g.

Why is antimicrobial de-escalation under-prescribed for urinary tract infections?

PURPOSE: To assess the frequency of de-escalation in inpatients treated for community-acquired urinary tract infection and the frequency of conditions legitimating not de-escalating therapy. METHODS: A retrospective study of inpatients (age >15 years) at a large academic hospital who were empirically treated for urinary tract infections due to Escherichia coli susceptible to at least one of the following antibacterial agents: amoxicillin, co-amoxiclav, and cotrimoxazole. De-escalation was defined as the replacement of the empirical broad-spectrum therapy by amoxicillin, co-amoxiclav, or cotrimoxazole. RESULTS: Eighty patients were included. De-escalation was prescribed for 32 of 69 patients for whom it was possible from both a bacteriological and clinical point of view (46 %, 95 % CI, 34-59 %). Initial treatment was switched to amoxicillin (n = 21), co-amoxiclav (n = 2), or cotrimoxazole (n = 8). Thirteen conditions justifying not de-escalating antibacterial therapy were detected in 11 of 48 patients who were not de-escalated (23 %, 95 % CI, 12-37 %): shock, n = 5; renal abscess, n = 1; obstructive uropathy, n = 4; bacterial resistance or clinical contraindication to both cotrimoxazole and ß-lactams, n = 3. CONCLUSIONS: De-escalation is under-prescribed for urinary tract infections. Omission of de-escalation is seldom legitimate. Interventions aiming to de-escalate antibacterial therapy for UTIs should be actively implemented.

Prevalence of a cefazolin inoculum effect associated with blaZ gene types, and clinical outcomes among methicillin-susceptible Staphylococcus aureus blood isolates of patients with infective endocarditis.

OBJECTIVES: A proportion of blaZ gene-positive methicillin-susceptible Staphylococcus aureus (MSSA) strains exhibits the cefazolin inoculum effect (CInE). Its clinical impact remains uncertain but could compromise the use of cefazolin in high-burden infections. To date, no study has been conducted in France or in Europe. We aimed to assess the prevalence of CInE and its association with blaZ beta-lactamase and S. aureus protein A (spa) types, and to assess the clinical outcomes in cefazolin-treated patients for infective endocarditis whose strain exhibited a CInE. METHODS: This was a French single-center retrospective study of 51 MSSA strains from patients of the Nantes endocarditis prospective cohort, conducted between 2013 and 2018. RESULTS: Cefazolin MIC50 at high inoculum was 2 mg/L (IQR 1-2). CInE was found in 17.6 % of tested strains. Among blaZ-positive strains (n = 44), type A beta-lactamase was predominant (n = 25, 57 %). Thirty-seven S. aureus protein A (spa) types were found. No statistical association was shown between blaZ or spa types and CInE. CInE was neither associated with a higher rate of persistent bacteremia (25 % vs 56.3 %, p = 0.58) nor with clinical failure in patients treated with cefazolin, in comparison to patients with no CInE strain (25 % vs 56.3 %, p = 0.58). CONCLUSION: The cefazolin inoculum effect was found in a substantial number of Staphylococcus aureus strains; however, minimum inhibitory concentrations remained globally low. CInE was not associated with a higher proportion of clinical failure on treatment.

Antenatal phosphodiesterase 4 inhibition restores postnatal growth and pulmonary development in a model of chorioamnionitis in rabbits.

Chorioamnionitis is implicated in the pathophysiology of bronchopulmonary disease, and the associated inflammatory response is responsible for adverse effects on alveolar development. The aim of this work was to analyze the effects of a phosphodiesterase 4 (PDE4)-selective inhibitor, rolipram (a modulator of the inflammatory response), in an experimental model of chorioamnionitis on pulmonary development and on the processes of infection and inflammation. Rabbit mothers were assigned to four groups: 1) saline serum inoculation (controls); 2) Escherichia coli intrauterine inoculation (C+); 3) rolipram infusion (R+); and 4) E. coli inoculation + rolipram infusion (C+R+). High rates of morbility and mortality were noticed in mothers and pups (5 of 13 pregnant rabbits in groups with rolipram). Alveolar development, inflammation, and infection were analyzed in pups at day 0 and day 5. At day 0, in the context of chorioamnionitis, rolipram significantly decreased birth weight (p < 0.01) relative to that of controls (p < 0.05). At day 5, weight normalized in group C+R+ but not in group C+ relative to controls (p < 0.001); moreover, alveolar airspace volume was preserved in group C+R+ but not in group C+ (p < 0.05). Interstitial volume decreased in group C+ versus controls (p < 0.05) but was preserved in group C+R+. Specific alveolar area was not significantly modified by rolipram. No significant difference was found concerning bronchoalveolar lavage cellularity, and all blood cultures remained sterile. In this model of impaired alveologenesis, rolipram significantly preserved specific alveolar density. However, PDE4 inhibition induced antenatal fetal demise and growth retardation.

The optimal aminoglycoside and its dosage for the treatment of severe Enterococcus faecalis infection. An experimental study in the rabbit endocarditis model.

Aminoglycosides are recommended for the treatment of Enterococcus faecalis infections, especially in severe and bacteremic infection. However, the optimal aminoglycoside or the optimal dosage remains uncertain. This study aimed to compare the activity of four aminoglycosides against E. faecalis (gentamicin, netilmicin, tobramycin, and amikacin) and two dosages of gentamicin. One clinical strain of E. faecalis was used to induce aortic endocarditis in the study rabbits. Each aminoglycoside was infused daily over 3 days with a computer-regulated flow simulating human pharmacokinetics of 15 mg/kg/day for amikacin, 6 mg/kg/day for netilmicin, and 3 mg/kg/day for gentamicin and tobramycin. Additionally, two dosages of gentamicin (simulating 3 or 6 mg/kg/day) were compared over 1 or 3 days of treatment. The in vivo efficacy was assessed according to the bacterial count in vegetations, in comparison with a control group. Of the four aminoglycosides tested, only gentamicin and netilmicin showed significant antibacterial efficacy after 3 days of treatment. After only 1 day of treatment, the high dosage of gentamicin (6 mg/kg/day) was more effective than the standard dosage (3 mg/kg/day). Among the tested aminoglycosides, gentamicin showed the best efficacy, with the best results after 24 h of treatment for the highest dosage.

Umbilical cord blood procalcitonin level in early neonatal infections: a 4-year university hospital cohort study.

This article describes a study of procalcitonin (PCT) measured in cord blood as a discriminating marker of early-onset neonatal infection. This was a monocenter retrospective study with prospective collection of data including all babies born during the study period. Those presenting infection risk factors had PCT measurement. Three groups were defined: certainly infected, probably infected, and non-infected. A total of 12,485 newborns were included, 2151 had PCT measurement, and 26 were infected. Receiver operating curves of PCT determined 0.6 ng/ml as the best cut-off, with an area under the curve of 0.96 (CI 95% 0.95-0.98). Sensitivity, specificity, positive and negative predictive value and positive and negative likelihood ratios were 0.92 (range, 0.75-0.98), 0.97 (0.96-0.98), 0.28 (0.20-0.36), 0.99 (0.99-0.99), 32 (24-41) and 0.08 (0.02-0.3), respectively. Post-test probabilities were 28% (23-33) if the test was positive, and less than 0.001% (0-1.10(-5)) if the test was negative. Gestational age between 28 and 32 weeks (OR 4.4; range, 1.2-16.2) and pH at birth < 7.10 (OR 2.9; 1.1-7.4) were other independent factors of increasing PCT (p < 0.05). PCT measured in umbilical cord blood is reliable to detect early infected and non-infected newborns.

A new experimental model of acute osteomyelitis due to methicillin-resistant Staphylococcus aureus in rabbit.

AIMS: To assess the impact of antibiotic therapy on severe osseous infections, animal models of chronic bacterial infections have been developed; however, these models suffer from many experimental limitations. The aim of this work was to develop a new model system in which high levels of bacteria are obtained within femoral bone marrow and bone tissue, and such infections are maintained for at least 14 days. METHODS AND RESULTS: Experimental osteomyelitis was induced in 25 New Zealand white rabbits. A 10(9) CFU ml(-1) suspension of methicillin-resistant Staphylococcus aureus was injected into the knee after bone trepanation. On day 3, surgical debridement was performed to mimic a surgical procedure. Animals were euthanized 1, 2, 3, 9 and 14 days post-inoculation to determine the bacterial counts in marrow and bone, and to evaluate the stability of the infection. Inoculated lesions also were assessed for changes in histological parameters on days 3 and 7 post-inoculation. At days 1, 2, 3, 9 and 14 post-inoculation, we observed 6·50 ± 0·64, 7·30 ± 0·49, 7·82 ± 0·19, 8·00 ± 1·48 and 8·99 ± 0·20 log10 CFU g(-1) in bone marrow and 8·40 ± 0·68, 7·65 ± 0·27, 7·58 ± 0·30, 8·88 ± 0·52 and 8·28 ± 0·39 log10 CFU g(-1) in bone tissue, respectively. No statistical differences in bacterial count were found between bone marrow and bone tissue at any time point. CONCLUSION: This new model of acute osteomyelitis was validated by histological and microbiological changes in the absence of sclerosing agents, and these changes remained stable for 14 days. SIGNIFICANCE AND IMPACT OF THE STUDY: These results describe a new experimental model of acute osteomyelitis and demonstrate its usefulness in assessing the activity of antibacterial agents in vivo soon after bone infection.

Staphylococcus aureus internalization impairs osteoblastic activity and early differentiation process.

Staphylococcus aureus is the most frequent aetiology of bone and joint infections (BJI) and can cause relapsing and chronic infections. One of the main factors involved in the chronicization of staphylococcal BJIs is the internalization of S. aureus into osteoblasts, the bone-forming cells. Previous studies have shown that S. aureus triggers an impairment of osteoblasts function that could contribute to bone loss. However, these studies focused mainly on the extracellular effects of S. aureus. Our study aimed at understanding the intracellular effects of S. aureus on the early osteoblast differentiation process. In our in vitro model of osteoblast lineage infection, we first observed that internalized S. aureus 8325-4 (a reference lab strain) significantly impacted RUNX2 and COL1A1 expression compared to its non-internalized counterpart 8325-4∆fnbAB (with deletion of fnbA and fnbB). Then, in a murine model of osteomyelitis, we reported no significant effect for S. aureus 8325-4 and 8325-4∆fnbAB on bone parameters at 7 days post-infection whereas S. aureus 8325-4 significantly decreased trabecular bone thickness at 14 days post-infection compared to 8325-4∆fnbAB. When challenged with two clinical isogenic strains isolated from initial and relapse phase of the same BJI, significant impairments of bone parameters were observed for both initial and relapse strain, without differences between the two strains. Finally, in our in vitro osteoblast infection model, both clinical strains impacted alkaline phosphatase activity whereas the expression of bone differentiation genes was significantly decreased only after infection with the relapse strain. Globally, we highlighted that S. aureus internalization into osteoblasts is responsible for an impairment of the early differentiation in vitro and that S. aureus impaired bone parameters in vivo in a strain-dependent manner.

In vivo assessment of the antimicrobial activity of a calcium-deficient apatite vancomycin drug delivery system in a methicillin-resistant Staphylococcus aureus rabbit osteomyelitis experimental model.

The antimicrobial activities of calcium-deficient apatite loaded with different concentrations (25, 100, and 500 microg/mg) of vancomycin as a filling biomaterial were evaluated in a methicillin-resistant Staphylococcus aureus (MRSA) rabbit acute osteomyelitis model. Bacterial counts in bone, bone marrow, and joint fluid samples treated with forms of the apatite were compared to those in tissue samples receiving a constant intravenous vancomycin infusion after 4 days. This study demonstrates that using a calcium-deficient apatite loaded with vancomycin dramatically decreases the bacterial counts in bone and marrow.

PK/PD targets of amikacin and gentamicin in ICU patients.

OBJECTIVES: We aimed to evaluate the probability to achieve PK-PD targets in patients with sepsis hospitalized in the intensive care unit (ICU) after a single dose of 30mg/kg of amikacin or 8mg/kg of gentamicin. PATIENTS AND METHODS: This single-center prospective study included 138 ICU patients with severe sepsis or septic shock with an indication for intravenous amikacin (N=89) or gentamicin (N=49). Maximum concentration (Cmax) was measured 30 minutes after infusion completion. PK/PD objectives were respectively Cmax≥60mg/L and ≥30mg/L for amikacin and gentamicin for empirical therapy, and a Cmax/MIC ratio≥8, as per French guidelines. RESULTS: The median Simplified Acute Physiology Score II was 43 and ICU case fatality rate was 34.8%. A causative bacterial agent was identified in 94 patients (68.1%). Three pathogens had acquired aminoglycoside resistance and 15 were naturally resistant. The targeted Cmax for the first dose was achieved in 53 patients (59.6%) receiving amikacin, and one (2.2%) patient receiving gentamicin. Cmax/MIC ratio≥8 was obtained in all patients infected with susceptible pathogens (N=72). Factors associated with Cmax≥60mg/L of amikacin in multivariate analysis were dose per kg of adapted body weight (OR=1.39, P<0.001) and renal clearance estimated with CKD-EPI formula (OR=0.98, P=0.003). CONCLUSIONS: Despite high doses, amikacin and gentamicin first Cmax remain dramatically low in ICU patients. However, an adequate Cmax/MIC ratio was reached in all patients.