Oral minocycline plus rifampicin versus oral linezolid for complicated skin and skin structure infections caused by methicillin-resistant Staphylococcus aureus: The AIDA open label, randomized, controlled Phase 4 trial.

Background: The need for oral, cost-effective treatment for complicated skin and skin structure infections (cSSSIs) due to methicillin-resistant Staphylococcus aureus (MRSA) was addressed by the non-inferiority comparisons of oral minocycline plus rifampicin with linezolid. Methods: In the AIDA multicenter, open label, randomized, controlled clinical trial, hospitalized adults with cSSSI and documented MRSA were randomly assigned at a 2:1 ratio to either oral 600 mg rifampicin qd plus 100 mg minocycline bid or oral 600 mg linezolid bid for 10 days. The primary endpoint was the clinical cure rate in the clinically evaluable (CE) population at the test-of-cure visit (14 days). Non-inferiority was confirmed if the lower confidence limit (CI) did not fall below the accepted error margin of 15%. The study is registered with EudraCT number 2014-001276-56. Findings: 123 patients recruited between November 2014 and January 2017 were randomly assigned to treatment (81 patients to minocycline plus rifampicin and 42 patients to linezolid). Cure rates were 78.% (46/59, 90% CI 67.3-86.5) and 68.6% (24/35, 90% CI 53.4-81.3), respectively (P = 0.337). The percent difference in cure rates was 9.4% (90% CI -7.2 to 26.8%). Minocycline plus rifampicin combination was deemed non-inferior to linezolid as the lower CI was -7.2% i.e. smaller than the accepted error margin of -15%. Although statistically not significant, the overall rate of adverse events was higher in the linezolid group (47.6%, 20/42 versus 38.3%, 31/81). Interpretation: Oral minocycline plus rifampicin was non-inferior to oral linezolid treatment providing alternative oral treatment for cSSSI. Funding: The EU Seventh Research Framework Programme.

Secondary substitutions in the hemagglutinin and neuraminidase genes associated with neuraminidase inhibitor resistance are rare in the Influenza Resistance Information Study (IRIS).

Amino acid substitutions in influenza virus neuraminidase (NA) that cause resistance to neuraminidase inhibitors (NAI) generally result in virus attenuation. However, influenza viruses may acquire secondary substitutions in the NA and hemagglutinin (HA) proteins that can restore viral fitness. To assess to which extent this happens, the emergence of NAI resistance substitutions and secondary - potentially compensatory - substitutions was quantified in influenza viruses of immunocompetent individuals included in the Influenza Resistance Information Study (IRIS; NCT00884117). Known resistance substitutions were detected by mutation specific RT-PCR in viruses of 57 of 1803 (3.2%) oseltamivir-treated individuals, including 39 individuals infected with A/H1N1pdm09 [H275Y] virus and 18 with A/H3N2 [R292K] virus. A total of fifteen and ten other amino acid substitutions were acquired in HA and NA respectively, of A/H1N1pdm09, A/H3N2 and influenza B viruses upon treatment with oseltamivir but none of these was associated with resistance to oseltamivir. All cultured viruses with the known resistance substitutions H275Y or R292K showed reduced susceptibility to oseltamivir in the NA-star assay. Upon next-generation sequencing, the vast majority of NAI resistant A/H1N1pdm09 and A/H3N2 viruses had no resistance-associated secondary substitutions at high frequency. Only in two A/H1N1pdm09 [H275Y] viruses, the potentially compensatory secondary substitutions HA-D52N and NA-R152K were detected. We conclude that the emergence of secondary substitutions that may restore viral fitness upon the emergence of known influenza virus NAI resistance substitutions was a rare event in this immunocompetent population.

Viral Kinetics and Resistance Development in Children Treated with Neuraminidase Inhibitors: The Influenza Resistance Information Study (IRIS).

BACKGROUND: We studied the effect of age, baseline viral load, vaccination status, antiviral therapy, and emergence of drug resistance on viral shedding in children infected with influenza A or B virus. METHODS: Samples from children (aged ≤13 years) enrolled during the 7 years of the prospective Influenza Resistance Information Study were analyzed using polymerase chain reaction to determine the influenza virus (sub-)type, viral load, and resistance mutations. Disease severity was assessed; clinical symptoms were recorded. The association of age with viral load and viral clearance was examined by determining the area under the curve for viral RNA shedding using logistic regression and Kaplan-Meier analyses. RESULTS: A total of 2131 children infected with influenza (683, A/H1N1pdm09; 825, A/H3N2; 623, influenza B) were investigated. Age did not affect the mean baseline viral load. Children aged 1-5 years had prolonged viral RNA shedding (±1-2 days) compared with older children and up to 1.2-fold higher total viral burden. Besides, in older age (odds ratio [OR], 1.08; confidence interval [CI], 1.05-1.12), prior vaccination status (OR, 1.72; CI, 1.22-2.43) and antiviral treatment (OR, 1.74; CI, 1.43-2.12) increased the rate of viral clearance. Resistance mutations were detected in 49 children infected with influenza A virus (34, A/H1N1pdm09; 15, A/H3N2) treated with oseltamivir, most of whom were aged <5 years (n = 39). CONCLUSIONS: Children aged 1-5 years had a higher total viral burden with prolonged virus shedding and had an increased risk of acquiring resistance mutations following antiviral treatment. CLINICAL TRIALS REGISTRATION: NCT00884117.

Demographic analysis of antimicrobial resistance among Streptococcus pneumoniae: worldwide results from PROTEKT 1999-2000.

DESIGN: The influence of demographic factors upon antimicrobial resistance among 3362 isolates of Streptococcus pneumoniae from 25 countries was investigated, using univariate comparison and multivariate logistic regression. RESULTS: Eleven countries had significantly higher rates (Odds ratios [OR]: 2.50-64.79) of penicillin and/or erythromycin resistance than the UK. After taking country effects into account, rates of penicillin resistance (OR 1.98) and erythromycin resistance (OR 1.89) were significantly higher among infants than adults. Fewer (OR 0.69) erythromycin-resistant isolates were collected from male than female patients. There was no difference in the incidence of penicillin or erythromycin resistance among inpatients or outpatients. Penicillin resistance was more prevalent among ear swabs than blood cultures (OR 2.07). Erm(B), the predominant macrolide resistance mechanism across all age groups, was particularly prevalent among bronchoalveolar lavage (69.1%) and sinus (68.8%) isolates. Isolates possessing both erm(B) and mef(A) were generally collected from South Korea and were most common among infants and children (10.3%) and ear samples (17.3%). Telithromycin susceptibility was >99.5%, irrespective of demography. CONCLUSIONS: Although demography had a significant impact on antimicrobial resistance of pneumococci, telithromycin remained highly active across all demographic groups.