Antecedent use of fluoroquinolones is associated with resistance to moxifloxacin in Clostridium difficile

ObjectiveMoxifloxacin is characterized by high activity against Gram-positive cocci and some Gram-positive and -negative anaerobes, including Clostridium difficile. This study investigates the role of prior quinolone use in relation to patterns of susceptibility of C. difficile to moxifloxacin.MethodsSixty-three clinical isolates of C. difficile were investigated for toxigenicity, susceptibility to moxifloxacin, and mutations in the DNA gyrase gene. The medical histories for 50 of these patients were available and used to identify previous fluoroquinolone use.ResultsThirty-three (52.4%) strains showed resistance to moxifloxacin (MICs ≥ 16 mg/L). All moxifloxacin-resistant strains harbored a mutation at amino acid codon Ser-83 of gyrA. Forty-five isolates (71.4%) were toxigenic; all moxifloxacin-resistant strains were in this group. Resistance to moxifloxacin was associated with prior use of fluoroquinolones (P-value 0.009, chi-square).ConclusionsAlthough the use of moxifloxacin to treat C. difficile-associated diarrhea is not likely to be common, these data show a relationship between antecedent fluoroquinolone use and resistance to moxifloxacin in C. difficile isolates, and raise questions regarding selection pressure for resistance placed on colonizing bacteria exposed to fluoroquinolones. Mutations in gyrA are involved in moxifloxacin resistance

Surveillance of resistance in bacteria causing community‐acquired respiratory tract infections

Bacterial resistance to antibiotics in community‐acquired respiratory tract infections is a serious problem and is increasing in prevalence world‐wide at an alarming rate. Streptococcus pneumoniae, one of the main organisms implicated in respiratory tract infections, has developed multiple resistance mechanisms to combat the effects of most commonly used classes of antibiotics, particularly the β‐lactams (penicillin, aminopenicillins and cephalosporins) and macrolides. Furthermore, multidrug‐resistant strains of S. pneumoniae have spread to all regions of the world, often via resistant genetic clones. A similar spread of resistance has been reported for other major respiratory tract pathogens, including Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pyogenes. To develop and support resistance control strategies it is imperative to obtain accurate data on the prevalence, geographic distribution and antibiotic susceptibility of respiratory tract pathogens and how this relates to antibiotic prescribing patterns. In recent years, significant progress has been made in developing longitudinal national and international surveillance programs to monitor antibiotic resistance, such that the prevalence of resistance and underlying trends over time are now well documented for most parts of Europe, and many parts of Asia and the Americas. However, resistance surveillance data from parts of the developing world (regions of Central America, Africa, Asia and Central/Eastern Europe) remain poor. The quantity and quality of surveillance data is very heterogeneous; thus there is a clear need to standardize or validate the data collection, analysis and interpretative criteria used across studies. If disseminated effectively these data can be used to guide empiric antibiotic therapy, and to support—and monitor the impact of—interventions on antibiotic resistance

EUCAST expert rules in antimicrobial susceptibility testing

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Supplementary Material for: Antimicrobial Susceptibility among European Gram-Negative and Gram-Positive Isolates Collected as Part of the Tigecycline Evaluation and Surveillance Trial (2004-2014)

<i>Background:</i> European centers (n = 226) involved in the Tigecycline Evaluation and Surveillance Trial (TEST, 2004-2014) submitted data and bacterial isolates. <i>Methods:</i>Minimal inhibitory concentrations and susceptibility were determined using Clinical and Laboratory Standards Institute methods and European Committee on Antimicrobial Susceptibility Testing breakpoints. <i>Results:</i> The rates of the following resistant pathogens increased from 2004 to 2014: extended-spectrum β-lactamase (ESBL)-positive <i>Escherichia coli</i> (from 8.9 to 16.9%), multidrug-resistant <i>Acinetobacter baumannii</i> complex (from 15.4 to 48.5%), and ESBL-positive <i>Klebsiella pneumoniae</i>(from 17.2 to 23.7%). The rate of methicillin-resistant <i>Staphylococcus aureus</i> was 27.5% in 2004 and 28.9% in 2014. Resistance to the carbapenems (imipenem and meropenem) was 37.4 and 14.5% for <i>A. baumannii</i> complex and <i>Pseudomonas aeruginosa</i>, respectively. Carbapenem resistance was ≤4.3% among the Enterobacteriaceae and 0.2% against <i>Streptococcus pneumoniae.</i> The resistance to tigecycline ranged between 7.4% against ESBL-producing <i>K. pneumoniae </i>and 0.0% against <i>S. aureus.</i><i>Conclusions:</i> The carbapenems and tigecycline were active against Enterobacteriaceae. Agents with activity against <i>A. baumannii</i> complex and <i>P. aeruginosa</i> are limited. The carbapenems, tigecycline, linezolid, and vancomycin were active against Gram-positive organisms