[Resistance to fluoroquinolones in 2013: what are the consequences in internal medicine?]

In Vitro Screening of a 1280 FDA-Approved Drugs Library against Multidrug-Resistant and Extensively Drug-Resistant Bacteria

Alternative strategies against multidrug-resistant (MDR) bacterial infections are suggested to clinicians, such as drug repurposing, which uses rapidly available and marketed drugs. We gathered a collection of MDR bacteria from our hospital and performed a phenotypic high-throughput screening with a 1280 FDA-approved drug library. We used two Gram positive (Enterococcus faecium P5014 and Staphylococcus aureus P1943) and six Gram negative (Acinetobacter baumannii P1887, Klebsiella pneumoniae P9495, Pseudomonas aeruginosa P6540, Burkholderia multivorans P6539, Pandoraea nosoerga P8103, and Escherichia coli DSM105182 as the reference and control strain). The selected MDR strain panel carried resistance genes or displayed phenotypic resistance to last-line therapies such as carbapenems, vancomycin, or colistin. A total of 107 compounds from nine therapeutic classes inhibited >90% of the growth of the selected Gram negative and Gram positive bacteria at a drug concentration set at 10 µmol/L, and 7.5% were anticancer drugs. The common hit was the antiseptic chlorhexidine. The activity of niclosamide, carmofur, and auranofin was found against the selected methicillin-resistant S. aureus. Zidovudine was effective against colistin-resistant E. coli and carbapenem-resistant K. pneumoniae. Trifluridine, an antiviral, was effective against E. faecium. Deferoxamine mesylate inhibited the growth of XDR P. nosoerga. Drug repurposing by an in vitro screening of a drug library is a promising approach to identify effective drugs for specific bacteria.

Prescription of Levofloxacin and Moxifloxacin in Select Hospitals in Uganda: A Pilot Study to Assess Guideline Concordance

Background: In Uganda, national tuberculosis (TB) treatment guidelines were revised to include the newer generation fluoroquinolones among the second-line treatment options for multidrug-resistant TB. This study was designed to analyze if the prescription of these quinolones is compliant with country recommendations. Methods: This was an observational retrospective study of consumption data for 2017 and 2018 across four selected regional referral hospitals. The sources of consumption data were hospital pharmacy stock cards and the dispensing register. The medical files of patients who had been prescribed fluoroquinolones were also assessed to study compliance with the Uganda Clinical Guidelines and the British National Formulary (BNF). Results: None of the 371 levofloxacin prescriptions analyzed complied with the Uganda Clinical Guidelines, although 250 (67.3%) were prescribed for indications included in the BNF. According to WHO prescription indicators, only 220 (59.3%) prescriptions were appropriate. Conclusion: The prescription of levofloxacin and moxifloxacin increased in the hospitals studied, but in a high proportion of cases, they were not compliant with country recommendations. The findings call for the strengthening of national antimicrobial stewardship programs.

Synthesis, Antibacterial Activities, Mode of Action and Acute Toxicity Studies of New Oxazolidinone-Fluoroquinolone Hybrids

To combat bacterial resistance, a series of new oxazolidinone-fluoroquinolone hybrids have been synthesized and characterized. All synthetic hybrids were preliminarily evaluated for their in vitro antibacterial activities against 6 standard strains and 3 clinical isolates. The majority of hybrids displayed excellent activities against Gram-positive bacteria, but limited activities against Gram-negative bacteria. Hybrids OBP-4 and OBP-5 were found to be the most promising compounds. Further, in vitro antibacterial activities, mode of action and acute toxicity in mice of hybrids OBP-4 and OBP-5 were investigated. Hybrids OBP-4 and OBP-5 exhibited potent activities against Gram-positive bacteria, including drug-resistant strains. Correspondingly, studies on the mode of action of hybrids OBP-4 and OBP-5 indicated a strong inhibitory activity on protein synthesis by binding the active site of 50S subunit, but a weak inhibitory action on DNA synthesis. In addition, LD₅₀ values of hybrids OBP-4 and OBP-5 in the acute oral toxicity were larger than 2000 mg/kg, suggesting a good safety profile.

Clinical Benefit of Appropriate Empirical Fluoroquinolone Therapy for Adults with Community-Onset Bacteremia in Comparison with Third-Generation-Cephalosporin Therapy

Both fluoroquinolones (FQs) and third-generation cephalosporins (3rd-GCs) are commonly prescribed to treat bloodstream infections, but comparative efficacies between them were rarely studied. Demographics and clinical characteristics of 733 adults with polymicrobial or monomicrobial community-onset bacteremia empirically treated by an appropriate FQ (n = 87) or 3rd-GC (n = 646) were compared. A critical illness (respectively, 8.0% versus 19.0%; P = 0.01), an initial syndrome with severe sepsis (33.3% versus 50.3%; P = 0.003), or a fatal outcome at 28 days (4.6% versus 10.5%; P = 0.08) was less common in the FQ group. A total of 645 (88.0%) patients were febrile at initial presentation, and the FQ group with (FQ group versus 3rd-GC group, respectively, 7.6 days versus 12.0 days; P = 0.04) and without (3.8 days versus 5.4 days; P = 0.001) a critical illness had a shorter time to defervescence than the 3rd-GC group. By the propensity scores, 87 patients with appropriate FQ therapy were matched with 435 treated by 3rd-GC therapy at a ratio of 1:5, and there were no significant differences in terms of bacteremia severity, comorbidity severity, major comorbidities, causative microorganisms, and bacteremia sources between groups. Moreover, crude mortality rates at 28 days (FQ group versus 3rd-GC group, respectively, 4.6% versus 7.8%; P = 0.29) did not differ significantly. However, the time to defervescence was shorter in the FQ group (4.2 ± 3.6 versus 6.2 ± 7.6 days; P < 0.001). Conclusively in the adults with community-onset bacteremia, appropriate empirical FQ therapy was related to shorter time to defervescence than with 3rd-GC therapy, at least for those without a critical illness.