Spectre d’activité antibactérien d’un antibiotique et catégorisation clinique

The war against bacteria, from the past to present and beyond

INTRODUCTION

The human defense against microorganisms dates back to the ancient civilizations, with attempts to use substances from vegetal, animal, or inorganic origin to fight infections. Today, the emerging threat of multidrug-resistant bacteria highlights the consequences of antibiotics inappropriate use, and the urgent need for novel effective molecules.

METHODS AND MATERIALS

We extensively researched on more recent data within PubMed, Medline, Web of Science, Elsevier's EMBASE, Cochrane Review for the modern pharmacology in between 1987 - 2021. The historical evolution included a detailed analysis of past studies on the significance of medical applications in the ancient therapeutic field.

AREAS COVERED

We examined the history of antibiotics development and discovery, the most relevant biochemical aspects of their mode of action, and the biomolecular mechanisms conferring bacterial resistance to antibiotics.

EXPERT OPINION

The list of pathogens showing low sensitivity or full resistance to most currently available antibiotics is growing worldwide. Long after the 'golden age' of antibiotic discovery, the most novel molecules should be carefully reserved to treat serious bacterial infections of susceptible bacteria. A correct diagnostic and therapeutic procedure can slow down the spreading of nosocomial and community infections sustained by multidrug-resistant bacterial strains.

Emergence of Resistance to Quinolones and β-Lactam Antibiotics in Enteroaggregative and Enterotoxigenic Escherichia coli Causing Traveler's Diarrhea

The objective of this study was to assess the antimicrobial resistance of enteroaggregative Escherichia coli (EAEC) and enterotoxigenic E. coli (ETEC) strains causing traveler's diarrhea (TD) and to investigate the molecular characterization of antimicrobial resistance genes to third-generation cephalosporins, cephamycins, and quinolones. Overall, 39 EAEC and 43 ETEC clinical isolates were studied. The susceptibilities of EAEC and ETEC against ampicillin, amoxicillin-clavulanic acid, cefotaxime, imipenem, chloramphenicol, tetracycline, co-trimoxazole, nalidixic acid, ciprofloxacin, azithromycin, and rifaximin were determined. All genes encoding resistance determinants were detected by PCR or PCR plus DNA sequencing. The epidemiology of selected EAEC and ETEC strains was studied using multilocus sequence typing (MLST). The resistance to quinolones of EAEC and ETEC strains causing TD has significantly increased over the last decades, and high percentages have been found especially in patients traveling to India and sub-Saharan Africa. Sequence type 38 (ST38) and ST131, carrying the bla _CTX-M-15 and bla _CTX-M-27 genes, respectively, are highly prevalent among extended-spectrum β-lactamase (ESBL)-producing EAEC and ETEC strains. The cephamycinase ACT-20 is described in the present study for the first time in EAEC and ETEC strains causing TD in patients who had traveled to Central America. The percentages of resistance to azithromycin in EAEC and ETEC isolates from patients to Southeast Asia/India and Africa are above 25%. Meanwhile, rifaximin is still active against EAEC and ETEC, with the prevalence of resistant strains not being high. In conclusion, fluoroquinolones should no longer be considered the drugs of choice for the prevention or treatment in TD for travelers traveling to India and Africa. Azithromycin and rifaximin are still a good alternative to treat TD caused by EAEC or ETEC.

Prevalence, risk factors, and impact on clinical outcome of extended-spectrum beta-lactamase-producing Escherichia coli bacteraemia: a five-year study

BACKGROUND

The impact of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (ESBL-EC) bacteraemia on outcome remains controversial.

METHODS

A retrospective analysis of the prevalence, risk factors, clinical features, and outcomes of all ESBL-EC bacteraemia in one French hospital over a 5-year period was performed. A case-control study was undertaken: cases had at least one ESBL-EC bacteraemia and controls a positive non-ESBL-EC bacteraemia.

RESULTS

The prevalence of ESBL-EC bacteraemia increased from 5.2% of all positive E. coli blood cultures in 2005 to 13.5% in 2009 (p<0.003). CTX-M represented 70% of ESBL-EC bacteraemia strains, and strains were not clonally related. On adjusted analysis, the only significant risk factor for ESBL-EC bacteraemia was a previous ESBL-EC colonization (odds ratio 11.3, 95% confidence interval 1.2-107; p=0.003). Initial antimicrobial therapy was less frequently adequate in the ESBL-EC group (48% vs. 85%; p=0.003). The presence of ESBL-EC bacteraemia was not associated with a longer hospital stay (p=0.088). Day 30 mortality was high, but not significantly different in the two groups (30% vs. 27%; p=0. 82).

CONCLUSION

The prevalence of ESBL-EC bacteraemia has been increasing dramatically. Previous colonization with ESBL-EC was a strong risk factor for ESBL-EC bacteraemia. More inadequate initial antimicrobial therapy was noted in the ESBL-EC group, but mortality and length of hospital stay were not significantly different from those of patients with non-ESBL-EC bacteraemia.