Saturday 05 December 2009, 02:43

Antibiotic-resistance: a challenge still open

How antibiotic-resistance develops

Antibiotic-resistance: a challenge still open

Bacterial antibiotic resistance is one of the greatest current challenges to the effective treatment of infectious diseases.


During the last decades there has been a dramatic increase in the development and dissemination of antibiotic-resistant bacteria, because of the widespread indiscriminate use of broad-spectrum antibiotics. That’s why it is so important to promote appropriate and judicious antibiotic use in clinical practice, because overuse encourages the growth and propagation of pathogens that are difficult or impossible to treat.


Bacterial antibiotic resistance may be intrinsic or acquired. Intrinsic resistance is a natural inherent property of a bacterial species or genus, while acquired resistance arises from a genetic alteration in the bacteria, that causes a once effective antibiotic to become ineffective. This acquired resistance can be either chromosomal (due to spontaneous mutations) or plasmid-mediated.


Plasmid-mediated resistance is a serious health problem, because a single transferred plasmid may code for resistance to multiple antibiotics simultaneously (multidrug resistance). Moreover plasmid transfer may take place between bacteria of different types (contagious resistance).


There are five known mechanisms whereby bacterial cells achieve their antibiotic resistance: 1) decreased permeability to the antibiotic, preventing its entry; 2) increased active efflux of antibiotics; 3) antibiotic inactivation (this is the predominant mechanism of resistance for several classes of antibiotics); 4) modification of the antimicrobial target; 5) development of pathways that bypass the target.


Regardless of the mechanism involved, the phenomenon of antibiotic resistance poses a serious threat to the future of antibiotic and chemotherapy. More than 70% of pathogen bacteria are resistant to at least one of the currently available antimicrobial.


Perhaps most concerning is the presence of antibiotic resistance in bacteria commonly responsible for hospital-acquired infections (staphylococci, enterococci and gram-negative organisms such as Pseudomonas aeruginosa). For example, vancomycin resistance in Enterococcus, methicillin resistance in Staphylococcus and broad-spectrum beta-lactam resistance in gram-negative bacteria have important therapeutic implications in the hospital setting.


Research is moving to counteract the continuous emergence of bacterial resistance. It has been suggested that the key to success in the fight against bacterial resistance lies in establishing which areas need attention. These are: 1) the development of new classes of antimicrobial drugs; 2) the development of quick inexpensive diagnostic tests to identify pathogens and their resistance properties, in order to prescribe the most appropriate and specific antibiotic treatment; 3) vaccine development; 4) epidemiological surveillance of antibiotic resistance in both human and animal pathogens.


By Chiara De Carli

Category: Pharmacy

Sign Up

Subscribe to our newsletter

Important news