Edition 1/96
Edition 1/96 |
Fighting Antimicrobial Resistance |
The establishment of a number of world-wide information networks - such as WHONET of the World Health Organization - demonstrates that medical staff and researchers believe that antimicrobial resistance is a serious problem in urgent need of a concerted international response.
The prevalence of resistant strains is due to, for instance:In the fight against resistant micro-organisms, the ability to characterize and preserve strains rapidly and reliably is essential. Many research teams work in close collaboration with the BCCM™’s collections to perform vital epidemiological studies.
Less than 10 years after bacterial infections were thought to be controllable, researchers are realizing that there could be a serious problem. Until recently, faith in modern antibiotics was so strong that killer bacterial epidemics (plague, leprosy, tuberculosis, cholera, etc.) were thought to be a thing of the past - at least in the industrialized world - and most pharmaceutical companies were developing drugs for other types of disease.
Bacteria, on the other hand, continued their natural evolution and developed resistance mechanisms at an incredible speed. The initial response was to turn to glycopeptide treatments such as vancomycin and teicoplanin but in 1986, the first plasmid-mediated resistance to these agents was detected in the clinical setting. Fortunately, glycopeptide resistance is mostly limited to enterococci at present and is not yet found clinically in staphylococci - much more commonly the cause of infection.
Nevertheless, many once-trusted combinations of antibiotics seem now to be impotent. And since the development and release of new antibiotics takes at least ten years, new agents are not expected in the short term.
In the meantime, much can be done to learn more about the situation and hence to develop alternative control strategies. Data are limited and considerable research is required to elucidate the epidemiology of vancomycin-resistant enterococci (VRE) and other resistant organisms such as methicilin-resistant Staphylococcus aureus (MRSA), and beta-lactam (e.g. penicillin) and aminoglycoside-resistant Gram-negative bacilli. Each may require different control methods.
BCCM™/LMG has started to collect and preserve VRE from a variety of origins. The strains are submitted to routine identification procedures used for Gram-positive cocci and can be made available for screening programmes and other relevant research activities.
Contact: Mr B. Pot, BCCM™/LMG
Tel: +32 9 264 51 13
Fax: +32 9 264 53 46
E-mail: bruno.pot@rug.ac.be
BCCM™/LMG Customer Testimony: Prof. Herman Goossens believes that the rapid identification of a bacterial strain and its level of resistance can help to establish more effective treatment strategies.
Yeasts are always the most frequent organism involved in invasive fungal infections. Candida albicans - is the fourth most common pathogen among micro-organisms isolated in intensive care units (after Staphylococcus aureus, Enterococcus and Gram-negative rods). An increase in infections due to non albicans species of Candida and other yeast species has been observed.
Infections due to moulds are also increasing. Commonly responsible are the Aspergillus species, and - more recently - Fusarium, Mucorales, Scedosporium apiospermum and Penicillium marneffei, the latter being strongly associated with HIV infection.
The main available antifungal drugs are:
Resistance mechanisms generally work through modification of the target: the membrane ergosterol for AmB, mutation of metabolic enzymes for 5-FC and modification of cytochrome P450 for azoles derivatives.
Until recently, it was not necessary to control susceptibility to antifungal agents except for research purposes. But the emergence of new pathogens and the shift to more resistant strains has led to the necessity of standardized methods.
In 1992, the US National Committee for Clinical Laboratory Standards - Antifungal Subcommittee published a provisional reference method for antifungal testing of susceptibility of yeasts (NCCLS M27-P). This method allows reproducible comparison of results from one lab to another. For this purpose, quality controlled reference strains are required - such as those of the BCCM™/IHEM collection.
For moulds, no standardized method for antifungal drug testing is available - inocula may be standardized only for species which sporulate readily, such as Aspergillus. Moreover, the growth incubation time for moulds varies from one group to another.
Research into antifungal susceptibility testing is necessary to establish a better definition of the threshold of resistance of each species to different antifungal drugs, and the corresponding relation with the clinical status of patients. The BCCM™/IHEM could be your research partner on this and other related issues.
Contact: IR. F. Symoens, BCCM™/IHEM
Tel: +32 2 642 56 30
Fax: +32 2 642 55 19
BCCM™/IHEM Customer Testimony: Dr Johan Boelaert explains the importance of access to selected strains with well documented characteristics.
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