Why is big Pharma getting out of antibacterial drug discovery?

The dearth of new antibiotic development: why we should be worried and what we can do about it

The emergence and spread of multidrug-resistant pathogens has increased substantially over the past 20 years. Over the same period, the development of new antibiotics has decreased alarmingly, with many pharmaceutical companies pulling out of antibiotic research in favour of developing "lifestyle" drugs. Reasons given for withdrawing from antibiotic development include poor "net present value" status of antibiotics, changes in regulations requiring larger drug trials and prolonged post-marketing surveillance, clinical preference for narrow-spectrum rather than broad-spectrum agents, and high new-drug purchase costs. Major improvements in infection control in Australia are needed to prevent further spread of resistant clones, buying some time to develop urgently needed new antibiotic agents. Perpetuating a culture of "pharma bashing" will simply lead to more pharmaceutical companies withdrawing from the market. A change in the health and research culture is needed to improve cooperation between public, academic and private sectors.

Antibacterial resistance worldwide: causes, challenges and responses

The optimism of the early period of antimicrobial discovery has been tempered by the emergence of bacterial strains with resistance to these therapeutics. Today, clinically important bacteria are characterized not only by single drug resistance but also by multiple antibiotic resistance--the legacy of past decades of antimicrobial use and misuse. Drug resistance presents an ever-increasing global public health threat that involves all major microbial pathogens and antimicrobial drugs.

Bad bugs need drugs: an update on the development pipeline from the Antimicrobial Availability Task Force of the Infectious Diseases Society of America

The Antimicrobial Availability Task Force (AATF) of the Infectious Diseases Society of America (IDSA) has viewed with concern the decreasing investment by major pharmaceutical companies in antimicrobial research and development. Although smaller companies are stepping forward to address this gap, their success is uncertain. The IDSA proposed legislative and other federal solutions to this emerging public health problem in its July 2004 policy report "Bad Bugs, No Drugs: As Antibiotic R&D Stagnates, a Public Health Crisis Brews." At this time, the legislative response cannot be predicted. To emphasize further the urgency of the problem for the benefit of legislators and policy makers and to capture the ongoing frustration our clinician colleagues experience in their frequent return to an inadequate medicine cabinet, the AATF has prepared this review to highlight pathogens that are frequently resistant to licensed antimicrobials and for which few, if any, potentially effective drugs are identifiable in the late-stage development pipeline.

Peptide Motifs for Cell-Surface Intervention

The discovery of new antimicrobial and anticancer drugs, and overcoming the problem of resistance to current anti-infective and anticancer drug therapies require innovation in the pharmaceutical and scientific research community. A further challenge of drug design is to make the therapeutic agent specific, long lasting, of minimal toxicity, and affordable. Microbial and cancer cell surfaces present molecular features that can differentially prefocus drugs within the human host. This property can localize drugs near cell-surface targets, thereby reducing opportunities for adverse effects, or the emergence of drug resistance caused by intracellular drug and target modification and by the induction of drug efflux pumps. The solubility demands on cell-surface targeting drugs should also be less stringent than for those drugs requiring transmembrane transport or internalization in order to reach intracellular targets. Cationic peptides have provided an increasingly important research focus in this regard. Although the cationic antimicrobial peptides are distributed widely in nature and provide localized primary defenses against microbial attack, the susceptibility of L-peptides to proteolysis and the known properties of successful antimicrobials have led to a focus on circularized peptides, D,L-peptides, and peptides containing unusual amino acids. New on the scene as lead antifungal agents are D-octapeptides and their derivatives that were developed from a combinatorial library produced through solid-phase peptide synthesis protocols. These peptides contain an amidated C-terminal tri-arginine motif, which confers membrane impermeability and focuses the peptides near the fungal cell surface. To date, the octapeptides and their derivatives also require some aromaticity, preferably the indole ring of tryptophan. In some cases, a single 4-methoxy-2,3,6-trimethylbenzenesulfonyl moiety remaining on the peptide after incomplete cleavage of the peptide from the solid phase produces a peptide with activity, whereas the parent shows little or no activity in the screen. Recent research advances that support the polycationic cell surface approach include the RGD (Arg-Gly-Asp) tripeptide and its mimetics, as well as aminoglycoside arginine drugs (e.g. neomycin coupled to small arginine polymers) and prodrugs. In the case of polycationic peptides, D-peptides could be used for intravenous injection and direct-surface drug applications, but mimetics will probably be needed for oral delivery.

Structure-activity relationship study of anoplin

Anoplin is a decapeptide amide, GLLKRIKTLL-NH2 derived from the venom sac of the solitary spider wasp, Anoplius samariensis. It is active against Gram-positive and Gram-negative bacteria and is not hemolytic towards human erythrocytes. The present paper reports a structure-activity study of anoplin based on 37 analogues including an Ala-scan, C- and N-truncations, and single and multiple residue substitutions with various amino acids. The analogues were tested for antibacterial activity against both S. aureus ATCC 25923 and E. coli ATCC 25922, and several potent antibacterial analogues were identified. The cytotoxicity of the analogues against human erythrocytes was assessed in a hemolytic activity assay. The antibacterial activity and selectivity of the analogues against S. aureus and E. coli varied considerably, depending on the hydrophobicity and position of the various substituted amino acids. In certain cases the selectivity for Gram-positive and Gram-negative bacteria was either reversed or altogether eliminated. In addition, it was generally found that antibacterial activity coincided with hemolytic activity.

Optimizing the antibacterial activity of a lead structure discovered by ‘SAR by MS’ technology

We report on lead optimization of a compound that was originally discovered to bind bacterial 23S rRNA near the L11 binding site and inhibit translation in vitro, but lacked detectable antibacterial activity. In this study, we were able to generate compounds with antibacterial activity against Gram-negative and Gram-positive pathogens, including a methicillin-resistant S. aureus strain.

Staphylococcus aureus : superbug, super genome?

Staphylococcus aureus is a common cause of infection in both hospitals and the community, and it is becoming increasingly virulent and resistant to antibiotics. The recent sequencing of seven strains of S. aureus provides unprecedented information about its genome diversity. Subtle differences in core (stable) regions of the genome have been exploited by multi-locus sequence typing (MLST) to understand S. aureus population structure. Dramatic differences in the carriage and spread of accessory genes, including those involved in virulence and resistance, contribute to the emergence of new strains with healthcare implications. Understanding the differences between S. aureus genomes and the controls that govern these changes is helping to improve our knowledge of S. aureus pathogenicity and to predict the evolution of super-superbugs.

Antimicrobial Stewardship Programs as a Means to Optimize Antimicrobial Use

Each year, approximately 2 million people in the United States contract an infection during a hospital stay. An increasing percentage of these institutionally acquired infections are attributed to antimicrobial-resistant organisms. At the same time, studies and surveys suggest that as much as half of all antimicrobial use is inappropriate. Recommendations for preventing and reducing antimicrobial resistance in hospitals stress the importance of improving antimicrobial use, referred to as antimicrobial stewardship, at the institutional level. Antimicrobial stewardship programs have served as wake-up calls to both clinicians and health care administrators. We review the more recent literature concerning the impact of antimicrobial stewardship programs on costs, outcomes, and resistance and summarize important considerations for implementation of these programs.

A new 2-carbamoyl pteridine that inhibits mycobacterial FtsZ

The preparation of a new 2-carbamoyl pteridine, its activity data against FtsZ from M. tuberculosis (Mtb), and in vitro antibacterial data against Mtb strain H37Ra are presented.

Trends in Antimicrobial Drug Development: Implications for the Future

The need for new antimicrobial agents is greater than ever because of the emergence of multidrug resistance in common pathogens, the rapid emergence of new infections, and the potential for use of multidrug-resistant agents in bioweapons. Paradoxically, some pharmaceutical companies have indicated that they are curtailing anti-infective research programs. We evaluated the United States Food and Drug Administration (FDA) databases of approved drugs and the research and development programs of the world's largest pharmaceutical and biotechnology companies to document trends in the development of new antimicrobial agents. FDA approval of new antibacterial agents decreased by 56% over the past 20 years (1998-2002 vs. 1983-1987). Projecting future development, new antibacterial agents constitute 6 of 506 drugs disclosed in the developmental programs of the largest pharmaceutical and biotechnology companies. Despite the critical need for new antimicrobial agents, the development of these agents is declining. Solutions encouraging and facilitating the development of new antimicrobial agents are needed.

Can better prescribing turn the tide of resistance?

In the wake of concerns about the level of antibiotic resistance, governments worldwide are pressing for reduced antibiotic use, hoping thereby to reverse resistance trends. Is success likely? The evidence is mixed, and expectations should be tempered by the growing realization that many resistant bacteria are biologically fit, making them difficult to displace. If resistance is unlikely to be reduced significantly by changing prescription practices, how can clinicians outpace increased resistance, particularly when much of 'big pharma' is abandoning antibiotic development?