CHRISTOPHER DYE Drugs, super-bugs and… Drugs, superbugs and… What is an antibiotic? Why do bugs turn into superbugs? Superbugs: the clean-up New antibiotics: science or economics? CHRISTOPHER DYE What is a superbug? What is a superbug? Superbugs, Super at what? Virulent, drug resistant, hospitals, rich countries MRSA methicillin resistant Staphylococcus aureus (UK 7000 cases falling) GRE Glycopeptide resistant Enterococcus (mostly vancomycin, 1000 cases rising) Virulent, hospitals Clostridium difficile (50,000 cases rising, slowing) Virulent, drug resistant, community, poor countries Resistant Streptococcus pneumonia (100s rising?) MDR tuberculosis (40 rising? Isoniazid in London) Not Ebola, Marburg, rabies, flu, HIV… MRSA: Methicillin resistant Staphylococus aureus More MRSA among elderly in UK, especially men 2006-7 1200 1000 800 600 400 Female Male 200 Age group (years) + 80 -7 9 70 -6 9 60 -5 9 50 -4 9 40 -3 9 30 -2 9 20 10 -1 9 0 09 Number of reported infections 1400 MRSA: coming out (of hospital) United States 2005 (and soon UK?) In hospital In community (after health care) In community (not after health care) 58% 27% 14% Of ≈ 100,000 invasive MRSA infections Of ≈ 20,000 deaths (1 in 5, > HIV/AIDS) VRE: vancomycin resistant Enterococci Urine infections Heart infections Blood poisoning Wound infection Clostridium difficile Diarrhoea Colitis Fever Abdominal cramp Abnormal heart rhythm Trend in C difficile in UK patients 65+ years Number of voluntary reports 50000 40000 30000 20000 10000 0 2000 2001 2002 2003 2004 2005 2006 (M)DR Streptococcus pneumoniae Middle ear infection Sinusitis Bronchitis Pneumonia Meningitis Out of hospitals… MDR Mycobacterium tuberculosis Lung destruction Bloody cough Spine/bone deformity Meningitis Britain beat TB in the 19th and 20th centuries? TB deaths England & Wales 1840-1991 300 C Bronte 1855 TB deaths/100,000/yr 250 200 150 Mansfield 1923 Keats 1821 E Bronte 1848 Orwell 1953 Leigh 1967 100 50 Lawrence 1930 0 1820 1840 1860 1880 1900 1920 1940 1960 1980 2000 MDR-TB among previously treated TB patients < 6% 6 – 20 % 20 – 40% > 40 % No estimate Proportion surviving Rapid death of TB XDR patients at Tugela Ferry: 52/53 died, half within 16 days Days since sputum collected The travels and travails of Andrew Speaker What is an antibiotic? "Antibiosis" Paul Vuillemin (1889) collaborator of Louis Pasteur … life could be used to destroy life….. Bacteriocides Bacteriostatics "Antibiosis" before Fleming Roberts (1874): Penicillium did not become contaminated with bacteria Pasteur (1822-95) and Joubert (1834-1910): mould-contaminated cultures stopped the growth of the anthrax Lister (1871): urine contaminated with mould did not allow the growth of bacteria Duchesne (1897): substance that stopped bacterial growth, penicillin mould Acid (lactic) producing bacteria: to treat diphtheria, meningitis, cystitis and open wounds Fungus-like bacteria (Actinomycetes): dissolves cell walls of other bacteria and fungi; used to treat TB and others; origin of streptomycin Skin bacteria: protect against pathogenic bacteria and fungi (ringworm) Beer yeast: long-used antibiotic effects Penicillin: the first antibiotic Fleming Chain Florey 1928/41 "Hunting a beast through endless forests" (Kafka d. TB 1924) The search for a TB cure Today's antibiotics CLASS Aminoglycosides Ansamycins Cephalosporins Glycopeptides Macrolides Penicillins Polypeptides Quinolones Sulfonamides Tetracyclines Others SOME EXAMPLES Streptomycin Geldanamycin Cefadroxil Vancomycin Erythromycin Penicillin Bacitracin Ciprofloxacin Mafenide Tetracycline Chloramphenicol, Isoniazid Metronidazole, Pyrazinamide How antibiotics work… and then don't work Interfering with... • Making DNA/RNA rifampicin, chloroquine • Making proteins tetracycline, chloramphenicol • Cell membranes polyenes, polymyxin • Enzymes sulphamethoxazole • Cell walls penicillin, vancomycin Total antibiotic dependency • 80 million prescriptions of antibiotics for human use each year • 12,500 tons each year • 50% humans, 50% animals • 1 million tons consumed by humans and animals in past 50 years Why do bugs turn into (drug resistant) super bugs? "The genetic lending library of evil…" Mutation Conjugation Transduction Transformation Down in the pathospere resistance profiling of soil bacteria D'Costa et al 2006 Resistance: complex genetics but a simple selection process Superbugs: not so super Rifampin-resistant mutants of TB from lab are less fit Relative fitness of mutants 1.3 1.2 1.1 Equal fitness 1 0.9 0.8 0.7 0.6 0.5 1 2 3 4 5 6 Resistant mutants Gagneux, Science 2006 7 8 9 Superbugs: overcoming the handicap Rifampin-resistant mutants from patients are not less fit Relative fitness of mutants 1.3 1.2 rpoB S531L m utation other rpoB mutations 1.1 1 Equal fitness 0.9 0.8 0.7 0.6 0.5 1 2 3 4 5 6 7 Resistant mutants Gagneux, Science 2006 8 9 10 The spread of "superbugs" Proportion resistant 1 0.8 Uninfected 0.6 Infected: drug sensitive 0.4 Infected: drug resistant 0.2 0 0 100 200 Months 300 400 Evolution in action: promoting resistance with sub-therapeutic doses 1. Self-medication 2. Patients forget to take medication, interrupt treatment, cannot afford full course 3. Belief in new medications over old 4. Preferred injections of broad-spectrum drugs 5. Physicians pressured to prescribe antimicrobials 6. Pharmaceuticals marketed directly to public 7. Antibiotics poorly formulated, counterfeit, expired 8. Hospitals with highly susceptible patients, intensive antimicrobial use, cross-infection 9. Failure of simple infection controls e.g. handwashing 10. Veterinary prophylaxis or growth promotion, Salmonella and Campylobacter through food to humans The arms race in Wonderland: at the court of the Red Queen Red Queen to Alice: “Now, here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!” Loss of resistance is slow Quickly in, slowly out Minimal fitness handicap Plasmids contain several resistance genes Resistant strains persist at low levels Finland: restricted macrolide use Erythromycin resistance in group A streptococci in Finland cut from 20% to 10% in 2 years Superbugs: the clean-up "Record numbers of Britons are flying abroad for medical treatment to escape…the rising threat of hospital superbugs...." "We shall fight them with bleaches… whatever the cost may be" "A ward at a time, walls, ceilings, fittings and ventilation shafts" "Every hospital will be disinfected and scrubbed clean over the next year" Superbugs in captivity (hospitals) Handwashing Limiting invasive devices Environmental cleaning Judicious antibiotic use Surveillance --------- hospital Assuming superbugs are less fit… In general Combination therapy In the community (>80% most respiratory) Restrict antibiotics for: coughs, colds, sore throats (unless strep), otitis media, sinusitis (or < 3 days) In hospital Minimize presumptive treatment, discontinue treatment asap, withhold key antibiotics In animals Minimize use sub-therapeutic dosing New antibiotics: hard science or hard sell? Only 2 new classes of antibacterials since 1970s Decade introduced Class of antibacterial 1930s 1940s 1950s 1960s sulphonamides penicillins, aminoglycosides chloramphenicol,tetracyclines macrolides, glycopeptides streptogramins, quinolones lincosamides trimethoprim 1970s 1980s 1990s 2000s oxazolidinones, lipopeptides Other licensed drugs since 1970s in same classes big pharma, bad karma? THE 2006 BITTER PILL AWARDS: While You Were Sleeping Award Overmarketing insomnia medications “Got Cholesterol?” Award Overpromoting brand-name statins Driven to Distraction Award For hawking an Attention Deficit drug Who will make new drugs? Mostly Pharma but… Escalating costs Net present value Strict license standards Post-market surveillance Resistance Generics (short patents) Narrow spectrum Variable licensure High purchase price Low unmet need Short treatment time 160 0.8 140 0.7 120 0.6 100 0.5 80 0.4 60 0.3 40 0.2 20 0.1 0 2007 0 2009 2011 2013 2015 2017 2019 Probability of one drug Net cost at present value ($m) New TB drugs: returns on investment 11 compounds, 73% chance by 2019 yp e rte Li ns pi io d n lo w er in A g nt ib A io ci tic d di s so rd er s A st hm D ep a r es Sc si hi on zo ph re Th ni ro a m bo H ae si s m at ol og y H R /o st eo H Billions of dollars Best selling drugs are not antibiotics 40 30 20 10 0 #1 Lipitor lowers cholesterol $11 billion #2 Nexium Heartburn Fastest sales growth Hy pe rte ns io De n pr es Sc si hi on zo ph re Ha ni em a at ol og y As th Li m pi a d lo w Ac er in id g di so rd er Th s ro m bo si An s tib io tic s HR /o st eo Drugs per billion dollar sales Antibiotics are not "blockbusters" 0.4 0.3 0.2 0.1 0 From "market failure" to market success Legislation Intellectual property (extended exclusivity) Tax incentives for R&D Guaranteed market Regulation Simplify regulation and clinical trials Financing Promote translational research and trials: bench to bedside Cash prizes (instead of patents) Surveillance Present and future drug needs End of the antibiotic era? 1. 2. 3. 4. Adjustable balance between resistance and susceptibility… Resistance genes are inevitable, but their spread is preventable Resistance is reversible, though slowly Economic and regulatory levers to make and distribute new antibiotics have growing political commitment Other solutions: prevention, vaccines