ANTIBIOTICS USE, MISUSE, consequences Dr.T.V.Rao MD Dr.T.V.Rao MD

What is a Antibiotic Antibiotic (from the Ancient Greek: ἀντί – anti, "against", and βίος – bios, "life") is a substance or compound that kills bacteria or inhibits its growth. Antibiotics belong to the broader group of antimicrobial compounds, used to treat infections caused by microorganisms, including fungi and protozoa. Dr.T.V.Rao MD

Early definition of Antibiotic The word antibiotic came from the word antibiosis a term coined in 1889 by Louis Pasteur's pupil Paul Vuillemin which means a process by which life could be used to destroy life Dr.T.V.Rao MD

Beginning of Antibiotics with Discovery of Penicillin The discovery of penicillin has been attributed to Scottish scientist Alexander Fleming in 1928 and the development of penicillin for use as a medicine is attributed to the Australian Nobel Laureate Howard Walter Florey Dr.T.V.Rao MD

Fleming and Penicillin Dr.T.V.Rao MD

Antibiotic/Antimicrobial agent Antibiotic: Chemical produced by a microorganism that kills or inhibits the growth of another microorganism Antimicrobial agent: Chemical that kills or inhibits the growth of microorganisms Dr.T.V.Rao MD

Early definition of Antibiotic The word antibiotic came from the word antibiosis a term coined in 1889 by Louis Pasteur's pupil Paul Vuillemin which means a process by which life could be used to destroy life Dr.T.V.Rao MD

Selman Waksman The term "antibiotic" was coined by Selman Waksman in 1942 to describe any substance produced by a microorganism that is antagonistic to the growth of other microorganisms in high dilution Dr.T.V.Rao MD

Discovery of Penicillin Awarded Nobel Prize Dr.T.V.Rao MD

Brief History of Antibiotics • 1928- Penicillin discovered by Fleming • 1932- Sulfonamide antimicrobial activity discovered {Erlich}• • 1943- Drug companies begin mass production of penicillin • 1948- Cephalosporins precursor sent to Oxford for synthesis • 1952- Erythromycin derived from Streptomyces erythreus • 1956- Vancomycin introduced for penicillin resistant staphylococcus • 1962- Quinolone antibiotics first discovered • 1970s- Linezolid discovered but not pursued • 1980s- Fluorinated Quinolones introduced, making then clinically useful • 2000- Linezolid introduced into clinical practice Dr.T.V.Rao MD

first description as anti-infective drug discoverer Antibiotic natural source sulfanilamide (prontosil G.Domagk 1932 1941 A.Fleming, Florey, Chain penicillin Penicillium notatum S.A.Waksman Streptomyces griseus streptomycin 1944 cephalosporin Cephalosporium acremonium G.Brotzu 1945 bacitracin B.A.Johnson Bacillus subtilis 1945 Streptomyces venezuellae 1947 I.Ehrlich chloramphenicol polymyxin Bacillus polymyxa 1947 C.G.Ainsworth Streptomyces aureofaciens B.M.Duggar 1948 chlortetracyclin Streptomyces fradiae neomycin S.A.Waksman 1949 A.C.Finlay oxytetracyclin Streptomyces rimosus 1950 Dr.T.V.Rao MD

Development of anti-microbials ertapenem tigecyclin daptomicin linezolid telithromicin quinup./dalfop. cefepime ciprofloxacin aztreonam norfloxacin imipenem cefotaxime clavulanic ac. cefuroxime gentamicin cefalotina nalidíxico ac. ampicillin methicilin vancomicin rifampin chlortetracyclin streptomycin pencillin G prontosil The development of anti-infectives … Dr.T.V.Rao MD

Definition Bacteriostatic - Antimicrobial agents that reversibly inhibit growth of bacteria are called as bacteriostatic (Tetracycline's, Chloramphenicol ) Bactericidal – Those with an irreversible lethal action on bacteria are known as bactericidal ( Penicillin, Isoniazid ) Dr.T.V.Rao MD

Chemotherapeutic Agents Antimicrobial agents – that are produced synthetically but have action similar to that of antibiotics and are defined as chemotherapeutic agents Eg Sulphonamides, Quinolones. Dr.T.V.Rao MD

Ideal Antibiotic Toxic to microbes, and not to humans Bactericidal rater than bacteriostatic Effective against broad range of bacteria Should not be allergic and hypersensitive reactions Should be active in plasma, and other body fluids Desired levels should be reached rapidly and maintained for adequate period of time. Should not give drug resistance, long shelf life, Cheaper Dr.T.V.Rao MD

How Drugs Act Drugs differ on their capabilities to act at different sites on bacteria. Some drugs have more than one site of action Dr.T.V.Rao MD

Resistance and Susceptibility Determined by in vitro activity, pharmacologic characteristics, and clinical evaluation. The minimal inhibitory concentration (MIC) can be comfortably exceeded by doses tolerated by the patient. Susceptible - implies their MIC is at a concentration attainable in the blood or other body fluid at the recommended dose. Resistant - MIC is not exceeded by normally attainable levels Dr.T.V.Rao MD

Major mechanisms of antimicrobial drugs 1 Inhibition of cell wall synthesis 2 Inhibition of cell membrane function 3 Inhibition of protein synthesis ( inhibition of translation and transcription of genetic material) 4 Inhibition of nucleic acid synthesis. Dr.T.V.Rao MD

Inhibition of cell wall synthesis Target: block peptidoglycan (murein) synthesis Peptidoglycan Polysaccharide (repeating disaccharides of N-acetyl glucosamine and N-acetylmuramic acid) + cross-linked pentapeptide Pentapeptide with terminal D-alanyl-D-alanine unit  required for cross-linking Peptide cross-link formed between the free amine of the amino acid in the 3rd position of the peptide & the D-alanine in the 4th position of another chain Dr.T.V.Rao MD

Inhibition of cell wall synthesis -lactam antibiotics inhibit transpeptidation reaction (3rd stage) to block peptidoglycan synthesis  involves loss of a D-alanine from the pentapeptide Steps: a. binding of drug to PBPs b. activation of autolytic enzymes (murein hydrolases) in the cell wall c. degradation of peptidoglycan d. lysis of bacterial cell Dr.T.V.Rao MD

Inhibition of cell wall synthesis -lactam antibiotics Penicillin binding proteins (PBPs) enzymes responsible for: a. cross-linking (transpeptidase) b. elongation (carboxypeptidase) c. autolysis Dr.T.V.Rao MD

Inhibition of cell wall synthesis -lactam antibiotics Lysis of bacterial cell Isotonic environment  cell swelling  rupture of bacterial cell Hypertonic environment – microbes change to protoplasts (gram +) or spheroplasts (gram -) covered by cell membrane  swell and rupture if placed in isotonic environment Dr.T.V.Rao MD

Penicillins and Cephalosporins Pencillin and cephalosporins act inhibiting Trans peptidases, the enzyme catalyses the final linking step in synthesis of peptidoglycan. Due to this reason Pencillin in bactericidal for grwoing bacteria since new peptidoglycan is synthesized at that stage only. In nongrwoing cells pencillin is inactive An intact beta – lactum is essential for antibacterial activity of pencillins Dr.T.V.Rao MD

Classification of Pencillins Natural Benzyl penicillin Phenoxymethyl penicillin Penicillin v Semi synthetic and pencillase resistant 1 Methicillin 2 Nafcillin 3 Cloxacillin 4 Oxacillin 5 Floxacillin Dr.T.V.Rao MD

Penicillinase (b Lactamase) Dr.T.V.Rao MD Figure 20.8

Semi synthetic Penicillins Penicilinase-resistant penicillins Carbapenem: very broad spectrum Monobactams: Gram negative Extended-spectrum penicillins Penicillins + -lactamase inhibitors Dr.T.V.Rao MD

Other Inhibitors of Cell Wall Synthesis Cephalosporins 2nd, 3rd, and 4th generations more effective against gram- negatives Dr.T.V.Rao MD Figure 20.9

Extended spectrum pencillins Aminopencillins - Ampicillin, Amoxycillin Carboxypencillins – Carbencillin, Ticarcillin Ureidopencillin - Piperacillin Resistance to penicillin is due to pencillinase commonly called as ßlactamase The enzyme opens Betalactum ring hydrolytically and thus converts the antibiotic to inactive pencillonic acid. Dr.T.V.Rao MD

Inhibitors to Betalactamase Clavulinic acid which is a product of Strept.clavuligerus Acts against the Staphylococcal beta ßlactamase. And plasmid mediated Betalactamase of Gram negative bacteria. Salbactum – this is a semisyntetic sulfone derivative with weak antibacterial activity Dr.T.V.Rao MD

Cephalosporins Like penicillin acts similar Products of the molds of genus Cephalosporium except cefoxilin Divided into 4 generation of Cephalosporins depending on the spectrum of activity. Dr.T.V.Rao MD

Different Generations of Cephalosporins Cephalosporins are grouped into "generations" based on their spectrum of antimicrobial activity. The first Cephalosporins were designated first generation while later, more extended spectrum Cephalosporins were classified as second generation Cephalosporins. Dr.T.V.Rao MD

Major generations of Cephalosporins Cephalosporins are divided into 3 generations: 1st generation: Cephelexin, cefadroxil, cephradine 2nd generation: Cefuroxime, cefaclor 3rd generation: cefotaxime, Ceftazidime, cefixime - these give the best CNS penetration 4th and 5th generation Cephalosporins are already available Dr.T.V.Rao MD

Basis of generations in Cephalosporins Cephalosporins are grouped into "generations" based on their spectrum of antimicrobial activity. The first cephalosporins were designated first generation while later, more extended spectrum cephalosporins were classified as second generation cephalosporins. Dr.T.V.Rao MD

Advantages with Newer generations Each newer generation of cephalosporins has significantly greater gram- negative antimicrobial properties than the preceding generation, in most cases with decreased activity against gram- positive organisms. Fourth generation cephalosporins, however, have true broad spectrum activity Dr.T.V.Rao MD

Other drugs Imipenem: a carbapenem with a broader spectrum of activity against Gram positive and negative aerobes and anaerobes. Needs to be given with cilastatin to prevent inactivation by the kidney. Dr.T.V.Rao MD

Quinolones Quinolones are the first wholly synthetic antimicrobials. The commonly used Quinolones. Act on the DNA gyrase which prevents DNA polymerase from proceeding at the replication fork and consequently stopping synthesis. Dr.T.V.Rao MD

Aminoglycosides Aminoglycosides are group of antibiotics in which amino sugars liked by glycoside bonds Eg Streptomycin, Act at the level of Ribosome's and inhibits protein synthesis Other Aminoglycosides – Gentamycin, neomycins,paromomycins,tobra mycins Kanamycins and spectinomycins Dr.T.V.Rao MD

Dr.T.V.Rao MD

Tetracycline's Broad spectrum antibiotic produced by Streptomyces species 1. Oxytetracycle, chlortetracycle and tetracycline Tetracyclnes are bacteriostatic drugs inhibits rapidly multiplying organisms Resistance develops slowly and attributed to alterations in cell membrane permeability to enzymatic inactivation of the drug Dr.T.V.Rao MD

Choramphenicol Chloramphenicol is bacteriostatic drug Can produce bone marrow depression Chloramphenicol interferes with protein synthesis. Dr.T.V.Rao MD

Macrolides,Azalides,Ketolides Contain macro cyclic lactone ring Erythromycin. Is popularly used drug Other drugs Roxithromycin,Azithromycin Inhibits the protein synthesis. Used as alternative to pencillin allergy patients. Dr.T.V.Rao MD

Dr.T.V.Rao MD

Other Antimicrobial agents Lincomycins Clindamycin resembles Macrolides in biting site and antimicrobial activity. Streptogramins Quinpristin / dalfopristin useful in gram positive bacteria Dr.T.V.Rao MD

Antibiotics in Anaerobes Major anaerobes – Anaerobic cocci, clostridia and Bactericides are susceptible to Benzyl pencillin Bact.fragilis as well as many other anaerobes are treatable with Erythromycin,Lincomycin, tetracycline and Chloramphenicol Clindamycin is effective against many strains of Bacteroides Dr.T.V.Rao MD

Metronidazole in Anaerobic Infections Since the discovery of Metronidazole in 1973 since then it was identified as leading agent anaerobes. But also useful in treating parasitic infections Trichomonas, Amoebiasis and other protozoan infections. Dr.T.V.Rao MD

Metronidazole in Anaerobic Infections Since the discovery of Metronidazole in 1973 since then it was identified as leading agent anaerobes. But also useful in treating parasitic infections Trichomonas, Amoebiasis and other protozoan infections. Dr.T.V.Rao MD

Other Beta-lactams include Aztreonam: a monocytic beta-lactam, with an antibacterial spectrum which is active only against Gram negative aerobes, including Pseudomonas aeruginosa, Neisseria meningitidis and N. gonorrhoea. Dr.T.V.Rao MD

Emergence of Antibiotic-Resistant Bacteria S aureus Gram-negative rods N. gonorrhoeae Penicillin Ampicillin H. influenzae M. catarrhalis S. pneumoniae Enterococcus sp. 1950 1960 1970 1980 1990 Quinolones 3rd gen Cephalosporins Cohen; Science 1992;257:1050 Dr.T.V.Rao MD

Dr.T.V.Rao MD

Antibiotic resistance Antibiotic resistance is the ability of a micro organism to withstand the effects of antibiotics. It is a specific type of drug resistance. Antibiotic resistance evolves naturally via natural selection acting upon random mutation, but it can also be engineered by applying an evolutionary stress on a population. Once such a gene is generated, bacteria can then transfer the genetic information in a horizontal fashion (between individuals) by plasmid exchange. Dr.T.V.Rao MD

Antibiotic Pressure and Resistance in Bacteria What is it ? ”Selection pressure of antibiotics has led to the emergence of antibiotic-resistant bacteria.” Antibiotics can effect bacteria unrelated to the targeted infectious agent; these may be “normal” flora, leading to the emergence of resistant mutants inhabiting the same environment. Baquero et al., International Report 1996;23:819 Dr.T.V.Rao MD

Antibiotic Pressure and Resistance in Bacteria How does it occur? All antibiotics do NOT kill bacteria in the same way. Various classes of antibiotics work on different aspects of bacterial replication. Dr.T.V.Rao MD

Resistance and Susceptibility Determined by in vitro activity, pharmacologic characteristics, and clinical evaluation. The minimal inhibitory concentration (MIC) can be comfortably exceeded by doses tolerated by the patient. Susceptible - implies their MIC is at a concentration attainable in the blood or other body fluid at the recommended dose. Resistant - MIC is not exceeded by normally attainable levels Dr.T.V.Rao MD

Dr.T.V.Rao MD

Drug Resistance In spite discovery of several antibiotics several microorganisms attained resistance. The major factor contributing to persistence of infectious disease has been the tremendous capacity of microorganisms for circumventing the action of inhibitory drugs. The drug resistance continues to be a threat for usefulness of the chemotherapeutic agents. Dr.T.V.Rao MD

ORIGIN OF DRUG RESISTANCE NON-GENETIC Metabolically inactive organisms may be phenotypically resistant to drugs – M. tuberculosis Loss of specific target structure for a drug for several generations Organism infects host at sites where antimicrobials are excluded or are not active – aminoglycosides (e.g. Gentamicin) vs. Salmonella enteric fevers (intracellular) Dr.T.V.Rao MD

DNA THFA mRNA Ribosomes DHFA PABA DNA-directed RNA polymerase DNA gyrase DNA-directed RNA polymerase Quinolones Cell wall synthesis Rifampin ß-lactams & Glycopeptide (Vancomycin) DNA THFA mRNA Trimethoprim Protein synthesis inhibition Ribosomes Folic acid synthesis DHFA 50 50 50 Macrolides & Lincomycins 30 30 30 Sulfonamides PABA Protein synthesis inhibition Protein synthesis mistranslation Tetracycline's Aminoglycosides Dr.T.V.Rao MD Cohen. Science 1992; 257:1064

Origin of Drug Resistant Strains The resistant strains arise either by mutation and selection or by genetic exchange in which sensitive organisms receive the genetic material ( part of DNA) from the resistant organisms and the part of DNA carries with it the information of mode of inducing resistance against one or multiple antimicrobial agents. Dr.T.V.Rao MD

Practices Contributing to Misuse of Antibiotics Inappropriate specimen selection and collection Inappropriate clinical tests Failure to use stains/smears Failure to use cultures and susceptibility tests Dr.T.V.Rao MD

Inappropriate Antibiotic Use Use of antibiotics with no clinical indication (eg, for viral infections) Use of broad spectrum antibiotics when not indicated Inappropriate choice of empiric antibiotics Dr.T.V.Rao MD

Inappropriate Drug Regimen Inappropriate dose - ineffective concentration of antibiotics at site of infection Inappropriate route - ineffective concentration of antibiotics at site of infection Inappropriate duration Dr.T.V.Rao MD

Antibiotic resistance Antibiotic resistance is a specific type of drug resistance when a microorganism has the ability of withstanding the effects of antibiotics. Antibiotic resistance evolves via natural selection acting upon random mutation, but it can also be engineered by applying an evolutionary stress on a population. Once such a gene is generated, bacteria can then transfer the genetic information in a horizontal fashion (between individuals) by conjugation, transduction, or transformation. Dr.T.V.Rao MD

Plasmids Plasmid seem to be ubiquitous in bacteria, May encode genetic information for properties 1 Resistance to Antibiotics 2 Bacteriocins production 3 Enterotoxin production 4 Enhanced pathogen city 5 Reduced Sensitivity to mutagens 6 Degrade complex organic molecules Dr.T.V.Rao MD

Resistance Transfer Factor RTF Plasmids – helps to spread multiple drug resistance Discovered in 1959 Japan Infections caused due to Shigella spread resistance to following Antibiotics Sulphonamides Streptomycin Choramphenicol, Tetracycline Dr.T.V.Rao MD

RTF Shigella + E.coli excreted in the stool resistant to several drugs in vivo and vitro Plasmid mediated –transmitted by Conjugation Episomes spread the resistance Dr.T.V.Rao MD

Transposons and R factor R forms may have evolved as a collection of Transposons Each carrying Genes that confers resistance to one or several Antibiotics Seen in Plasmids, Microorganisms Animals Laboratory Manipulations are called as Genetic Engineering Dr.T.V.Rao MD

Multi Drug resistant pathogens If a bacterium carries several resistance genes, it is called multiresistant or, informally, a superbug. The term antimicrobial resistance is sometimes use to explicitly encompass organisms other than bacteria Dr.T.V.Rao MD

Biochemical mechanisms of Drug resistance Resistance arises due to Biochemical changes Increased synthesis of drug antagonist Decreased permeability to drug Increased destruction of inhibitor Dr.T.V.Rao MD

Differentiation of Mutation and transferable drug resistance Usually one drug Low degree of resistance Increasing dose can benefit Prevented by combination of drugs Low virulence of bacteria Transferable Multiple drugs High degree of resistance Increasing dose do not benefit Can not be prevented by combination of drugs High virulence of bacteria Dr.T.V.Rao MD

Plasmid Mediated Drug resistance Sulphonamides --- Reduce permeability Erythromycin ---- Modification of ribosome's Tetracyclnes ----- Reduced permeability Chloramphenicol ---- Acetylation of drug Streptomycin ----- Adenylation of drug Pencillin ----- Hydrolysis of lactum ring Dr.T.V.Rao MD

Antibiotics resistance and plasmids Many antibiotic resistance genes reside on plasmids facilitating their transfer. If a bacterium carries several resistance genes, it is called multiresistant or, informally, a superbug. The term antimicrobial resistance is sometimes used to explicitly encompass organisms other than bacteria Dr.T.V.Rao MD

Antibiotic Resistance Threat to Humans and Animals Antibiotic resistance has become a serious problem in both developed and underdeveloped nations. By 1984 half of those with active tuberculosis in the United States had a strain that resisted at least one antibiotic. In certain settings, such as hospitals and some childcare location Dr.T.V.Rao MD

Between 1962 and 2000, no major classes of antibiotics were introduced Fischbach MA and Walsh CT Science 2009 Dr.T.V.Rao MD

Extended-Spectrum β-Lactamases β-lactamases capable of conferring bacterial resistance to the penicillins first-, second-, and third-generation cephalosporins aztreonam (but not the cephamycins or carbapenems) These enzymes are derived from group 2b β-lactamases (TEM-1, TEM-2, and SHV-1) differ from their progenitors by as few as one AA Dr.T.V.Rao MD

Carbapenemases Ability to hydrolyze penicillins, cephalosporins, monobactams, and carbapenems Resilient against inhibition by all commercially viable ß- lactamase inhibitors Subgroup 2df: OXA (23 and 48) carbapenemases Subgroup 2f : serine carbapenemases from molecular class A: GES and KPC Subgroup 3b contains a smaller group of MBLs that preferentially hydrolyze carbapenems IMP and VIM enzymes that have appeared globally, most frequently in non-fermentative bacteria but also in Enterobacteriaceae Dr.T.V.Rao MD

K. pneumonia carbapenemases) KPCs are the most prevalent of this group of enzymes, found mostly on transferable plasmids in K. pneumonia Substrate hydrolysis spectrum includes cephalosporins and carbapenems A few class A enzymes, notably the plasmid-mediated KPC enzymes, are effective carbapenemases as well. Three variants are known, distinguished by one or two amino-acid substitutions. KPC-1 was found in North Carolina, KPC-2 in Baltimore and KPC-3 in New York. They have only 45% homology with SME and NMC/IMI enzymes and, unlike them, can be encoded by self-transmissible plasmids. Dr.T.V.Rao MD

K.pneumoniae carbapenemase-producing bacteria A few class A enzymes, notably the plasmid-mediated KPC enzymes, are effective carbapenemases as well. Three variants are known, distinguished by one or two amino-acid substitutions. KPC-1 was found in North Carolina, KPC-2 in Baltimore and KPC-3 in New York. They have only 45% homology with SME and NMC/IMI enzymes and, unlike them, can be encoded by self-transmissible plasmids. Dr.T.V.Rao MD Nordmann P et al. LID 2009

Antibiotic resistance “Antibiotic resistance continues to plague antimicrobial chemotherapy of infectious diseases” Keith. Poole. J Antimicrob Chemother 2005; 56: 20-51 “Evolution of bacteria towards resistance… …is unavoidable because it represents a particular aspect of the general evolution of bacteria that is unstoppable” Patrice Courvalin. Emerg Infect Dis 2005; 11: 1507-6 “Antibiotic resistance has resulted in a continuous need for new therapeutic alternatives” Carl Erik Nord. Clin Microbiol Infect 2004;10 (Supp 4) “There is a need to re-invigorate antimicrobial development, which has been downgraded by major pharmaceutical houses” David Livermore. Lancet Infect Dis 2005; 5:450-59 Dr.T.V.Rao MD

Practices Contributing to Misuse of Antibiotics Inappropriate specimen selection and collection Inappropriate clinical tests Failure to use stains/smears Failure to use cultures and susceptibility tests Dr.T.V.Rao MD

Inappropriate Antibiotic Use Use of antibiotics with no clinical indication (eg, for viral infections) Use of broad spectrum antibiotics when not indicated Inappropriate choice of empiric antibiotics Dr.T.V.Rao MD

Physicians Can Impact Patients Optimize patient evaluation Adopt judicious antibiotic prescribing practices Immunize patients Dr.T.V.Rao MD

Physicians Can Impact Other clinicians Optimize consultations with other clinicians Use infection control measures Educate others about judicious use of antibiotics Dr.T.V.Rao MD

Antibiotic Pressure and Resistance in Bacteria: Conclusions Bacteria evolve resistance to antibiotics in response to environmental pressure exerted by the use of antibiotics. Many of these bacteria are significant pathogens. Our responsibility to our community is to use antibiotics prudently, for appropriate indications. Dr.T.V.Rao MD

Are we overusing Antibiotics Dr.T.V.Rao MD

Dedicated handwashing has many solutions to prevent spread of drug resistant strains Dr.T.V.Rao MD

Programme created by Dr. T. V Programme created by Dr.T.V.Rao MD for Medical Professionals in the Developing World Email doctortvrao@gmail.com Dr.T.V.Rao MD