Younas Masih RN, Post RN BSc.N (Lecturer ) New Life College Of Nursing Karachi 11/7/20141Antimicrobial medications

Objectives By the end the unit students will be able to: 1. Discuss and review common terms and concepts related to antimicrobial therapy. 2.Discuss mechanism of action and indication of using antimicrobial therapy. 3. State appropriate nursing implications for a client receiving antimicrobial drugs. 4. Discuss general principles and consideration related to antimicrobial therapy. 5. Calculate the drug dosage for oral and parental antimicrobial drugs. 11/7/20142Antimicrobial medications

Terms Antimicrobial agent It is a chemical substance derived from a biological source or produced by chemical synthesis that kills or inhibits the growth of microorganisms. Before antimicrobials, large number of people died from common illnesses Now many illnesses easily treated with antimicrobials However, many antimicrobial drugs are becoming less useful. 11/7/20143Antimicrobial medications

Antimicrobial drugs Different types of antimicrobial drugs: Antibacterial drugs Antifungal drugs Antiprotozoan drugs 11/7/20144Antimicrobial medications

Antibiotics Antibiotic It is a chemical substance produced by a microorganism that inhibits the growth of or kills other microorganisms. Or A chemical substance derivable from a microorganism or produced by chemical synthesis that kills or inhibits microorganisms and cures infections. 1. Bacteriostatic: inhibit growth of microorganisms 2. Bactericidal: Kill microorganisms 11/7/20145Antimicrobial medications

Sources of Antibacterial Agents Natural - mainly fungal sources(The original antibiotics were derived from fungal sources. These can be referred to as “natural” antibiotics) e.g. Benzylpenicillin and Gentamicin are natural antibiotics Semi-synthetic - chemically-altered natural compound (developed to decrease toxicity and increase effectiveness). E.g. Ampicillin and Amikacin are semi-synthetic antibiotics Synthetic - chemically designed in the lab(bacteria are not exposed to the compounds until they are released. They are also designed to have even greater effectiveness and less toxicity). E.g. Moxifloxacin and Norfloxacin are synthetic antibiotics 11/7/20146Antimicrobial medications

Mechanisms of action of Antibacterial Drugs 1. Inhibit cell wall synthesis 2. Inhibit protein synthesis 3. Inhibit nucleic acid synthesis 4. Injury to plasma membrane 5. Inhibit synthesis of essential metabolites 11/7/20147Antimicrobial medications

Mechanisms of Action -Antibiotics operate by inhibiting crucial life sustaining processes in the organism: the synthesis of cell wall material the synthesis of DNA, RNA, ribosomes and proteins. Target The target of the antibiotic should be selective to minimize toxicity…but all antibiotics are toxic to some degree! Harm the bacteria, not the host 11/7/20148Antimicrobial medications

Bacterial cell 11/7/20149Antimicrobial medications

Staining and Identification Gram Staining In this procedure bacteria are washed with a decolorizing solution after being dyed with crystal violet. On adding a counterstain such as safranin or fuchsine after washing, Gram-negative bacteria are stained red or pink Gram-positive bacteria retain their crystal violet dye. 11/7/201410Antimicrobial medications

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Spectrum of Activity Antimicrobial medications vary with respect to the range of microorganisms they kill or inhibit Narrow-spectrum antimicrobial (Some kill only limited range) : Broad-spectrum antimicrobial (While others kill wide range of microorganisms) 11/7/201412Antimicrobial medications

Adverse Effects 1. Allergic Reactions: some people develop hypersensitivities to antimicrobials 2. Toxic Effects: some antimicrobials toxic at high concentrations or cause adverse effects 3. Suppression of normal flora: when normal flora killed, other pathogens may be able to grow to high numbers 11/7/201413Antimicrobial medications

Selection of the appropriate antibiotic It depends upon knowledge of organism’s natural resistance pharmacological properties of the antibiotic toxicity, binding, distribution, absorption achievable levels in blood, urine previous experience with same species nature of patients underlying pathology patient’s immune status 11/7/201414Antimicrobial medications

Ideal Antibacterial Selective target – target unique Bactericidal – kills Narrow spectrum – does not kill normal flora High therapeutic index – ratio of toxic level to therapeutic level Few adverse reactions – toxicity, allergy Various routes of administration – IV, IM, oral Good absorption Good distribution to site of infection Emergence of resistance is slow 11/7/201415Antimicrobial medications

Effects of Combining Drugs 1. Combinations are sometimes used to fight infections 2. Synergistic: action of one drug enhances the activity of another or vice versa. 3. Antagonistic: activity of one drug interferes with the action of another. 11/7/201416Antimicrobial medications

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