Antimicrobial Resistance and Microbes

• Antimicrobial resistance (AMR) occurs in bacteria, viruses, parasites, and fungi when antimicrobials become ineffective.

Microbial Infection

• Microorganisms exist everywhere in both external and internal environments of bodies.
• Microorganisms may be either harmful or beneficial.
• Health status can be affected by conditions that alter microorganisms.
• People are typically healthy and resistant to infectious microorganisms due to host defenses.
• Physical barriers like skin and respiratory mucosa and physiological defenses such as gastric acid and antibodies are examples of host defenses.
• Phagocytic cells (macrophages and polymorphonuclear neutrophils) are part of the mononuclear phagocyte system and act as other defenses.

Bacteria Classification

• Microbes contain organisms that can infect human, Bacteria, viruses, fungi, and protozoa are different shapes.
• Morphology is the property of bacteria that describes shape.
• Bacteria are grouped according to recognizable characteristics.
• Gram staining is a procedure used to categorize bacteria.
• Gram-positive organisms stain purple.
• Gram-negative organisms stain red; this difference guides antibiotic therapy choices.

Infections

• Community-acquired infections are acquired by a person who has not been hospitalized or had a medical procedure within the past year.
• Health care-associated infections are contracted in a healthcare facility.
• Health care-associated infections were not present upon admission, occur more than 48 hours after admission, and are a leading cause of death.
• Causative microorganisms are often drug resistant and virulent, making them difficult to treat.
• Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) are examples of healthcare-associated infections.
• Hospital-acquired infections were formerly known as nosocomial infections.
• Serious pathogens include Klebsiella, Acinetobacter, and Pseudomonas aeruginosa, which are resistant to many antibiotics.
• Gram-negative bacteria produce beta-lactamase, breaking down antibiotics.
• Escherichia coli and Klebsiella pneumoniae are common ESBL producers.
• Carbapenemase-producing Enterobacteriaceae (CPE) are resistant to carbapenems.

Preventing Infections

• Hand washing is the most important prevention method
• Disinfectants kill organisms; used on nonliving objects and are cidal agents.
• Antiseptics inhibit growth on living tissue and are static agents.

Antibiotics

• Antibiotics are medications used to treat bacterial infections.
• Areas of suspected infection should be cultured to identify organisms and susceptibilities before antibiotic therapy.
• Empiric therapy treats infections before specific culture results.
• Definitive therapy is tailored to the organism identified with cultures.
• Prophylactic therapy prevents infection, such as before surgery (60 min).

Antibiotic Responses

• Therapeutic response shows a decrease in signs and symptoms, like fever, elevated white blood cell count, redness, inflammation, drainage, and pain.
• Subtherapeutic response shows that signs and symptoms do not improve.

Antibiotic Resistance

• Superinfection can occur during antibiotic therapy
• Clostridium difficile can cause pseudomembranous colitis.
• Secondary infections, resistance, food-drug interactions, and host factors are all considerations.
• Antimicrobial stewardship is part of accreditation in Canada since 2014.
• Allergic reactions can occur, such as with penicillins and sulfonamides.
• Anaphylactic reactions include difficulty breathing, rash, hives, or GI intolerance.
• Host factors include pregnancy, age, allergies, kidney and liver function, genetic characteristics, infection site, and host defenses.
• Glucose-6-phosphate dehydrogenase (G6PD) deficiency and slow acetylation are host factors to consider.
• Antibiotics are grouped into classes.
• Sulfonamides, penicillins, cephalosporins, carbapenems, macrolides, quinolones, aminoglycosides, and tetracyclines are all antibiotic classes.

How Antibiotics Work

• Cell wall synthesis is interfered with.
• Protein synthesis is interfered with.
• Deoxyribonucleic acid (DNA) replication is interfered with.
• Critical metabolic reactions can be disrupted inside the bacterial cell.

Types Of Antibiotic Actions

• Bactericidal antibiotics kill bacteria.
• Bacteriostatic antibiotics inhibit growth of susceptible bacteria but do not kill them immediately.

Sulfonamides

• One of the first antibiotic groups, they inhibit growth but do not destroy bacteria.
• Sulfonamides prevent synthesis of folic acid, hindering synthesis of purines and nucleic acid.
• These drugs do not affect human cells or bacteria using preformed folic acid.
• Sulfonamides only affect organisms that synthesize their own folic acid and are often combined with another antibiotic.
• Sulfamethoxazole/trimethoprim contains a 5:1 ratio of sulfamethoxazole to trimethoprim, available in oral and injectable forms.

Sulfonamide Indications and Adverse Effects

• Effective against gram-positive and gram-negative bacteria.
• Used in urinary tract infections caused by susceptible strains.
• Used to treat Pneumocystis jiroveci pneumonia (sulfamethoxazole/trimethoprim).
• Useful in upper respiratory tract and outpatient Staphylococcus infections due to MRSA.
• Blood adverse effects include hemolytic and aplastic anemia, agranulocytosis, and thrombocytopenia.
• Photosensitivity, exfoliative dermatitis, Stevens-Johnson syndrome, and epidermal necrolysis are integumentary adverse effects.
• Nausea, vomiting, diarrhea, pancreatitis, and hepatotoxicity are GI adverse effects.
• Convulsions, crystalluria, toxic nephrosis, headache, peripheral neuritis, urticaria, and cough are other adverse effects.

Beta-Lactam Antibiotics

• Commonly used to inhibit bacterial peptidoglycan cell wall synthesis.
• Beta-lactamase provides bacterial resistance, breaking down the beta-lactam ring and all Beta-lactam drugs lose their antibacterial efficacy.
• Penicillins, cephalosporins, carbapenems, and monobactams are all within this class.
• A large group of chemically related antibiotics, first derived from a fungus, are also within this class.
• Bacteria cells die from from cell lysis
• Penicillins do not kill cells in the body

Penicillin Characteristics

• Bactericidal.
• natural, penicillinase-resistant, amino-, and extended-spectrum penicillins are examples.
• They enter bacteria via the cell wall.
• Inside the cell, they bind to penicillin-binding protein.
• Normal cell wall synthesis is disrupted once the Penicillins are bound.

Safe Use Of Penicillin

• Used to prevent and treat infections caused by susceptible organisms.
• Effective against gram-positive bacteria, including Streptococcus spp., Enterococcus spp., and Staphylococcus spp.
• Contraindicated in known medication allergy
• Reactions occur in patients who are allergic to penicillins.

Cephalosporins

• Generally safe and well-tolerated medications
• Usually safe and well-tolerated medications
• Cephalosporins are safe unless the patient has a history of throat swelling or hives from penicillin
• allergic reactions occur in 0.7% to 4% of treatment courses, with urticaria, pruritus, and angioedema occurring
• Have interactions such as nonsteroidal anti-inflammatory drugs, oral contraceptives and warfarin
• Divided into first, second, third, fourth, and fifth, which depend on gram positive and gram negative coverage and antimicrobial activity

Carbapenems

• Cephazolin and Cephalexin are part of the first generation family (with various generations to follow)
• Have a risk of cross-sensitivity with penicillins if allergies exist
• broad antibacterial action, complicated body cavity and are effective if infused over 60 minutes, but may cause drug-induced seizure activity.
• Imipenem/cilastatin (Primaxin®), meropenem (Merrem®) and ertapenem (Invanz®) all are included within this class

Macrolides

• Include erythromycin (E-Mycin®, many others), azithromycin (Zithromax®), clarithromycin (Biaxin®), and fidaxomicin (Dificid®)
• Prevent protein synthesis within bacterial cells, are bacteriostatic, lead to bacteria death and are bactericidal at high concentrations
• Used on Strep infections, upper and lower respiratory illnesses, STI's such as gonorrhea, Chlamydia, Mycoplasma

Fidaxomicin

• A macrolide that is for treating C. difficile associated diarrhea and is safe for use during pregnancy/low absorption.

Adverse Effects of Macrolides

• Mainly GI effects with erythromycin.
• Fewer GI adverse effects in azithromycin and clarithromycin, while offering longer durations of action, better efficacy and better tissue penetration

Nursing Considerations for Erythromycin, Azithromycin, and Clarithromycin:

• Absorption enhanced if taken on an empty stomach, but many forms taken as a meal of snack
• Clarithromycin and Azithromycin are semi synthetic macrolide antibiotics and have better adverse effect profiles including GI comfort
• May cause interactions with protein bound drugs

Tetracyclines

• doxycycline hyclate (Doxycin®, Vibramycin®, others), minocycline hydrochloride (Minocin®), and tigecycline (Tygacil®)
• Natural and semisynthetic/ inhibit bacterias essential functions. Natural and semisynthetic
• Natural and semisynthetic/ inhibit bacterias essential functions, inhibit protein synthesis and bacterial growth
• Avoid milk products, iron preparations, antacids, because of chelation/binding
• Because of photosensitivity, sunlight should be avoided
• Can cause alteration of flora, candidiasis, Enterocolitis, rashes, upset

Aminoglycosides

• gentamincin sulphate, streptomycin sulphate, tobramycin sulphate, amikacin sulphate, paromocyin sulphate, neomycin sulphate
• Most are needed and most often for gram negative, parenterally
• Therapeutic drug monitioring is needed and also has serious toxicity, nephrotoxicity and ototoxicity

Quinolones

• The action is bactericidal and kills serratia, marcescens
• Gram Negative bacteria and complicated Urinary tract, respiratory, skin, G.I
• Cipro flocacin and low flocacin withhold form children.
• Dairy products, enteral tube feeding, probenicid, nitrofurantoin are all things to avoid.

Miscellaneous Antibiotics

• Metronidazole, is used for aenorobic organisms
• Primarly used in UTIs are nirtfruitoin- •vancomiacin for mrsa- monitor blood, toxcity, oto, nephro Red men syndrom