Chapter 38 outline. - I Microbial Infection Microorganisms...

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I. Microbial Infection Microorganisms can be found internal or external They can be harmful or beneficial They become harmful when conditions become altered in some way Usually able to resist due to normal defenses Physical barriers- skin and mucosa membranes Physiologic defenses- gastric acids, antibodies Phagocytic cells- macorophages A. Bacteria Morphology- can take a number of different shapes and is the main means of classification Maybe grouped by other means such as gram stain 1. Gram Positive – Stain purple Very thick cell walls- peptidoglycan May have thick outer capsule 2. Gram Negative- stain red Complex cell walls Outer capsule and peptidoglycan layer Two membranes- outer and inner More difficult to treat due to complex walls
B. Infection Results from normal host cells defenses being compromised Invades multiplies overwhelms defense system clinically apparent S&S Fever, chills, redness, sweat, pain, swelling, fatigue, weight loss, increase WBC, pus Antibiotics are often required to assist normal defenses but not always needed When a host is colonoized but shows no S&S treatment is not required but is often d done anyways and results in antibiotic resistant microbes. 1. community associated infection- defined as an infection that acquired by a person who has not recently been hospitalized or had a medical procedure 2. Health Care-associated infection- Previously known as nosocomial infection that a patient acquired during the course of receiving treatment for another condition in a health care facility. Occurs more than 48 hours after admission More difficult to treat cause organisms are often drug resistant and most virulent Top 10 leading cause of death in US MRSA; methicillin-resistant Staphylococcus aureus being the most common Enterococcus, Klebsiella, Acinetobacter, Pseudomonas aeruginosa Most are UTI or post-op wound infections Areas most common for these type of infections; Critical Care, dialysis, oncology, transplant and burn units. – (due to immunocompromised pts) Prevention- 70% are preventable and most common transmission by direct contact HAND WASHING the single most important thing Disinfectant- able to kill organisms and is used only on nonliving organisms that may be present; cidal agents Antiseptics- generally only inhibits the growth of organisms, not necessarily kills them. Applied exclusively to living tissue ; static agents Bactericidal- kills bacteria Bacteriostatic- inhibits growth of bacterial rather than killing them immediately; eventually leads to bacterial death II. Pharmacology Overview - Antibiotics Antibiotics have three general uses: A. Empiric therapy- Treatment of an infection before specific culture information has been provided. The antibiotic selected is one that can best kill the microorganisms known to be the most common cause of the infection.

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