Basic Microbiology Vaneet Arora, MD MPH D(ABMM) FCCM Associate Director of Clinical Microbiology, UK HealthCare Assistant Professor, Department of Pathology and Laboratory Medicine University of Kentucky Objectives Identify normal flora, opportunistic and pathogenic organisms by body site Recognize empiric antimicrobial therapies based on microbe and body site Director, Microbiology; Environmental Microbiology and Preparedness Associate Director, Division of Laboratory Services Kentucky Department for Public Health Infectious Disease Influencing factors- How to decide empiric therapy Antimicrobial Patient related Age Adult vs Pediatric Body site Normally sterile Normal Commensals Immune status Immunocompetent Immunocompromised History Co-morbidities/ Family history Allergies Hepatic/Renal dysfunction Environment related Setting Community vs Healthcare facility vs Long term care facility Outpatient vs Inpatient vs ICU Circulating organisms/strains Antibiograms Exposures Childcare/workplace Catheter/IV line/ PICC line/prosthesis Travel Type Bacteria Fungi Parasites (Protozoa/Helminths) Virus Others Pathogenicity Commensals Opportunistic Pathogenic Organism related Propensity to cause infection Common Uncommon/rare Virulence High/Moderate/Low Predilection for body site Localized Systemic Organ system Susceptibility patterns Sensitive/Resistant 1
Antimicrobial related All factors are interrelated Group Mechanism of action Spectrum Broad spectrum vs narrow spectrum Penetration Availability Pharmacy formulary Site of infection type of organisms antibiotic that reaches the site Allergies what not to give second line antimicrobial Travel endemic organisms immune status More about Bugs Microbes outnumber our own cells by 10 to 1 Microbiome studies- just beginning to yield useful information Bacteria Oxygen requirement Obligate aerobes: Require O 2 Microaerophilic: Require a lower oxygen concentration for growth Obligate anaerobes: Cannot grow in presence of O 2 Facultative anaerobes: Grow with or without O 2 (switch between aerobic and anaerobic metabolism) Aerotolerant anaerobes: Ignore O 2 (only use anaerobic metabolism) Gram characteristic Gram Positive or Gram Negative Gram Variable/Gram neutral Cocci or rods 2
Gram staining Bacterial cell wall Gram positive Cocci Staphylococcus S. aureus» MSSA/MRSA Coagulase negative staphylococci (CoNS) Streptococcus GAS/GBS S. pneumoniae Enterococci E. faecium / E. faecalis VRE 3
Gram Positive Rods Listeria Corynebacteria Diphtheroids Clostridium (Anaerobe spore forming) C. perfringens C. tetani C. difficile C botulinum Bacillis (Aerobe spore forming) B. anthracis B. cereus Gram Negative Rods Enterobacteriaceae E. coli Klebsiella Salmonella Shigella Yersinia Proteus Pseudomonads P. aeruginosa Burkholderia Stenotrophomonas Vibrios V. cholerae Non cholera vibrio Body sites normally sterile Colonized by Commensals Normal flora 1. Bladder 2. Lower Respiratory Tract 3. Tissues (beyond epithelial barriers) 4. Fluids: a) Blood b) Cerebrospinal fluid (CSF) c) Pleural and pericardial fluids 1. Skin 2. Mucosal Surfaces: a) Gastrointestinal Tract b) Upper Respiratory Tract c) Urogenital Tract (female) d) Urethra 4
Normal flora Normal flora Normal flora 5
Common VIRAL pathogens More about Drugs 6
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Classes of antibacterial agents Classes of antibacterial agents Spectrum of activity Hospitalized Adults: Skin and Soft Tissue Infections: Cellulitis Hospitalized Adults: Septic Shock, Source Unknown: Hospital-Onset or Community Onset with Recent Healthcare Exposure 8
Hospitalized Adults: Respiratory Tract Infections: Hospital- Acquired Pneumonia Hospitalized Adults: Respiratory Tract Infections: Community-Acquired Pneumonia Hospitalized Adults: Intravascular Catheter-Related Infections Hospitalized Adults: Healthcare- Associated Urinary Tract Infection Body site Organism Spectrum of Antimicrobial activity Key to appropriate therapy Common denominator? 9
Thank you 10