Antibiotics: An Overview

Pre-Test  Which statements are true about E.coli? a)It is a Gram positive bacteria. b)It is a Gram negative bacteria. c) It is a bacteria normally found in the colon. d)It is the most common cause of a UTI. e)It can cause diarrhea.

Pre-Test  The 6 year old boy has high volume watery diarrhea that looks like ‘rice in water’. He is dehydrated. You resuscitate him with IV normal saline. What is the best antibiotic treatment? a)Penicillin G or Penicillin V b)Ampicillin or Amoxicillin c)Doxycycline or Erythromycin d)Cefalexin or Cefazolin

Pre-Test  A 3-year old child is brought to the emergency. The child is irritable and complains of a headache. On exam, the child has a fever of 39ºC and has neck stiffness. You are worried about meningitis. What antibiotic should you consider? a)Metronidazole b)Ciprofloxicillin c)Cefazolin d)Cloxicillin e)Ceftriaxone

Pre-Test  What statements are true about rickettesia? a)Typhus fever is caused by rickettesia. b)Rickettesia is an atypical bacteria. c)Rickettesia can be treated with doxycycline. d)Rickettesia can be treated with tetracycline. e)Rickettesia can be treated with chloramphenicol.

Pre-Test  A 20-year old male comes in with 2 week history of general malaise and recurrent fever. He recently developed a papular rash on his chest. His abdomen is tender and distended. The patient should be treated with: a)Ampicillin for a probable UTI. b)Levofloxacin for a probable lobar pneumonia. c)Cloxicillin for a probable Staphylococcus rash. d)Ceftriaxone for probable Salmonella typhi. e)No antibiotics.

Types of Microorganisms that cause Infectious Disease  Bacteria  Protozoa  Fungi  Helminths  Viruses

Types of Microorganisms that cause Infectious Disease  Bacteria  Single cell organism with cell wall  No nucleus / Has circular DNA within cell  Protozoa (ie. Plasmodium, Entamoeba, Giardia)  Single cell organism with nucleus  Fungi : Yeast (ie. Candida albicans)  Helminths : Worms  Viruses  Not a cell, but are DNA or RNA wrapped in protein coat  They reproduce by taking over an animal cell and reproducing

Types of Microorganisms that cause Infectious Disease  Antibiotics treat bacteria and protozoans

Type of Bacteria  TYPICAL Bacteria  Gram positive  Gram negative  ATYPICAL Bacteria  Acid fast  No cell wall  Intracellular (lives inside host cells)

Gram Stains  Divides bacteria into 2 groups  Gram positive  Gram negative  Based on cell wall differences  Detects peptidogylcan which is a part of the cell wall  Gram positive = THICK peptidoglycan layer  Gram negative = Thin petidoglycan layer  Detects shape of bacteria  Cocci - circle  Bacillus - rod (straight or curved)  Spirochete - spiral

What color are the gram positive bacteria on gram stain?

Can you give some examples of Gram + and Gram – BACTERIA? Gram positiveGram negative

Can you give some examples of Gram + and Gram – BACTERIA? Gram positive  Staphylococcus  Streptococcus  Enterococcus  Clostridium Gram negative  E. coli  Klebsiella  Hemophilus  Pseudomonas  Niesseria

Classification of Bacteria Typical BacteriaAtypical Bacteria Gram + Gram - CocciRod Staphylococcus Streptococcus Enterococcus Clostridium (anaerobic) CocciRod Niesseria StraightCurved E.coli Salmonella /Shigella Proteus / Enterobacter Klebsiella Hemophilus Bordetella Pseudomonas Bacteroides (anaerobic) Vibrio Campylobacter Helicobacter Spiral Treponema Acid fast No cell wall Intracellular Rickettsia Chlamydia Mycoplasma Mycobacterium

Protozoans  Examples:  Plasmodium: malaria  Entamoeba histolytica: dysentery and liver abscesses  Giardia intestinalis: diarrhea  Trichimonal vaginalis: STI

Types of Antibiotics  Beta-Lactams  Sulpha drugs  Fluroquinolones  Aminoglycocides  Tetracyclines  Macrolides

Beta-Lactam Antibiotics  Detects peptidogylcan which is a part of the cell wall  Gram positive = thick peptidoglycan layer  Gram negative = thin petidoglycan layer  Inhibit the synthesis of peptidoglycan cell wall of bacteria  The peptidoglycan layer is important in cell wall structure, especially in Gram positive bacteria  Can you give some examples of beta-lactam antibiotics?

Beta-Lactam Antibiotics  Types of beta-lactam antibiotics  Penicillins  Cepalosporins

Penicillins  There are different kinds of penicillins  Each kind has slightly different bacterial coverage  Can you give me some names of penicillins that you have heard of?

Penicillins  Natural penicillins  Penicillin G (IM or IV)  Penicillin V (PO)  What bacteria do the natural penicillins cover?

Penicillins  Natural penicillins  Penicillin G (IM or IV)  Penicillin V (PO)  What bacteria does it cover?  Some Gram +  Streptococci  Enterococci  Few Gram -  Neisseria

Penicillins  Aminopenicillins  Ampicillin  Amoxicillin  What bacteria does it cover?

Penicillins  Aminopenicillins  Ampicillin  Amoxicillin  What bacteria does it cover?  Some Gram +  Streptococcus  Enterococci  More Gram – than natural penicillins  E. Coli, Salmonella, Shigella, Hemophilus

Penicillins  Anti-staphylococcal penicillins  Cloxacillin  Methicillin  What bacteria does it cover?

Penicillins  Anti-staphylococcal penicillins  Cloxacillin  Methicillin  What bacteria does it cover?  More Gram +  Staphylococcus  Streptococcus  No enterococcus  No Gram - coverage

Penicillins  Extended Spectrum  Piperacillin  What bacteria does it cover?

Penicillins  Extended Spectrum  Piperacillin  What bacteria does it cover?  Some Gram +  Streptococcus  Enterococcus  Staphylococcus if tazobactam added  Most Gram –  E. coli, Klebsiella, Proteus, Pseudomonas  Anaerobic bacteria

Cephalosporins  Divided into 4 generations  As generation increases  Decreasing Gram + activity  Increasing Gram – activity  3 rd generation cephalosporins can penetrate the CNS (so use these for meningitis)  What cephalosporin antibiotics do you know?

Cephalosporins: Examples  1 st generation  Cefalexin, Cephalothin, Cefazolin, Cefadroxil  2 nd generation  Cefuroxime, Cefaclor, Cefprozil, Cefoxitin  3 rd generation  Ceftriaxone, Ceftazidime, Cefotaxime, Cefixime

1 st gen.2 nd gen3 rd gen Gram +StaphYY StrepYYY Gram -ProteusYYY E. coliYYY KlebsiellaYYY HemophilusYY EnterobacterYY NeisseriaYY Pseudomonas(Y) Cephalosporin coverage

Trimethoprim-Sulfamethoxazole  What bacteria does it cover?

Trimethoprim-Sulfamethoxazole  Gram positive  Staphylococcus  Weak Streptococcus coverage  Gram negatives  E. coli, Klebsiella, Proteus  Salmonella, Shigella  Hemophilus  Side effects: Rash, allergy, Bone marrow suppression

Fluoroquinolones  2 types  Ciprofloxacin  Good Gram -  Good atypical coverage: Mycoplasma, Chlamydia  No Gram +  Respiratory Fluoroquinolones (levofloxacin, moxifloxacin)  Good Gram –  Better Gram +, especially Streptococcus  Moxifloxacin also good for anaerobes  Good antibiotic choice for respiratory infections

Aminoglycosides  Gentamicin, Tobramycin  Activity  Good Gram –  No Gram + or Anaerobic coverage  Side effects  Hearing loss (permanent)  Renal failure (reversible)

Tetracyclines  Tetracycline, Doxycycline  Activity  Better Gram + than Gram –  Good for atypical bacteria: Rickettsia, Chlamydia  Good for protozoans: Plasmodium, Entamoeba  In children (<8 years old) can cause permanent teeth staining

Macrolides  Erythromycin, Clarithromycin, Azithromycin  Activity  Some Gram +: Streptococci  Some Gram -: Hemophilus, Neisseria, Campylobacter  Atypicals: Mycoplasma, Chlamydia, Rickettsia  Mostly for respiratory and soft tissue infections

Antibiotics against anaerobes  Clindamycin  Good Gram positive coverage:  Staphylococcus  Streptococcus  Good Gram negative anaerobic coverage:  Bacteroides  Poor Gram negative aerobic coverage  Used for:  Skin and soft tissue infections  Pelvic and Intraabdominal infections (in combination with other antibiotics that cover Gram negative bacteria)

Antibiotics against anaerobes  Metronidazole  Good anaerobic coverage  Bacteroides, Clostridium  Good protozoal coverage  Entamoeba, Giardiasis  Use: Intraabdominal and pelvic infections (in combination with other antibiotics to cover anaerobic Gram -)  Good for Clostridium difficile (diarrheal infection especially in patients who have received antibiotics for another reason)

Chloramphenicol  Activity  Gram +: Staphylococci, Streptococci, Clostridium  Gram -: Hemophilus, Neisseria, E. coli, Vibrio, Salmomella  Side effects  Bone marrow toxicity; Pancytopenia  Common uses  Typhoid fever  Scrub typhus / Rickettsia  Meningitis

Summary Antibiotics should be chosen based on what the most likely bacteria are causing the disease and what antibiotics will target those bacteria

Case 1  Diagnosis?  Common Bacteria?

Case 1  Diagnosis?  Common Bacteria?  Streptococci  Staphylococci  Treatment ?

Case 1  Diagnosis?  Common Bacteria?  Streptococci  Staphylococci  Treatment ?  Penicillins  Amoxicillin  Cloxacillin  1 st gen cephalosporin

Case 2: Meningitis  What are common bacteria?

Case 2: Meningitis  What are common bacteria?  Streptococcus pneumoniae  Neisseria meningitidis  Hemophilus influenzae  Listeria monocytogenes  Treatment ?

Case 2: Meningitis  What are common bacteria?  Streptococcus pneumoniae  Neisseria meningitidis  Hemophilus influenzae  Listeria monocytogenes  Treatment ?  High dose Ceftriaxone (2g IV q12 h)  Add Ampicillin if age > 50 for Listeria

Case 2: Quality Assurance  A 20year old male presents with fever, chills, severe headache, and neck stiffness  He traveled 6 hours to get to the hospital  When he arrives, he is drowsy and BP is 100/60. He waits in the emergency room for another 2 hours  A medical student sees him first, but is not sure what to do, so waits to discuss with the teacher who arrives 1 hour later  In the meantime, the patient becomes hypotensive, has a seizure, and loses consciousness

Case 2: Quality Assurance  Why did the patient deteriorate so quickly?

Case 2: Quality Assurance  Why did the patient deteriorate so quickly?  Delaying antibiotics in meningitis increases risk of death and irreversible neurologic deficits

Case 2: Quality Assurance  What could have been done differently to improve patient care?  By the student?  By the teacher?  By the hospital/ health care system?

Case 3  Probable Diagnosis?

Case 3  Probable Diagnosis?  Lobar Pneumonia  Common bacteria?

Case 3  Common bacteria?  Streptococcus pneumoniae  Mycoplasma, Chlamydia  Hemophilus (if chronic lung disease)  Treatment ?  Outpatients  In patients

Case 3  Common bacteria?  Streptococcus pneumoniae  Mycoplasma, Chlamydia  Hemophilus (if chronic lung disease)  Treatment ?  Outpatients  Doxycycline  Amoxicillin  2 nd gen cephalosporin  In patients  Ceftriaxone + macrolide  Levofloxacin or Moxifloxacin

Case 4: Urinary Tract Infection  What are common bacteria?

Case 4: Urinary Tract Infection  What are common bacteria?  E. coli** (Most common)  Proteus  Klebsiella  Treatment?

Case 4: Urinary Tract Infection  What are common bacteria?  E. coli** (Most common)  Proteus  Klebsiella  Treatment ?  TMP-SMX  Ciprofloxacin  Amoxicillin/Clavulanate  Ceftriaxone if severe  Aminoglycosides if severe

Case 5: Bloody Diarrhea  Common bacteria?

Case 5: Bloody Diarrhea  Common bacteria?  Salmonella  Shigella,  Campylobacter  E. coli  These are all Gram negatives  Treatment ?

Case 5: Bloody Diarrhea  Salmonella  Fluoroquinolone, Ceftriaxone  More resistance to TMP-SMX, Macrolides, and Amoxicillin  Shigella  Fluoroquinolone, Ceftriaxone  More resistance to TMP-SMX, Macrolides, and Amoxicillin  Campylobacter  Fluoroquinolone  All are resistant to TMP-SMX, Penicillins, and Cephalosporins  E. coli  No antibiotics

Case 6  Diagnosis?

Case 6  Diagnosis?  Bacteria?  Scrub typhus  Rickettsia family  Treatment ?

Case 6  Diagnosis?  Bacteria?  Scrub typhus  Rickettsia family  Treatment ?  Doxycycline  Chloramphenicol  Tetracycline

Case 7  Patient presents with:  Fever, Relative bradycardia  Develops abdominal pain and rash  Diagnosis?

Case 7  Patient presents with:  Fever, Relative bradycardia  Develops abdominal pain and rash  Diagnosis?  Bacteria?  Salmonella typhi (Gram negative)  Treatment ?

Case 7  Patient presents with:  Fever, Relative bradycardia  Develops abdominal pain and rash  Diagnosis?  Bacteria?  Salmonella typhi (Gram negative)  Treatment ?  Ciprofloxacin  Ceftriaxone

Post Test  Which statements are true about E.coli? a)It is a Gram positive bacteria. b)It is a Gram negative bacteria. c) It is a bacteria normally found in the colon. d)It is the most common cause of a UTI. e)It can cause diarrhea.

Post Test  A 6 year old boy has high volume watery diarrhea that looks like ‘rice in water’. He is dehydrated. You resuscitate him with IV normal saline. What is the best antibiotic treatment? a)Penicillin G or Penicillin V b)Ampicillin or Amoxicillin c)Doxycycline or Erythromycin d)Cefalexin or Cefazolin

Post Test  A 3-year old child is brought to the emergency. The child is irritable and complains of a headache. On exam, the child has a fever of 39ºC and has neck stiffness. You are worried about meningitis. What antibiotic should you consider? a)Metronidazole b)Ciprofloxicillin c)Cefazolin d)Cloxicillin e)Ceftriaxone

Post Test  What statements are true about rickettesia? a)Typhus fever is caused by rickettesia. b)Rickettesia is an atypical bacteria. c)Rickettesia can be treated with doxycycline. d)Rickettesia can be treated with tetracycline. e)Rickettesia can be treated with chloramphenicol.

Post Test  A 20-year old male comes in with 2 week history of general malaise and recurrent fever. He recently developed a papular rash on his chest. His abdomen is tender and distended. The patient should be treated with: a)Ampicillin for a probable UTI. b)Levofloxacin for a probable lobar pneumonia. c)Cloxicillin for a probable Staphylococcus rash. d)Ceftriaxone for probable Salmonella typhi. e)No antibiotics.

Questions