II. Definitions

  1. Antibiotic
    1. Substances that selectively kill or inhibit Microorganisms
    2. Targets specific to Microbes include Bacterial cell walls, cell membrane, and 30S or 50S ribosomal subunits
    3. Most Antibiotics are either naturally produced by Microorganisms, or their synthetic derivatives
  2. Bacteriocidal Antibiotic
    1. Bacteriocidal Antibiotics kill Bacteria
  3. Bacteriostatic Antibiotic
    1. Bacteriostatic Antibiotics inhibit Bacterial proliferation and spread, but do not kill the Bacteria
    2. Often works in concert with the Immune System, which subsequently kills Bacteria
  4. Minimum Inhibitory Concentration (MIC)
    1. Minimum concentration of an Antibiotic in a culture medium that will suppress Bacterial growth
    2. MIC cutoffs vary by organism and by Antibiotic, and are typically categorized as susceptible, intermediate or resistant
    3. One drug's lower MIC values than another drug, does not imply greater efficacy
    4. (2024) Presc Lett 31(1): 2-3
  5. Minimum Bactericidal Concentration (MBC)
    1. Antibiotic concentration killing 99.9% of Bacterial inoculum (Microbes in culture)

III. Mechanism: Bacterial Cell Wall Inhibitors (Beta Lactams)

  1. General: Beta Lactam
    1. Transpeptidase cross-links peptidoglycan mesh in the synthesis of the Bacterial cell wall
      1. Beta-Lactam's inhibition of Transpeptidase results in lysis and death of the Bacterial cell
    2. Beta-Lactams are inactivated by the enzyme Beta-Lactamase
      1. Beta-Lactamase is produced by beta-lactam resistant Bacteria
    3. Beta-Lactamase inhibitors have been developed to counter Beta Lactam resistance
      1. Amoxicillin-clavulanic acid (Augmentin)
      2. Ampicillin-Sulbactam (Unasyn)
      3. Ceftazidime-Avibactam
  2. Penicillins
    1. Natural Penicillins (e.g. Penicillin V) and semisynthetic Penicillins (e.g. Benzathine Penicillin)
      1. Cover Streptococci and Anaerobes
    2. Penicillinase-Resistant Semisynthetic Penicillin (e.g. Dicloxacillin, Nafcillin)
      1. Cover streptococci and MSSA (Methicillin-Sensitive Staphylococcus Aureus)
    3. Aminopenicillins (e.g. Amoxicillin, Augmentin)
      1. Cover streptococci and Gram Negative Bacteria
    4. Extended Spectrum Penicillin (e.g. Piperacillin Tazobactam)
      1. Cover streptococci, Gram Negatives and Pseudomonas
  3. Cephalosporins
    1. First Generation Cephalosporins (Cephalexin, Cefazolin)
      1. Covers Gram Positive Cocci (Streptococcus and MSSA), EKP Gram Negative Bacteria
    2. Second Generation Broad-spectrum Cephalosporins (e.g. Cefuroxime )
      1. Covers Gram Positive Cocci, EKP Gram Negative Bacteria, Haemophilus Influenzae
    3. Second Generation Anti-anaerobe Cephalosporins (e.g. Cefotetan, Cefoxitin)
      1. Covers Gram Positives, Gram Negatives, Bacteroides fragilis
    4. Third Generation Broad-Spectrum Cephalosporins (e.g. Ceftriaxone, Cefixime, Cefdinir)
      1. Covers Gram Positive Cocci, EKP and ESP Gram Negative Bacteria
    5. Third Generation Anti-Pseudomonal Cephalosporins (e.g. Ceftazidime)
      1. Covers EKP and ESP Gram Negative Bacteria, Pseudomonas
      2. Poor Gram Positive Cocci coverage, and no Coccobacilli coverage
    6. Fourth Generation Cephalosporins (e.g. Cefepime)
      1. Adds to broad spectrum third generation (broad spectrum Gram-positive and Gram-negative organisms)
      2. Additionally covers Beta-Lactamase resistant organisms and Pseudomonas
    7. Fifth Generation Cephalosporins (e.g. Ceftaroline)
      1. Adds to broad spectrum third generation (broad spectrum Gram-positive and Gram-negative organisms)
      2. Covers Pseudomonas and MRSA (Methicillin Resistant Staphylococcus Aureus)
  4. Other Bacterial Cell Wall Inhibitors
    1. Carbapenems (e.g. Meropenem, Ertapenem)
      1. Cover Gram Positive Bacteria, Gram Negative Bacteria and Anaerobic Bacteria
    2. Monolactams (e.g. Aztreonam)
      1. Cover Gram Negative aerobic Bacteriaa
    3. Lipopeptides (e.g. Daptomycin)
      1. Covers MRSA, Streptococcal Species, Vancomycin Sensitive Enterococcus

IV. Mechanism: DNA Inhibitors (Antimetabolites)

  1. Fluoroquinolone
    1. First Generation Quinolones (Nalidixic Acid)
      1. Gram Negative Rod efficacy (no Pseudomonas coverage)
    2. Second Generation Quinolones (e.g. Ciprofloxacin )
      1. Covers Aerobic Gram Negative Rods (including Pseudomonas), and some Gram Positive coverage
    3. Third Generation Quinolones (e.g. Levofloxacin)
      1. Covers Gram Negative Rods, with greater Gram Positive Cocci coverage
    4. Fourth Generation Quinolones (e.g. Trovafloxacin)
      1. Covers Gram Negative Rods, Gram Positive Cocci and Anaerobes
  2. Sulfonamides (Inhibit DNA, as well as RNA and Protein synthesis)
    1. Trimethoprim Sulfamethoxazole (Bactrim, Septra)
      1. Covers enteric Gram Negative Bacteria (Urinary Tract Infections) and some Gram Positive organisms
      2. Also used in PCP Pneumonia treatment and prophylaxis (AIDS) and MRSA Skin Infections
    2. Other Sulfonamides
      1. Sulfadiazine (Toxoplasmosis prophylaxis)
      2. Sulfisoxazole (UTI prophylaxis)
  3. Other DNA Inhibitors
    1. Metronidazole
      1. Covers Anaerobes (e.g. Bacteroides, Peptococcus, Clostridioides difficile)
    2. Nitrofurantoin
      1. Covers many urinary pathogens (but NOT Pseudomonas, Klebsiella, Proteus Serratia or Acinetobacter)
    3. Rifamycin (e.g. Rifampin)
      1. Covers Mycobacterium (esp. Tuberculosis as part of multi-drug regimen)

V. Mechanism: Protein Synthesis Inhibitors (at 30s or 50s ribosome)

  1. Macrolides
    1. Erythromycin
      1. Covers Bacteria without cell walls (Mycoplasma, Legionella, Chlamydia)
      2. Covers Aerobic Bacteria, Gram Positive Aerobes, Gram Negative Aerobes (except Campylobacter, Pasteurella)
    2. Extended Spectrum Macrolides (e.g. Azithromycin, Clarithromycin)
      1. Coverage includes organisms covered by Erythromycin
      2. Cover Chlamydia Trachomatis, Non-tuberculous Mycobacteria, Helicobacter and some respiratory infections
    3. Fidaxomicin (Dificid)
      1. Narrow spectrum Antibiotic (C. difficile, Staphylococcus, Enterococcus)
      2. Minimal systemic absorption when taken orally
  2. Tetracyclines (e.g. Doxycycline)
    1. Cover MRSA, Helicobacter Pylori, Tick-borne illness (e.g. Lyme Disease), STDs (e.g. Chlamydia Trachomatis)
  3. Aminoglycosides (e.g. Gentamicin)
    1. Cover aerobic and facultative Gram Negative Rods (including Pseudomonas)
    2. NO anaerobic activity
  4. Other Protein Synthesis Inhibitors
    1. Chloramphenicol
      1. Bacteriostatic activity against Gram Positives, Gram Negatives and Anaerobic Bacteria
    2. Linezolid
      1. Bacteriostatic against VRE, MRSA and bactertiocidal against Streptococcus species
    3. Clindamycin
      1. Covers Anaerobes and Gram Positive Bacteria (including MRSA coverage, but with high risk of resistance)

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Related Studies

Ontology: Antibiotics (C0003232)

Definition (HL7V3.0) <p><b>Description:</b>Non-person living subject used as antibiotic.</p><p><b>Examples:</b>Bacteriophage, is a virus that infects bacteria.</p>
Definition (MEDLINEPLUS)

Antibiotics are powerful medicines that fight bacterial infections. Used properly, antibiotics can save lives. They either kill bacteria or keep them from reproducing. Your body's natural defenses can usually take it from there.

Antibiotics do not fight infections caused by viruses, such as

  • Colds
  • Flu
  • Most coughs and bronchitis
  • Sore throats, unless caused by strep

If a virus is making you sick, taking antibiotics may do more harm than good. Each time you take antibiotics, you increase the chances that bacteria in your body will be able to resist them. Later, you could get or spread an infection that those antibiotics cannot cure. Methicillin-resistant Staphylococcus aureus (MRSA) causes infections that are resistant to several common antibiotics.

When you take antibiotics, follow the directions carefully. It is important to finish your medicine even if you feel better. If you stop treatment too soon, some bacteria may survive and re-infect you. Do not save antibiotics for later or use someone else's prescription.

Centers for Disease Control and Prevention

Definition (NCI) Substances naturally produced by microorganisms or their derivatives that selectively target microorganisms not humans. Antibiotics kill or inhibit the growth of microorganisms by targeting components of the microbial cell absent from human cells, including bacterial cell walls, cell membrane, and 30S or 50S ribosomal subunits. These substances are used in the treatment of bacterial and other microbial infections.
Definition (NCI_NCI-GLOSS) A substance that kills microorganisms such as bacteria or mold, or stops them from growing and causing disease.
Definition (MSH) Substances produced by microorganisms that can inhibit or suppress the growth of other microorganisms.
Definition (CSP) substances produced by microorganisms or biomimetics that can inhibit or suppress the growth of other microorganisms; frequently used without reference to the microbial origins of the original substance.
Concepts Antibiotic (T195)
MSH D000900
SnomedCT 41000005, 255631004
HL7 ANTIBIOT
LNC LP31426-7
French Médicaments antibiotiques, Agents antibiotiques, Antibiotiques
Czech antibiotika
Portuguese Antibióticos
Spanish Antibióticos, antibiótico (sustancia), antibiótico (concepto no activo), antibiótico (producto), antibiótico
German Antibiotika
Italian Antibiotici
English antibiotic products, antibiotics, Antibiotic (substance), Antibiotic, Antibiotic (product), antibiotic, drug, antibiotic, Antibiotic, NOS, Antibiotic Agents, Antibiotic Drugs, Antibiotics

Ontology: Anti-Bacterial Agents (C0279516)

Definition (NCI_NCI-GLOSS) A substance that kills bacteria or stops them from growing and causing disease.
Definition (NCI) A family of substances capable of destroying or inhibiting the growth of bacteria.
Definition (MSH) Substances that reduce the growth or reproduction of BACTERIA.
Definition (CSP) substance that destroys bacteria or prevents their growth or replication.
Concepts Antibiotic (T195)
MSH D000900
SnomedCT 28320003, 283019008, 346325008, 419241000
Spanish agente antibacteriano (sustancia), agente antibacteriano, Antibacterianos, Agentes Antibacterianos, Fármacos Antibióticos, Medicamentos Antibióticos, Fármacos Antibacterianos, drogas antibacterianas (producto), drogas antibacterianas (sustancia), drogas antibacterianas, fármaco antibacteriano (producto), fármaco antibacteriano
French Antibactériens, Anti-bactériens, Médicaments antibactériens, Agents antibactériens
Swedish Antibakteriella medel
English ANTIBACTERIAL AGENTS, antibacterial agents (medication), antibacterial agents, Antibacterial Agent, Antibacterial Agent [TC], antibacterial, antibacterials, antibacterial drug, anti-bacterial agents, antibacterial drugs, Antibacterial drugs (substance), Agents, Antibacterial, Anti Bacterial Agents, Antibacterial Agents, Agents, Anti-Bacterial, Antibacterial drugs, Antibacterial drugs (product), antibacterial agent, Antibacterial, NOS, Anti-Bacterial Agents, Antibacterials, Antibacterial, Antibacterial agent (substance), Antibacterial agent
Czech antibakteriální látky
Finnish Bakteerilääkkeet
Russian TETRATSIKLINOVYE ANTIBIOTIKI, ANTIBIOTIKI AMINOGLIKOZIDNYE, ANTIBIOTIKI PEPTIDNYE, ANTIBIOTIKI GLIKOZIDNYE, AMINOGLIKOZIDNYE ANTIBIOTIKI, ANTIBIOTIKI MAKROLIDNYE, ANTIMIKOBAKTERIAL'NYE SREDSTVA, ANTIBIOTIKI BETA-LAKTAMNYE, ANTIBIOTIKI LAKTAMNYE, GLIKOZIDNYE ANTIBIOTIKI, MAKROLIDNYE ANTIBIOTIKI, PEPTIDNYE ANTIBIOTIKI, ANTIBIOTIKI, ANTIBIOTIKI GLIKOPEPTIDNYE, ANTIBAKTERIAL'NYE SREDSTVA, ANTIBIOTIKI TETRATSIKLINOVYE, BETA-LAKTAMNYE ANTIBIOTIKI, АМИНОГЛИКОЗИДНЫЕ АНТИБИОТИКИ, АНТИБАКТЕРИАЛЬНЫЕ СРЕДСТВА, АНТИБИОТИКИ, АНТИБИОТИКИ АМИНОГЛИКОЗИДНЫЕ, АНТИБИОТИКИ ГЛИКОЗИДНЫЕ, АНТИБИОТИКИ МАКРОЛИДНЫЕ, АНТИБИОТИКИ ТЕТРАЦИКЛИНОВЫЕ, АНТИМИКОБАКТЕРИАЛЬНЫЕ СРЕДСТВА, ГЛИКОЗИДНЫЕ АНТИБИОТИКИ, МАКРОЛИДНЫЕ АНТИБИОТИКИ, ТЕТРАЦИКЛИНОВЫЕ АНТИБИОТИКИ, АНТИБИОТИКИ БЕТА-ЛАКТАМНЫЕ, АНТИБИОТИКИ ЛАКТАМНЫЕ, БЕТА-ЛАКТАМНЫЕ АНТИБИОТИКИ, АНТИБИОТИКИ ГЛИКОПЕПТИДНЫЕ, АНТИБИОТИКИ ПЕПТИДНЫЕ, ПЕПТИДНЫЕ АНТИБИОТИКИ
Japanese 抗細菌剤, 抗生物質, 抗生剤, 抗生物質-ペプチド系, ペプチド系抗生物質
Croatian ANTIBAKTERIJSKI LIJEKOVI
Polish Leki przeciwbakteryjne, Antybiotyki, Środki przeciwbakteryjne
Portuguese Antibacterianos, Fármacos Antibióticos, Medicamentos Antibióticos, Fármacos Antibacterianos, Agentes Antibacterianos
Norwegian Antibiotika
German Antibakterielle Mittel
Italian Agenti antibatterici

Ontology: antibiotic with bacteriostatic action (C0280050)

Concepts Pharmacologic Substance (T121)
English antibiotic with bacteriostatic action

Ontology: Minimum bactericidal concentration (C0427975)

Concepts Laboratory or Test Result (T034)
SnomedCT 250478006, 385465001
English MBC - Minimum bactericidal concentration, MBC-Min bactericidal concentr, Min bactericidal concentration, Minimum bactericidal concentration, Minimum bactericidal concentration (procedure), Minimum bactericidal concentration finding (finding), Minimum bactericidal concentration finding
Spanish concentración bactericida mínima - hallazgo (hallazgo), concentración bactericida mínima - hallazgo

Ontology: Minimum Inhibitory Concentration measurement (C0427978)

Definition (HL7V3.0) <p>Testing to measure the minimum concentration of the antibacterial agent in a given culture medium below which bacterial growth is not inhibited.</p>
Concepts Laboratory Procedure (T059)
MSH D008826
SnomedCT 39334004
HL7 0272
LNC LP6389-3
English Concentration, Minimum Inhibitory, Concentrations, Minimum Inhibitory, Inhibitory Concentration, Minimum, Inhibitory Concentrations, Minimum, Minimum Inhibitory Concentrations, MIC, minimum inhibitory concentration, Antibiotic sensitivity, minimum inhibitory concentration (MIC), MIC - Minimum inhibitory concentration, Minimum inhibitory concentration, Broth microdilution susceptibility test (procedure), Broth microdilution susceptibility test, MIC susceptibility test, Broth microdilution susceptibility test, NOS, MIC susceptibility test, NOS, Minimum Inhibitory Concentration measurement, Minimum Inhibitory Concentration
French CMI (Concentration Minimale Inhibitrice), Concentration minimale inhibitrice, CIM (Concentration Inhibitrice Minimale), Concentration inhibitrice minimale
Japanese サイショウハツイクソシノウド, 最小発育阻止濃度
Portuguese Concentração Inibitória Mínima, Concentração inibidora mínima
Spanish Concentración Inhibitoria Mínima, antibiograma CIM, antibiograma, concentración inhibitoria mínima (CIM) (procedimiento), antibiograma, concentración inhibitoria mínima (CIM), prueba de sensibilidad en caldo de microdilución antibiótica, Concentración mínima inhibitoria
German Minimale Hemmkonzentration, minimale Hemmkonzentration
Italian Concentrazione minima inibitoria
Czech Minimální inhibiční koncentrace
Hungarian Minimum inhibitoros koncentráció (MIC)
Norwegian Minimal inhibitorisk konsentrasjon, MIC
Dutch minimale inhiberende concentratie, Minimum-inhibitieconcentratie

Ontology: Bacteriocidal Agents (C1258056)

Definition (MSH) Substances that kill BACTERIA.
Concepts Antibiotic (T195)
MSH D000900
French Médicaments bactéricides, Bactéricides, Agents bactéricides
Czech baktericidní látky
German Bakterizide Mittel
Italian Battericidi, Agenti battericidi
English Agents, Bacteriocidal, Bacteriocides, Bacteriocidal Agents