PHARM ABX STUDY GUIDE MODULE 3 STUDY GUIDE | TERMS
& DEFINITIONS | 100% CORRECT | THE ULTIMATE STUDY
GUIDE FOR YR. (2026/2027)
Chapter 23: Bacterial Infections
• Antimicrobial resistance o Contributing factors:
Increase in immunocompromised patients
Increase in invasive medical procedures
Increase in patients with chronic diseases o Risk factors:
Recent use of antibiotics
Age < 2 years or > 65 years
Day-care attendance
Exposure to young children
Multiple medical comorbidities
Recent hospitalization
Immunosuppression o Stewardship strategies:
Treatment pathways for infectious diseases
Formulary restrictions
Dose optimization
Prospective audits of prescribed antimicrobials
Continued education for prescribers o CDC Core Elements of Abx
stewardship:
Includes – outpatient, nursing homes, and hospitals
1.) Commitment – dedication to & accountability for optimizing Abx
prescribing and patient safety
2.) Action for policy and practice – implement at least 1 policy or practice
to improve Abx prescribing, assess if it is working and modify as needed
3.) Tracking and reporting – monitor Abx prescribing and offer regular
feedback to clinicians or have clinicians self-assess their Abx prescribing
practices
4.) Education and expertise – provide educational resources to clinicians
and patients on Abx prescribing and ensure access to needed expertise
• PENICILLINS
o Most effective against rapidly growing organisms forming cell walls o
Penicillins:
6-aminopenicillanoc acid joined to the beta-lactam ring
Subclasses:
• 1.) penicillinase-sensitive or natural penicillins
• 2.) amino penicillins
,• 3.) penicillinase-resistant or antistaphylococcal penicillins
• 4.) antipseudomonal or extended-spectrum penicillins
Pharmacodynamics:
• Hinder bacterial growth by inhibiting the biosynthesis of a bacterial cell
wall mucopeptide (murein or peptidoglycan)
o Penicillin:
Natural penicillins:
Administration:
o PO – penicillin V
o IM – procaine penicillin & benzathine penicillin o IV –
penicillin G
Bacteria against:
Aerobic, gram positive organisms:
o Streptococcus (S. pneumoniae & group A beta-hemolytic
Streptococcus, some Enterococcus strains and some
nonpenicillinase-producing staphylococci)
• Pasteurella multocida
• Actinomyces
• Clostridium
• Peptostreptococcus
• Treponema pallidum
• Group A streptococci & Group B streptococci
• Listeria monocytogenes – Penicillin G o NOT effective against
Neisseria gonorrhoeae or
Staphylococcus (resistant)
Resistance:
• Penicillin-resistant strains are commonly resistant to: (often called
drug resistant S. pneumoniae) o Cephalosporins o Macrolides
o Sulfonamides o Clindamycin (lesser extent)
o Aminopenicillins:
Bacteria against:
Gram positive organisms (Streptococcus and Enterococcus)
Gram negative bacteria:
o Greater activity d/t their ability to penetrate the outer
membrane of these organisms
• Methicillin-susceptible Staphylococcus aureus (MSSA)
• Moraxella catarrhalis
• Haemophilus influenzae
• Neisseria meningitidis
• Salmonella
, • Some Shigella, Pasteurella multocida, Actinomyces, Clostridium,
Peptostreptococcus, and Bacteroides fragilis o NOT effective
against E. coli, Klebsiella & Proteus mirabilis
Examples:
• Ampicillin
• Amoxicillin
Beta-lactamase
• Increased beta-lactamase production
• Often combined with beta-lactamase inhibitors – clavulanic acid
and sulbactam o Enhances gram-negative and anaerobic activity
Beta-lactamase inhibitors:
o Prevent destruction of beta-lactamase Abx by serving as a
competitive inhibitor of beta-lactamase o Poor antimicrobial activity
alone
o Penicillinase-resistance penicillins:
Examples: (antistaphylococcal penicillins)
• Nafcillin
• Oxacillin Dicloxacillin (PO) Bacteria against:
• Streptococcus species
• MSSA
• Some coagulase-negative staphylococci and
Peptostreptococcus o NOT effective against Enterococcus, Listeria,
gramnegative bacteria, and most anaerobes Resistance by
staphylococci:
• Mediated via mecA gene, which encodes the low-affinity
PBP2a
• Will manifest as MRSA and MRSE
• Methicillin resistant strains of staphylococci are resistant
to all penicillins, cephalosporins & carbapenems (except Ceftaroline)
o Antipseudomonal penicillins
Comprised of Piperacillin combined with a beta-lactamase inhibitor,
tazobactam
• Ex: Piperacillin/tazobactam
Bacteria against:
• Gram-negative bacilli o
Pseudomonas aeruginosa o
Enterobacter o Morganella o
E. coli o Klebsiella o Proteus
mirabilis
, • Retains activity against
Ampicillin-sulbactam-susceptible
organisms
Administration – IV
o Resistance:
Due to:
Inactivation by beta-lactamases o
Most common mechanism
Include – penicillinases, cephalosporinases, &
carpapenemases
• Alteration in target PBPs
• Alteration in the outer membrane of cell wall that decreases
permeability to the site of action
o Pharmacokinetics:
Absorption and distribution
• Absorption depends on structure of Abx, pH of stomach, and
presence of food
• Well-absorbed from GI tract
• Higher doses cause GI distress and diarrhea
• Amoxicillin more completely absorbed than ampicillin o Should
be used for oral administration
• Cross the placenta and enter breast milk
Metabolism and excretion
• Primarily excreted as unchanged drugs in the urine o Excluding
nafcillin and oxacillin
• Renal excretion is by active tubular secretion
• Probenecid – prolongs the half-life and raises the peak plasma
concentrations o Can be given concurrently to treat more
serious infections Renal insufficiency:
o Prolongs the half-life and increases the risk of toxicity
o Precautions and contraindications:
Most common Abx to cause an allergic reaction
• Due to cross-reactivity Contraindications:
• Severe type 1 allergic reaction to cephalosporins,
carbapenems, or beta-lactamase inhibitors Piperacillin:
• May induce hemorrhagic manifestations
• Caution with – anemia, thrombocytopenia,
granulocytopenia, or bone marrow depression Pregnancy:
• Category B
& DEFINITIONS | 100% CORRECT | THE ULTIMATE STUDY
GUIDE FOR YR. (2026/2027)
Chapter 23: Bacterial Infections
• Antimicrobial resistance o Contributing factors:
Increase in immunocompromised patients
Increase in invasive medical procedures
Increase in patients with chronic diseases o Risk factors:
Recent use of antibiotics
Age < 2 years or > 65 years
Day-care attendance
Exposure to young children
Multiple medical comorbidities
Recent hospitalization
Immunosuppression o Stewardship strategies:
Treatment pathways for infectious diseases
Formulary restrictions
Dose optimization
Prospective audits of prescribed antimicrobials
Continued education for prescribers o CDC Core Elements of Abx
stewardship:
Includes – outpatient, nursing homes, and hospitals
1.) Commitment – dedication to & accountability for optimizing Abx
prescribing and patient safety
2.) Action for policy and practice – implement at least 1 policy or practice
to improve Abx prescribing, assess if it is working and modify as needed
3.) Tracking and reporting – monitor Abx prescribing and offer regular
feedback to clinicians or have clinicians self-assess their Abx prescribing
practices
4.) Education and expertise – provide educational resources to clinicians
and patients on Abx prescribing and ensure access to needed expertise
• PENICILLINS
o Most effective against rapidly growing organisms forming cell walls o
Penicillins:
6-aminopenicillanoc acid joined to the beta-lactam ring
Subclasses:
• 1.) penicillinase-sensitive or natural penicillins
• 2.) amino penicillins
,• 3.) penicillinase-resistant or antistaphylococcal penicillins
• 4.) antipseudomonal or extended-spectrum penicillins
Pharmacodynamics:
• Hinder bacterial growth by inhibiting the biosynthesis of a bacterial cell
wall mucopeptide (murein or peptidoglycan)
o Penicillin:
Natural penicillins:
Administration:
o PO – penicillin V
o IM – procaine penicillin & benzathine penicillin o IV –
penicillin G
Bacteria against:
Aerobic, gram positive organisms:
o Streptococcus (S. pneumoniae & group A beta-hemolytic
Streptococcus, some Enterococcus strains and some
nonpenicillinase-producing staphylococci)
• Pasteurella multocida
• Actinomyces
• Clostridium
• Peptostreptococcus
• Treponema pallidum
• Group A streptococci & Group B streptococci
• Listeria monocytogenes – Penicillin G o NOT effective against
Neisseria gonorrhoeae or
Staphylococcus (resistant)
Resistance:
• Penicillin-resistant strains are commonly resistant to: (often called
drug resistant S. pneumoniae) o Cephalosporins o Macrolides
o Sulfonamides o Clindamycin (lesser extent)
o Aminopenicillins:
Bacteria against:
Gram positive organisms (Streptococcus and Enterococcus)
Gram negative bacteria:
o Greater activity d/t their ability to penetrate the outer
membrane of these organisms
• Methicillin-susceptible Staphylococcus aureus (MSSA)
• Moraxella catarrhalis
• Haemophilus influenzae
• Neisseria meningitidis
• Salmonella
, • Some Shigella, Pasteurella multocida, Actinomyces, Clostridium,
Peptostreptococcus, and Bacteroides fragilis o NOT effective
against E. coli, Klebsiella & Proteus mirabilis
Examples:
• Ampicillin
• Amoxicillin
Beta-lactamase
• Increased beta-lactamase production
• Often combined with beta-lactamase inhibitors – clavulanic acid
and sulbactam o Enhances gram-negative and anaerobic activity
Beta-lactamase inhibitors:
o Prevent destruction of beta-lactamase Abx by serving as a
competitive inhibitor of beta-lactamase o Poor antimicrobial activity
alone
o Penicillinase-resistance penicillins:
Examples: (antistaphylococcal penicillins)
• Nafcillin
• Oxacillin Dicloxacillin (PO) Bacteria against:
• Streptococcus species
• MSSA
• Some coagulase-negative staphylococci and
Peptostreptococcus o NOT effective against Enterococcus, Listeria,
gramnegative bacteria, and most anaerobes Resistance by
staphylococci:
• Mediated via mecA gene, which encodes the low-affinity
PBP2a
• Will manifest as MRSA and MRSE
• Methicillin resistant strains of staphylococci are resistant
to all penicillins, cephalosporins & carbapenems (except Ceftaroline)
o Antipseudomonal penicillins
Comprised of Piperacillin combined with a beta-lactamase inhibitor,
tazobactam
• Ex: Piperacillin/tazobactam
Bacteria against:
• Gram-negative bacilli o
Pseudomonas aeruginosa o
Enterobacter o Morganella o
E. coli o Klebsiella o Proteus
mirabilis
, • Retains activity against
Ampicillin-sulbactam-susceptible
organisms
Administration – IV
o Resistance:
Due to:
Inactivation by beta-lactamases o
Most common mechanism
Include – penicillinases, cephalosporinases, &
carpapenemases
• Alteration in target PBPs
• Alteration in the outer membrane of cell wall that decreases
permeability to the site of action
o Pharmacokinetics:
Absorption and distribution
• Absorption depends on structure of Abx, pH of stomach, and
presence of food
• Well-absorbed from GI tract
• Higher doses cause GI distress and diarrhea
• Amoxicillin more completely absorbed than ampicillin o Should
be used for oral administration
• Cross the placenta and enter breast milk
Metabolism and excretion
• Primarily excreted as unchanged drugs in the urine o Excluding
nafcillin and oxacillin
• Renal excretion is by active tubular secretion
• Probenecid – prolongs the half-life and raises the peak plasma
concentrations o Can be given concurrently to treat more
serious infections Renal insufficiency:
o Prolongs the half-life and increases the risk of toxicity
o Precautions and contraindications:
Most common Abx to cause an allergic reaction
• Due to cross-reactivity Contraindications:
• Severe type 1 allergic reaction to cephalosporins,
carbapenems, or beta-lactamase inhibitors Piperacillin:
• May induce hemorrhagic manifestations
• Caution with – anemia, thrombocytopenia,
granulocytopenia, or bone marrow depression Pregnancy:
• Category B
