Las 7 Pcol

ANTIBACTERIAL
AGENTS
GROUP 7
CASE ONE
A 44- year-old female presented to the hospital 3 days
ago with severe cellulitis and a large abscess on his
left leg. Incision and drainage were performed on the
abscess, and cultures revealed methicillin-resistant
Staphylococcus aureus (MRSA). She is given
Daptomycin once-daily outpatient intravenous therapy
at 6 mg/kg per day
SPECTRUM OF ACTIVITY OF DAPTOMYCIN
Daptomycin is a cyclic lipopeptide antibacterial

agent with a broad spectrum of activity against
Gram-positive bacteria, including methicillin-
susceptible and -resistant Staphylococcus aureus
(MSSA/MRSA) and vancomycin-resistant
Enterococci (VRE).
MOA OF DAPTOMYCIN
Mechanism of action of daptomycin remains poorly

understood
Studies have suggested that it is known to bind to
the cell membrane via calcium-dependent insertion
of its lipid tail which results in depolarization of the
cell membrane with potassium efflux and rapid cell
death.
CLINICAL USES OF DAPTOMYCIN
Daptomycin injection is used to treat

complicated skin and skin structure infections
(cSSSI). It is also used to treat infections in the
bloodstream (bacteremia), including right-
sided infective endocarditis.
MONOTHERAPY FOR MRSA
Preferred agents:
Vancomycin
Daptomycin
Teicoplanin (in areas where available)
Agents warranting further study
Combination therapy of Daptomycin and
ceftaroline.
WHAT SHOULD BE MONITORED WHILE
ON DAPTOMYCIN?
Patients should also receive monitoring for muscle
pain or weakness, new-onset or worsening
peripheral neuropathy, and signs or symptoms of
eosinophilic pneumonia. Furthermore, patients who
develop diarrhea should have testing for C. difficile
infection.
CASE TWO
A 24-year-old female presents with acute appendicitis
that ruptures shortly after admission. She is taken to
the operating room for surgery, and postsurgical
cultures reveal E. coli and B. fragilis, susceptibilities
pending. IV Piperacillin + Tazobactam 4.5 g every 6
hours is given to provide adequate empiric coverage of
these two pathogens.
EMPIRIC ANTIMICROBIAL THERAPY
The empiric antimicrobial property refers to the use of
antibiotics or antimicrobial agents based on empirical
evidence and clinical judgment, without specific
knowledge of the exact causative microorganism. It is
commonly used in situations where a patient presents
with an infection, but the specific pathogen causing the
infection is unknown or has not been identified yet.
CLASSIFY PIPERACILLIN AS TO
SPECTRUM OF ACTIVITY
Piperacillin is a broad-spectrum antibiotic. It belongs to the
class of extended-spectrum penicillins and has activity
against a wide range of bacteria. It is effective against both
Gram-positive and Gram-negative bacteria, including many
strains that are resistant to other penicillins. Piperacillin is
commonly used to treat severe bacterial infections, such as
pneumonia, urinary tract infections, intra-abdominal
infections, and skin and soft tissue infections.
MECHANISM OF ACTION OF PIPERACILLIN
Piperacillin works by binding to and

inhibiting the activity of a group of
enzymes called penicillin-binding
proteins (PBPs).
PIPERACILLIN USED IN FIXED
COMBINATION WITH TAZOBACTAM
to enhance its antibacterial

activity.
FOUR (4) MECHANISM OF RESISTANCE
TO PENICILLIN
inactivation of antibiotic by
B-lactamase
modification of target
PBPs
impaired penetration
of drug to target PBPs
antibiotic efflux
CASE THREE
A 68-year-old male presents from a nursing home
with fever, increased urinary frequency and urgency,
and mental status changes. He is allergic to
penicillin. Aztreonam 500 mg IV every 8 hours is given
as the most appropriate choice for gram-negative
coverage of this patient’s urinary tract infection.
AZETREONAM
Aztreonam is a monocyclic beta-lactam antibiotic
Exhibits a potent and specific activity against a wide
variety spectrum of gram-negative aerobic bacteria
It has no useful activity against gram-positive
bacteria/anaerobes
Aztreonam, unlike the majority of beta-lactam
antibiotics, does not induce beta-lactamase activity
AZETREONAM PHARMACODYNAMICS
Mechanism of Action of this drug is to

inhibits cell wall synthesis by binding to
penicillin binding proteins
AZETREONAM PHARMACOKINETICS
A.) ABSORPTION
best absorbs in IM AND IV administration
B.) DISTRIBUTION
distributes widely to most body fluids and
tissues - cross placenta and enter breast milk
AZETREONAM PHARMACOKINETICS
C.) METABOLISM
metabolized mainly in the liver
D.) ELIMINATION
adults with normal renal function ( 1.7-2.9 hrs)
adults with end stage renal disease (6-8 hrs)
MICROORGANISMS SUSCEPTIBLE TO
AZTREONAM
Acinetobacter anitratus,
Escherichia coli
Pseudomonas aeruginosa
Proteus mirabilis
CLINICAL USES OF AZTREONAM
Treatment of urinary tract
Lower respiratory tract
Intra-abdominal infections
Septicemia
Endometritis
Pelvic cellulitis
ADVERSE EFFECTS
Dermatologic
rash
painful injection site reactions
Gastrointestinal
nausea
vomiting
diarrhea
CASE FOUR
A 21-year-old female presents to the emergency
room with headache, stiff neck, and fever for 2 days
and is diagnosed with meningitis. Cefotaxime
200mg/kg/day IV is given as the best choice for the
treatment of meningitis in this patient.
CLASSIFY CEFOTAXIME. WHAT ARE THE OTHER
CEPHALOSPORINS WITH THE SAME CLASS AS CEFOTAXIME?
Cefotaxime is an antibiotic medication that belongs to the class of

drugs known as cephalosporins.They belong specifically to the third
generation cephalosphorins.
Other cephalosphorins with the same class as cefotaxime include:

Cefoperazone, cefotaxime, ceftazidime, ceftizoxime, ceftriaxone,
cefixime, cefpodoxime proxetil, cefdinir, cefditoren pivoxil, ceftibuten,
and moxalactam.
DISCUSS ITS MECHANISM OF ACTION.
Cefotaxime exerts its mechanism of action by
inhibiting bacterial cell wall synthesis. It achieves
this by binding to bacterial penicillin-binding
proteins (PBPs), particularly transpeptidases, which
are essential enzymes involved in cross-linking the
peptidoglycan strands during cell wall formation.
WHAT ARE THE ADVERSE EFFECTS ASSOCIATED
TO CEPHALOSPORINS?
Cephalosporins may elicit a variety of hypersensitivity

reactions, including anaphylaxis, fever, skin rashes, nephritis,
granulocytopenia, and hemolytic anemia.
Patients with documented penicillin anaphylaxis have an

increased risk of reacting to cephalosporins compared with
patients without a history of penicillin allergy.
WHAT ARE THE ADVERSE EFFECTS ASSOCIATED TO
CEPHALOSPORINS?
Local irritation can produce pain after intramuscular injection

and thrombophlebitis after intravenous injection.
Renal toxicity, including interstitial nephritis and tubular

necrosis, may occur uncommonly.
Cephalosporins that contain a methylthiotetrazole group may

cause hypoprothrombinemia and bleeding disorders.
CASE FIVE
A patient is being discharged from the hospital on a

3-week course of clindamycin.
MOA
antibiotic that works by inhibiting bacterial
protein synthesis.
It binds to the 50S rRNA of the large bacterial
ribosome subunit and prevents the formation of
new protein chains.
This has a bacteriostatic effect, meaning it stops
the growth of bacteria, but does not kill them
directly
CLINICAL USES
serious infections caused by susceptible
anaerobic bacteria, as well as susceptible
staphylococci, streptococci, and pneumococci.
acne vulgaris
bacterial vaginosis in non-pregnant females
used off-label in the treatment of toxoplasmosis,
malaria, and babesiosis.
ADVERSE EFFECTS
Clostridium difficile-associated diarrhea (CDAD)
All healthcare workers who prescribe this agent
should monitor the patient for changes in bowel
frequency, colitis, and resolution of symptoms.
Clindamycin is well known to cause Clostridium
colitis, which extends hospital stays and increases
healthcare costs.
ADVERSE EFFECTS
nausea
vomiting
unpleasant or metallic taste in the mouth
joint pain
pain when swallowing
heartburn
white patches in the mouth
thick, white vaginal discharge
burning, itching, and swelling of the vagina
CASE SIX
A 4-year-old child is brought to the hospital after ingesting
chloramphenicol that a parent had used for bacterial
dysentery when traveling outside the United States. The
child has been vomiting for more than 24 h and has had
diarrhea with green stools. She is now lethargic with an
ashen color. Other signs and symptoms include
hypothermia, hypotension, and abdominal distention.
MOA
Chloramphenicol is an inhibitor of microbial protein
synthesis and is bacteriostatic against most susceptible
organisms. It binds revers-ibly to the 50S subunit of the
bacterial ribosome and inhibits peptide bond formation.
CLINICAL USES OF CHLORAMPHENICOL
Used in the treatment of cholera, as it

destroys the vibrios and decreases the
diarrhea
Management and treatment of superficial eye

infections (bacterial conjunctivitis, otitis
externa)
CHLORAMPHENICOL?
Adults occasionally develop gastrointestinal disturbances,

including nausea, vomiting, and diarrhea. These symptoms are
rare in children.
Oral or vaginal candidiasis may occur as a result of alteration of

normal microbial flora
commonly causes a dose-related revers ible suppression of red

cell production at dosages exceeding 50 mg/kg/d after 1–2
weeks.
CHLORAMPHENICOL?
In infants, it could cause gray baby syndrome, with vomiting,

flaccidity, hypothermia, gray color, shock, and vascular
collapse.
Aplastic anemia, which is an idiosyncratic reaction unrelated to

dose, but usually occurs after prolonged use.
DEFINITION
OF TERMS
Bactericidal
antibiotics kill the bacteria B
Bacteriostatic
antibiotics suppress the growth of bacteria
β-lactam antibiotics
antibiotics that contain a beta-lactam ring in their chemical
structure. This includes penicillin derivatives, cephalosporins
and cephamycins, monobactams, carbapenems and
carbacephem
Beta-lactamases
diverse class of enzymes produced by bacteria that break open the
beta-lactam ring, inactivating the beta-lactam antibiotic
Minimum inhibitory concentration (MIC)
defined as the lowest concentration of an antimicrobial agent that
will inhibit the visible growth of a microorganism after overnight
incubation.
The Minimum Bactericidal Concentration (MBC)
the lowest concentration of an antibacterial agent required to kill a
bacterium over a fixed, somewhat extended period, such as 18 hours
or 24 hours, under a specific set of conditions
Penicillin-binding proteins (PBPs)
Membrane-associated proteins involved in the biosynthesis of
peptidoglycan (PG), the main component of bacterial cell
walls.
Peptidoglycan
An essential component of the bacterial cell envelope that
protects the cell from bursting due to turgor and maintains cell
shape. Composed of glycan chains connected by short
peptides, peptidoglycan forms a net-like macromolecule
around the cytoplasmic membrane.
Selective toxicity
The ability of an antimicrobial agent to kill or harm the
microorganism cells without harming the cells of the host
organism.
Transpeptidase
Catalyzes the nucleophilic carbonyl substitution process
required for the cross-linking of the peptidoglycan in bacterial
cell walls. Antibiotics like penicillin primarily target it.
Minimum Inhibitory Concentration (MIC)
The higher the drug concentration relative to the pathogen
minimum inhibitory concentration (MIC), the greater the rate
and extent of antimicrobial activity.
Time-dependent killing
The time-dependent killing pattern is dependent on the
duration of pathogen exposure to an antibiotic
Post-antibiotic effect (PAE)
Refers to a period of time after complete removal of an
antibiotic during which there is no growth of the target
organism.
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ANTIBACTERIAL

Daptomycin is a cyclic lipopeptide antibacterial

Mechanism of action of daptomycin remains poorly

Daptomycin injection is used to treat

Piperacillin works by binding to and

to enhance its antibacterial

Mechanism of Action of this drug is to

Cefotaxime is an antibiotic medication that belongs to the class of

Other cephalosphorins with the same class as cefotaxime include:

Cephalosporins may elicit a variety of hypersensitivity

Patients with documented penicillin anaphylaxis have an

Local irritation can produce pain after intramuscular injection

Renal toxicity, including interstitial nephritis and tubular

Cephalosporins that contain a methylthiotetrazole group may

A patient is being discharged from the hospital on a

Used in the treatment of cholera, as it

Management and treatment of superficial eye

Adults occasionally develop gastrointestinal disturbances,

Oral or vaginal candidiasis may occur as a result of alteration of

commonly causes a dose-related revers ible suppression of red

In infants, it could cause gray baby syndrome, with vomiting,

Aplastic anemia, which is an idiosyncratic reaction unrelated to

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