Intro to Antibiotics, Penicillins, Other Beta-Lactams & Cephalosporins

This set of flashcards covers the introduction to antibiotics, including penicillins, beta-lactams, cephalosporins, and relevant concepts in microbiology, pharmacology, and nursing considerations.

What is bacteria and how does it reproduce?

Bacteria is a single-celled organism that reproduces by cell division approximately every 20 minutes.

What determines the shape of bacteria?

The structure of the bacteria's rigid cell wall determines its shape.

What are the three basic shapes of bacteria and their names?

Bacilli (rod-shaped), Cocci (spherical), and spiral-shaped.

How is gram staining used to classify bacteria?

Gram staining determines the ability of the cell wall to retain a purple stain. Gram-positive bacteria turn purple; gram-negative bacteria do not retain the stain.

Give examples of gram-positive bacteria.

Staphylococcus aureus, Streptococcus pneumoniae, Group B Streptococcus.

Give examples of gram-negative bacteria.

Neisseria meningitidis, Escherichia coli (E. coli), and Haemophilus influenzae.

What is the difference between an antibacterial and an antibiotic?

Antibacterials/antimicrobials inhibit bacterial growth or kill bacteria and other microorganisms. Antibiotics specifically are chemicals produced by one kind of microorganism to inhibit or kill bacteria.

What is the difference between bacteriostatic and bactericidal drugs?

Bacteriostatic drugs inhibit the growth of bacteria; bactericidal drugs kill the bacteria.

Give examples of bacteriostatic drugs.

Tetracycline and sulfonamides are bacteriostatic.

Give examples of bactericidal drugs.

Penicillin (PCN) and cephalosporins are bactericidal.

What is the purpose of a culture and sensitivity (C&S) test?

Culture identifies the organism causing the infection; sensitivity determines which antibiotic(s) the organism is sensitive to.

What is cross-resistance in antibacterials?

Cross-resistance can occur between antibacterials that have similar actions, such as penicillin and cephalosporins.

When should a C&S be obtained in relation to starting antibiotic therapy?

C&S must be obtained BEFORE antibiotic therapy is started to identify the organism and the most effective drug.

What is antibiotic stewardship?

A patient safety program that optimizes the use of antibiotics, supports appropriate prescribing practices, and reduces antibiotic resistance.

What are the 5 mechanisms of action of antibiotics?

1) Inhibition of bacterial cell wall synthesis, 2) Alteration of membrane permeability, 3) Inhibition of protein synthesis, 4) Inhibition of bacterial RNA and DNA synthesis, 5) Interference with metabolism within the cell.

What is the MEC in relation to antibacterial therapy?

MEC (minimum effective concentration) is the drug concentration necessary to halt the growth of a microorganism.

What body factors affect the effectiveness of an antibacterial drug?

Age, nutrition, immunoglobulins, circulation, white blood cells (WBCs), and organ function.

What other factors work alongside antibiotics to treat infection?

Natural body defenses, surgical procedures to excise infected tissue, and dressing changes.

What is inherent (intrinsic) antibiotic resistance?

Resistance that exists without prior exposure to the antimicrobial drug.

What is acquired antibiotic resistance?

Resistance caused by prior exposure to an antimicrobial.

What behaviors lead to the development of antibiotic resistance?

Taking antibiotics unnecessarily, taking them incorrectly, or stopping them prematurely.

What are nosocomial (healthcare-acquired) infections?

Infections acquired while patients are hospitalized.

What are common types of nosocomial infections?

CAUTI, CLABSI, VAP, Surgical Site Infections, and CDI.

What is MRSA and what is the current drug of choice to treat it?

MRSA is highly resistant to all penicillins and cephalosporins; the drug of choice is vancomycin.

What are VREF and VRSA?

VREF is vancomycin-resistant Enterococcus faecium, VRSA is vancomycin-resistant Staphylococcus aureus.

What approaches are being developed to combat drug-resistant bacteria?

New antibiotic classes, antibiotic-resistance disablers, and bacterial vaccines.

What is empiric antibiotic therapy?

Antibiotic therapy started prior to a definitive diagnosis.

What is prophylactic antibiotic therapy?

Medication or treatment designed to prevent disease before it occurs.

What is therapeutic antibiotic therapy?

Medication or treatment designed to treat a disease that is currently occurring.

What are narrow-spectrum antibiotics and give examples?

Narrow-spectrum antibiotics are primarily effective against one type of organism. Examples: Penicillin and Erythromycin.

What are broad-spectrum antibiotics and give examples?

Broad-spectrum antibiotics are effective against both gram-positive and gram-negative organisms. Examples: Tetracyclines and cephalosporins.

When are broad-spectrum antibiotics most commonly used?

When the offending microorganism has not yet been identified.

Should combination antibiotics be routinely prescribed?

No, combination antibiotics should not be routinely prescribed.

What are the three possible effects when antibiotics are combined?

Additive, potentiative (synergistic), or antagonistic effects.

What are the general adverse reactions of antibacterials?

Allergic reactions, superinfection, and organ toxicity.

What is anaphylactic shock and how is it treated?

Severe hypersensitivity reaction causing vascular collapse and treated with epinephrine.

What is a superinfection?

A secondary infection that occurs when normal flora is destroyed by antibiotics.

How are mild superinfections of the skin or mouth treated?

With nystatin (antifungal).

What are the 4 categories of beta-lactam antibacterials?

Penicillins, Cephalosporins, Carbapenems, and Monobactams.

What is the mechanism of action of all beta-lactam antibacterials?

They interfere with bacterial cell wall synthesis.

Why are they called beta-lactam antibacterials?

Because of the beta-lactam ring that is part of their chemical structure.

What is the source of penicillin?

A natural antibacterial agent obtained from mold of the genus Penicillium.

What is the mechanism of action of penicillins?

They inhibit bacterial cell wall synthesis.

Are penicillins bacteriostatic or bactericidal?

Both — depending on the drug and dosage.

What was Penicillin G (PCN G) and why are IM/IV preferred over PO?

PCN G was the first penicillin, and IM/IV are preferred because oral absorption is limited.

Why is Penicillin G painful when given IM?

Because it is an aqueous solution, which is painful when injected intramuscularly.

What infections does Penicillin G treat?

Pneumococcal pneumonia, staphylococcal and streptococcal infections, syphilis, endocarditis.

How does Penicillin V differ from Penicillin G?

PCN V is better absorbed via the GI tract but is less potent.

What infections does Penicillin V treat?

Streptococcal infections, ulcerative gingivitis, otitis media.

What are broad-spectrum (aminopenicillin) penicillins used for?

Used to treat both gram-positive and gram-negative bacteria.

What organism are broad-spectrum penicillins NOT effective against?

S. aureus.

What are examples of broad-spectrum (aminopenicillin) penicillins?

Amoxicillin and Ampicillin.

What infections does amoxicillin treat?

Respiratory tract infections, UTIs, otitis media, skin infections.

What is the oral absorption rate of amoxicillin?

Greater than 80% absorbed in the GI tract.

What is the protein binding and half-life of amoxicillin?

Protein binding: 20%; half-life: 1–1.5 hours.

How is amoxicillin excreted?

70% excreted in urine.

What is the peak action time for oral amoxicillin?

Peak: 1–2 hours.

What is beta-lactamase and what does it do?

An enzyme that destroys the beta-lactam ring, causing resistance.

What are beta-lactamases that specifically attack penicillins called?

Penicillinases.

What are penicillinase-resistant (antistaphylococcal) penicillins used for?

Used to treat penicillinase-producing Staphylococcus aureus infections.

What are examples of penicillinase-resistant penicillins and their routes?

Dicloxacillin sodium (PO); Nafcillin and Oxacillin Sodium (IM/IV).

What is the protein binding and half-life of penicillinase-resistant penicillins?

Protein binding: 95–99%; half-life: 30–42 minutes.

What are extended-spectrum (antipseudomonal) penicillins used for?

Treats gram-negative bacteria.

What are examples of extended-spectrum penicillins?

Piperacillin/tazobactam and Ticarcillin/clavulanate.

What are beta-lactamase inhibitors and what is their purpose?

Drugs that inhibit bacterial beta-lactamases, extending the antimicrobial spectrum.

What are the three beta-lactamase inhibitors?

Clavulanic acid, Sulbactam, and Tazobactam.

What are examples of penicillin + beta-lactamase inhibitor combinations?

Amoxicillin/clavulanic acid, Ampicillin/sulbactam, Piperacillin/tazobactam.

How do broad-spectrum penicillins interact with oral contraceptives?

They may decrease the effectiveness of oral contraceptives.

What interaction occurs between potassium supplements and Penicillin G or V?

Potassium supplements can increase serum potassium levels.

What happens when PCN is mixed with aminoglycosides in IV solution?

The action of BOTH drugs is inactivated.

How are most beta-lactam antibacterials excreted?

Through the kidneys.

What renal function labs should be assessed in patients on beta-lactam antibacterials?

BUN and Creatinine.

What percentage of patients receiving PCN experience an allergic response?

5–10%.

What is an important nursing action before starting any antibiotic?

Obtain a C&S sample.

What patient teaching is important for female patients of childbearing age taking penicillin?

Advise use of an alternative form of birth control.

How can GI distress from penicillin be reduced?

Take the medication with food.

What teaching is needed for children taking chewable penicillin tablets?

Warn parents that chewable tablets must be chewed or crushed.

What is the mechanism of action of cephalosporins?

They inhibit bacterial cell wall synthesis.

What cross-sensitivity risk exists between cephalosporins and penicillin?

There is a 10% cross-sensitivity.

How many generations of cephalosporins are there and how are they classified?

Five generations, classified by pharmacology.

What is the spectrum of first-generation cephalosporins?

Effective mostly against gram-positive bacteria.

What are examples of first-generation cephalosporins?

Cefadroxil, Cefazolin sodium, Cephalexin.

What is the spectrum of second-generation cephalosporins?

Broader activity against some gram-negative organisms.

What are examples of second-generation cephalosporins?

Cefaclor, Cefotetan, Cefprozil, Cefuroxime.

What is the spectrum and key features of third-generation cephalosporins?

Broad-spectrum; resistant to beta-lactamases.

What are examples of third-generation cephalosporins?

Cefdinir, Cefixime, Ceftazidime, Cefpodoxime, Ceftriaxone.

What is ceftriaxone (Rocephin) used for?

Otitis media, bacteremia, skin, respiratory, and urinary tract infections.

What is the protein binding and half-life of ceftriaxone?

Protein binding: 85–95%; half-life: 6–9 hours.

What is the peak for IM ceftriaxone vs IV ceftriaxone?

IM peak: 1.5–4 hours; IV peak: 30 minutes.

What is the spectrum of fourth-generation cephalosporins?

Broad-spectrum; highly resistant to beta-lactamases.

What is the example of a fourth-generation cephalosporin?

Cefepime.

What makes fifth-generation cephalosporins unique?

They are the ONLY cephalosporins active against resistant gram-positive organisms.

What are examples of fifth-generation cephalosporins and their uses?

Ceftaroline fasamil, Ceftolozane/tazobactam, Ceftobiprole.

What are the side effects of cephalosporins?

Anaphylaxis, GI distress, increased bleeding, nephrotoxicity.

What reaction can occur when alcohol is consumed with cephalosporins?

A disulfiram-like reaction.

How do anticoagulants interact with cephalosporins?

Cephalosporins may increase bleeding.

What drugs increase nephrotoxicity when combined with cephalosporins?

Loop diuretics, aminoglycosides, and vancomycin.

What effect does cefotetan have on warfarin, aminoglycosides, and salicylates?

Cefotetan may increase the effects.

What should a patient be advised to eat while taking cephalosporins and why?

Buttermilk, yogurt, or acidophilus to help prevent superinfection.

Why should patients taking cephalosporins increase fluid intake?

To avoid dehydration from diarrhea.