Antibacterial Agents Flashcards
What are the organisms that can produce infections in humans?
bacteria, mycoplasma, spirochaetes, fungi and viruses.
What is the ideal antibacterial drug?
The ideal antibacterial drug is one that is harmful to the invading organism without being harmful to the host. (known as selective toxicity)
How do antibacterial agents work in general?
Antibacterial agents exploit the differences between the host and the invading organism.
List the five (5) ways in which antibacterial agents work? Give and example of medication for each mechanism of action.
> Inhibiting bacterial cell wall synthesis
e.g. penicillins, cephalosporins, monobactams and carbapenems, glycopeptides
> Inhibiting bacterial protein synthesis
e.g. aminoglycosides, tetracyclines, chloramphenicol, macrolides, lincosamides, oxazolidinones, streptogramins
> Inhibiting synthesis of bacterial DNA
e.g. quinolones
> disrupting bacterial cell membrane
e.g. colistimethate
> Interfering with metabolic processes such as bacterial nucleic acid synthesis or folate metabolism
e.g. sulfonamides, trimethoprim
(REFERENCE: Havard’s nursing guide to drugs, 10E ELSEVIER, pg 136.)
What is the difference between Bactericidal and Bacteriostatic drugs?
Bactericidal drugs kill the susceptible micro-organism, whereas bacteriostatic drugs inhibit their growth but do not kill the organisms.
- *whether a drug is bacteriostatic or bactericidal may be dependent on the dose given and the concentration achieved at the site of action.
- *Because bacteriostatic drugs slow the growth of the organisms, they give the body’s immune system time to become activated and rid itself of the invading organism.
What are some general nursing points/cautions for antibacterial agents?
> careful routine history is taken to exclude previous reactions to antibacterial agents (e.g. penicillin, cephalosporin), other allergens or severe asthma in order to avoid anaphylaxis.
all relevant medical staff must be informed of any antibiotic allergy, and medical history, medication chart and patient suitably labelled (e.g. patient identification label) (as per workplace guidelines)
after administration of drug (especially penicillins and cephlosporins), observe patient closely for bronchospas, urticarial rash, signs of cardiovascular collapse or angioneurotic oedema.
note and report GI disturbances, especially diarrhoea)
ensure administration at regular (and prescribed) intervals to maintain adequate plasma drug levels.
What are some general patient teaching points and advice for bacterial agents?
*The patient should be encouraged to obtain a medicAlert braclet if they have an allergy to antibacterial agent
*Instruct patient to inform nursing of medical personnel of allergy, espeically when antibacterial agent is administered.
*Emphasise the importance of completing entire course prescribed, even if the patient feels better quickly. Discourage keeping any antibacterial agents and self-medicating if symptoms recur.
Instruct patient to immediately seek medical advice if any of the following occur:
>Diarrhoea (especially if severe, watery or bloody), severe stomach cramps and/or fever during therapy or up to several weeks after stopping antibacterial agents. It is essential to stress the importance of not taking ant medication to stop the diarrhoea as this may worsen the condition.
>skin rash or hives, blistering or peeling of the skin, swelling to the face., lips, mouth or throat making it difficult to breathe or swallow or any breathing difficulty , including wheezing.
>ensure patient understands when to take oral preparations in relation to food. (e.g. before or after meals.)
>instruct patient to keep any antibacterial mixtures/suspensions/syrups in refrigerator (not freezer) and discard if advised by a pharmacist.
Which class of antibacterial agents are inhibitors of bacterial wall synthesis?
Penicillins, cephalosporins, monobactams and carbapenems all contain a beta-lactam ring, which relates to them structurally. It is this ring that is essential i for antibacterial activity. Many bacteria produce beta-lactamase (penicillinase), an enzyme that breaks the beta-lactam ring, thereby rendering the antibacterial agent ineffective against that bacterial strain, it is now possible to add beta-lactamase inhibiotors to penicillins, making them active against previously resistant strains; however this does increase cost.
These inhibitors include clavulanic acid and tazobactam, furthermore, some gram-negative organisms have a phopholipid membrane that prevents some of the penicillins from entering the cell, making those organisms resistant to penicillin. (pg 140 guide to drugs)
Explain the general action of penicillins? List four classifications and an example of each.
The general actions of penicillins include:
* selectively inhibit the formation of a rigid bacterial cell wall.
*bactericidal
*gram-negative bacilli are generally resistant to penicillins
*penicillins are classified as:
>narrow spectrum: (e.g benzylpenicillin)
>narrow spectrum, penicillinase resistant (e.g dicloxacillin)
>moderate spectrum beta-lactamase sensitive aminopenicillins (e.g amoxicillin, ampicillin)
>broad and extended spectrum (e.g pipercillin, ticarcillin)
List some general uses of penicillins
INFECTIONS WHERE THE ORGANISMS ARE NOT RESISTANT TO PENICILLINS, including:
>upper and lower respiratory tract infections
>skin and skin structure infections
>urinary tract infections
>septicaemia
>intra-abdominal infections
>STI’s (e.g. gonorrhoea, syphilis)
>scarlet fever
>meningitis
>Group A strepococci infection without bacteraemia
>surgical prophylaxis
General adverse effects of penicillins
hypersensitivity reaction, including
- urticaria, exfoliative dermatitis, maculopapular rash, rash, pruritus
- anaemia, leucopenia, thrombocytopenia, agranulocytosis, purpura and, rarely, prolongation of bleeding time and prothrombin time
- headache
- diarrhoea, nausea, vomiting, abdominal pain.
- fever
List some general interactions of penicillins
- aminoglycosides and penicillins are physically and/or incompatible
- Increased risk of aminoglycosides and penicillins are given together, especially in those with renal impairment. If given together renal function should be closely monitored.
List three carbapenems and this antibiotics mechanism of action
Three Carbapenems include Meropenem Ertapenem Imipenem Carbapenems are beta lactam antibiotics
List one monobactam, its action, use and available form
Aztreonam GENERIC Azactam BRAND
action:
synthetic monocyclic beta-lactam (monobactam) that binds to penicillin binding proteins resulting in bacterial cell wall synthesis inhibition
use:
reserved for infections where other antibacterial agents are inappropriate or contraindicated.
BRAND NAME: Augmentin. Name the anitobiotic and beta-lactamase inhibitor
Antibiotic: amoxicillin
Beta - lactamase inhibitor: Clavulanic acid
Treats easy gram negative bacteria
