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Keflex (cephalexin) and penicillin are antibiotics used to treat a variety of bacterial infections. Keflex and What's the Difference Between Keflex and Penicillin? What are Keflex . Multimedia: Slideshows, Images & Quizzes. This quiz is to help in understanding of how penicillin and macrolides work. Cephalosporins are drugs used in the treatment of bacterial infections - test your knowledge of this drug class with our cephalosporins quiz.
Risk factors Patients aged 20—49 years are at increased risk of anaphylaxis although the reasons are unknown. There is no evidence to suggest a hereditary link to anaphylaxis and therefore family history is irrelevant. Thelatest data suggest there is no link between atopic disease e.
Penicillin And Cephalosporins - ProProfs Quiz
An allergic reaction is most commonly seen after parenteral administration . Less commonly, penicillin allergy reactions can occur days or weeks after exposure and may persist after treatment has stopped.
Other conditions associated with penicillin allergy include serum sickness, drug-induced anaemia, drug reaction with eosinophilia and systemic symptoms DRESS and nephritis . Does the patient recall the reaction, and if not, who informed them of it? How long after beginning penicillin did the reaction occur? What was the route of administration? What antibiotics has the patient reacted to in the past? What antibiotics has the patient taken and tolerated since the allergy diagnosis?
What was the nature of the reaction? If a rash was present then: Describe the nature of the rash e. Could the rash be related to an underlying condition e. How long after commencing the antibiotic did the rash appear? Why was the patient taking the antibiotic? Did this reaction result in hospitalisation? Did the reaction resolve on stopping the antibiotic?
If so, what happened after stopping the drug? What other medications was the patient taking? Why and when were they prescribed? Has the patient taken antibiotics similar to penicillin e. If so, did anything happen? Histories can be unreliable and can result in over diagnosis of allergy. Some patients may have been too young to fully remember the reaction and patients who report a vague history of symptoms or gastrointestinal intolerance are probably not truly allergic to penicillins.
If a patient reports a rash after ingestion or administration of a medicine containing penicillin, its type can be used to guide whether a related drug e. Rashes that involve hives raised, intensely itchy spots that come and go over hoursor occur with other penicillin allergic symptoms e. Rashes that are flat, non-itchy, develop over days and do not change in appearance are less likely to represent a dangerous allergy. Treatment options Patients who have experienced a type I allergic reaction with penicillins e.
Cephalosporins and carbapenems can be used with caution in patients that do not have a history of a type I mediated allergic reaction. Cephalosporin allergy is largely dependent on the generation of cephalosporin used .
First generation cephalosporins e. However, at the time of these early studies, cephalosporin formulations contained trace amountsof penicillin so this figure is thought to be an overestimate. The true incidence of cross-sensitivity is unknown but there are data to suggest that it is muchlower . Second and third generation cephalosporins e. However, alternatives should be used wherever possible see below. A thorough clinical history should be taken before prescribing this class of drugs to a patient with known or suspected penicillin allergy.
Aztreonam is a monobactam that does not contain a bicyclic-ring structure  similar to penicillins, cephalosporins and carbapenems.
It can therefore be used safely in patientswith a history of penicillin allergy unless the patient is known to be allergic to ceftazidime, which has an identical side chain to aztreonam . However, patients with penicillin allergy are more likely to react to any class of drug . The extended-spectrum agents mezlocillin and piperacillin are unique in that they have greater activity against gram-negative bacteria, including Pseudomonas aeruginosa, a bacterium that often causes serious infection in people whose immune systems have been weakened.
They have decreased activity, however, against penicillinase-producing Staphylococcus aureusa common bacterial agent in food poisoning. The penicillins are the safest of all antibiotics. The major adverse reaction associated with their use is hypersensitivity, with reactions ranging from a rash to bronchospasm and anaphylaxis.
The more serious reactions are uncommon. Cephalosporins The cephalosporins have a mechanism of action identical to that of the penicillins.
Penicillin And Cephalosporins
However, the basic chemical structure of the penicillins and cephalosporins differs in other respects, resulting in some difference in the spectrum of antibacterial activity. Modification of the basic molecule 7-aminocephalosporanic acid produced by Cephalosporium acremonium resulted in four generations of cephalosporins.
The first-generation cephalosporins cefazolin, cephalothin, and cephalexin have a range of antibacterial activity similar to the broad-spectrum penicillins described above. For instance, they are effective against most staphylococci and streptococci as well as penicillin-resistant pneumococci. The second-generation cephalosporins cefamandolecefaclor, cefotetan, cefoxitinand cefuroxime have an extended antibacterial spectrum that includes greater activity against additional species of gram-negative rods.
Thus, these drugs are active against Escherichia coli and Klebsiella and Proteus species though several strains of these organisms have developed resistance. Cefamandole is active against many strains of Haemophilus influenzae and Enterobacterwhile cefoxitin is particularly active against most strains of Bacteroides fragilis. Second-generation cephalosporins have decreased activity, however, against gram-positive bacteria.
The third-generation cephalosporins ceftriaxone, cefixime, and ceftazidime have increased activity against the gram-negative organisms compared with the second-generation agents. Most Enterobacter species are susceptible to these drugs, as are H. Like the penicillins, the cephalosporins are relatively nontoxic. Because the structure of the cephalosporins is similar to that of penicillin, hypersensitivity reactions can occur in penicillin-hypersensitive patients.
This drug must be given by intramuscular injection or intravenous infusion because it is not absorbed from the gastrointestinal tract. Imipenem is hydrolyzed by an enzyme present in the renal tubule; therefore, it is always administered with cilastatin, an inhibitor of this enzyme. Neurotoxicity and seizures have limited the use of imipenem. Antituberculosis antibiotics Isoniazidethambutolpyrazinamideand ethionamide are synthetic chemicals used in treating tuberculosis.
Isoniazid, ethionamide, and pyrazinamide are similar in structure to nicotinamide adenine dinucleotide NADa coenzyme essential for several physiological processes.
Ethambutol prevents the synthesis of mycolic acid, a lipid found in the tubercule bacillus. All these drugs are absorbed from the gastrointestinal tract and penetrate tissues and cells.ß-Lactams: Mechanisms of Action and Resistance
An isoniazid-induced hepatitis can occur, particularly in patients 35 years of age or older. Cycloserinean antibiotic produced by Streptomyces orchidaceus, is also used in the treatment of tuberculosis. A structural analog of the amino acid d-alanine, it interferes with enzymes necessary for incorporation of d-alanine into the bacterial cell wall. It is rapidly absorbed from the gastrointestinal tract and penetrates most tissues quite well; high levels are found in urine.
Rifampin, a semisynthetic agent, is absorbed from the gastrointestinal tract, penetrates tissue well including the lungand is used in the treatment of tuberculosis. Rifampin administration is associated with several side effects, mostly gastrointestinal in nature. The drug can turn urinefecessalivasweat, and tears red-orange in colour.