Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved. Microbiology: A Clinical Approach © Garland Science ANTIBIOTICS ANTIBIOTICS © CDC.

Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.Microbiology: A Clinical Approach © Garland Science

ANTIBIOTICS ANTIBIOTICS

© CDC / Gilda L. Jones

Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.

WHY IS THIS IMPORTANT?WHY IS THIS IMPORTANT?

• Antibiotics have drastically reduced the number Antibiotics have drastically reduced the number of deaths due to infection.of deaths due to infection.

• They have changed the face of health care.They have changed the face of health care.


OVERVIEWOVERVIEW


Anti-Infective AgentsAnti-Infective AgentsAntibiotics:Antibiotics:

SulfonamidesSulfonamides

PenicillinsPenicillins

CephalosporinsCephalosporins

TetracyclinesTetracyclines

AminoglycosidesAminoglycosides

QuinolonesQuinolones

MacrolidesMacrolides


AntibioticsAntibiotics

• Medications used to treat bacterial infectionsMedications used to treat bacterial infections

• Ideally, before beginning antibiotic therapy, Ideally, before beginning antibiotic therapy, the suspected areas of infection should be the suspected areas of infection should be cultured to identify the causative organism cultured to identify the causative organism and potential antibiotic susceptibilities.and potential antibiotic susceptibilities.


HISTORICAL PERSPECTIVESHISTORICAL PERSPECTIVES

• The discovery of the first antibiotic was an The discovery of the first antibiotic was an accident.accident.– Alexander Fleming accidentally contaminated a plate Alexander Fleming accidentally contaminated a plate

with a fungus. with a fungus.

– He observed a clearly defined region of no bacterial He observed a clearly defined region of no bacterial growth where the fungi had contaminated the plate.growth where the fungi had contaminated the plate.

– The area around the fungus was eventually referred to The area around the fungus was eventually referred to as a zone of inhibition.as a zone of inhibition.


……HISTORICAL PERSPECTIVESHISTORICAL PERSPECTIVES

• It is estimated that over 80 million prescriptions It is estimated that over 80 million prescriptions are written in America each year.are written in America each year.

• 12,500 tons of antibiotics are produced annually.12,500 tons of antibiotics are produced annually.

– 25-50 % is fed to livestock to increase the rate of 25-50 % is fed to livestock to increase the rate of weight gain.weight gain.

• From 1900 to 1980, mortality from infectious From 1900 to 1980, mortality from infectious diseases dropped from 797 per 100,000 persons diseases dropped from 797 per 100,000 persons to 36 per 100,000 persons.to 36 per 100,000 persons.



• Empiric therapy: treatment of an infection Empiric therapy: treatment of an infection before specific culture information has been before specific culture information has been reported or obtainedreported or obtained

• Prophylactic therapy: treatment with Prophylactic therapy: treatment with antibiotics to prevent an infection, as in intra-antibiotics to prevent an infection, as in intra-abdominal surgeryabdominal surgery



• Bactericidal: kill bacteriaBactericidal: kill bacteria

• Bacteriostatic: inhibit growth of susceptible Bacteriostatic: inhibit growth of susceptible bacteria, rather than killing them immediately; bacteria, rather than killing them immediately; will eventually lead to bacterial deathwill eventually lead to bacterial death


……ANTIBIOTIC TARGETSANTIBIOTIC TARGETS


Antibiotics: SulfonamidesAntibiotics: Sulfonamides

One of the first groups of antibioticsOne of the first groups of antibiotics

• sulfadiazinesulfadiazine

• sulfamethizolesulfamethizole

• sulfamethoxazolesulfamethoxazole

• sulfisoxazolesulfisoxazole


Sulfonamides: Mechanism of ActionSulfonamides: Mechanism of Action

• Bacteriostatic actionBacteriostatic action

• Prevent synthesis of folic acid required for Prevent synthesis of folic acid required for synthesis of purines and nucleic acidsynthesis of purines and nucleic acid

• Does not affect human cells or certain Does not affect human cells or certain bacteria—they can use preformed folic acidbacteria—they can use preformed folic acid


Sulfonamides: sulfamethoxazole Sulfonamides: sulfamethoxazole Therapeutic UsesTherapeutic Uses

Azo-GantanolAzo-Gantanol• Combined with phenazopyridine Combined with phenazopyridine

(an analgesic-anesthetic that affects the mucosa (an analgesic-anesthetic that affects the mucosa of the urinary tract).of the urinary tract).

• Used to treat urinary tract infections (UTIs) and to Used to treat urinary tract infections (UTIs) and to reduce the pain associated with UTIsreduce the pain associated with UTIs..

BactrimBactrim• Combined with trimethoprim.Combined with trimethoprim.

• Used to treat UTIs, Pneumocystis carinii pneumonia, Used to treat UTIs, Pneumocystis carinii pneumonia, ear infections, bronchitis, gonorrhea, etc.ear infections, bronchitis, gonorrhea, etc.


Sulfonamides: sulfisoxazole Sulfonamides: sulfisoxazole Therapeutic UsesTherapeutic Uses

Azo-GantrisinAzo-Gantrisin

• Combined with phenazopyridine Combined with phenazopyridine

• Used for UTIsUsed for UTIs

PediazolePediazole

• Combined with erythromycinCombined with erythromycin

• Used to treat otitis media Used to treat otitis media


Sulfonamides: Side EffectsSulfonamides: Side Effects

Body SystemBody System EffectEffect

BloodBlood Hemolytic and aplastic Hemolytic and aplastic anemia, anemia,

thrombocytopeniathrombocytopenia

IntegumentaryIntegumentary Photosensitivity, exfoliative Photosensitivity, exfoliative dermatitis, Stevens-dermatitis, Stevens-

Johnson Johnson syndrome, epidermal syndrome, epidermal necrolysisnecrolysis


Sulfonamides: Side EffectsSulfonamides: Side Effects

Body SystemBody System EffectEffect

GIGI Nausea, vomiting, Nausea, vomiting, diarrhea,diarrhea, pancreatitispancreatitis

OtherOther Convulsions, crystalluria,Convulsions, crystalluria,toxic nephrosis, toxic nephrosis,

headache, headache, peripheral neuritis, peripheral neuritis, urticariaurticaria


Antibiotics: PenicillinsAntibiotics: Penicillins

• Natural penicillinsNatural penicillins

• Penicillinase-resistant penicillinsPenicillinase-resistant penicillins

• AminopenicillinsAminopenicillins

• Extended-spectrum penicillinsExtended-spectrum penicillins



Natural penicillinsNatural penicillins

• penicillin G, penicillin V potassiumpenicillin G, penicillin V potassium

Penicillinase-resistant penicillinsPenicillinase-resistant penicillins

• cloxacillin, dicloxacillin, methicillin, nafcillin, oxacillincloxacillin, dicloxacillin, methicillin, nafcillin, oxacillin



AminopenicillinsAminopenicillins

• amoxicillin, ampicillin, bacampicillinamoxicillin, ampicillin, bacampicillin

Extended-spectrum penicillinsExtended-spectrum penicillins

• piperacillin, ticarcillin, carbenicillin, mezlocillinpiperacillin, ticarcillin, carbenicillin, mezlocillin



• First introduced in the 1940sFirst introduced in the 1940s

• Bactericidal: inhibit cell wall synthesisBactericidal: inhibit cell wall synthesis

• Kill a wide variety of bacteriaKill a wide variety of bacteria

• Also called “beta-lactams”Also called “beta-lactams”



• Bacteria produce enzymes capable of Bacteria produce enzymes capable of destroying penicillins.destroying penicillins.

• These enzymes are known as These enzymes are known as beta-lactamases.beta-lactamases.

• As a result, the medication is not effective.As a result, the medication is not effective.



• Chemicals have been developed to inhibit Chemicals have been developed to inhibit these enzymes:these enzymes:

– clavulanic acidclavulanic acid

– tazobactamtazobactam

– sulbactamsulbactam

• These chemicals bind with beta-lactamase These chemicals bind with beta-lactamase and prevent the enzyme from breaking down and prevent the enzyme from breaking down the penicillinthe penicillin



• Penicillin-beta-lactamase inhibitor Penicillin-beta-lactamase inhibitor combination drugs:combination drugs:

– ampicillin + sulbactam = Unasynampicillin + sulbactam = Unasyn

– amoxicillin + clavulanic acid = Augmentinamoxicillin + clavulanic acid = Augmentin

– ticarcillin + clavulanic acid = Timentinticarcillin + clavulanic acid = Timentin

– piperacillin + tazobactam = Zosynpiperacillin + tazobactam = Zosyn


Penicillins: Mechanism of ActionPenicillins: Mechanism of Action

• Penicillins enter the bacteria via the cell wall.Penicillins enter the bacteria via the cell wall.

• Inside the cell, they bind to penicillin-binding protein.Inside the cell, they bind to penicillin-binding protein.

• Once bound, normal cell wall synthesis is disrupted.Once bound, normal cell wall synthesis is disrupted.

• Result: bacteria cells die from cell lysis.Result: bacteria cells die from cell lysis.

• Penicillins do not kill other cells in the body.Penicillins do not kill other cells in the body.


Penicillins: Therapeutic UsesPenicillins: Therapeutic Uses

• Prevention and treatment of infections Prevention and treatment of infections caused by susceptible bacteria, such as:caused by susceptible bacteria, such as:

– gram-positive bacteriagram-positive bacteria

– Streptococcus, Enterococcus, Staphylococcus Streptococcus, Enterococcus, Staphylococcus speciesspecies


Penicillins: Adverse EffectsPenicillins: Adverse Effects

• Allergic reactions occur in 0.7% – 8% of Allergic reactions occur in 0.7% – 8% of treatments treatments

– urticaria, pruritus, angioedemaurticaria, pruritus, angioedema

• 10% of allergic reactions are life-threatening10% of allergic reactions are life-threatening

and and

• 10% of these are fatal10% of these are fatal


Penicillins: Side EffectsPenicillins: Side Effects

• Common side effects:Common side effects:

– nausea, vomiting, diarrhea, abdominal painnausea, vomiting, diarrhea, abdominal pain

• Other side effects are less commonOther side effects are less common


Antibiotics: CephalosporinsAntibiotics: Cephalosporins

• First GenerationFirst Generation

• Second GenerationSecond Generation

• Third GenerationThird Generation

• Fourth GenerationFourth Generation


Antibiotics: CephalosporinsAntibiotics: Cephalosporins

• Semisynthetic derivatives from a fungusSemisynthetic derivatives from a fungus

• Structurally and pharmacologically related Structurally and pharmacologically related to penicillinsto penicillins

• Bactericidal actionBactericidal action

• Broad spectrumBroad spectrum

• Divided into groups according to their Divided into groups according to their antimicrobial activityantimicrobial activity


Cephalosporins: First GenerationCephalosporins: First Generation

• cefadroxilcefadroxil

• cephalexincephalexin

• cephradinecephradine

• cefazolincefazolin

• cephalothincephalothin

• cephapirincephapirin

– Good gram-positive coverageGood gram-positive coverage

– Poor gram-negative coveragePoor gram-negative coverage


Cephalosporins: First GenerationCephalosporins: First Generation

cefazolincefazolin cephalexincephalexin

(Ancef and Kefzol)(Ancef and Kefzol) (Keflex and Keftab)(Keflex and Keftab)

IV and POIV and PO POPO

used for surgical prophylaxis, URIs, otitis mediaused for surgical prophylaxis, URIs, otitis media


Cephalosporins: Second GenerationCephalosporins: Second Generation

• cefaclorcefaclor •• cefonicidcefonicid

• cefprozilcefprozil •• ceforanide ceforanide

• cefamandolecefamandole •• cefmetazolecefmetazole

• cefoxitincefoxitin •• cefotetancefotetan

• cefuroximecefuroxime

– Good gram-positive coverageGood gram-positive coverage

– Better gram-negative coverage than first generationBetter gram-negative coverage than first generation


Cephalosporins: Second GenerationCephalosporins: Second Generation

CefoxitinCefoxitin cefuroximecefuroxime

(Mefoxin)(Mefoxin) (Kefurox and Ceftin)(Kefurox and Ceftin)

IV and IMIV and IM POPO

Used prophylactically forUsed prophylactically for Surgical prophylaxisSurgical prophylaxisabdominal or colorectalabdominal or colorectalsurgeriessurgeries Does not killDoes not killAlso kills anaerobesAlso kills anaerobes anaerobesanaerobes


Cephalosporins: Third GenerationCephalosporins: Third Generation

• cefiximecefixime •• ceftizoxime ceftizoxime

• cefpodoxime proxetilcefpodoxime proxetil •• ceftriaxone ceftriaxone

• cefoperazonecefoperazone •• ceftazidime ceftazidime

• cefotaximecefotaxime •• moxalactam moxalactam

– Most potent group against gram-negativeMost potent group against gram-negative

– Less active against gram-positiveLess active against gram-positive



cefixime (Suprax)cefixime (Suprax)• Only oral third-generation agentOnly oral third-generation agent

• Best of available oral cephalosporins against Best of available oral cephalosporins against gram-negativegram-negative

• Tablet and suspensionTablet and suspension

ceftriaxone (Rocephin)ceftriaxone (Rocephin)• IV and IM, long half-life, once-a-day dosingIV and IM, long half-life, once-a-day dosing

• Easily passes meninges and diffused into CSF Easily passes meninges and diffused into CSF to treat CNS infectionsto treat CNS infections



ceftazidime (Ceptaz, Fortaz, Tazidime, Tazicef)ceftazidime (Ceptaz, Fortaz, Tazidime, Tazicef)

• IV and IMIV and IM

• Excellent gram-negative coverageExcellent gram-negative coverage

• Used for difficult-to-treat organisms such as Used for difficult-to-treat organisms such as Pseudomonas spp.Pseudomonas spp.

• Eliminated renally instead of biliary routeEliminated renally instead of biliary route

• Excellent spectrum of coverageExcellent spectrum of coverage


Cephalosporins: Fourth GenerationCephalosporins: Fourth Generation

cefepime (Maxipime)cefepime (Maxipime)

• Newest cephalosporin agents.Newest cephalosporin agents.

• Broader spectrum of antibacterial activity than Broader spectrum of antibacterial activity than third generation, especially against gram-positive third generation, especially against gram-positive bacteria.bacteria.


Cephalosporins: Side EffectsCephalosporins: Side Effects

• similar to penicillins similar to penicillins


Antibiotics: TetracyclinesAntibiotics: Tetracyclines

• demeclocycline (Declomycin)demeclocycline (Declomycin)

• oxytetracyclineoxytetracycline

• tetracyclinetetracycline

• doxycycline (Doryx, Doxy-Caps, Vibramycin)doxycycline (Doryx, Doxy-Caps, Vibramycin)

• minocyclineminocycline



• Natural and semi-syntheticNatural and semi-synthetic

• Obtained from cultures of StreptomycesObtained from cultures of Streptomyces

• Bacteriostatic—inhibit bacterial growthBacteriostatic—inhibit bacterial growth

• Inhibit protein synthesisInhibit protein synthesis

• Stop many essential functions of the bacteriaStop many essential functions of the bacteria



• Bind to CaBind to Ca2+2+ and Mg and Mg2+2+ and Al and Al3+3+ ions to ions to form insoluble complexesform insoluble complexes

• Thus, dairy products, antacids, and iron Thus, dairy products, antacids, and iron salts reduce absorption of tetracyclinessalts reduce absorption of tetracyclines


Tetracyclines: Therapeutic UsesTetracyclines: Therapeutic Uses

• Wide spectrum:Wide spectrum:

– gram-negative, gram-positive, protozoa, gram-negative, gram-positive, protozoa, Mycoplasma, Rickettsia, Chlamydia, syphilis, Mycoplasma, Rickettsia, Chlamydia, syphilis, Lyme diseaseLyme disease

• Demeclocycline is also used to treat SIADH, Demeclocycline is also used to treat SIADH, and pleural and pericardial effusionsand pleural and pericardial effusions


Tetracyclines: Side EffectsTetracyclines: Side Effects

Strong affinity for calcium Strong affinity for calcium

• Discoloration of permanent teeth and tooth Discoloration of permanent teeth and tooth enamel in fetuses and childrenenamel in fetuses and children

• May retard fetal skeletal development if taken May retard fetal skeletal development if taken during pregnancyduring pregnancy



Alteration in intestinal flora may result in:Alteration in intestinal flora may result in:

• Superinfection (overgrowth of nonsusceptible Superinfection (overgrowth of nonsusceptible organisms such as Candida)organisms such as Candida)

• DiarrheaDiarrhea

• Pseudomembranous colitisPseudomembranous colitis



May also cause:May also cause:

• Vaginal moniliasisVaginal moniliasis

• Gastric upsetGastric upset

• EnterocolitisEnterocolitis

• Maculopapular rashMaculopapular rash


Antibiotics: AminoglycosidesAntibiotics: Aminoglycosides

• gentamicin (Garamycin)gentamicin (Garamycin)

• kanamycinkanamycin

• neomycinneomycin

• streptomycinstreptomycin

• tobramycintobramycin

• amikacin (Amikin)amikacin (Amikin)

• netilmicin netilmicin



• Natural and semi-syntheticNatural and semi-synthetic

• Produced from StreptomycesProduced from Streptomyces

• Poor oral absorption; no PO formsPoor oral absorption; no PO forms

• Very potent antibiotics with serious toxicitiesVery potent antibiotics with serious toxicities

• BactericidalBactericidal

• Kill mostly gram-negative; some Kill mostly gram-negative; some gram-positive alsogram-positive also



• Used to kill gram-negative bacteria such as Used to kill gram-negative bacteria such as Pseudomonas spp., E. coli, Proteus spp., Pseudomonas spp., E. coli, Proteus spp., Klebsiella spp., Serratia spp. Klebsiella spp., Serratia spp.

• Often used in combination with other Often used in combination with other antibiotics for synergistic effect.antibiotics for synergistic effect.



• Three most common (systemic): gentamicin, Three most common (systemic): gentamicin, tobramycin, amikacintobramycin, amikacin

• Cause serious toxicities:Cause serious toxicities:

– Nephrotoxicity (renal failure)Nephrotoxicity (renal failure)

– Ototoxicity (auditory impairment and vestibular Ototoxicity (auditory impairment and vestibular [eighth cranial nerve])[eighth cranial nerve])

• Must monitor drug levels to prevent toxicitiesMust monitor drug levels to prevent toxicities


Aminoglycosides: Side EffectsAminoglycosides: Side Effects

Ototoxicity and nephrotoxicity are Ototoxicity and nephrotoxicity are the most significantthe most significant

• HeadacheHeadache

• ParesthesiaParesthesia

• Neuromuscular blockadeNeuromuscular blockade

• DizzinessDizziness

• VertigoVertigo

• Skin rashSkin rash

• FeverFever

• SuperinfectionsSuperinfections


Antibiotics: QuinolonesAntibiotics: Quinolones

• ciprofloxacin (Cipro)ciprofloxacin (Cipro)

• enoxacin (Penetrex)enoxacin (Penetrex)

• lomefloxacin (Maxaquin)lomefloxacin (Maxaquin)

• norfloxacin (Noroxin)norfloxacin (Noroxin)

• ofloxacin (Floxin)ofloxacin (Floxin)



• Excellent oral absorptionExcellent oral absorption

• Absorption reduced by antacidsAbsorption reduced by antacids

• First oral antibiotics effective against First oral antibiotics effective against gram-negative bacteriagram-negative bacteria


Quinolones: Mechanism of ActionQuinolones: Mechanism of Action

• BactericidalBactericidal

• Effective against gram-negative organisms Effective against gram-negative organisms and some gram-positive organismsand some gram-positive organisms

• Alter DNA of bacteria, causing deathAlter DNA of bacteria, causing death

• Do not affect human DNADo not affect human DNA


Quinolones: Therapeutic UsesQuinolones: Therapeutic Uses

• Lower respiratory tract infectionsLower respiratory tract infections

• Bone and joint infectionsBone and joint infections

• Infectious diarrheaInfectious diarrhea

• Urinary tract infectionsUrinary tract infections

• Skin infectionsSkin infections

• Sexually transmitted diseasesSexually transmitted diseases


Quinolones: Side EffectsQuinolones: Side Effects

Body SystemBody System EffectsEffects

CNSCNS headache, dizziness, headache, dizziness, fatigue, fatigue, depression, restlessnessdepression, restlessness

GIGI nausea, vomiting, diarrhea, nausea, vomiting, diarrhea, constipation, thrush, constipation, thrush,

increased liver increased liver functionfunction studiesstudies


Quinolones: Side EffectsQuinolones: Side Effects

Body SystemBody System EffectsEffects

IntegumentaryIntegumentary rash, pruritus, urticaria, rash, pruritus, urticaria, flushing, photosensitivity flushing, photosensitivity (with lomefloxacin)(with lomefloxacin)

OtherOther fever, chills, blurred vision, fever, chills, blurred vision, tinnitustinnitus


Antibiotics: MacrolidesAntibiotics: Macrolides

• erythromycin erythromycin

• azithromycin (Zithromax)azithromycin (Zithromax)

• clarithromycin (Biaxin)clarithromycin (Biaxin)

• dirithromycindirithromycin

• troleandomycintroleandomycin

– bactericidal actionbactericidal action


Instructors may wish to insert Instructors may wish to insert EIC Image #102: EIC Image #102:

Erythromycin FormulationsErythromycin Formulations


Macrolides: Therapeutic UsesMacrolides: Therapeutic Uses

Strep infectionsStrep infections

• Streptococcus pyogenes Streptococcus pyogenes (group A beta-hemolytic streptococci)(group A beta-hemolytic streptococci)

Mild to moderate URIMild to moderate URI

• Haemophilus influenzaeHaemophilus influenzae

Spirochetal infectionsSpirochetal infections

• Syphilis and Lyme diseaseSyphilis and Lyme disease

Gonorrhea, Chlamydia, MycoplasmaGonorrhea, Chlamydia, Mycoplasma


Macrolides: Side EffectsMacrolides: Side Effects

GI effects, primarily with erythromycin:GI effects, primarily with erythromycin:

• nausea, vomiting, diarrhea, hepatotoxicity, nausea, vomiting, diarrhea, hepatotoxicity, flatulence, jaundice, anorexiaflatulence, jaundice, anorexia

• Newer agents, azithromycin and clarithromycin: Newer agents, azithromycin and clarithromycin: fewer side effects, longer duration of action, fewer side effects, longer duration of action, better efficacy, better tissue penetrationbetter efficacy, better tissue penetration


Antibiotics: Nursing ImplicationsAntibiotics: Nursing Implications

• Before beginning therapy, assess drug allergies; Before beginning therapy, assess drug allergies; hepatic, liver, and cardiac function; and other lab hepatic, liver, and cardiac function; and other lab studies.studies.

• Be sure to obtain thorough patient health history, Be sure to obtain thorough patient health history, including immune status.including immune status.

• Assess for conditions that may be contraindications Assess for conditions that may be contraindications to antibiotic use, or that may indicate cautious use.to antibiotic use, or that may indicate cautious use.

• Assess for potential drug interactions.Assess for potential drug interactions.



• It is ESSENTIAL to obtain cultures from It is ESSENTIAL to obtain cultures from appropriate sites BEFORE beginning appropriate sites BEFORE beginning antibiotic therapy.antibiotic therapy.



• Patients should be instructed to take antibiotics Patients should be instructed to take antibiotics exactly as prescribed and for the length of time exactly as prescribed and for the length of time prescribed; they should not stop taking the prescribed; they should not stop taking the medication early when they feel better.medication early when they feel better.

• Assess for signs and symptoms of superinfection: Assess for signs and symptoms of superinfection: fever, perineal itching, cough, lethargy, or any fever, perineal itching, cough, lethargy, or any unusual discharge.unusual discharge.



• For safety reasons, check the name of the For safety reasons, check the name of the medication carefully since there are many medication carefully since there are many agents that sound alike or have similar agents that sound alike or have similar spellings.spellings.



• Each class of antibiotics has specific side Each class of antibiotics has specific side effects and drug interactions that must be effects and drug interactions that must be carefully assessed and monitored.carefully assessed and monitored.

• The most common side effects of antibiotics The most common side effects of antibiotics are nausea, vomiting, and diarrhea.are nausea, vomiting, and diarrhea.

• All oral antibiotics are absorbed better if All oral antibiotics are absorbed better if taken with at least 6 to 8 ounces of water.taken with at least 6 to 8 ounces of water.



SulfonamidesSulfonamides

• Should be taken with at least 2400 mL of fluid Should be taken with at least 2400 mL of fluid per day, unless contraindicated.per day, unless contraindicated.

• Due to photosensitivity, avoid sunlight and Due to photosensitivity, avoid sunlight and tanning beds.tanning beds.

• These agents reduce the effectiveness of These agents reduce the effectiveness of oral contraceptives.oral contraceptives.



PenicillinsPenicillins

• Any patient taking a penicillin should be carefully Any patient taking a penicillin should be carefully monitored for an allergic reaction for at least 30 monitored for an allergic reaction for at least 30 minutes after its administration.minutes after its administration.

• The effectiveness of oral penicillins is decreased The effectiveness of oral penicillins is decreased when taken with caffeine, citrus fruit, cola beverages, when taken with caffeine, citrus fruit, cola beverages, fruit juices, or tomato juice.fruit juices, or tomato juice.



CephalosporinsCephalosporins

• Orally administered forms should be given with food Orally administered forms should be given with food to decrease GI upset, even though this will delay to decrease GI upset, even though this will delay absorption.absorption.

• Some of these agents may cause an Antabuse-like Some of these agents may cause an Antabuse-like reaction when taken with alcohol.reaction when taken with alcohol.



TetracyclinesTetracyclines

• Milk products, iron preparations, antacids, and other Milk products, iron preparations, antacids, and other dairy products should be avoided because of the dairy products should be avoided because of the chelation and drug-binding that occurs.chelation and drug-binding that occurs.

• All medications should be taken with 6 to 8 ounces All medications should be taken with 6 to 8 ounces of fluid, preferably water.of fluid, preferably water.

• Due to photosensitivity, avoid sunlight and Due to photosensitivity, avoid sunlight and tanning beds.tanning beds.




• Monitor peak and trough blood levels of these Monitor peak and trough blood levels of these agents to prevent nephrotoxicity and ototoxicity.agents to prevent nephrotoxicity and ototoxicity.

• Symptoms of ototoxicity include dizziness, tinnitus, Symptoms of ototoxicity include dizziness, tinnitus, and hearing loss.and hearing loss.

• Symptoms of nephrotoxicity include urinary casts, Symptoms of nephrotoxicity include urinary casts, proteinuria, and increased BUN and serum proteinuria, and increased BUN and serum creatinine levels.creatinine levels.




• Should be taken with at least 3 L of fluid per day, Should be taken with at least 3 L of fluid per day, unless otherwise specifiedunless otherwise specified



MacrolidesMacrolides

• These agents are highly protein-bound and will These agents are highly protein-bound and will cause severe interactions with other protein-bound cause severe interactions with other protein-bound drugs.drugs.

• The absorption of oral erythromycin is enhanced The absorption of oral erythromycin is enhanced when taken on an empty stomach, but because when taken on an empty stomach, but because of the high incidence of GI upset, many agents of the high incidence of GI upset, many agents are taken after a meal or snack.are taken after a meal or snack.



Monitor for therapeutic effects:Monitor for therapeutic effects:

• Disappearance of fever, lethargy, drainage, Disappearance of fever, lethargy, drainage, and rednessand redness

Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved. Microbiology: A Clinical Approach © Garland Science ANTIBIOTICS ANTIBIOTICS © CDC.

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