This document discusses various classes of antibiotics including penicillins, cephalosporins, macrolides, tetracyclines, aminoglycosides, and quinolones. It describes their mechanisms of action, common uses, and potential adverse effects. Specifically, it provides details on common drugs in each class, how they work at the cellular level to kill bacteria, infections they can treat, and side effects to monitor like ototoxicity and nephrotoxicity. The document stresses the importance of obtaining cultures before treatment and monitoring patients for both therapeutic responses and unwanted reactions.

1. Dr.Gurumeet C Wadhawa ,Assistant
Professor, Department of Chemistry.
Rayat Shikshan sansthas Veer Wajekar ASC
College,Phunde,Uran

2.  Medications used to treat bacterial
infections
 Ideally, before beginning antibiotic
therapy, the suspected areas of
infection should be cultured to
identify the causative organism and
potential antibiotic susceptibilities

4.  Empiric therapy: treatment of an infection
before specific culture information has
been reported or obtained
 Prophylactic therapy: treatment with
antibiotics to prevent an infection, as in
intra-abdominal surgery or after trauma

5.  Therapeutic response
 Decrease in specific signs and symptoms of
infection are noted (fever, elevated WBC, redness,
inflammation, drainage, pain)
 Subtherapeutic response
 Signs and symptoms of infection do not improve

6.  Superinfection
 Antibiotic resistance
 Host factors
 Genetic host factors
 G6PD deficiency
 Slow acetylation
 Allergic reactions

7. • Sulfonamides
• Penicillins
• Cephalosporins
• Tetracyclines
• Aminoglycosides
• Quinolones
• Macrolides

8. • clindamycin (Cleocin)
• dapsone
• linezolid (Zyvox)
• metronidazole (Flagyl)
• nitrofurantoin (Macrodantin)
• quinupristin and dalfopristin (Synercid)
• daptomycin (Cubicin)

9. Four common mechanisms of action
 Interference with cell wall synthesis
 Interference with protein synthesis
 Interference with DNA replication
 Acting as a metabolite to disrupt critical
metabolic reactions inside the bacterial cell

11.  Bactericidal: kill bacteria
 Bacteriostatic: inhibit growth of susceptible
bacteria, rather than killing them immediately;
will eventually lead to bacterial death

12. One of the first groups of antibiotics
 Sulfadiazine (Coptin)
 Sulfamethoxazole
 Sulfisoxazole (Gantrisin)
 Used to treat otitis media, UTIs, other conditions
Often combined with another antibiotic
 Sulfamethoxazole-trimethoprim (Bactrim)

13.  Bacteriostatic action
 Prevent synthesis of folic acid required
for synthesis of purines and nucleic acid
 Do not affect human cells or certain
bacteria—they can use preformed folic acid
 Only affect organisms that synthesize their
own folic acid

14.  Treatment of UTIs caused by susceptible strains
of:
 Enterobacter spp., Escherichia coli, Klebsiella spp.,
Proteus mirabilis, Proteus vulgaris, Staphylococcus
aureus
 Nocardiosis (caused by Nocardia - pneumonia)
 Pneumocystis jiroveci pneumonia (PJP)
 co-trimoxazole (Bactrim, Septra)
 Upper respiratory tract infections

15.  trimethoprim/sulfamethoxazole (co-trimoxazole,
Bactrim, Septra)
 Used to treat UTIs, PJP, otitis media, other conditions
 erythromycin/sulfisoxazole (Pediazole)
 Used to treat otitis media

16. Body System Adverse Effects
Blood Hemolytic and aplastic anemia,
agranulocytosis, thrombocytopenia
Integumentary Photosensitivity, exfoliative dermatitis,
Stevens-Johnson syndrome, epidermal
necrolysis
GI Nausea, vomiting, diarrhea,
pancreatitis
Other Convulsions, crystalluria, toxic
nephrosis, headache,
peripheral neuritis, urticaria

17. Sulfonamides
 Should be taken with at least 2000 mL
of fluid per day, unless contraindicated
 Oral forms should be taken with food or
milk to reduce GI upset

18.  Natural penicillins
 Penicillinase-resistant penicillins
 Aminopenicillins
 Extended-spectrum penicillins

20. Natural penicillins
 penicillin G, penicillin V potassium
Penicillinase-resistant drugs
 cloxacillin, dicloxacillin, nafcillin, oxacillin
Aminopenicillins
 amoxicillin, ampicillin, bacampicillin
Extended-spectrum drugs
 piperacillin, ticarcillin, carbenicillin

21.  First introduced in the 1940s
 Bactericidal: inhibit cell wall synthesis
 Kill a wide variety of bacteria
 Also called “β-lactams”
 Bacteria produce enzymes capable of
destroying penicillins
 These enzymes are known as β-lactamases
 As a result, the medication is not effect

22.  Chemicals used to inhibit these enzymes:
Clavulanic acid Tazobactam Sulbactam
 Bind with β-lactamase and prevent the enzyme
from breaking down the penicillin -- making the
drug more effective
 Penicillin-β-lactamase inhibitor
combination drugs
 ampicillin + sulbactam = Unasyn
 amoxicillin + clavulanic acid = Augmentin
 ticarcillin + clavulanic acid = Timentin
 piperacillin + tazobactam = Zosyn

23.  Penicillins enter the bacteria via the cell wall
 Inside the cell they bind to penicillin-binding protein
 Once bound, normal cell wall synthesis is
disrupted
 Result: bacteria cells die from cell lysis
 Penicillins do not kill other cells in the body

24.  Prevention and treatment of infections
caused by susceptible bacteria, such as:
 Gram-positive bacteria
 Streptococcus, Enterococcus, Staphylococcus

25.  Allergic reactions occur in 0.7% to 4% of cases
 Urticaria, pruritus, angioedema
 Those allergic to penicillins have a fourfold to sixfold increased
risk of allergy to other β-lactam antibiotics
 Cross-reactivity between penicillins and cephalosporins is
between 1% and 18%
 Common adverse effects
 Nausea, vomiting, diarrhea, abdominal pain
 Other adverse effects are less common

26.  MANY interactions!
 NSAIDs
 Oral contraceptives
 warfarin
 Others

27.  Any patient taking a penicillin should be carefully
monitored for an allergic reaction for at least
30 minutes after its administration
 The effectiveness of oral penicillins is
decreased when taken with caffeine, citrus
fruit, cola beverages, fruit juices, or tomato
juice
 Administer with at least 6 ounces of water

28.  Four Generations:
 Semisynthetic derivatives from a fungus
 Structurally and pharmacologically related
to penicillins
 Bactericidal action
 Broad spectrum
 Divided into groups according to antimicrobial activity

29.  Used for surgical prophylaxis, URIs,
otitis media
 cefazolin (Ancef and Kefzol): IV or IM
 cephalexin (Keflex): PO

30.  Good gram-positive coverage
 Better gram-negative coverage than first
generation
 Cefmetazole IV Cefprozil (Cefzil) PO
 Cefoxitin (Mefoxin) IV Cefaclor (Ceclor) PO
 cefoxitin (Mefoxin): IV and IM
 Used prophylactically for abdominal or colorectal surgeries
 Also kills anaerobes
 cefuroxime (Kefurox and Ceftin): PO
 Surgical prophylaxis
 Does not kill anaerobes

31. ceftriaxone (Rocephin)
 IV and IM, long half-life, once-a-day dosing
 Elimination is primarily hepatic
 Easily passes meninges and diffused into CSF to treat CNS
infections
 ceftazidime (Fortaz, Tazidime)
 IV and IM forms
 Excellent gram-negative coverage
 Used for difficult-to-treat organisms such as Pseudomonas
 Eliminated renally instead of biliary route
 Excellent spectrum of coverage

32.  Newest cephalosporin drugs
 Broader spectrum of antibacterial activity than
third generation, especially against gram-
positive bacteria
 Tx: UTI, Skin infections, pneumonia
 cefepime (Maxipime) GM +/-
 cefdinir
 cefditoren pivoxil (Spectracef)

33.  Similar to penicillins
 Mild diarrhea, abdominal cramps, rash, pruritis,
redness, edema
 Potential cross-sensitivity with penicillins
if allergies exist

34.  Orally administered forms should be given
with food to decrease GI upset, even
though this will delay absorption
 Some of these drugs may cause a
disulfiram (Antabuse)-like reaction when
taken with alcohol

35.  Very broad-spectrum antibacterial action
 Reserved for complicated body cavity and
connective tissue infections
 May cause drug-induced seizure activity
 All given parenterally
imipenem-cilastatin (Primaxin)
 Used for treatment of bone, joint, skin, and soft
tissue infections
 Cilastatin inhibits an enzyme that breaks down
imipenem
meropenem (Merrem) – bacterial meningitis
ertapenem (Invanz) - newest

36. aztreonam (Azactam)
 Synthetic β-lactam antibiotic
 Primarily active against aerobic gram-negative
bacteria (E. coli, Klebsiella spp., Pseudomonas spp.)
 Bactericidal
 Used for moderately severe systemic infections
and UTIs

37.  Prevent protein synthesis within bacterial cells
 Considered bacteriostatic - Bacteria will eventually die
 In high enough concentrations, may also be
bactericidal
 erythromycin (E-mycin
 azithromycin (Zithromax)
 clarithromycin (Biaxin)
Adverse Effects: GI effects, primarily with erythromycin
 Nausea, vomiting, diarrhea, hepatotoxicity, flatulence,
jaundice, anorexia
 Newer drugs, azithromycin and clarithromycin: fewer GI
adverse effects, longer duration of action, better efficacy,
better tissue penetration

38.  These drugs are highly protein-bound and will cause
severe interactions with other protein-bound
drugs
 The absorption of oral erythromycin is enhanced
when taken on an empty stomach, but because
of the high incidence of GI upset, many drugs
are taken after a meal or snack

39. telithromycin (Ketek)
 Only drug in this class
 Better antibacterial coverage than macrolides
 Active against gram-positive bacteria, including
multi-drug resistant strains of S. pneumoniae
 Active against selected gram-negative bacteria
 Indications:
 Community-acquired pneumonia, acute bacterial sinusitis,
bacterial exacerbations of chronic bronchitis
 Adverse reactions include:
 Headache, dizziness, GI discomfort, altered potassium levels,
prolonged QT intervals

40.  Natural and semisynthetic
 Obtained from cultures of Streptomyces
 Bacteriostatic—inhibit bacterial growth
 Inhibit protein synthesis
 Stop many essential functions of the bacteria
 demeclocycline (Declomycin)
 oxytetracycline
 tetracycline
 doxycycline (Doryx, Vibramycin)
 Minocycline

41. Strong affinity for calcium
 Discoloration of permanent teeth and tooth
enamel in fetuses and children, or nursing infants if
taken by the mother
 May retard fetal skeletal development if taken
during pregnancy
Alteration in intestinal flora may result in:
 Superinfection (overgrowth of nonsusceptible
organisms such as Candida)
 Diarrhea
 Pseudomembranous colitis

42.  Milk products, iron preparations, antacids, and
other dairy products should be avoided because of
the chelation and drug-binding that occurs
 All medications should be taken with 6 to 8 ounces
of fluid, preferably water
 Due to photosensitivity, avoid sunlight and
tanning beds

43.  Before beginning therapy, assess drug allergies; renal,
liver, and cardiac function; and other lab studies
 Be sure to obtain patient health history, including
immune status
 Assess for conditions that may be contraindications to
antibiotic use or that may indicate cautious use
 Assess for potential drug interactions
 It is ESSENTIAL to obtain cultures from
appropriate sites BEFORE beginning
antibiotic therapy

44.  Each class of antibiotics has specific adverse
effects and drug interactions that must be
carefully assessed and monitored
 The most common adverse effects of antibiotics
are nausea, vomiting, and diarrhea
 All oral antibiotics are absorbed better if taken with
at least 6 to 8 ounces of water

45. Monitor for therapeutic effects
 Improvement of signs and symptoms of infection
 Return to normal vital signs
 Negative culture and sensitivity tests
 Disappearance of fever, lethargy, drainage, and
redness
Monitor for adverse reactions

46.  Therapeutic drug monitoring
 Minimum inhibitory concentration (MIC)
 Concentration-dependent killing
 Once-daily dosing vs. multi-daily dosing
 Peak and trough blood levels
 Synergistic effects
 Post-antibiotic effect (PAE)

47.  Ototoxicity
 Temporary or permanent hearing loss, balance
problems
 Nephrotoxicity
 Varying degrees of reduced renal function
 Rising serum creatinine may indicate reduced creatinine
clearance
Monitor trough levels every 3 days while on
therapy or as ordered

48.  gentamicin (Garamycin)
 kanamycin
 neomycin (Neo-Fradin)
 streptomycin
 tobramycin (Nebcin)
 amikacin (Amikin)
 netilmicin
 paromomycin

49.  Natural and semisynthetic
 Produced from Streptomyces
 Poor oral absorption; no PO forms
 Very potent antibiotics with serious toxicities
 Bactericidal; prevents protein synthesis
 Kill mostly gram-negative; some gram-positive

50.  Used to kill gram-negative bacteria Pseudomonas,
E. coli, Proteus, Klebsiella, Serratia
 Often used in combination with other antibiotics for
synergistic effects
 Certain gram-positive infections that are resistant to other
antibiotics
 Aminoglycosides poorly absorbed through the GI tract - given IV
 Exception: neomycin
 Given orally or by enema - decontaminate the GI tract
before surgical procedures

51.  Ototoxicity and nephrotoxicity are
the most significant
 Headache
 Paresthesia
 Fever
 Superinfections
 Vertigo
 Skin rash
 Dizziness


52.  ciprofloxacin (Cipro)
 norfloxacin (Noroxin)
 levofloxacin (Levaquin)
 gatifloxacin (Tequin)
 moxifloxacin (Avelox)
 gemifloxacin (Factive)

53.  Also called “quinolones”
 Excellent oral absorption
 Absorption reduced by antacids
 Effective against gram-negative organisms and
some gram-positive organisms
 Mechanism of Action:
 Bactericidal
 Alter DNA of bacteria, causing death
 Do not affect human DNA

54.  Lower respiratory tract infections
 Bone and joint infections
 Infectious diarrhea
 Urinary tract infections
 Skin infections
 Sexually transmitted diseases
 Anthrax

55. Body System Adverse Effects
CNS Headache, dizziness, fatigue,
depression, restlessness, insomnia
GI Nausea, vomiting, diarrhea,
constipation, thrush, increased LFTs
Integumentary Rash, pruritus, urticaria, flushing,
photosensitivity (with lomefloxacin)
Other Fever, chills, blurred vision, tinnitus

56.  clindamycin (Cleocin)
 dapsone
 linezolid (Zyvox)
 metronidazole (Flagyl)
 nitrofurantoin (Macrodantin)
 quinupristin and dalfopristin (Synercid)
 daptomycin (Cubicin)

57.  clindamycin (Cleocin)
 Used for chronic bone infections, GU
infections, intraabdominal infections, other
serious infections
 May cause pseudomembranous colitis

58.  dapsone
 Used for leprosy (Hansen’s disease), PJP
pneumonia associated with HIV/AIDS, other
uses

59.  linezolid (Zyvox)
 New class: oxazolidinones
 Used to treat vancomycin-resistant Enterococcus
faecium (VREF, VRE), hospital-acquired skin and
skin structure infections, including those with
MRSA
 May cause hypotension, serotonin syndrome if taken
with SSRIs, and reactions if taken with tyramine-
containing foods

60.  nitrofurantoin (Macrodantin)
 Primarily used for UTIs (E. coli, S. aureus,
Klebsiella spp., Enterobacter spp.)
 Use carefully if renal function is impaired
 Drug concentrates in the urine
 Usually well-tolerated if patient is kept well-
hydrated

61.  quinupristin and dalfopristin (Synercid)
 30:70 combination, work synergistically
 Used for bacteremia and infections caused by
vancomycin-resistant Enterococcus (VRE) and
other complicated skin infections
 May cause arthralgias, myalgias

62.  daptomycin (Cubicin)
 New class: lipopeptide
 Used to treat complicated skin and soft-tissue
infections

63.  Natural, bactericidal antibiotic - Destroys cell wall
 Treatment of choice for MRSA, and other gram-positive infections
 Must monitor blood levels to ensure therapeutic levels and prevent toxicity
 May cause ototoxicity and nephrotoxicity
 Should be infused over 60 minutes -- Monitor IV site closely
 Red man syndrome may occur
 Flushing/itching of head, neck, face, upper trunk
 Antihistamine may be ordered to reduce these effects
 Ensure adequate hydration (2 L fluids/24 hr) if not contraindicated to
prevent nephrotoxicity

64.  Before beginning therapy, assess drug allergies;
hepatic, renal, and cardiac function
 Be sure to obtain thorough patient health history,
including immune status
 Assess for conditions that may be contraindications
to antibiotic use or that may indicate cautious use
 Assess for potential drug interactions

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

66.  Patients should be instructed to take antibiotics
exactly as prescribed and for the length of time
prescribed; they should not stop taking the
medication early when they feel better
 Assess for signs and symptoms of superinfection:
fever, perineal itching, cough, lethargy, or any
unusual discharge
 For safety reasons, check the name of the
medication carefully because there are many drugs
that sound alike or have similar spellings

67.  Each class of antibiotics has specific
adverse effects and drug
interactions that must be carefully
assessed and monitored

68. Aminoglycosides
 Monitor peak and trough blood levels of
these drugs to prevent nephrotoxicity and
ototoxicity
 Symptoms of ototoxicity include dizziness,
tinnitus, and hearing loss
 Symptoms of nephrotoxicity include urinary
casts, proteinuria, and increased BUN and
serum creatinine levels

69. Monitor for therapeutic effects
 Improvement of signs and symptoms of infection
 Return to normal vital signs
 Negative culture and sensitivity tests
 Disappearance of fever, lethargy, drainage, and
redness
Monitor for adverse reactions