The document discusses various classes of β-lactam antibiotics including penicillins, cephalosporins, carbapenems, and monobactams. It describes their mechanisms of action, classifications, pharmacokinetics, clinical uses, and adverse effects. The penicillins are further broken down into narrow spectrum, broad spectrum, and extended spectrum categories. Mechanisms, classifications, and uses are provided for each class and some individual antibiotics.

1. β-Lactam Antibiotics
 1. PENICILLINS
2.Cephalosporins
 3.Carbapenems ( Imipenems )
 4. Monobactams ( Aztreonam)

2. Penicillins
 Classification
 Narrow spectrum penicillins
 Antistaphylococcal penicillins
 Broad spectrum penicillins
 Extended –spectrum penicillins
( antipseudomonal penicillins).

3. Mechanism of action
 Like all β-lactam antibiotics , inhibit the
synthesis of bacterial cell wall .
 Through inhibition transpeptidase enzyme
 They are bactericidal on the actively
growing bacteria.

4. Pharmacokinetics
 Absorption
 Depending on acid stability
 Absorption of most oral penicillins is
impaired by food except amoxicillin .

5. Metabolism & Excretion
 Not metabolised
 Excreted unchanged in urine
 Probenecid blocks their secretion
 Nafcillin is mainly cleared by biliary route
 Oxacillin by both kidney & biliary route.

6. Distribution
 Relatively insoluble in lipid
 Poor penetration into cells and BBB
Inflammation permits entrance into CSF.
 Proteins binding vary from 20%-90%

7. Narrow spectrum penicillins
 Penicillin G
 Short duration
 Acid unstable
 Penicillinase sensitive
 Used in enterococcal endocarditis usually
with aminoglycosides
 To prevent gonorrheal opthalmia in new
born .

8. Procaine penicillin
 Long acting (every 12 h ) .
 Acid unstable
 Penicillinase sensitive
 Used to prevent subacute bacterial
endocarditis due to dental extraction or
tonsillectomy in patients with congenital or
acquired valve disease .

9. Benzathine penicillin
 Long acting (every 3-4 weeks )
 Acid unstable
 Penicillinase sensitive
 Treatment of β-hemolytic streptococcal
pharyngitis.
 Used as prophylaxis against reinfection with β-
hemolytic streptococci so prevent rheumatic
fever .
 Once a week for 1-3 weeks for treatment of
syphilis (2.4 milloion units I.M.)

10. Phenoxymethyl penicillin (P. V)
 Less effective than penicillin G
 Acid stable
 Penicillinase sensitive
 Short acting
 Used in minor infections

11. Penicillinase resistant to
staphylococcal β-lactamase producer
 Methicillin acid unstable
 Nafcillin its absorption is erratic
 Oxacillin, Cloxacillin,Dicloxacillin (acid
stable ).
 Used in minor & severe Stap. infections

12. Broad &Extended spectrum
penicillins
 Aminopenicillins
 Carboxypenicillins
 Ureidopenicillins

13. Aminopenicillins(Ampicillin
&Amoxicillin)
 Therapeutic uses
 1)H.influenza
 2)E.coli
 3)Salmonella&Shigella infections only ampicillin
 4)Prophylaxis of infective endocarditis
 5) Urinary tract infections
 6) Effective against penicillin –resistant
pneumococci

14. Carboxypenicillins(Ticarcillin)&Ur
eidopenicillin(Piperacillin)
 Effective against pseudomonas
aeruginosa & Enterobacter.
 Penicillinase sensitive
 Can be given in combination with β-
lactamase inhibitors as clavulanic acid
,sulbactam, tazobactam.

15. Adverse effects
 Hypersensitivity reactions
 High dose in renal failure ---seizure
 Naficillin (neutropenia)
 Oxacillin (hepatitis)
 Methicillin(nephritis)
 B.S.P.(pseudomembraneous colitis )
 Secondary infections

16. Problems relating to use &
misuse of penicillins
 1- 90% of staphylococcal strains both in
hospital or community are β-lactamase
producers
 2- New generations of microorganisms as
H.influenzae , N.gonorrhoeae or
pneumococci are resistant to penicillins
 3- Broad spectrum penicillins eradicate
normal flora causing superinfections

17. Cephalosporins
 First-Generation
 Cefazolin, Cephalexin, cephradin.
 They are very effective against gram-
positive cocci
 They are given orally ,except cefazolin
given I.V.I ,or I.M.

18. Excretion
 Mainly through kidney
 Probenecid block tubular secretion and
increase plasma level .
 They can not cross B.B.B.

19. Clinical uses
 Urinary tract infections
 Minor Staph.infections or minor
polymicrobial infections as cellulitis or soft
tissue abscess.
 Cefazolin is the drug of choice for surgical
prophylaxis,also as alternative to
antistaph.penicillin in allergic patients .

20. Second -Generations
 Cefaclor ,Cefamandole, Cefonicid
 Less active against gram-positive bacteria
than first generation
 They have extended gram –negative
effect
 No effect on P-aeruginosa or E-cocci.

21. Pharmacokinetics
 Given orally or parenterally
 Can not cross B.B.B.
 Excreted through kidney
 Cefonicid is highly protein binding

22. Clinical uses
 H-influenza infections
 Mixed anaerobic infections as peritonitis .
 Community acquired pneumonia

23. Third -Generations
 Cefoperazone,Cefixime,Ceftriaxone
 They have extended gram- negative
spectrum.
 Have an effect on P-aeruginosa .
 No effect on E-coli.

24. Pharmacokinetics
 Main route I.V.I.
 Cefixime can be given orally
 Ceftriaxone has a long half- life (7-8h).can
be given once every 24h.
 Cross B.B.B.
 Excreted through kidney .Ceftriaxone
through bile.

25. Clinical uses
 Serious infections
 Cefixime ,first line in treatment of
gonorrhea.
 Meningitis
 P-aeruginosa infections.

26. Fourth -Generations
 Cefepime
 More resistant to hydrolysis by β-
lactamase
 Active against P-aeruginosa & E-coli
 Clinical use as third generations.

27. Adverse Effects
 Allergy
 Thrombophilibitis
 Interstitial nephritis and tubular necrosis
mainly with cephaloridine.
 Cephalosporins that contain a
methylthiotetrazole group as
cefamandole ,cefperazone cause
hypoprothrombinemia

28.  And bleeding disorders .
 Vit.K twice weekly can prevent this .
 Methylthiotetrazole ring causes severe
disulfiram-like reaction.
 Superinfections.
 Diarrhea.

29. Carbapenems
 Imipenem
 Bctericidal, inhibit bacterial cell wall
synthesis.
 Has a wide spectrum of activity
 Sensetive to metallo-β lactamase .

30. Pharmacokinetics
 Not absorbed orally,taken by I.V.I.
 Inactivated by dehydropeptidases in renal
tubules, so it is given with an inhibitor of
renal dehydropeptidases,cilastatin for
clinical use.
 Penetrates body tissues and fluids
including c.s.f.

31. Clinical uses
 Mixed aerobic and anaerobic infections
 Carbapenem is the β lactam of choice for
treatment of enterobacter infections.
 Pseudomonal infections
 Intraabdominal infections
 Febrile neutropenic patient
 Septicaemia.

32. Meropenem
 Similar to imipenem but it is highly active
against gram-negative aerobes .
 Not degraded by renal dehydropeptidase

33. Adverse effects
 Nausea,vomiting,diarrhea
 Skin rash and reaction at the site of
infusion
 High dose with imipenem in renal failure
cause seizure
 Patients allergic to penicillin may be
allergic to carbapenems .

34. Monobactams
 Aztronam
 Active only against gram-negative aerobic
bacteria.
 Given I.V.
 Similar to β-lactam in mechanism of action
and adverse effects.

35. Macrolides(MACROCYCLIC
LACTONE RING 14-16 ATOMS)
 Erythromycin(14 atom lactone ring )
 Is effective against
 Legionella,cornybacteria,gram-positive
cocci,chlamydia,helicobacter
 Less effective on gram-negative
organisms.

36. Mechanism of action
 Inhibit protein synthesis via binding to 50
S ribosomal RNA subunit.
 Bactericidal at high conc.and
bacteriostatic at low conc.

37. Pharmacokinetics
 Destroyed by stomach acid and must be
administered with enteric coating .
 Food interferes with absorption
 Half-life 1.5h
 Excreted mainly through bile,5%only in
urine.
 Cross placenta not B.B.B.

38. Clinical uses
 Drug of choice of corynebacterial
infections
 Chlamydial infections
 Community acquired pneumonia
 Mycoplasma
 Legionella
 Penicillin allergic patients.

39. Adverse effects
 Anorexia,nausea,vomiting,diarrhea.
 Liver toxicity especially with the estolate
coat produce acute cholestatic hepatitis
 Drug interactions as it is cytochrome p450
inhibitor.
 Hypersensitivity reactions .

40. Clarithromycin(14 atom lactone
ring)
 Acid stable
 Mechanism of action as erythromycin
 Spectrum as erythromycin but more active
against Mycobacterium avium
complex.m.leprae.Toxoplasma gondii.
 Half –life 6h.
 Metabolised in liver (active metabolites ).

41. Partially excreted in urine
 Drug interactions similar to erythromycin
 Has a lower frequency of gastric upset
 And less frequent dosing
 More tolerable
 More expensive

42. Azithromycin(15 lactone ring )
 Same mechanism of action
 Similar spectrum as clarithromycin,but
more active on H-influenza &chlamydia.
 Half-life 3 days .
 Rapidaly absorbed and well tolerated .
 Free of drug interactions
 Excreated in bile and urine

43. Clinical uses
 Upper and lower respiratory tract
infections
 Skin infections
 Alternative to penicillin in allergic patients
 Urethritis or cervicitis mainly by chlamydial
infections .

44. Adverse effects
 Gstric upset (less than erythromycin )
 Allergic
 Superinfections
 Liver affection

45. Tetracyclines
 Broad spectrum antibiotics
 Bacteriostatic,inhibits protein synthesis
reversibly by binding to 30 S ribosomal
subunits .

46. Pharmacokinetics
 Absorption:
 Poorly absorbed 30% as chlortetracycline
 Medialy absorbed 60-70% as
tetracycline ,oxytetracycline and
demeclocycline
 Highly absorbed 95-100% as doxycycline
and minocycline.
 Absorption is impaired by food except

47. Doxycycline and minocycline
 Absorption of all preparations is impaired
by divalent cations,milk and its products
,antacids and alkaline pH.
 Plasma protein binding 40-80%.
 Minocycline reaches very high conc. In
tears and saliva, makes it useful in
eradication of meningococcal carrier.

48. They cross placenta barrier .
 Excreated through bile and urine
 Doxycycline is eliminated by nonrenal
route .
 According to half-life :
 Long acting; doxycycline &minocycline
 (16-18h once daily ).
 Intermediate (12h) demeclocycline

49. Short acting (6-
8h)oxy,tetracyclines.
 Clinical uses:
 Mycoplasma pneumonia
 Chlamydial infections
 Rickettsial infections
 Spirocates
 Brucellosis
 Anthrax

50. Clinical uses
 Cholera
 Traveller,s diarrhea
 Helicobacter pylori
 Acne(minocycline&doxycycline)
 Bronchitis
 Protozoal infections
 Minocycline to eradicate meningococci carrier

51. Not used in:
 Streptococcal & staphylococcal
infections .
 Gonococcal infections
 Meningococcal infections
 Typhoid fever

52. Adverse effects
 I.M.(pain & inflammation)
 I.V.(thrombophilbitis)
 Gastric upset (N.,V.,D.)
 Enterocolitis
 Super infections
 Damage growing bone &teeth.

53. Adverse effects
 Yellowish brown discolorationof teeth
&dental caries.
 Liver toxicity
 Kidney toxicity (tubular necrosis).
 Photosensitization(demeclocycine)
 Vestibular reaction(vertigo,dizziness,)
 (Doxycycline &minocycline).

54. Contraindications
 With milk or its products,or antacids.
 Pregnancy
 Children under 8 years.

55. Chloramphenicol
 Broad spectrum antibiotics
 Bacteriostatic,inhibits protein synthesis by
binding to 50S ribosomal subunits.
 Rapidly &completely absorbed
 Rapidly distributed
 Cross placental barrier &B.B.B.
 Metabolised in liver
 Excreted mainly through urine
 Enzyme inhibitor(p450)

56. Clinical uses
 Serious rickettsial infections
 In children whom tetracyclines are
contraindicated
 Meningitis
 In allergic patients to penicillin
 Topically in bacterial eye infections except
in chlamydial infections.

57. Adverse effects
 Gastric upset (N.,V.,D.)
 Super infections
 Bone marrow depression
 Gray baby syndrome
 Hypersensitivity reactions
 Drug interactions

58. Aminoglycosides
 Bactericidal antibiotics
 Inhibits protein synthesis by binding to
30S ribosomal subunits.
 Active against gram negative aerobic
organisms.
 Poorly absorbed orally
 Given parenterally (I.M,I.V.)
 Not freely cross BBB

59. Aminoglycosides
 Excreted mainly unchanged in urine
 More active in alkaline medium
 Have common adverse effects :
 Ototoxicity
 Nephrotoxicity
 Neuromuscular blocking effect
 CNS (not common ).

60. Clinical uses
 Streptomycin
 T.B. in combination with other
antituberculous drugs.
 Enterococcal endocarditis with penicillin.
 Severe brucellosis with tetracycline

61. Gentamicin
 Severe infections caused by gram
negative organisms as sepsis ,urinary
tract infections & pneumonia caused by
pseudomonas.
 Topically for the treatment of infected
burns,wounds,skin lesions,ocular, ear
infections.

62. Tobramycin
 More active against pseudomonas than
gentamicin.
 Ineffective against mycobacteria
 Less nephrotoxic and ototoxic than
gentamicin.
 Used in treatment of bacteremia,
osteomyelitis and pneumonia.

63. Amikacin
 Has the broadest spectrum
 Used for serious nosocomial infections by
gram negative organisms.
 In T.B. as alternative to streptomycin
 Atypical mycobacterial infections

64. Neomycin
 Highly nephrotoxic ,used only orally for gut
sterilization before surgery or topically in
skin infections,burn or eye infections.

65. Contraindications of
aminoglycosides
 Renal dysfunction
 Pregnancy
 Diminished hearing
 Myasthenia gravis
 Respiratory problems

66. Precautions with:
 Loop diuretics
 Cephalosporins
 Monitor plasma level is useful.
 Neostigmine reverses respiratory
depression.

67. FLUOROQUINOLONES
(Ciprofloxacin,ofloxacin,norfloxaci
 Mechanism of action:
 Block bacterial DNA synthesis by inhibiting
bacterial topoisomerase11(DNA gyrase ) and
topoisomerase 1V.
 Antibacterial activity :
 Highly active against gram-negative aerobic
bacteria.
 Active against gram-positive bacteria.
 Mycoplasma,chlamydia,legionella,mycobacteria.

68. Pharmacokinetics
 Well absorbed orally.
 Widely distributed in body fluids & tissues.
 Half-life(3-10h).
 Absorption is impaired by antacids.
 Concentrated mainly in
prostate,kidney,neutrophils ,macrophages.
 Excreted through kidney.

69. Clinical uses
 U.T.I.caused by multidrug resistance organisms
as pseudomonas.
 Bacterial diarrhea.
 Soft tissues,bones,joints,intra-abdominal,
respiratory infections caused by multidrug
resistance organisms.
 Gonococcal infections.
 Legionellosis.
 Chlamydial urethritis or cervicitis
 T.B & atypical T.B.

70. Adverse effects
 N.V.D.
 Headache,dizziness,insomnia
 Skin rash ,abnormal liver enzymes.
 QT prolongation
 Damage growing cartilage causing
arthropathy.
 Tendinitis in adults

71. Drug interactions &
contraindications
 With antacids
 Elevate serum levels of theophyline
increase the risk of seizure.
 Contraindicated in children ,adolescents
,pregnancy ,lactation ,epileptic patients.

72. Miscellaneous Antibiotics
 Polymyxins
 Active against gram-negative including
pseudomonas.
 Polymyxin B is only available.
 Bactericidal inhibits cell wall synthesis.
 Used only topically .
 Highly nephrotoxic.


73. Spectinomycin
 Bactericidal,inhibits protein synthesis by
binding to 30S ribosomal subunits.
 Given I.M.I.as a single dose in treatment
of gonorrhea.
 Pain at the site of injection.
 Excreted through kidney .
 Nephrotoxicity is rare.

74. Clindamycin
 Active against gram-positive and anaerobic
bacteria.
 Inhibits protein synthesis by binding to 50S
ribosomal subunits.
 Given orally or parenterally
 Widely distributed
 Cross placenta not BBB.
 Metabolised in liver giving active metabolites.

75. Excreted in bile & 10% in urine.
 Clinical uses:
 Anaerobic infections minly in bones and joints .
 Conjunctivitis.
 In combination with aminoglycosides or
cephalosporin is used to treat penetrating
wounds of the abdomen & the gut.
 Female genital tract e.g. septic abortion ,pelvis
abscess.
 Instead of erythromycin for prophylaxis of
endocarditis.
 Adverse effects :

76. Other inhibitors to cell wall
synthesis
 Vancomycin
 Bactericidal
 Active only on gram +ve bacteria.
 Poorly absorbed orally
 Given by I.v.I
 Not freely cross BBB
 Excreted mainly through kidney

77. Clinical uses
 Endocarditis mainly caused by methicillin –
resistant staphylococci.
 Alternative to penicillin in enterococcal
endocarditis( in combination with gentamicin).
 Meningitis( in combination with ceftriaxone or
rifampin in highly resistant pneumococcus
strains).
 Orally in antibiotic associated enterocolitis

78. Adverse effects
 Irritation at the site of injection
 Ototoxicity & nephrotoxicity .
 Red man or red neck syndrome.
 Gastric upset.

79. Bacitracin
 Bactericidal
 No cross resistance between it and other antimicrobial
drugs.
 Active against gram +ve organisms
 Used only topically in skin ,eye ,nose infections .
 Highly nephrotoxic producing proteninuria, hematuria
 Hypersensitivity reactions
 As ointment in combination with polymyxin or neomycin
for mixed bacterial infections.
 As solution in saline for irrigation of joints, wounds or
pleural cavity.

80. Teicoplanin
 Glycopeptide antibiotic
 Bactericidal
 Inhibits bacterial cell wall
 Active against gram positive organisms
 Given I.M. or I.V.
 Has a long half-life(45-70 h).
 Given once daily.

81. Cycloserine
 Bactericidal
 Inhibits bacterial cell wall
 Broad spectrum antibiotic
 Effective on gram positive & gram negative organisms as well as
M.tuberculosis.
 Unstable in acid or neutral medium
 When given orally 70%- 90% of the drug is rapidly absorbed.
 Widely distributed in body tissues & fluids.
 Excreted as active form in urine
 Used in treatment of pulmonary & extrapulmonary tuberculosis
 Causes serious dose related C.N.S. toxicity ( headaches, tremors,
acute psychosis, convulsions)
 Contraindicated in epileptic & psychotic patients