Unit 4 Infectious Disease

Question 1

Infectious disease

Answer 1

Basic understanding of the definition, pathophysiology, causes, sign and symptoms, management and complication of common community and hospital acquired infection
- viral, bacterial, fungal, protozoa, parasitic infection

Question 2

Microorganism

Answer 2

organism that is microscopic (cannot seen by human eye) and have to use a microscope (light or electron)
• MICROBIOLOGY = The study of microorganisms

Question 3

Type of microorganism

Answer 3

 Bacteria : Single-celled organisms with a cell wall and cellular organelles that allow them to live independently
in the environment
 Viruses : Require the host cell to replicate and spread
 Fungi : Group of eukaryotic organisms that includes microorganisms like yeasts and molds
 Parasites : Takes advantage of the host without making any useful return. Protozoa, roundworms

Question 4

Definition

Answer 4

• Pathogen: An organism that can cause disease in human
• Pathogenicity: The ability of an organism to cause infection
• Virulence: Another common word used to describe a pathogen

Question 5

How to clasify bacteria

Answer 5

A. Staining Method: (Gram’s crystal violet stain) e.g. gram
positive and gram negative bacteria.
B. Shape Method: e.g. Bacillus (rod), cocci (spherical) and spirilla (spiral)
C. Ability to use oxygen: e.g. Aerobic (with oxygen) and anaerobic (without oxygen)

Question 6

Bacteriostatic and bacteriocidal

Answer 6

• Bacteriostatic
If antibacterial agents are capable of inhibiting or slowing the microbial growth
- example
Sulfonamides
Tetracyclines
Chloramphenicol
Ethambutol
Clindamycin

• Bacteriocidal
Certain antibacterial agents are capable of killing microbes or bacteria

BACTERICIDAL
- example
Penicillin
Aminoglycosides
Isoniazid
Cephalosporins
Ciprofloxacin

Question 7

Anti infective

Answer 7

Something capable of acting against
infection, by inhibiting the spread of an infectious agent or by killing the infectious agent outright
- Example
 Antibiotics
 Antifungals
 Antiprotozoans
 Antivirals

Question 8

Antibiotics

Answer 8

▪ A drug used to treat infections caused by bacteria and other microorganisms. - Antibiotics is a substance produced by one microorganism that selectively inhibits the growth of another

Question 9

Penicillin

Answer 9

CLASS
A. Natural Penicillin’s
- Penicillin G ,Penicillin V.
B. Semi synthetic Penicillin’s
- Cloxacillin sodium, Nafcillin, Oxacillin sodium
C. Aminopenicillins
- Amoxicillin, Ampicillin, Bacampicillin
D. Extended-Spectrum Penicillin’s
- Mezlocillin sodium, Piperacillin sodium

MOA
- kills bacteria by disrupting and inhibiting the synthesis of peptidoglycan cross

PHARMACOKINETIC
- The extent of absorption depends on the presence of food in the gastrointestinal tract, gastric and intestinal pH and relative acid-stability of penicillin derivative

ADVERSE EFFECT
- itchy skin rash, fever, difficulty in
breathing, lowered RBC, WBC or Platelet counts and nephropathy

CONTRAINDICATION
- patients with a history of hypersensitivity to penicillin or cephalosporin

THERAPEUTIC USES
- UTIs, gonorrhea, syphilis,
septicemia, meningitis, pneumonia

Question 10

Cephalosporin

Answer 10

Cephalosporin compounds were first isolated from cultures of Cephalosporium acremonium from a sewer in Sardinia in 1948 by Italian scientist Giuseppe Brotzu

GENERATION CLASS
• First generation
-contain beta-lactam ring, and bacteria producing beta-lactamase will normally be resistant to these agents
e.g. cefadroxil, cephalexin, cephradine
•Second generation
- more potent and resistant to beta-lactamase and exhibit broader spectrum than first generation drugs. E.g. cefaclor, cefoxitin, cefuroxime
• Third generation
- They have longer duration of action, an even broader spectrum and are resistant to beta-lactamases
E.g. cefixime, cefotaxime, ceftriaxone
• Fourth generation
- more effective against bacteria that have developed resistance to earlier cephalosporin’s
E.g. cefepime, cefozopran, cefquinome
• Fifth generation
- powerful antipseudomonal characteristics (Pseudomonas infection) and appears to be less susceptible to development of resistance
E.g. ceftobiprole

MOA
disrupt the synthesis of the peptidoglycan layer of bacterial cell walls

PHARMACOKINETIC
- distributed through most body fluids and tissues, including kidneys, lungs, joints, bone, soft tissues, and biliary tract

ADVERSE EFFECT
- Skin rash, fever, serum sickness, anaphylaxis, neutropenia, nephritis, nausea, vomiting, diarrhea and abdominal pain

CONTRAINDICATION
- patient previously experienced severe allergic reaction
- should not be used in combination with other antibiotics and potassium sparing diuretics
- oral contraceptives containing estrogen

USES
- for prophylaxis during certain surgical procedures to reduce the risk of postoperative wound infections

Question 11

Tetracycline

Answer 11

Broad-spectrum antibiotic produced /extracted from Streptomyces aureofaciens in 1948

CLASSIFICATION
1. Naturally occurring
- Tetracycline, chlortetracycline, oxytetracycline
2. Semi synthetic
- Doxycycline, Lymecycline, Meclocycline

MOA
- protein synthesis inhibitors prevents the amino-acyl tRNA from binding to the A site of the ribosome and prevent protein synthesis

PHARMACOKINETIC
- absorbed in the upper small intestine and effective blood levels are reached in 2-4 h

ADVERSE EFFECT
- GI toxicity, nausea, vomiting, diarrhea and heart burn

CONTRAINDICATION
- Certain foods (milk and dairy products) and drugs antacids, laxatives and iron preparations
- phenytoin
- barbiturate

THERAPEUTIC USES
- treatment of infections of
the respiratory tract, sinuses, middle ear, urinary tract, intestines, and also gonorrhea

Question 12

Define fungi

Answer 12

single-celled or multicellular organism similar to a human cell
- eukaryotic (nucleus)
- eg : mushrooms, yeasts and moulds

Question 13

Fungal infection

Answer 13

enter the body mainly via respiratory, mucous and cutaneous
- develop in patients whose immune
system is depressed by disease, drug therapy

SYMPTOM
- Itch red , bald patches, nails discolored and thick

DIAGNOSE
- based on appearance of skin
- Wood’s lamp that makes fungi appears fluorescent under blue light
- scrab or swab

PREVENT
- Keep your skin and feet clean and dry
- Shampoo regularly
- Do not share personal items

DRUGS
- Echinocandins : Caspofungin, Anidulafungin
- Pyrimidine Analogs : Flucytosine
- Miscellaneous Antifungals : Griseofulvin

Question 14

Mycoses ( fungal infection in human )

Answer 14

fungi pass the resistance barriers of the human or animal body and establish infections

TYPES
1.superficial mycoses
- affect hair, scalp, outermost layers of epidermis, nails and mucous membranes like oral cavity
- treatment : topical & oral medications
2. Systemic
- affects the internal organs like lungs, brain and digestive tracts
- treated with oral or parenteral medications
3. Cutaneous
- Extend deeper into the epidermis, as well as invasive hair and nail diseases
4. Subcutaneous
- confined to the dermis, subcutaneous tissue or adjacent structures

Question 15

Amphotericin B

Answer 15

PHARMACOKINETIC
 Poorly absorbed from GIT
 Start with small initial dose then gradually increase
 circulating in plasma is highly bound (>90%) to plasma proteins

SYMPTOMS
- fever, chills, hypotension, anorexia and nausea

PRECAUTION
- Acute reactions including fever,
shaking chills, hypotension are common 1 to 3 hours after starting an intravenous infusion
- Pregnancy : Teratogenic Effects
- Pediatric Use

CONTRAINDICATION
- hypersensitivity to Amphotericin B or any component in formulation

THERAPEUTIC USES
- life-threatening mycotic infections and serious fungal infections

Question 16

Nystatin

Answer 16

isolated from Streptomyces noursei in 1950 by Elizabeth Lee Hazen and Rachel Fuller Brown research for the Division of Laboratories

PHARMACOKINETIC
- Poorly absorbed from GIT
 unchanged in the stool
 patients with renal insufficiency significant plasma concentrations of nystatin may occur

CONTRAINDICATIONS
- patients with history of hypersensitivity to any of components

THERAPEUTIC USES
- wide spectrum of antifungal activity
- Treating oral or gastrointestinal fungal infections
- for vaginal, mucosal and esophageal Candida infections

ADVERSE EFFECT
- Diarrhea ,nausea, vomiting, gastrointestinal upset /disturbances, Rash, Tachycardia, bronchospasm, and facial swelling

Question 17

Azoles

Answer 17

MOA
- Inhibit fungal cytochrome P450 enzyme which responsible for converting lanosterol to ergosterol for fungal cell membrane synthesis

CLASSIFICATION
1. Imidazole
- Ketoconazole, Miconazole, Clotrimazole
2. Triazole
- Fluconazole, Itraconazole, Voriconazole

THERAPEUTIC USES
- Oral & vaginal Candidiasis, Dermatophytosis, Systemic mycoses, Mucocutaneous Candidiasis

PHARMACOKINETIC
- Well absorbed orally
- Bioavailability is decreased with antacids, H2 blockers &
proton pump inhibitors
- Half-life is 7-8 hrs

ADVERSE EFFECT
- Nausea, vomiting and anorexia

CONTRAINDICATION
- lactation ,hepatic dysfunction

Question 18

Allylamines ( Terbinafine )

Answer 18

inhibit enzyme squalene epoxidase required for ergosterol synthesis
- treat dermatophytes

ADVERSE EFFECT
- Severely hepatotoxic, liver failure even death, GI tract infection, taste and visual disturbance

Question 19

Echinocandins ( caspofungin )

Answer 19

inhibit synthesis of glucan in the cell wall via enzyme 1,3-β glucan synthase
- half life ( 9 - 11 hours
- Given by IV route only, highly bound to plasma proteins

Question 20

Pyrimidine analog

Answer 20

Pyrimidine Analogs (e.g. Flucytosine) incorporated into RNA in place of uracil where it inhibits protein synthesis
Metabolized 5- fluorodeoxy-uridylic acid where it inhibits thymidylatesynthetase, blocking DNA synthesis

Question 21

Miscellaneous antifungal

Answer 21

Causes disruption of the mitotic spindle by interacting with polymerized microtubules through binding to microtubule protein and inhibit fungal cell mitosis
- prevents proliferation and function of cell

Question 22

Griseofulvin

Answer 22

Given orally and ineffective , half-life is 24 hours
 given for 2-6 weeks for skin & hair infections to allow replacement of infected keratin by the resistant structure
 Adverse effect : mental confusion, fatigue, vertigo, GI upset

Question 23

Virus

Answer 23

small infectious agent that can
replicate only inside the living cells of other organisms
- all made from nucleic acid DNA or RNA

Question 24

Antiviral drug

Answer 24

class of medication used specifically
for treating viral infections
- Antiviral drugs do not destroy their target pathogen

Question 25

Acyclovir

Answer 25

MOA • Inhibits viral DNA synthesis • It is a prodrug, a precursor of the antiviral compound • Activation of the drug requires three enzymes activities to be present in the cell to convert acyclovir to a triphosphate derivative PHARMACOKINETIC - Poor water soluble • Poor oral bioavailability (10–20%), peak plasma concentration occurs after 1–2 hours • IV administration is necessary if high concentrations are required ADVERSE EFFECT • Vomiting • Constipation • Burning CLINICAL USE - for the treatment of Herpes Simplex Virus (HSV) and Varicella Zoster Virus (VZV)

Question 26

Human Immunodeficiency Virus (HIV)

Answer 26

- infects human immune system cells Eg : helper T cells, macrophages, and dendritic cells - Acquired immunodeficiency syndrome (AIDS) disease caused by HIV - spherical enveloped virus

Question 27

HIV replication

Answer 27

capsid in the host cell present in immature viral particles • Then capsid will leave the host cell and viral protein will build up the envelope of the viral and become mature outside the host cell

Question 28

HIV transmission

Answer 28

• Sexual • Blood or blood product • Mother-to-child

Question 29

Hiv therapy

Answer 29

• Integrase inhibitors - inhibit enzyme integrase which responsible for integration of viral DNA into DNA of infected cell - Raltegravir, Elvitegravir • Protease Inhibitors (PI) -.Preventing the maturation of virions capable of infecting other cells • Saquinavir, Ritonavir, Indinavir

Question 30

HAART

Answer 30

Treatment regimens used to suppress HIV viral replication and progression of HIV disease - Combines three or more different drugs • Two nucleoside reverse transcriptase inhibitors (NRTIs) and protease inhibitor (PI) • Two NRTIs and non-nucleoside reverse transcriptase inhibitor (NNRT)

Question 31

Zidovudine

Answer 31

• NRTI • can slow down HIV spread but doesn't stop it entirely • Well absorbed from gut and distributed to most body tissues and fluids including the cerebrospinal fluid • Treatment HIV-associated dementia and thrombocytopenia ADVERSE EFFECT - Anaemia, Neutropenia, Gastrointestinal intolerance

Question 32

Types of viral infections

Answer 32

• Respiratory infections - Infections of the nose, throat, upper airways, and lungs Eg : sore throat, cold, sinusitis • Gastrointestinal tract - Infections of the gastrointestinal tract such as gastroenteritis caused by virus such as noroviruses and rotaviruses • Liver - cause hepatitis • Nervous system - Some viruses, such as the rabies virus and West Nile virus infect brain causing encephalitis

Question 33

Spread of virus

Answer 33

• Swallowed • Inhaled • Spread by the bites of insects

Question 34

Protozoa disease

Answer 34

- unicellular eukaryotic organisms - malaria, African sleeping sickness, leishmaniasis - immune response develops depends in the location of the parasite in the host • Bloodstream : humoral antibody most effective • Intracellular : cell-mediated immune reactions

Question 35

Malaria

Answer 35

- life-threatening disease caused by parasites that transmitted to people through the bites of infected female Anopheles mosquitoes - affect more than 200 million people and kill more than 3 million every year SYMPTOMS - Diarrhea, cough, fever, chills, sweat

Question 36

Antimalarial Quinolone

Answer 36

- bactericidal - inhibit bacterial DNA synthesis by bind the DNA-DNA gyrase, thus block further DNA replication PHARMACOKINETIC - Well absorbed orally - bioavailability ≥ 50% - Some fluoroquinolones available parenterally - Excellent tissue distribution ADVERSE EFFECT • Gastrointestinal • CNS symptoms • Allergic reactions • Photosensitivity • Liver function abnormalities • Joint symptoms - arthralgias -Cartilage damage

Question 37

Parasite

Answer 37

- organism that lives on or in other organisms from which obtains nutrients to live and causes harm in the process - dependent on host for its life functions, live, grow and multiply - Parasites rarely kill their hosts - eg : hookworm

Question 38

Parasite types

Answer 38

1. Ectoparasites - remain external to host - eg : ticks, fleas, leech 2. Endoparasite - live inside the host - eg : liver flukes, tapeworm, malarial parasite

Question 39

Protozoa

Answer 39

- single cell parasites - eg: amoebae - irregular shaped that infects the end of the smaller intestine and colon - Amoebiasis common infection  release an enzyme causes ulcers or abscesses where they enter the bloodstream  can eventually reach other organs like brain or liver

Question 40

Trematodes ( Fluke )

Answer 40

• Types : Bladder, blood, liver, lung, kidney and intestinal flukes • Disease Schistosomiasis • cause severe disease of gastrointestinal tract, bladder, liver and destroy blood cells

Question 41

Cestodes ( Tapeworm )

Answer 41

• Bladder worms, broad fish tapeworms, dog tapeworms, and rat tapeworms • Broad fish tapeworms may grow to 35 feet long and live ten years inside person's intestines

Question 42

Nematodes

Answer 42

- common : roundworms, hookworms, whipworms, pinworms, heart worms - Size vary from 2 to 35 centimeters - symptom : upper abdominal discomfort, asthma, eye pain, insomnia and rashes

Question 43

Parasite infections

Answer 43

SYMPTOMS - anemia, constipation, fatigue, depression, irritation, immune dysfunction TRANSMISSION - Ingestion of eggs from fecal material of infected individual - larva of the parasite burrow into skin of a person - insect vector -Sexual transmission PREVENTION - Wash all fruits and vegetables - cook fish and meat well - drink filtered water ANTIPARASITIC DRUGS • Anthelminths • Schistosomicides • Antimalarials • Protozoacides • Parasiticides

Question 44

Anthelminths

Answer 44

Drugs that are active against roundworms and flatworms • Benzimidazoles • Macrocyclic lactones - Symptoms of a round or flatworm infection: • Loss of appetite, distended abdomen, painful abdomen, coughing, fever, vomiting, diarrhoea - Can lead to malnutrition and anemia

Question 45

Anthelminths type

Answer 45

1. Benzimidazole - eg : mebendazole, albendazole, triclabendazole, tinidazole - treat intestinal infections caused by nematodes and cestodes - MOA Inhibits the polymerization of tubulin into microtubules 2. Macrocyclic lactones - chemically related to the insecticide - The drugs kill by interfering with target animal's nervous system - Drugs bind to glutamate-gated Cl ion channels in musculature of the worm

Question 46

Schistosomiasis

Answer 46

- parasitic disease caused by several species of fluke of the genus Schistosoma - commonly found in Asia, Africa and South America in areas where water may carry parasite SYMPTOM - Abdominal pain, diarrhea, cough, fever, fatigue

Question 47

Schistosomides

Answer 47

- Drugs that are active against schistosomiasis • PRAZIQUANTEL is a common drug used for treatment of all species of schistosomes - difficult to kill because they disguise themselves within the host by coating their outer membrane with host’s molecules - immune system will not respond to infection because it won't recognize invading schistosomes as a threat MOA • Disrupting the membrane of schistosome that coats parasite with host molecules