Infection

Bacterial Virulence Factors

Factor Bacteria
A protein Staphylococcus aureus
Biofilm -
Capsule -
Endotoxin Gram negative bacteria
Exotoxin Gram positive & negative bacteria
Fimbria Gram negative bacteria
IgA protease -
M protein Streptococcus pyogenes
Pili -
Teichoic acid Gram positive bacteria

Bacterial Exotoxins

Bacteria Exotoxin Target Mechanism
Corynebacterium diphtheriae Diphtheria toxin Elongation factor (EF-2) ↓ Protein synthesis
Pseudomonas aeruginosa Exotoxin A Elongation factor (EF-2) ↓ Protein synthesis
Shigella Shiga toxin 60S ribosome ↓ Protein synthesis
EHEC Shiga-like toxin 60S ribosome ↓ Protein synthesis
ETEC Heat-stable toxin (ST) ↑ GsPCR ↑ cGMP → ↑ fluid secretion
ETEC Heat-labile toxin (LT) ↑ GsPCR ↑ cAMP → ↑ fluid secretion
Vibrio cholerae Cholera toxin ↑ GsPCR ↑ cAMP → ↑ fluid secretion
Bacillus anthracis Edema toxin ↑ GsPCR ↑ cAMP → ↑ fluid secretion
Bordetella pertussis Pertussis toxin ↓ GiPCR ↑ cAMP → ↓ phagocytosis
Clostridium botulinum Botulinum toxin SNARE ↓ ACh release
Clostridium tetani Tetanus toxin SNARE ↓ GABA & Glycine release

Microbes Producing Shiga Toxin

  • Shigella dysenteriae serotype 1
  • Shiga-toxin-producing Escherichia coli (STEC)

Microbes with Toxins Carried on Lysogenic Phages {ABCDE}

Toxin Bacteria
Shiga-like toxin EHEC
Botulinum toxin Clostridium botulinum
Cholera toxin Vibrio cholera
Diphtheria toxin Corynebacterium diphtheria
Erythrogenic toxin Streptococcus pyogenes

Presentation of Staphylococcus Aureus Infection {SOFT-PENIS}

  • Staphylococcal scalded skin syndrome (SSSS)
  • Osteomyelitis
  • Food poisoning
  • Toxic shock syndrome
  • Pneumonia
  • Endocarditis
  • Necrotizing fasciitis
  • Infectious arthritis
  • Impetigo
  • Sepsis

Presentation of Streptococcus Pneumonia Infection {MOPS}

  • Meningitis
  • Otitis media
  • Pneumonia :: lobar
  • Sinusitis

Presentation of Streptococcus Pyogenes Infection

  • Erysipelas
  • Glomerulonephritis :: APGN
  • Impetigo
  • Lymphangitis
  • Necrotizing fasciitis
  • Pharyngitis
  • Rheumatic fever
  • Scarlet fever
  • Toxic shock-like syndrome

Tetanus Prophylaxis

Dirty Wounds

Setting Management
< 3 lifetime toxoid Toxoid & IVIG
Last toxoid > 5 years ago Toxoid
Otherwise No prophylaxis

Clean Wound

Setting Management
< 3 lifetime toxoid Toxoid
Last toxoid > 10 years ago Toxoid
Otherwise No prophylaxis

Facts About Corynebacterium Diphtheria {ABCDEFG}

  • ADP-ribosylation
  • β prophage
  • Corynebacterium
  • Diphtheria
  • Elongation
  • Factor 2
  • Granule :: metachromatic

Antibiotics for Tuberculosis {RIPE}

Mechanism Target Medication
↓ RNA synthesis RNA polymerase Rifampin
↓ Mycolate synthesis Enoyl-ACP reductase Isoniazid
- - Pyrazinamide
↓ Arabinogalactan synthesis Arabinosyl transferase Ethambutol

Treatment of Latent Tuberculosis

Regimen Medication Duration (months)
9H Isoniazid 9
4R Rifampin 4
3HR Isoniazid & Rifampin 3

Classification of Leprosy [Hansen Disease]

  Tuberculoid Lepromatous
AFB Paucibacillary Multibacillary
Immunity Cellular Humoral
Neuropathy Localized Generalized

Treatment of Leprosy [Hansen Disease]

Tuberculoid Disease

  • Dapsone
  • Rifampin

Lepromatous Disease

  • Dapsone
  • Rifampin
  • Clofazimine

Presentation of Haemophilus Influenzae Infection {POEM}

  • Pneumonia
  • Otitis media
  • Epiglottitis
  • Meningitis

Associations with Pseudomonas Aeruginosa Infection {PSEUDO}

  • Pneumonia
  • Sepsis
  • Endocarditis :: tricuspid valve
  • Ecthyma gangrenosum
  • Urinary tract infection (UTI)
  • Drugs
  • Diabetes
  • Otitis externa
  • Osteomyelitis

Antibiotics for Pseudomonas Aeruginosa Infection

  • Penicillin :: Piperacillin & Ticarcillin
  • Cephalosporins
    • 3°: Ceftazidime & Cefoperazone
    • 4°: Cefepime
  • Carbapenems - Ertapenem
  • Monobactams
  • Aminoglycosides
  • Fluoroquinolones - Moxifloxacin

Triple Therapy for Helicobacter Pylori Infection {MAP}

  • Macrolides
  • Amoxicillin
    Metronidazole
  • Proton pump inhibitors (PPI)

Presentation and Stages of Syphilis

Stage Presentation
1 Painless chancre
2 Condylomata lata
Maculopapular rash
3 Gummas
Aortitis
Tabes dorsalis
Argyll Robertson pupil

VDRL/RPR False Positives {VDRL}

  • Virus
    • Hepatitis virus
    • EBV
  • Drugs
  • Rheumatic fever
  • Rheumatoid arthritis
  • Lupus
  • Leprosy

Presentation of Lyme Disease {FACE}

  • Facial palsy
  • Arthritis :: migratory
  • Cardiac :: AV nodal block
  • Erythema migrans

Antibiotics

Cell Wall Inhibitors

Mechanism Medication
↓ Peptidoglycan crosslinking Penicillin
Cephalosporins
Carbapenems
Monobactams
↓ Peptidoglycan synthase Glycopeptides:
Vancomycin
Teicoplanin

Protein Inhibitors

Mechanism Medication
↓ 30S ribosome :: initiation complex Aminoglycosides
↓ 30S ribosome :: tRNA binding Tetracyclines
↓ 50S ribosome :: initiation complex Linezolid
↓ 50S ribosome :: peptidyl transferase Chloramphenicol
↓ 50S ribosome :: mRNA translocation Macrolides
↓ 50S ribosome :: mRNA translocation Clindamycin

Cell Membrane Inhibitors

Mechanism Medication
↑ Phosphatidylglycerol damage Daptomycin
↑ Phosphatidylglycerol damage Polymyxins:
Polymyxin B
Colistin

Metabolite Inhibitors

Mechanism Medication
↓ Dihydrofolate reductase Trimethoprim
↓ Dihydropteroate synthase Sulfonamides

DNA Inhibitors

Mechanism Medication
↓ Topoisomerase Fluoroquinolones
↑ DNA intercalation Metronidazole

Classification of Penicillin

Class Penicillin
Penicillin Penicillin G
Penicillin V
Penicillinase-sensitive Ampicillin
Amoxicillin
Penicillinase-resistant Methicillin
Nafcillin
Oxacillin
Dicloxacillin
Anti-pseudomonal Piperacillin
Ticarcillin

Classification of Cephalosporins

Generation Penicillin
1° Cefazolin
Cephalexin
2° Cefaclor
Cefoxitin
Cefotetan
Cefuroxime
Cefmetazole
3° Non-anti-pseudomonal:
Ceftriaxone
Cefotaxime
Cefixime
Cefpodoxime
Ceftibuten
  Anti-pseudomonal:
Ceftazidime
Cefoperazone
4° Cefepime
5° Ceftaroline

β-lactamase Inhibitors

  • Clavulanate
  • Avibactam
  • Sulbactam
  • Tazobactam

Combinations of β-lactams and β-lactamase Inhibitors

Brand β-lactam β-lactamase Inhibitor
Unasyn Ampicillin Sulbactam
Augmentin Amoxicillin Clavulanate
Tazocin Piperacillin Tazobactam
Timentin Ticarcillin Clavulanate
Brosym Cefoperazone Sulbactam

Spectrum of Antibiotics

Side Effects of Antibiotics

Side Effect Drugs
Nephrotoxicity Cephalosporins
Vancomycin
Aminoglycosides
Ototoxicity Vancomycin
Aminoglycosides
Photosensitivity Tetracyclines
Sulfonamides
Tooth & Bone toxicity Tetracyclines
Cartilage & Tendon toxicity Fluoroquinolones
Marrow toxicity Chloramphenicol
Trimethoprim
QT prolongation Macrolides
Fluoroquinolones

Therapeutic Antibiotics

Microbe Antibiotics
Staphylococcus aureus Penicillinase-resistant penicillin
Cephalosporins
Streptococcus Penicillinase-sensitive penicillin
Cephalosporins
Macrolides
Bacillus anthracis Carbapenems
Tetracyclines
Fluoroquinolones
Clostridium perfringens Penicillin
Clindamycin
Clostridium difficile Vancomycin
Metronidazole
Corynebacterium Penicillin
Macrolides
Listeria Penicillinase-sensitive penicillin
Mycobacterium tuberculosis Rifampin
Isoniazid
Pyrazinamide
Ethambutol
Mycobacterium leprae Dapsone
Rifampin
Clofazimine
Mycobacterium avium Macrolides
Tropheryma whipplei Penicillin
TMP/SMX
Actinomyces Penicillin
Nocardia TMP/SMX
Neisseria meningitides Penicillinase-sensitive penicillin
3° Cephalosporins
Neisseria gonorrhoeae 3° Cephalosporins
Macrolides
Acinetobacter baumannii Anti-pseudomonal β-lactams
Bordetella pertussis Macrolides
Haemophilus influenzae Penicillinase-sensitive penicillin
3° Cephalosporins
Legionella pneumophilia Macrolides
GNB :: enteric 3° Cephalosporins
Aminoglycosides
Fluoroquinolones
TMP/SMX
Bacteroides fragilis Carbapenems
Metronidazole
Pseudomonas aeruginosa Anti-pseudomonal β-lactams
Aminoglycosides
Fluoroquinolones
Bartonella henselae Tetracyclines
Macrolides
Pasteurella multocida Penicillinase-sensitive penicillin
Helicobacter pylori Penicillinase-sensitive penicillin
Macrolides
Metronidazole
Borrelia burgdorferi Tetracyclines
Penicillinase-sensitive penicillin
3° Cephalosporins
Treponema pallidum Penicillin
Tetracyclines
3° Cephalosporins
Chlamydia Tetracyclines
Macrolides
Rickettsia Tetracyclines
Macrolides
Pneumocystis jiroveci TMP/SMX
Anaerobes β-lactams & β-lactamase inhibitors
Carbapenems
Clindamycin
Metronidazole

Therapeutic Antibiotics for Drug-resistant Bacteria

Microbe Antibiotics
MRSA Clindamycin
TMP-SMX
Ceftaroline
Vancomycin
Teicoplanin
Linezolid
Daptomycin
VRE Teicoplanin
Linezolid
Daptomycin
ESBL Carbapenems
Tigecycline
Polymyxins
CRE Tigecycline
Polymyxins
MDRAB Tigecyclin
Polymyxins

Antifungals

Mechanism Medication Indications
↓ β-Glucan synthase Echinocandins [-Fungins]:
Anidulafungin
Capsofungin
Micafungin		 Candida
Aspergillus
↑ Ergosterol damage Amphotericin B Fungus
  Nystatin Candida
↓ Squalene epoxidase Terbinafine Dermatophytes
↓ Demethylase -Conazoles Fungus
↓ Thymidylate synthase Flucytosine Cryptococcus
↓ Microtubule assembly Griseofulvin Dermatophytes

Parasitic Infections

Protozoan Parasites

GI Infections {ECG}

Parasite Disease Treatment
Entamoeba histolytica Amebiasis & Bloody diarrhea Metronidazole
Cryptosporidium Watery diarrhea Nitazoxanide
Giardia lamblia Giardiasis & Fatty diarrhea Metronidazole

CNS Infections {ANT}

Parasite Disease Treatment
Acanthamoeba Amebic meningoencephalitis -Conazoles
Naegleria fowleri Amebic meningoencephalitis Amphotericin B
Toxoplasma gondii Toxoplasmosis Pyrimethamine
Sulfadiazine
Trypanosoma brucei African sleeping sickness Suramin
Melarsoprol

Hematologic Infections

Parasite Disease Treatment
Babesia Babesiosis Atovaquone
Azithromycin
Plasmodium Malaria Chloroquine
Primaquine
Mefloquine
Atovaquone-Proguanil
Artemisinin

Visceral Infections

Parasite Disease Treatment
Trypanosoma cruzi Chagas disease Benznidazole
Nifurtimox
Leishmania donovani Leishmaniasis Amphotericin B
Stibogluconate

Sexually Transmitted Diseases (STD)

Parasite Disease Treatment
Trichomonas vaginalis Vaginitis Metronidazole

Animalian Parasites

Cestodes [Tapeworms]

Parasite Disease Treatment
Taenia solium Neurocysticercosis Praziquantel
Taenia saginata Cysticercosis Praziquantel
Echinococcus Hydatid cyst disease Benzimidazole
Diphyllobothrium latum Vitamin B12 deficiency Praziquantel

Trematodes [Flukes]

Parasite Disease Treatment
Clonorchis sinensis Biliary Tract Infection (BTI)
Cholangiocarcinoma		 Praziquantel
Paragonimus westermani Respiratory symptoms Praziquantel
Schistosoma Katayama fever Praziquantel
Schistosoma haematobium Hematuria
Bladder cancer		 Praziquantel
Schistosoma mansoni Portal hypertension Praziquantel
Schistosoma japonicum Portal hypertension Praziquantel

Nematodes [Roundworms] :: Fecal-oral Transmission {EAT}

Parasite Disease Treatment
Enterobius vermicularis Perianal pruritis Benzimidazole
Pyrantel pamoate
Ascaris lumbricoides GI symptoms
Respiratory symptoms		 Benzimidazole
Pyrantel pamoate
Trichuris trichiura GI symptoms Benzimidazole
Trichinella spiralis Myalgia & Periorbital edema Benzimidazole
Toxocara Visceral larva migrans Benzimidazole

Nematodes [Roundworms] :: Contact Transmission {SAN}

Parasite Disease Treatment
Strongyloides stercoralis GI symptoms Benzimidazole
Ivermectin
Ancylostoma duodenale Iron deficiency anemia (IDA)
Cutaneous larva migrans		 Benzimidazole
Pyrantel pamoate
Necator americanus Iron deficiency anemia (IDA) Benzimidazole
Pyrantel pamoate

Nematodes [Roundworms] :: Arthropod-Borne {WOLD}

Parasite Disease Treatment
Wucheria bancrofti Elephantiasis Diethylcarbamazine
Onchocerca volvulus River blindness Ivermectin
Loa loa Calabar swelling Diethylcarbamazine
Dracunculus medinensis Skin ulceration Niridazole

Serological Test for HBV Infection

Diagnosis HBsAg Anti-HBs Anti-HBc
Infection :: acute + - IgM
Infection :: chronic + - IgG
Window - - IgM / IgG
Recovery - + IgG
Vaccination - + -

Serological Test for EBV Infection

Presentation of Mumps Virus Infection {MOPS}

  • Meningitis
  • Orchitis
  • Parotitis
  • Sterility

Presentation of Measles Virus Infection {3C1K1R}

  • Conjunctivitis
  • Coryza
  • Cough
  • Koplik spot
  • Rash :: downward

Presentation of Rubella Virus Infection {RUBELLA}

  • Rash :: downward
  • -
  • Blueberry muffin rash
  • Eyes :: cataract
  • Ears :: deafness
  • Lymphadenopathy
  • -
  • Arthritis

Highly Active Antiretroviral Therapy (HAART) for HIV Infection

  • 2 NRTI
  • NNRTI / INSTI / PI

Urgent Indications for Highly Active Antiretroviral Therapy (HAART)

  • CD4 < 200/mm3
  • Acute HIV infection
  • AIDS-defining illnesses
  • Pregnancy

Antivirals

Mechanism Medication Indications
↓ Gp120 Maraviroc HIV
↓ Gp41 Enfuvirtide HIV
↓ M2 channel Amantadine
Rimantadine		 Influenza
↓ Neuraminidase Oseltamivir
Zanamivir		 Influenza
↓ IMP dehydrogenase Ribavirin RSV & HCV
↓ Reverse transcriptase
:: nucleoside (NRTI)		 Adefovir
Entecavir
Telbivudine		 HBV
  Abacavir
Emtricitabine
Stavudine
Zidovudine
Didanosine		 HIV
  Lamivudine
Tenofovir		 HBV & HIV
↓ Reverse transcriptase
:: non-nucleoside (NNRTI)		 Delavirdine
Efavirenz
Nevirapine		 HIV
↓ Integrase (INSTI) -Gravirs HIV
↓ Protease (PI) :: Pol -Navirs HIV
↓ Protease (PI) :: NS3/4A -Previrs HCV
↓ DNA polymerase Acyclovir HSV & VZV
  Famciclovir HSV & VZV
  Ganciclovir CMV
  Cidofovir HSV & CMV
  Foscarnet HSV & CMV
↓ Protein synthesis IFN-α HBV & HCV

Systemic Inflammatory Response Syndrome (SIRS)

  • Temperature > 38°C / < 36°C
  • Heart rate > 90
  • Respiratory rate > 20 / PaCO2 < 32 mmHg
  • WBC > 12,000/mm3 / < 4,000/mm3 / > 10% bands

Infections Causing Palms & Soles Rashes {CARS}

Microbe Rash
Coxsackie A virus Hand-foot-mouth disease
Rickettsia rickettsii Rocky Mountain spotted fever (RMSF)
Treponema pallidum Syphilis

Lymphocutaneous Infections {LMNS}

  • Leishmania brasiliensis
  • Mycobacterium
  • Nocardia brasiliensis
  • Sporothrix schenckii

Perinatal Infections {TORCH}

Pathogen Presentation Transmission
Toxoplasma Intracranial calcifications
Hydrocephalus
Chorioretinitis		 Transplacental
Rubella Cataracts
Deafness
PDA		 Transplacental
CMV Periventricular calcifications
Chorioretinitis
Deafness		 Transplacental
HSV Encephalitis
Herpetic whitlow		 Intrapartum
HIV AIDS Intrapartum
Breastfeeding
Syphilis Deafness
Saddle nose
Hutchinson teeth
Saber shins		 Transplacental
Intrapartum
Parvovirus B19 Hydrops fetalis Transplacental
GBS
Escherichia coli
Listeria		 Pneumonia
Meningitis		 Intrapartum
Neisseria gonorrhoea
Chlamydia trachomatis		 Conjunctivitis Intrapartum

Routes of Transmission

  • Airborne
  • Blood
  • Contact
  • Droplet
  • Fecal-oral
  • Vector-borne

Levels of Isolation Precautions

  • Contact precaution
  • Droplet precaution
  • Airborne precaution

Infections Requiring Airborne Precaution

  • Tuberculosis
  • Chickenpox
  • Disseminated herpes zoster
  • Measles
  • SARS

Arthropod-Borne Microbes

Microbe Arthropod Disease
Babesia Tick Babesiosis
Borrelia burgdorferi Tick Lyme disease
Borrelia recurrentis Louse Relapsing fever
Francisella tularensis Tick Tularemia
Ehrlichia chaffeensis Tick Ehrlichiosis
Rickettsia rickettsii Tick Rocky Mountain spotted fever (RMSF)
Rickettsia tsutsugamushi Mite Scrub typhus
Rickettsia prowazekii Louse Epidemic typhus
Rickettsia typhi Flea Endemic typhus
Yersinia pestis Flea Plague
Yellow fever virus Mosquito :: Aedes Yellow fever
Dengue virus Mosquito :: Aedes Dengue fever
Chikungunya virus Mosquito :: Aedes Chikungunya fever
Zika virus Mosquito :: Aedes Zika fever
Japanese encephalitis virus Mosquito :: Culix Japanese encephalitis
Plasmodium Mosquito :: Anopheles Malaria
Trypanosoma brucei Tsetse fly African sleeping sickness
Trypanosoma cruzi Reduviid bug [Kissing bug] Chagas disease
Leishmania donovani Sandfly Leishmaniasis

Vaccines

Type Vaccines
Live attenuated BCG
Rotavirus
Varicella zoster virus (VZV)
Mumps & Measles & Rubella (MMR)
Yellow fever
Inactivated Poliovirus
Hepatitis A virus (HAV)
Influenza
Rabies
Subunit Hepatitis B virus (HBV)
Human papillomavirus (HPV)
Pneumococcus
Meningococcus
Haemophilus influenzae type B (Hib)
Pertusis
Toxoid Diphtheria
Tetanus

Contraindications to Live Attenuated Vaccines

  • Pregnancy
  • Immunodeficiency
  • IVIG within a year

Childhood Vaccination

Vaccine Month
BCG 0
Hepatitis B virus (HBV) 0 & 1 & 6
Rotavirus 2 & 4 & 6
Pneumococcus 2 & 4 & 6 & 12
Haemophilus influenzae type B (Hib) 2 & 4 & 6 & 12
Diphtheria & Tetanus & Pertussis (DTaP) 2 & 4 & 6 & 18 & 48
Poliovirus 2 & 4 & 6 & 48
Hepatitis A virus (HAV) 12 & 18
Varicella zoster virus (VZV) 12 & 48
Mumps & Measles & Rubella (MMR) 12 & 48
Japanese encephalitis (JE) 15 & 27

Post-Exposure Prophylaxis

Microbe Source Immunity Management
HBV + -/? Vaccine & IVIG
  ? -/? Vaccine
VZV + -/? Vaccine / IVIG
Measles + -/? Vaccine / IVIG
Rubella + -/? Vaccine / IVIG
Rabies +/? - Vaccine & IVIG
    ? Vaccine
HIV +/? -/? HAART
Meningitis + -/? Rifampicin
3° Cephalosporins
Pertusis + -/? Antibiotics
Tetanus + - Vaccine & IVIG
    ? Vaccine
  ? -/? Vaccine
Tuberculosis + -/? Antibiotics
Anthrax + -/? Vaccine & Antibiotics