General Pathology Of Infectious Diseases

GENERAL PATHOLOGY OF INFECTIOUS DISEASES LUMINITA MARINESCU, MD

INFECTIOUS AGENTS 

VIRUSES



BACTERIA



RICKETTSIAE



FUNGI



PARASITES



BACTERIOPHAGES AND PLASMIDS



CHLAMYDIA



MYCOPLASMA

BACTERIA 

 



Unicellular, prokaryotic cells (no nc/endoplasmic reticulum) Gram positive or negative Identified in micro lab by cultures and chemical properties Bacteriophages and plasmids are genetic elements that infect bacteria, encoding for virulence and enzymes that confer drug resistance

C hapter 6

C ha

P a t h o g e n ic M i c ro o rg a n i sm s

P ath M icr

P a th o g e n ic B a c te B a c t e r ia C l a s s i f ic a ti o n D ise a se s • G r a m s ta in –G ra m – p o s iti v e –G ra m – n e g a t iv e

• G r a m -n e g a tiv e c o c c i

–M e n in g o c o c c i – m e n i n –G o n o c o c c i – g o n o rrh e

• G r a m p o s i t i v e b a c i l l • B i o c h e m i c a l a n d c u l tu r a l c h a r a c t e r i s t i c s –A e ro b ic – d ip h th e ria b • A n tig e n stru c tu re

C hapter 6

C ha

P a t h o g e n ic M i c ro o rg a n i sm s

P ath M icr

P a t h o g e n i c B a c t e r i a a Pn ad t hP or ign ecni ipc l eB a c t e D ise a se s D ise a se s • S t a p h y lo c o c c i

• G r a m -n e g a tiv e b a c te

– B o i l s , s k i n i n f e c t i o n s , t o x i c s h o –c Sk ys sy tne dmr o imc ei n, f e c t i o n s , i n p u lm o n a r y i n fe c t io n s

• S trep to co c ci – S tr e p th r o a t, s c a r le t f e v e r

• Pn eum oco cci

• S p ir a l o r g a n i s m s

–S y p h i lis , L y m e d is e a s e

• A c id -fa s t o r g a n is m s

BACTERIA INDUCED INJURY  -adhere

to cells and deliver toxins  -bacterial endotoxins cause septic shock, DIC, ARDS. Secreted by Gram-negative  -bacterial exotoxins are potentially harmful. Act in different ways; ex:diphteria toxin

Spread of infection -

Local Lymphatic Hematogenous Tissue fluids Neural spread

Types of inflammation  Acute

: can lead to the formation of

pus  Chronic : granulomatous, like TB,lepra, cat-scratch disease, Yersinia enterocolitica, syphilis

Mycobacterium tuberculosis Acid fast bacillus  Seen on ZiehlNielsen stain  TB, treated with tuberculostatic antibiotics  Produces granulomatous inflammation 

ACTINOMYCES ISRAELII Causes granulomatous inflammation, like chronic abscess of the neck, appendix  Yellow granules in the discharge 

TREPONEMA PALLIDUM Causes syphilis  Transmitted through sexual contact  Pattern-primary -secondary -tertiary Congenital syphilis 

CHLAMYDIA Intracellular agents  GU tract, causing sterility in women  Conjunctivitisblindness 

MYCOPLASMA Spread from person to person  Bind to airway epithelial cells and causes atypical pneumonia  Can cause autoimmune hemolytic anemia 

RICKETTSIA  

 

Intracellular cocco-bacilli, transmitted by tick bites in general Rocky Mountains spotted fever - R. rickettsii. Transmitted by ticks. Symptoms: hemorrhagic rash, encephalitis. Typhus - R. prowazekii. From louse Q fever - R. burnetti. By inhalation or ingestion

VIRUSES Intracellular agents  Contain either DNA/RNA but not both  Inclusion bodies may help in identification: HSV, CMV, rabies v  Most common agents of human illness 

VIRUS INDUCED-INJURY  -bind

to surface proteins on cells  -penetrate the cell  -uncoats and replicates  -kill host cell by inhibiting DNA/RNA or protein synthesis, by damaging the membrane’s integrity, by lysing the cell, by damaging the cells involved in defense

FUNGI 





Thick cell wall organisms Can be dermatophytes or can invade deep organs Ex: Histoplasma (Ohio River Valley) Coccidiodes (west) Blastomyces (tropical areas)

Coccidioides and Blastomyces

Aspergillus fumigatus

Chapter 7

Animal Par

Animal Parasites • Protozoa – One cell organisms

• Metazoa – Multicellular structures

• Arthropods

PROTOZOAN Motile, singlecelled eukaryotes  Ex: Trichomonas vaginalis, causes vulvovaginitis, sexually transmitted disease 

Protozoan infection         

CNS-Acanthamoeba, Toxoplasma, malaria Lymphoid tissue- Toxoplasma, Leishmania Heart- Trypanosoma cruzi (Chagas’ disease) Liver- Entamoeba, Plasmodium, Leishmania Blood- Trypanosoma, Plasmodium Gut- Entamoeba, Giardia, Cryptosporidium, Isospora Genital- Trichomonas Skin- Leishmania (cutaneous leishmaniasis) Lung- Pneumocystis carinii

Chapter

A nimal P a

Metazoal Infestations • Roundworm – Ascaris – Pinworms – Trichinella

• Tape worms

HELMINTHS 

Multicellular worms that have strict specificities for the definitive host, in which sexual reproduction takes place or for the intermediate host or vector, in which reproduction is asexual

Categories:trematodes (flukes)  Nematodes (roundworms)  Cestodes (tapeworms) 

TREMATODES SCHISTOSOMA  -North Africa  -fresh water  -chronic inflammation of the bladder/squamous carcinoma 

CESTODES  





TAENIA SOLIUM -undercook infected pork -many sites but the most important:brain and spinal cord where it produces cysts. -severe symptoms when the cyst dies

NEMATODES ASCARIS LUMBRICOIDES  -in children  -small intestine  -abdominal pain and failure to thrive if the infestation is heavy 

Chapter

Animal P ar

Arthropods • Scabies • Crab louse

PRIONS Normal host protein called prion  In many tissues; unknown function  Structural change makes it infective  Diseases: CREUTZFELD-JAKOB disease KURU disease SCRAPIE BOVINE SPONGIFORM ENCEPHALOPATHY 