ABSTRACT
Ehrlichia infections, also “piggyback infections”
CLOSTRIDIAL INFECTIONS
●● Toxins produced by bacteria involved in disease pathogenesis
TUBERCULOSIS
tuberculosis ●❑ Disseminated: M. avium infection in pedi-
atric HIV infection ●❑ Lymphadenopathy: Atypical Mycobacte-
rium usually M. fortuitum, M. scrofulaceum, M. avium-intracellulare
cell function in children ●● Children develop Th-2-type T-cell responses
to mycobacterial infection; absent CD8+ve cell response and production of IL-K and IL-5 by CD4+ve cells
●● BCG vaccine: May not prevent infection but reduces the chances of hematogenous spread/tubercular meningitis
●● Miliary tuberculosis: Numerous bacilli disseminate through bloodstream causing simultaneous disease in two or more organs with millet-sized lesions. Tuberculin test may be negative
polymerase chain reaction
Note: Congenital and perinatal TB usually elude diagnosis until autopsy
RICKETTSIAL DISEASES
Arthropod borne
Spotted fever group
Rickettsia ricketsii ●● Rickettsial pox: R. akari
Typhus group
●● Epidemic typhus (R. prowazekii-louse borne)
Ehrlichiosis
●● Smallest free-living micro-organisms lacking cell-wall peptidoglycans
moniae)
CHLAMYDIA TRACHOMATIS
junctival epithelial cells
CHLAMYDIA PNEUMONIAE
CHLAMYDOPHILA PSITTACI
granules with peripheral clubbing ●● Cervicofacial form common ●● Usually immunosuppressed patients
through ascending transcervical route ●● Malassezia furfur: In children on long-
term parenteral alimentation using lipid emulsion
Endemic fungi
purative ●● Blastomycosis (Eastern United States), his-
toplasmosis (Ohio and Mississippi), coccidiomycosis (southwest)
Opportunistic
Zygomycosis)
CRYPTOCOCCUS
●● Multiple budding yeasts with thick mucoid capsule showing clear halo
●● Granulomatous inflammation and gelatinous mass
●● Pneumonia, meningitis, and cutaneous lesions
ASPERGILLOSIS
●● Dichotomously branching septate hyphae, uniform diameter of 7-8 µ
ZYGOMYCOSIS (MUCORMYCOSIS)
tions ●● Diabetic children ●● Hyphae branch at right angle and diameter
varies from 5 to 20 µ
●● Aseptate hyphae (folds and wrinkles may mimic septation)
INTESTINAL PROTOZOA
●● Entamoeba histolytica, Giardia, Balantidium coli, Cryptosporidium
EXTRA-INTESTINAL PROTOZOA
●● Naegleria fowleri, Toxoplasma gondii, Trichomonas vaginalis, Pneumocystis carinii
BLOODBORNE PROTOZOA
●● Plasmodium, Leishmania donovani (KalaAzar), Trypanosoma cruzi (Chagas disease)
NEMATODES (ROUNDWORM)
●● Ascaris lumbricoides, Enterobius vermicularis, Necator americanus, Ancylostoma duodenale, Strongyloides stercoralis
CESTODES (TAPEWORM)
●● Taenia solium (larva causes cysticercosis), T. saginatum, Hymenolepis nana, Diphyllobothrium latum
TREMATODES (FLATWORM)
●● Schistosoma japonicum, S. mansoni, S. haematobium
TOXOPLASMOSIS
brain ●● In tissues; both encysted and free forms
exist ●● Cysts: Are round to oval, 10-30 µ ●● Stains-H&E, PAS, silver ●● Trophozoites: Within cyst are tiny, densely
packed 2 µ structures ●● Granulomatous and suppurative reaction
CUTANEOUS LEISHMANIASIS
plast
●● Wide variety of infectious organisms are causative
erythrophagocytosis (engulfed red blood cells)
