-Localized pyogenic bacterial infection w/in brain parenchyma

- Signs and symptoms due to space-occupying mass in brain

-Commonly present w/headache and change in mental status

- Predisposing factors include distants site infections or recent dental work, can spread from middle ear, mastoid, or sinuses

- 20% have no predisposing factors, on average 2 types of bacteria are found

- Most common are viridans streptococci

- Peptostreptococcus most common anaerobic bacteria

- Fungi seen only in immunocompromised pts, w/candida being most prevalent

- Parasites include Toxoplasma gondii

- Lumbar puncture not recommended, need a CT scan

- Can be fatal, treat w/surgery, penicillin G for streptococi, metronidazole for resistant anaerobes, plus cephalospori

-Can survive in many conditions, making it an important food-borne pathogen, serotype 4b causes most of these

- 2500 infections in US annually

Sheep Blood agar, Facultative anaerobe, esculin hydrolysis positive, end-over-end tumbling motion when a drop of broth is examined microscopically, need cold enrichment

- enters through GI tract after ingestion of contaminated foods

- adhesin proteins (Ami, Fbp A, and flagellin)

- cell wall surface proteins called internalin A that interacts w/E-cadherin which promotes phagocytosis into epithelial cells

-bacterium produces listeriolysin O

- organisms proliferate and ActA induces actin polymerization to propel them to cell membrane

- develop filopods which causes listeria to be released again

- can move from cell to cell w/out being detected

- prfA gene is responsible for membrane lysis, intracellular replication, and directional movement

- iron is important virulence factor

- Two forms of perinatal human listeriosis, early onset is granulomatosis infantseptica (infection in utero) results in death, late-onset causes meningitis

-Adults can develop listeria meningoencephalitis and bactermia, mostly occurs in immunocompromised patients

-Diagnosis  of listeriosis rests on isolation of organism in cultures of blood and spinal fluid

- Spontaneous infection occurs in many domestic and wild animals

 - Incidence peaks in warmer months

-Ampicillin w/erythromycin or w/IV trimethoprim-sulfamethoxazole (Jawetz)

-Gentamicin w/penicillin or ampicillin (Murray)

- Gram-negative bacteria, oxidase positive

- 13 serogroups (polysaccharide capsule), most important are A, B, C, X, Y and W-135

- Group A is N-acetylmannosamine phosphate and C is N-acetyl-O-acetylneuraminic acid

- Groups C and A associated w/epidemic disease

- Major virulence factor is polysaccharide capsule

- Contain pili made up of pilins, PilC contributes to antigenic diversity

- PorA and PorB genes are porin proteins

- Opa proteins mediate binding to epithelial and phagocytic cells

- Rmp proteins black serum bactericidal activity

- Iron is essential for growth

-Lipooligosaccharide (LOS) is a major antigen in cell wall

- Humans only natural hosts, entry via nasopharynx

- Infants have immunity until 6 months due to passive transfer

- Transmitted by respiratory droplets

- Most common complication of meningococcemia, begins w/intense headache, vomiting, and stiff neck, come w/in a few hours

-Thrombosis of many small blood vessels in many organs occurs

- Culture media w/o sodium polyanethol sulfonate are helpful in blood, CSF uses chocolate agar in a candle jar

-Thayer-Martin medium

- Penicillin G

- Rifampin can be taken as a prophylaxis

- Called acid-fast bacteria

- Classified according to acid-fastness, presence of mycolic acids, high guanine to cytosine content

- Have a complex, lipid-rich cell wall, responsible for slow growth, resistance to detergents, resistance to antiobiotics, antigenicity, clumping

- Gram-positive bacteria

-Anchored in plasma membrane are proteins, phosphatidylinositol, and lipoarabinomanna (LAM)

- arabinogalactans

- Causes leprosy (also called Hansen disease)

- Clinical presentation ranges from tuberculosis to leprosy

- In tuberculosis, bacteria induces cytokine productionand strong cellular immune rxn

- In leprosy, a strong antibody response but a specific defect in cellular response, therefore, an abundance of bacteria is observed in dermal macrophages and Schwann cells of peripheral nerves

- More than 5 million cases detected in 1985 and fewer than 300,000 in 2005

- 90% of cases are in Brazil, Madagascar, Mozambique, Tanzania, Nepal

- Leprosy is endemic in armadillos in Texan and Louisiana

- Spread by person-to-person contact

- Cannot grow in cell-free cultures, must use histopathological findings and test w/reactivity to lepromin

- Leprosy is a chronic infection of skin and peripheral nerves

- Associated w/skin lesions, nodules, plaques, thickened dermis, involvement of nasal mucosa

- Cause primary amebic meningoencephalitis (PAM) and granulomatous amebic encephalitis (GAE)

- Live in soil, most cases develop in children who swim in warm, soil-contaminated water

- Enter via nose and cribiform plate, especially Naegleria, and form nests that causes hemorrhage and damage mainly in the basilar portion of cerebrum and cerebellum

- Most cases result in comatoses

- Entry of acanthamoeba into CNS occurs from skin ulcers or traumatic penetration such as keratitis, also through contamination of contact lenses

- Granulomatous amebic encephalitis (GAE)

- Eye and skin infection, produces corneal ulceration severe ocular pain

- Primary amebic meningoencephalitis (PAM)

- Fulminant, rapidly fatal meningoencephalitis

- Intense frontal headache, sore throat, fever, blocked nose, stiff neck, Kernig sign

- Death in 4 to 5 days

- Amphotericin B for Naegleria, only when diagnosis made quickly

- Acanthamoeba, pentamidine, ketocanzole and flucytosine

- Corneal transplantation may occur

- Infections, nasal discharge, CSF and corneal scrapings should be collected and examined using a saline wet prep and iodine-stained smears

- In Naegleria, amoeboid trophozoites are found w/in tissues, the others cysts and troph. are found

- Agar plates w/live gram-negative enteric bacilli

- Typical coccidian intracellular sporozoan found in wide variety of animals

- Only one species exists

- Common reservoir is common house cat

- Develop in intestinal cells of cats

- Passed in cat feces and mature into infective cysts in 3 to 4 days in external environment

- Some infective forms (trophozoites) develop as slender, crescentic types called (tachyzoites) which are responsible for initial infection and tissue damage, slow-growing, shorter forms are called bradyzoites which also develop and form cysts in chronic infections

- Can reproduce only asexually in humans, opens in duodenum and releases sporozoites, invade macrophages and form trophozoites, spread to lymph nodes and other organs, rapidly multiplying tachyzoites initiate acute stage, penetrate nerve cells and multiply as bradyzoites, initiating chronic stage

- Human infection is ubiquitous, but certain immunocompromised individuals are more susceptible

- Infected by two sources, ingestion of improperly cooked meat from infected animals and ingestion of contaminated cat feces

- Transplacental infection can occur in pregnancy

- Most infections benign, symptoms occur from cell destruction, reproduction, and cyst formation and parasite moves from cell to cell

- Has a preference for lung, heart, lymphoid organs, and CNS (including eye)

- Symptoms occasionally resemble mononucleosis in acute disease

- Chronic disease include lymphadenitis, rash, hepatitis, encephalomyelitis, myocarditis and maybe blindness

- Congenital infection also occurs

In immunocompromised older pts, reactivation of latent toxo. is a special problem, symptoms usually neurologic, , multifocal brain lesions

- Have a predilection for parenchymal cells and reticuloendothelial cells

- for acute active inf., serologic profile must be done

- test includes Sabin-Feldman dye test to measure IgG, ELISA to measure other anti., ISAGA to measure IgE, differential agglutination test for IgG

- Initial test requres screening for IgG

- Twofold rise in titers indicates acute infection

- Detection difficult for chronic

-IgM test in pregnant women can carry false results

- Definitive method is demonstration of these organisms as trophozoites and cysts from biopsy

- most mono-like infections resolve themselves

- CNS infection in immunocomp. must be treated

- HIV pts treated w/initial high dose of pyrimethamine plus sulfadiazine

- Clindamycin plus pyrimethamine is best studied alternative

- Trimethoprim-sulfamethoxazole is used as prophylaxis

- Blood flagellates

- Two kinds of human: African, which causes sleeping sickness and transmitted by tsetse flies, T. brucei rhodesiense and T. brucei gambiense, and American, which causes Chagas disease and is transmitted by kissing bugs, T. cruzi

- Elongated bodies w/longitudinal lateral undulating membrane and a flagellum that baorders the free edge of the membrane

- Kinetoplast is darkly staining body lying adjacent to basal body

- Organisms indistinguishable morphologically, but differ biochemically, ecologically , and epidemiologically

- Introduced bite of tsetse fly and multiply at site of inoculation to cause swelling which may progress to chancre

- Spread as trypomastigotes to CNS in terminal stages where they produce sleeping sickness syndrome: lassitude, inability to eat, tissue wasting, unconsciousness, death

- T b rhodesiense appears in CSF in one month, Tb gambiense in several moths

- Tb is chronic and leads to meningoencephalitis, w/death from sleeping synd. in 1-2 yrs

- Tb rhodesiense is more rapidly fatal producing somnolence and coma

- Transmissible through placenta and congenital in hyperendemic areas

- T brucei undergo antigenic variation through surface glycoproteins tht coat surface of organism, mosaic gene formation

- Swelling of lymph nodes is called Winterbottom sign

- Restricted to tsetse flies

- Tb gambiense transmitted by streamside fly, Glossina palpalis, West to Central Africa

- T b rhodesiense transmitte by woodland-savanna, other Glossinas, eastern and SEtern savannas

-Bushbucks and antelope reservoirs for rhodesiense, humans for gambiense

- Three developmental stages, epimastigotes in vector (salivary glands), trypomastigotes in blood stream, rounded intracellular stage in tissue forms called amastigote

- Present in feces of reduviid bug (kissing bug), frequently bite people around mouth

- Infective forms pass to humans through infected bug feces rubbed into conjunctiva, bite site, or break in skin, chagoma

-Reproduce by binary fission

- Subcutanous inflammation at site, unilateral swelling of eyelid, fever, lymphadenitis

- Interstitial myocarditis is most common condition in Chagas disease

- American is especially important in Central and South America, infection of animals extends from Maryland to SoCal

- No treatment in Jawetz, Murray says nifurtimox, DDT can also be used in homes

8-12 (16-18 in Murray) million people harbor parasite and sustain heart damage

- Suramin (does not cross BBB) is drug of choice for acute, melarsoprol when CNS suspected

- Diflouromethylornithine is a cytostatic drug

- E. Coli

- group B streptococci

- Streptococcus pneumoniae

- Listeria monocytogenes

- Exudate is evident over surface of brain

- Chronic adhesive arachnoiditis

- less fulminant than bacterial

- lymphocytic pleocytosis, protein elevation normal, glucose content normal

- hard to identify agent

- chronic

- diffuse meningoencephalitis

- obliterative endarteritis

- tuberculoma, which may be associated with meningitis

- most serious symptom is arachnoid fibrosis causing hydrocephalus