Microorganisms are:

Gram positive

Spore-forming

Anaerobes

They are saphrophytes that exist in the soil and feed off of dead Organic Matter

They exist in the GI tract of humans as Natural Flora

Gas found in the tissue is caused by the metabolic activities of the rapidly dividing bacteria.

Usually occurs following wounds in which there is a foreign object and necrotic tissue.

Lactic Acid accumulation decreases the pH and further decreases the Eh. Endogenous proteases may be activated to further caues tissue damage.

Bacteria that cause this condition:

C. perfringens, C. septicum, C. histolyticum, C. novyi, C. sordellii

Seen in this disease: Clostridial myonecrosis

(a soft-tissue infection)

Incidence in US: Common

Symptoms: skin becomes darker

Prevention: thorough cleansing of the wound

Disease: Pseudomembranous colitis

More severe form of disease with profuse diarrhea, abdominal cramping, and fever; whitish plaques (pseudomembranes) over intact colonic tissue seen on colonoscopy

Predisposed: Due to extended use of broad-spectrum antibiotics elimates natural flora of the gut BUT this bacteria remains and overgrows and forms pseudomembranes

Incidence in US: common

Prevention: Eating yogurts (Pro-biotics) to replenish norml flora of gut

Disease: Enteritis necroticans

A fatal type of food poisoning

Intestinal perforation

This organism is a Anaerobic Gram-positive rod and usually forms spores BUT in this case, spores are rare/absent 

Predisposed: People that eat pigs that are inadequately cooked and sweet potatoes that are consumed in large amounts (a trypsin inhibitor)

Incidence in US: rare

Death is highly possible

Disease: Tetanus

Incidence in US: uncommon

Predisposed: Drug Addicts & Neonates

Puncture wounds or those with deep tissue destruction of foreign material (glass, soil, cloth, and other microbes)

In Neonates, when the umbilical stump becomes with organism

Symptoms: Spastic paralysis

Treatment: Antitoxin and Supportive care

Prevention: Vaccine- Tetanus toxoid

Mode of Action: Occurs after intro into wounds. As toxin is reaseased from the metabolizing bacteria, the toxin can become blood borne and travel to sites distant from the wound. When the tetanus toxin binds to nerve endings, it prevents the relaxation of contracted muscles.

Ascending (Immunized): toxin travels along peripheral nerves

Descending (Unimmunized): toxin can't be absorbed by local nerve endings and so enters blood and lymphs

Disease: Botulism

Other organisms that cause it:

C. botulinum, C. baratii, C. butyricum

Coined in Europe in 1870 following fatal food poisoning associated with eating sausage.

In the US, most cases occur when canned vegetables have not been heated prior to sealing the can.

Predisposed: Infants, Adults

Infant Botulism: occurs if the infant is fed certain foods that contain spores (honey)

Wound Botulism (rare): when the wound is contaminated with soil containing spores

Symptoms: paralysis of muscles

Treatment: Antiserum

Prevention: proper canning procedures, and not feeding baby honey

Mode of action: Toxin is absorbed mainly in the small intestine, traveling by lymph and blood to nerves where it interferes with release of Ach (result: no more muscle contractions)

Order:

Spirochaetales

Two Families:

Spirochetaceae and Leptospiraceae

Family Spirochetaceae contains two pathogenic genra:

Treponema and Borrelia

Family Leptospiraceae contains pathogenic genra:

Leptospira

Order: Spirochaetales

are

Gram-negative cell wall

They are helically coiled with at least one or more complete turns of the helix

Poor gram-stain ability

Order:

Spirochaetales

Family:

Spirochetales

Genus:

Treponema pallidum

An STD, not highly contagious during normal sexual intercourse, infection rate is about 30%

Incidence in US: Common (3rd most common STD in US)

Predisposed: Homosexuals (rectal tissue more delicate)

Gonorrhea was taught to be the pre-disposing factor for Syphilis, but wa discovered it was not

Transmission: Direct contact (sexually), congenitally via placental transfer of untreated mothers, blood transfusion

Signs/Symptoms:

Primary-

Spread through lymph and blood

- Chancre--a painless lesion with a raised, firm border

Secondary-

--Alopecia (hair loss), rash

Tertiary-

Least Infectious

--Gummas- Granulomatous lesions found in bone, skin, and other tissue

--Dementia- memory loss

--Tabes dorsalis- is a slow degradation of the spinal cord (syphilis of CNS)

--Paresis- partial paralysis

--Saddle nose AND Saber shins- Associated with congenital syphilis; bone and teeth malformation

Treatment: Penicillin

Prevention: No vaccine available, safe sex

Order:

Spirochaetales

Family:

Spirochetales

Genus:

Borrelia burgdorferi

Vector: tick

(East Coast- tick is of Ixodes scapularis, CA- tick is of Ixodes pacificus)

Incidence in US:

Common (In most of the states)

Predisposed:

People living in heavily wooded areas

It was later determed that deer play a key role in the life cycle of the tick that harbors the Lyme disease agent. Connecticut with the increased deer population

Symptoms:

(Although patients do not exhibit all three stages)

1. Erythema (EM)- expanding annular skin lesion like a "Bull's Eye" rash

2. Neurological and/or chardiac involvment

3. Arthritis

Treatment:

Antibiotics

Prevention:

No Vaccine

Precausions in tick-infested areas

Order: Spirochaelales

Family: Leptospiraceae

Genus: Leptospira

Transmission: direct contact with contaminated water

Symptoms: typhoid, nephritis, malaria, septicemia, influenza, etc. (symptomology may not be a reliable indicator or diagnosis)

Treatment: Antibiotic Penicillin

Prevention: Protective gear when working in highly endemic areas

Aerobic gram-negative rods

Means of survival:

In the cytoplasm or nucleus of the cell

Lysis of the host cell is the basis of pathogenicity

Rickettsia prowazekii

The members of the typhus group grow in the cytoplasm & do not polymerize actin so they are released only when the host cell is lysed

Vector: lice (worldwide)

flea of a flying squirrel (US)

Incidence in US: rare

Predisposed: Unsanitary, crowded areas like concentration camps, soldier barracks

Symptoms: headache, fever and chills, myalgia, petechial rash, hypotension, mortality

Prevention:

Vaccine- a formaldehyde inactivated typhus vaccine

Treatment:

Antibiotics, effective lice control

Endemic (murine) Typhus

Also known as Brill Zinsser Disease

Rickettsia typhi

The members of the typhus group grow in the cytoplasm & do not polymerize actin so they are released only when the host cell lyses

Vector: rat flea and/or rat lice

Incidence in US: Southeastern region

Milder than epidemic typhus

Rash is Trunk--> Extremeties

Treatment: Antibiotics

Prevention: Sanitation to reduce rat populations

Rickettsia rickettsii

The members of the RMSF group grow in the cytoplasm & polymerize actin so they can infect neighboring cells

Vectors: hard ticks (dog tick, wood tick), must feed for about 6 hours for infection to occur

Incidence in US: common

Symptoms: rash is extremeties--> trunk

Treatment: Antibiotics

Prevention: No vaccine available, protective clothing in tick infested areas

Rickettsia akari

Reservoir: mouse

Vector: mite

Incidence in US: common

Predisposed: Occurs in large mouse populations, and may happen with unsanitary conditions

Symptoms: Regional lymph nodes become swollen, and there is a vesicular rash

Treatment: Antibiotics

Prevention: No vaccine available, control of house mice

Organism:

Ehrlichiae chaffeensis

Causes disease:

Human monocytic ehrlichioisis

Intracellular bacteria that parasitizes granulocytes, monocytes, erythrocytes, and platelets

Present in the lysosome of cells till cell lysis

Reservoir: White-tailed deer

Vector: Lone Star Tick

Incidence in US: Common 

Treatment: Antibiotics

Prevention: Vaccine not available

Avoidance of tick-infested areas

Ehrlichiae chaffeensis

Gram-negative

But lack cell wall

Coxiella burnetii

Reservoir: Birds

The term Q-fever was first coined in Australia in late 1930s (Q=query) when packinghouse workers became sick

Transmission: Inhaling the organism in contaminated air-borne dust, handing infected animal products, or drinking upasteurized milk

Symptoms: Similar to Rickettsial disease but NO rash, end result: Endocarditis in extreme cases

Treatment: Antibiotics

Prevention: No Vaccine, good sanitation such as keeping barns and surroundings clean, pasteurization of milk

Gram-negative bacteria

Stains weaky

Grows intracellularly in eukaryotic cells

Bortonella henselae

Pathogen enters skin via scratches or bites. Localized lesions result. Regional Lymph Nodes become enlarged

Invaginates RBC membrane, leaving it within the erythrocyte

Predisposed: AIDS patients

Treatment: Antibiotics

Prevention: No vaccine, AIDS patients should be aware of the risk associated with having pet cats, etc. Bites should be thouroughly cleaned

Gram-negative rods

Polymorphic both in shape (coccoid to long rod forming) and size

Smallest free-living bacteria

Lacks a cell wall

Slow growth

Causes PAP (Primary atypical pneumonia)

Reservoir: a strict human pathogen

Predisposed: school-age children and young adults

Transmitted by inhalation of aerosilized droplets

Incidence in US: every 4 to 8 yrs

Treatment: Active antibiotics

Prevention: no vaccine, by not sharing towels, utensils because organism is spread by fomites

Causes NGU (non-gonococcal urthritis)

Organism is part of the normal genital flora of both men and women. It is found in about 70% of sexually active humans

Treatment: Antibiotics

Prevention: Abstinence or same sex practices

Gram-negative

Obligate intracellular parasites

Elementary body (EB)= smaller, inactive but infectious

Internal (reticulate) body (RB)= larger, active but non-infectious

Causes Psittacosis (Parrot fever)

A type of pneumonia

Reservoir: birds

Predisposed: bird owners, workers in chicken and turkey packing plants

Transmission: Respiratory route from airborne dust containing droppings or secretion from birds

Treatment: Antibiotics

Prevention: Bird owners can significantly reduce their risk by keeping the bird's surroundings clean. Proper sanitation

Causes Trachoma

Greatest cause of preventable blindness in the world

In Trachoma, the inclusion bodies damage the epithelial cells of the conjunctiva resulting in scarring. Scarring of the conjuctiva causes trichiasis in which the eyelashes turn under and scrape he cornea

Incidence in US: occurs among some American Indian Pop

Predisposed: Adults, Neonates, and Infants

Treatment: Antibiotics

Prevention: No vaccine, good sanitation, personal hygeine, and good nutrition

Causes Pneumoniae

Reservoir: Human 

Transmission: Human to Human

Treatment: Antibiotics

Prevention: Prophylactic antibiotics

Causes LGV (Lymphogranuloma venereum)

Incidence in US: rare

Predisposed: homosexuals

Transmittance: #1 STD in America (Chlamydia)in homos

Symptoms: 3 stages; painless lesion on genitalia, lymph nodes swealing and pain, eventually lymphatic obstruction leads to elephantiasis of the genitalia

Prevention: Abstenence & Same Sex partner

Treatment: Antibiotics