Aerobic G+ bacilli, Coccobacilli, and Coreform bacilli

Aerobic Gram-Positive Bacilli, Coccobacilli, and Coryneform Bacilli
Chapter 11
Microbiology for Surgical Technologists
Bacillaceae
Bacillaceae
Endospore forming bacteria
51 species are classified as genus Bacillus
Few cause human disease except one
All are aerobic or facultative anaerobes
Are Gram-positive or Gram-variable
Most are motile
Found abundantly in soil
Can live for years in adverse conditions
Are saprophytes
Bacillus anthracis
Clinical diagnosis
Culture characteristics
Sticky adherence of the colonies
Chains of bacilli
Nonmotility
Absence of hemolysis
Virulence
Spore forming
Antiphagocytic capsule
Edema factor – produces profuse swelling
Lethal factor
Contributes to death by oxygen depletion, shock, respiratory failure, and cardiac failure

Bacillus anthracis
(continued)
Each of the virulence factors alone are ineffective, but when combined they are lethal
Anthrax toxins are also antiphagocytic and blocks the activities of leucocytes
The capsule is important in the first part of the disease, then the toxin dominates
Bacillus anthracis
(continued)
Acquired by exposure to contaminated animals or direct contact (biological weapons)
Majority of infections result from exposure to spores
Can be contracted through the skin, inhalation and ingestion
Person to person transmission has not happened and is not likely to occur
Bacillus anthracis
(continued)
Cutaneous Anthrax
Enter through a cut or other break in skin
Usually from handling horses, sheep or goats
Starts as a painless bump and turns into a necrotic ulcer in 1 to 2 days
If not treated promptly, can be fatal
Cutaneous Anthrax
Bacillus anthracis
(continued)
Inhalation Anthrax
Rapidly progressive pulmonary disease that leads to respiratory failure
Mortality rate is high even with treatment early in course of disease
Incubation is about 7 days and death usually results in 1 to 3 day after symptom start
Bacillus anthracis
(continued)
Gastrointestinal Anthrax
Acquired by eating contaminated meat
Causes inflammation of the mucous membrane of the GI tract
Symptoms include nausea, vomiting, high fever, and loss of appetite
Pts experience abdominal pain, severe diarrhea, and vomiting blood
Becomes systemic with a high mortality rate
Bacillus anthracis
(continued)
Control and Treatment
Penicillin, erythromycin, and tetracycline
Effective if administered before the onset of lymphatic spread or septicemia
Animal control
Vaccinations
Infected animals should be cremated
Bacillus anthracis
(continued)
Human vaccine developed in 1970
93%effective
Vaccine is cell free
Does not contain either live or dead bacteria
Consists of three shots given 2 weeks apart
Followed by three more shots given at 6, 12 and 18 months
Annual boosters are recommended
Only given to healthy adults 18 to 65
Bacillus anthracis
(continued)
Nonendospore cells can be killed by 0.05% hypochlorite solution
1 tablespoon bleach per gallon of water
Spores can only be killed by steam or gas sterilization, or boiling at 100 degrees C for 30 minutes
Bacillus cereus
Found in soil
Gram-positive, facultative aerobic
Motile and hemolytic
the Bacillus subtilits var. niger strain globingi is used for biological indicator tests for (EtO) gas sterilization
Causes ocular infection, IV catheter sepsis, and gastroenteritis (from food poisoning)
Bacillus cereus
Bacillus cereus
(continued)
Two types of gastroenteritis from two enterotoxins
The emetic form
Results from eating contaminated rice
Enterotoxin produced by bacteria is not killed in cooking process
Symptoms – nausea, vomiting, and abdominal cramps
Begins in 1 to 6 hours and lasts for 24 hours
Bacillus cereus
(continued)
The diarrheal form
Results from eating meat, milk, fish or vegetables
Enterotoxin produces symptoms of diarrhea, nausea, and abdominal cramps
Lasts for more than 24 hours

Bacillus cereus
(continued)
Ocular infections are caused by three toxins
Causes rapid destruction of the tissue of the eye by the combination of toxins
Usually attributed to a traumatic puncture wound
Causes Bacillus panophthalmitis
100% rate of losing light perception within 48 hours
Bacillus cereus
(continued)
Septicemia infection are primarily introduced with contaminated IV catheters
Can cause endocarditis
CNS infection can be contracted after the insertion of ventriculoperitoneal and ventriculoatrial shunt used to treat hydrocephalus
Listeria Species
Listeria Species
Listeria monocytogenes is the only one of 6 species that causes disease in humans
Listeriosis
Non-spore forming, facultative anaerobe
Causes meningitis, food poisoning and bacteremia
Motile at room temperature but not at 37ºC
Most likely to cause disease in immunocomprimised, elderly and pregnant pts
Listeria monocytogenes
Found in water, soil, plants, and animals
1% to 5% of healthy people are known to be fecal carriers
Fourth most common causes of community-acquired meningitis
Approx 2000 will be infected this year, of them 500 will die
1/3 of those infected are pregnant women
20 times more likely to get listeriosis
Peaks during warmer months

Listeria monocytogenes
(continued)
Majority of cases are food borne
20% to 30% mortality rate
Refrigeration slows, but does not stop the growth rate
Vegetables become contaminated from soil and manure fertilizer
Animals are carriers
Listeria is killed by pasteurization
Listeria monocytogenes
(continued)
Two forms of neonate disease
Early onset – granulomatosis
Caused by the mother eating contaminated food while pregnant
Cells are transferred to the fetus either through the placenta or after ROM at birth
Can cause spontaneous abortion or still births
Causes abscesses and granulomas in the infants internal organs
Infant mortality is high
Listeria monocytogenes
(continued)
Late onset
Occurs two to three weeks after delivery
Causes meningitis or meningoencephalitis with septicemia
Listeria monocytogenes
(continued)
Treatment
Penicillin and ampicillin, either alone or in combination with gentamicin
Erythromycin is used for those with PCN allergy
Control
Avoid eating raw animal foods, cheeses, and unwashed raw vegetables
A vaccine is not available
Erysipelothrix rhusiopathiae
The only member of the Erysipelothrix genus
Gram_positive, non spore forming
Widespread in both wild and domestic animals
Causes disease mostly in pigs
Not common in humans
Occupational disease
Butchers, farmers, vets, etc.
Erysipelothrix rhusiopathiae
(continued)
Three forms of the disease
Localized skin infection (erysiploid)
Lesion with raised edges that increases in size
Edemic, painful, and pruritic
Usually resolves on it’s own, meds speed the process

Erysipelothrix rhusiopathiae
(continued)
Generalized cutaneous infection
Rare
Localized infection that spreads to the cutaneous tissue
Septicemia
Causes endocarditis
Attacks HEALTHY heart valves
Erysipelothrix rhusiopathiae
(continued)
Treated with PCN, cephalosporins, clindamycin and erythromycin
A vaccine is used to control the disease in pigs
No human vaccine
Patients that have been infected do not develop immunity
Relapse can occur
Lactobacillus Species
Lactic acid producing bacteria (homolactic)
Facultative or strictly anaerobic
The lactic acid can spoil food but is important in the food industry
Creating pickles, sauerkraut, and yogurt
Lactobacillus Species
(continued)
In humans lactobacillus is part of the normal flora of the oral cavity, GI tract and vagina
Causes endocarditis
Is dangerous because it is resistant to Vancomycin and other types of antibiotics only inhibit its growth
Corynebacterium Species
Also produce lactic acid
Aerobic or facultative anaerobe
Non spore forming, non motile
Normal flora of the skin, GI and GU tracts, and upper respiratory tract
Corynebacterium Species
(continued)
Corynebacterium diphtheriae
Diphtheria
The first clinical description was by Hippocrates in the 4th century B.C.
In the 1920’s 150,000 cases with 13,000 deaths
In the 1980’s only 24 cases were reported
Due to vaccinations
Corynebacterium diphtheriae
(continued)
Diphtheria is found worldwide
Particularly in overcrowded, poor urban areas
Immunity is low because of the lack of vaccination
Humans are the only known reservoir for the bacteria
Transmitted by skin contact or respiratory droplets
Primarily a disease that affects children
Corynebacterium diphtheriae
(continued)
Three strains
Gravis – most sever
Intermedius
Mitis – least severe
Diphtheria toxin is an exotoxin that is secreted by the bacteria at the site of infection
Once the toxin enters the cell, it is irreversible and cell death occurs
Corynebacterium diphtheriae
(continued)
Diseases
Respiratory Diphtheria
Incubation period of 2 to 6 days
Attach to the epithelial cells of the pharynx
A lesion develops and necrosis begins
Blood plasma leaks and a fibrin network forms
The fibrin network becomes a pseudomembrane
Composed of bacteria, dead cells, plasma cells, and lymphocytes
Corynebacterium diphtheriae
(continued)
Respiratory Diphtheria (continued)
The pseudomembrane covers the uvula, tonsils, and palate and extends into the nasopharynx and into the larynx
It adheres to the underlying tissue and is difficult to remove due to bleeding
Disease lasts about a week
Pts that recover will expectorate the membrane
Corynebacterium diphtheriae
(continued)
Respiratory Diphtheria (continued)
Complications – breathing and respiratory problems, cardiac arrhythmia, neurologic symptoms, and possibly coma
Death can result
Treatment
Administer antitoxin before pseudomembrane forms
PCN and erythromycin
Isolation
Corynebacterium diphtheriae
(continued)
Respiratory Diphtheria
Immunization
Beginning at three to four months of age
Three injections, once a month, for 3 months
Booster at one year
Recommendation for booster every 10 years
The vaccine contains diphtheria toxoid, pertussis vaccine, and tetanus toxoid
DPT
Corynebacterium diphtheriae
(continued)
Cutaneous Diphtheria
Acquired through skin contact with infected person
Gains access through a break or cut in skin
Papule that progresses to an ulcer with a grayish-colored membrane covering
Corynebacterium jeikeium
Well known in the medical community
Very rare
As many as 40% of hospitalized pts are colonized
Affects immunocomprimised pts with IV access
Very resistant to antibiotics
Corynebacterium urealyticum
Also very rare
Causes urinary infections
Produces urease, an enzyme that decomposes urine to ammonia and carbon dioxide
Can lead to the formation of calculi (stones) in the kidney, ureter, and bladder
Resistant to most antibiotics except vancomycin