Nonfermenting Aerobic G- bacilli/Curved

Nonfermenting Aerobic Gram-negative Bacilli
Chapter 16
Microbiology for Surgical Technologists
Pseudomonas
Short straight or slightly curved rods
Non-spore forming
Motile – some species exhibit one or more polar flagella that are visible under a compound microscope
Some exhibit an outer slime layer around a single cell or group of cells forming a microcolony
Pseudomonas
(continued)
Found worldwide
Can exist under harsh conditions that would kill other bacteria
Because of it’s cell wall and the production of enzymes that destroy toxic substances
There are 13 species of P. But the most common species is P. aeruginosa
It has 17 subtypes
Pseudomonas Aeruginosa
Responsible for 20% of nosocomial infections
Causes deep-tissue damage
The 2nd most common Gram-negative infection
E. coli being the first
Pts with cystic fibrosis, burns, and leukemia, and pts on respirators or have tracheotomy are at greater risk
They have low nutritional requirements
Can live in sinks, drinking fountains, soaps used by hospital staff and pt humidifiers
Most are antibiotic resistant
Lab colonies produce a fruity smell and an extracellular pigment
Virulence factors
Primarily infect hospital pts with « resistance
Invades damaged cells
Produces tissue necrosis and thrombosis in the circulatory system
Produces a blue pus due to the pigment pyocyanin produced by the bacteria
The pyocyanin can help with tissue damage
As the infection progresses, colonization can occur in the intestines, followed by bacteremia
The organism shows an affinity for invading blood vessels called ecthyma gangrenosum
It begins as superficial skin lesions usually on the buttocks, perineum, axillary region or extremities and become necrotic
Pts with deep wounds, open bone fractures, and severe burns are subject to osteomyelitis
Occasionally P. aeruginosa can cause otitis externa
Malignant external otitis is a more virulent form
Occurs in elderly
Can penetrate the mastoid bone damaging cranial nerve VII
Surgical intervention may be needed to I & D the bone of the auditory region
Life threatening
Found in great numbers in hot tubs that have low chlorine levels
The EPA has set strict rules for public hot tubs and whirlpools
Prior to the standards, outbreaks of folliculitis were reported
Folliculitis is the infection of hair follicles resulting in a rash
Can be localized or widespread and can develop into widespread gangrenosis within 24 hours
P. aeruginosa is often the cause of conjunctivitis, keratitis, and other eye infections
This infection is often the result of trauma or surgery
Lenses can be destroyed due to corneal ulcer
The tissue of the entire eye can be destroyed
Conjunctivitis
Scleritis
UTIs caused outside of the hospital are caused by P. aeruginosa
Can be caused by self catheterization or contaminated irrigation solutions
Pts with cystic fibrosis are especially venerable to P. aeruginosa pneumonia
The cells form a biofilm around the colony and are impossible to eliminate
Pts with prosthetic heart valves and IV drug users are prone to endocarditis from P. aerugnosa
Drug addicts tend to be young men with no other health problems
Caused by drug paraphernalia, contaminated with water borne bacteria
The tricuspid valve in the right atrium is usually infection site
If the left side of the heart is involved then prognosis is poor
Treatment
The organism is very resistant to antibiotic therapy
PCN is combined usually with gentamicin, ciprofloxacin, or a third-generation cephlosporin
It is virtually impossible to prevent burn pts from acquiring a P. aeruginosa infection
The goal is to keep colonization as low as possible to prevent septicemia
Treatment
Burn pts will be treated with a topical medication such as silver nitrate solution, sulfamylon cream, or silver sulfadiazine
Pt will undergo multiple surgical debridments to help control infection
Pick and pack
Surgical Implications
Osteomylitis
May require bone debridement to remove necrotic bone
Using ronguers,curettes, saws, and copious amounts of irrigation
Corneal ulcers
May require the removal and possible replacement of the lens
In severe cases, enucleation will be performed
Postoperative renal transplant UTIs
Usually the result of a break in sterile technique during harvesting or implantation
The primary duty of the ST is to observe sterile field for breaks in aseptic technique
Endocarditis
May require a tricuspid heart valve replacement
Vocabulary
leucopenia
The reduction of leucocytes
keratitis
Infection of the cornea
cystic fibrosis
A hereditary pulmonary disease that causes accumulation of thick and tenacious mucus
Curved Aerobic Gram-negative Bacilli
Chapter 17
Microbiology for Surgical Technologists
Helicobacter
Are microaerophilic and need a highly enriched carbon dioxide environment
Require oxygen for growth, but at a lower concentration than found in the atmosphere
Are motile and have curved cell bodies
Helicobacter pylori
In the past it was thought that spicy food, lifestyle , and stress caused ulcers
Pts were treated with H2 blockers and acid reducing agents
The meds would relieve symptoms, heal gastritis, and sometimes the ulcer itself
Once the medications were discontinued the ulcer would recur
It is now known that most ulcers are due to an infection of H. pylori
Treatment now includes antibiotic therapy
60% to 80% of pts diagnosed with stomach ulcers are infected
90% or more diagnosed with duodenal ulcers are infected
It infects the mucous lining of the stomach, not the gastric cells themselves
Protects itself by producing an enzyme called urease
Converts the abundant urea in the stomach to an alkaline based ammonia and bicarbonate, neutralizing the digestive acids
The body’s own immune system contributes to the survival of the organism
Leukocytes, killer T cells and other components are sent to destroy the bacteria
Yet they are unable to penetrate the mucous lining
The body sends nutrients to feed the immunity cells, which in turn feed the bacteria
In many cases the pt will be asymptomatic
It is thought to be transmitted orally through fecal contaminated food and water
Most pts with gastric adenocarsinoma are presently or have previously been infected with H. pylori
Precipitory factors for infection
Low socioeconomic status
Immigrants from developing countries
Young children are rarely infected
Infects 20% of individuals below 40 and 50% over the age of 60
(MALT) Mucosal-associated lymphoid-type lymphoma and stomach cancer are known to be associated with H. pylori infections
This does not mean that every pt with the infection will get cancer, yet most that do have had long term infections
Diagnosis
Three methods
Esophagoduodenoscopy (EGD)
Blood test
Breath test
EGD
Performed in hospitals, outpatient facilities, or physicians office
Pts are usually sedated
The throat is sprayed with a localizing agent, and a teeth guard is placed in the mouth
The surgeon inserts an endoscope into the stomach of the patient by way of the mouth and esophagus
Biopsies are taken and analyzed in the lab
Gastric Ulcer
Blood test
Measures the protein antibodies against the bacteria
The test confirms that the patient has either an active infection or a past infection that has resolved
Breath test
Pt swallows a urea solution
Urease is secreted by the bacteria converting the urea into ammonia and bicarbonate, forming a cloud of substances in the stomach
This is exhaled and measured
Treatment
Acid reducing agents and antibiotics
Bismuth subsalicylate
Campylobacter
16 species with 6 subspecies
S-shaped, spiral-shaped, curved, or rod shaped
Microaerophilic
Polar flagella for motility
Most common human pathogens are C. jejuni and C. coli
Campylobacteriosis
Campylobacteriosis is the disease caused by campylobacters
It is a zoonosis
Disease caused by animals or animal products
Leading cause of gastroenteritis in the world
The main route of transmission is ingestion of raw or undercooked meat, unpasteurized milk or contaminated water
Can be eliminated from food through cooking or pasteurization
Occurs mostly in summer months
Is self limiting so treatment is usually not necessary
Rarely fatal except in infants, elderly, a immunocomprimised pts
Severe cases may need antibiotic therapy
Campylobacter jejuni
The leading cause of diarrheal disease in the US
Causing more disease than Salmonella or Shigella
Caused by ingesting undercooked chicken or contaminated water or milk
The majority of healthy chickens carry C. jejuni in their GI tract
Cows can also be carriers
Campylobacter jejuni
The bacteria invade the lining of the small intestine, causing bloody diarrhea
The pathogenesis is not completely understood, but it is thought that their toxin produces the diarrhea
Rare complications associated with C. jejuni
Reactive arthritis
Septicemia
Hemolytic uremic syndrome
Meningitis
Cholecystitis
Guillain-Barré syndrome
Septic abortion
Guillain-Barré syndrome
The pt’s own immune system is triggered to attack the body’s nervous system
Resulting in paralysis that can last for weeks
Surgical Implications
STs must be familiar with the procedures performed for hyperacidity, ulcers, and cancer of the stomach and duodenum
Vagotomy
The vagus nerve stimulates the stomach to release gastric acids
Small portions of the nerve are removed to reduce hyperacidity
Gastric/Duodenal resection
Portion of the stomach or duodenum is resected to remove the disease
Pyloroplasty
Performed on constricted pyloric sphincter to enlarge communication with duodenum