Infections (skin,RTI,GI) Flashcards
What bacteria commonly infect skin, soft tissues and bones?
Staphylococcus aureus
Streptococcus pyogenes
Anaerobes
Describe normal skin flora
Mosy gram positice bacteria
Staphylococcus spp.
corynebacterium spp.
Cutibacterium acne
Describe staphylococcus species
Grape like sphericle clusters
Gram POSITIVE cocci
Catalase POSITIVE
All staphylococcus aureus are coagulase POSITIVE
Describe staphylococcus aureus virulence factors
Produces toxins that break down red blood cells
Coagulase
Hemolysins
Enterotoxins (GI toxins)
Pyrogenic toxins
Exfolactins (kill and slough off skin cells)
Some isolates are resistant to antibiotics
Describe streptococcus species
Spherical chains
Gram POSITIVE
Classified by ability to product hemolysins (alpha, beta, gamma)
Describe hemolysins
Alpha: PARTIAL hemolysis of RBC Alpha includes streptococcus pneumoniae Beta: COMPLETE hemolysis of RBC Beta includes streptococcus pyrogenes Gamma: NO hemolysis of RBC
Describe streptococcus pyrogenes
Group A classification
Gram POSITIVE
Beta hemolysis
Does NOT produce catalase or coagulase but is an aggressive organism
What streptococcus bacteria produce alpha hemolysis
Viridians strep & S. Pneumoniae
What streptococcus bacteria producse beta hemolysis?
S. Agalactiae & S. Pyrogenes
Streptococcus are catalase ___________
Negative
Staphylococcus are catalase ___________
Positive
What staphylococcus bacteria is coagulase negative?
S. Epidermidis
What staphylococcus bacteria are coagulase positibe
S. Aureus ONLY
Describe anaerobes
Bacteeia which grow in the ABSENCE of oxygen
2 types:
Facultative (s.aureus & e.coli)
Obligate
Commonly found as normal flora in mourh and bowel but can infect necrotic skin and tissues
What are some anaerobic gram positive Baccili
Clostridium perfringens and C. Difficile
What are some gram negative anaerobic bacilli
Bacteroides fragilis and fusobacterium spp.
What are vesicles
Small, fluid filled lesions in the epidermis (chicken pox, herpes simplex, shingles)
What are bullae
Larger, fluid filled lesions in the epidermis that may pop. Usually caused my staphylococcus
Describe macules
Flat, reddish lesion from inflammatory infiltrate that are sometimes infectious
What causes folliculitis
S. Aureus
What is impetigo
Vesicular, later crushed honey like, superficial infection of the skin
Caused by S. Pyrogenes and S. Aureus
Describe cellulitis
Acute spreading infection of tbe smkn extending to involve the subcutaneous tissues
Caused by S. Aureus, S. Pyrogenes and anaerobes
Describe erysipelas
A distinctive type of superficial cellulitis of the skin with prominent lymphatic involvment
Caused by S. Pyrogenes
What are some complications of skin diseases?
Furuncle: deep inflammatory nodule usually developed from folloculitus (S. Aureus)
Carbuncle: more extensive than furuncle with involvment of subcutaneous fat (S. Aureus)
Staphylococcal TSS (S. Aureus)
Scalded skin syndrome: wide spread bullae and exfoliation from S. Aureus producinf exfoliative exotoxin
Describe necrotizing fasciitis
Severe infection involving subcutaneous soft tissue
Usually caused by S. Pyrogenes, C. Perfringens & mixed anaerobic and aerobic bacteria
What are some predispositions for necrotizing faciitis
Diabetes, abdominal surgery, perineal infection and trauma
How is necrotizing faciitis treated?
Surgical debridement, antibiotics and sometimes immunoglobulins
What is myositis
Infection of the skeletal myscle
Caused by S. Aureus and S. Pyrogenes
What is Gas Gangrene?
Rapidly progressive, life threatening, toxemic infection of skeleral muscle due to clostridia
C. Perfringens
What is septic arthritis
Infection of joint spaces
Caused by S. Aureus. streptococcus spp., GRAM NEGATIVE BACILLI
What is osteomyelitis
Infection of the bone caused by S. Aureus, S pyrogenes H. Influenzae
GRAM NEGATIVE BACILLI
What organisms are typically involved in diabetic foot infection
S. Aureus, group B streptococcus, corynebacterium spp.
GRAM NEGATIVE BACILLI
Anaerobes
What are normal flora in the oral cavity?
Gram negative coccobacilli, anaerobes
What happens if there is no acid production in the stomach
Fecal flora found
What are normal flora in the small bowel/colon
Fecal flora (mixed gram negative rods), enterococci, large numbee of both gram negative and positive anaerobes
Describe helicobacter pylori
Causes Infection in the stomach, microaerophilic spiral gram negative rod, very fastidious
Route of transmission not well defined
Causes gastritis, can lead to ulcers and stomach cancer
How is helicobacter pylori infection detected
Detected by histology, antigen detection in stool or culture of stomach biopsy
Treated with antibiotics
What are the 2 types of food poisoning
Performed toxin ingested
Organisms ingested and initiate infection and make toxin
What causes food poisoning
Staphylococcus aureus
Bacillus cereus (associated with recooked rice)
Clostridium perfringens (diarrhea)
Botulism (neurotoxin)
Describe GI infection with non toxin producer
Bowel wall may be coated with organisms to prevent absorption of nurtients
Malabsorption can lead to bulky stool (beaver fever or giardia)
Describe infection worh superficial invasion or gut wall destruction
Bowel wall gets damaged and causes ulcers in areas of invasion, and bleeds
Diarrhea passed in small vokumes blood And pus may be present
Mediated by CYTOTOXIC toxins
Toxin damages cells
Concern of colon ballooning
What organisms Are involved in superficial invasion
E. Coli, enterohaemorrhagic e. Coli, shingella species
Clostridium difficile
Describe e. Coli 0157 & Enterohaemorrhagic E. coli
Toxin which attacks the colon and kidney after absorption into body
Acquired from food especially undercooked hamburger, unpasteurized milk and contaminated food
What symptoms to E. coli 0157 and Enterohemorrhagic e. Coli cause
Diarrhea, abdominal pain, hemorrhagic colitis (passing blood per rectum)
Antibiotics can not be used to treat as they will cause toxin release
Describe Shigella spp.
4 species with the most severe being S. Dysenteriae
Poor sewage disposal
Low infective dose
Can be in food and water
Cytotoxic toxins produced with superficial invasion thay can lead to diarrhea/dysentery, antibiotics are a useful trearment here!
Describe clostridioides difficile
Anaerobic gram positibe rod which forms spores
Most common agent causing infective diarrhea in hospitals
Can cause colonic distention and rupture
Treated with antibiotics
Describe campylobacter spp.
2 common species of microaerophilic curved rods that produce toxins
Usuakly acquired from poorly cooked poultry, unpasteurized milk, water and pets
Causes severe diarrhea that can lead to dehydration
How do you treat campylobacter spp.
Usually settles without therapy but can be treated with erythimycin if severe
Describe salmonella spp.
> 2500 serotyoes
Acquired from poorly cooked poultry, eggs, pet reptiles, contaminated food, water
Diarreha can be bloody, may lead to invasive disease (enteric fever)
What causes typhoid and enteric fever
S. Typhi and S. Paratyphi
How are salmonella infections treated
If mild antibiotics, can be risk of chronic carriage of the organism, not treated if there is a risk of invasive infection
Describe yersinia enterocolitica
Coliform associated with pigs
Slow growing and able to grow at refrigerator temperature
Abdominal pain mimicking appendicitis and diarrhea present
Antibiotics can treat here for severe cases
What is an intra abdominal infection?
Infection of the normally sterile abdominal cavity that causes Inflammation of the peritoneum (perionitis)
Describe causes of intra abdominal infection
Release of fecal flora into abdominal cavity
Organisms involved typically a mixture of anaerobic and aerobics and sometimes yeast
Describe mono microbial peritonitis
A single species infects the peritoneum (s. Pneumoniae, M. Tuberculosis)
Complication of perironeal dialysis
What are common organisms causing diarreah in canada
Clostridioides Salmonella E.coli 0157 Shingella Yersinia Campylobacter
How is community acquired enteric illness diagnosed
Stool sent using enteric transport medium for culture
This preserves the stool and allows pathogens to survibe
How is hospital acquired enteric illness diagnosed
For detection of C. Difficile should be sent for toxin detection, or pcr for toxin genes
