DB-Skin Bacteria

Medical Sciences Medical School 5030 with Davis,hada,mayi at Nova Southeastern University

About this deck

By: Danielle Beharie
Created: 2012-03-26
Size: 110 flashcards
Views: 23

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What layer of the skin contains keratin?

Stratum Corneum

What are the Defensese of the Skin?

Keratinized Surface
low pH (sebum)
High Salt (Sweat)
Lysozyme (Sweat)
Antimicrobial peptides

_______ areas of the body have few G- bacteria in the normal biota. However, the G- predominates in the ______ overall.

Moist Skin
Skin Flora

What are the predominant G+ bacteria of skin?

Staph. epidermis
Micrococcus spp (Propionbacteria acnes, Cornebacterius, Staph. aureus)

The normal biota of the skin is composed of bacteria and

yeasts

Pathogenesis of Acne

Abnormal follicular keratinization and occlusion
Excessive oil/sebum production
Bacterial superinfection
Release of inflammatory Mediators

Pt. presents with multiple follicular lesions with periods of improvement and exacerbation.
Lesions are open and closed comedone, inflammatory papules, pustules, nodules and cysts presenting on back, face, neck, upper chest. What do they have? What are the associated symptoms?

Acne
Associated-oiliness, post-inflammatory hyper/hypo pigmentation, atrophic or hypertrophic scars, excoriations

How do you diagnose acne?

Lesions in characteristic locations

Prevention and Treatment of Acne

Topical Sloghing agents
Antibiotics
Oral contraceptives
Accutane

Primary etiologic agent of acne

Propionibacterium acne

What Bacteria?

G+, Rod bacteria that occurs in short chains/clumps.
Anaerobic/aerotolerant anaerobe

Propionibacterium acne

How does Propionibacterium acne cause infection?

Uses lipases
Digestive products + bacterial antigens = local inflammation

Benzoyl peroxide, erythromycin, and benzoyl peroxide/erythromycin combinations are used to treat

Propionibacterium acne

Pt. presents with non-bulbous, single/multiple isolated or coalescent small, superficial pustules that progress to erosions with honey-colored crusts. What is the bacterial infection?

Impetigo by either Staph. aureus or Strep. pyogenes.

Pt. presents with bullous (blister-like) bullae, with minimal/no inflammtion. Areas of blister rupture are covered with varnish-like brown crusts. What is the bacterial infection?

Impetigo
-Staph. aureus or Strep. pyogenes

Who generally becomes affected by impetigo?

Children 2-5, often contagious with poor hygiene/minor trauma

Impetigo means

Acute, superficial pyoderma

What bacteria can cause cellulitis?

S. pyogenes
S. aureus
Haemophilius influenzae

What common clinical infection can be caused by Streptococci (S. pyogenes), Enterobacteriaceae, Clostridium perfringfrens, Bacteriodes gradilis, and MRSA?

Necrotizing Fasciitis

What are the organisms of HACEK? What is the importance of the this group?

Haemophilus
Actinobacillus
Cardiobacterium
Kingella
***Agents of endocarditis

What etiologic agents should you be concerned about following a Dog Bite? A Cat bite?`

Dog-P. Canis
Cat-Pasteurella multocida

What clinical features follow a bite from a domestic animal?

Local abcess with swelling and discoleration associated with bites
Regional lymphadenitis

Hansen's Dz is also known as ____ and is caused by _____.

Leprosy
Mycobacterium leprae

Acid-fast positive bacteria with lengthy generation time, with slow clinical manifestation. Pt. can present with either tuberculoid or lepromatous forms, is caused by what bacteria?

Mycobacterium leprae

The primary reservoirs of Mycobacterium leprae are:

Humans
Armadillos

What is the treatment for leprosy? How is it transmitted?

Long term Anitbiotics
Person-person transmission

The majority of Staphylococcaceae infections are caused by:

S. aureus
S. epidermidis
S. saprophyticus

What species are Staphyloccocae are Coagulase negative?

S. epidermidis
S. saprophyticus

What species are Staphyloccocae are Coagulase positive?

S. aureus

What is the most common cause of suppurative (pus-forming) diseases seen in medical practices?

S. aureus

S. aureus often causes _____ infections, of what body part?

Nosocomial Skin infections

You are looking at a G+, bacteria arranged in clusters of cocci.

S. aureus

The peptidoglycan of S. aureus is susceptible to ______.

Lysostaphin

Pt. presents with suppurative infection on upper arm. Culture is positive for Catalase, coagulase, and staphylokinase. The bacteria is susceptible to lysostaphin. What is the bacteria?

S. aureus

What are the types of toxins that S. aureus produces?

Cytolytic
Enterotoxins
Exfoliative Toxins
TSST-1

What do Cytolytic Toxins do? Give an example

membrane-active exotoxins that lyse RBCs and other cells.
Ex-alpha toxin

What do enterotoxins cause? How are they successful?

Cause Food Poisioning.
They are resistant to gastric enzymes and heating, and act as a Superantigen

What do exfoliative toxins cause? How do they work?

Cause Scalded-skin syndrome
Due to lysis of intracellular attachment between cells of the granular layer of the epidermis occurs

What is TSST-1 and what does it cause?

Toxic Shock Syndrome Toxin-1 causes superantigen fever, lethal hypotension, rash, systemic.

Death to TSST-1 is due to

hypovolemic shock leading to multiorgan failure.

TSST-1 have direct effects of endothelial cells that cause

capillary leakage and hypotension

S. aureus are resistant to _____ due to acquisition of ______.

β-lactams, erythromycin, and tetracycline due to the acqusition of Mec A gene.

True/False: All pathogenic staphylococci can survive in dried pus or sputum

True

True/False:

All pathogenic staphylococci can be killed by household Lysol

False, they are resistant to common disinfectants

What is the pathogenesis of S. Aureus?

Development of an abscess includes erosion and rupture of skin & drainage of pus.

Stye, a form of folliculitis.
-Infection of hair follicle, that is raised and reddened with a small amount of pus beneath the surface.

More that 50% of bactermia/endocarditis that are acquired in the hospital following surgery is caused by

S. aureus

Hematogenous pneumonia is common for patients with

Bacterimia or endocarditis

Osteomyelitis and septic arthritis are spread through ________, and are often associated with pain ______.

Blood
Bone Pain

Erythemaous joint, with purulent material obtained on aspiration, generally at large joints are characters of

Osteomyelitis or septic arthritis caused by S. aureus

Enterocolitis is often caused by

Clostridium difficile

Shortly after eating a hamburger, I suffered from severe cramping, abdominal pain, nausea, vomiting, and diarrhea. What do you think caused my symtoms?

Enterotoxins produced by S. aureus on the contaminated hamburger.

Pt. presents hypotensive, with vascular coagulation, renal failure, acidosis, and rash. What is the differential diagnosis? What do you suspect if the bacteria is G+, and + for catalase and coagulase?

Rocky Mountain Spotted Fever
Leptospirosis
Meningococcemia
Strep. Scarlet Fever
Bacterial Sepsis
Drug Eruption
TSS

What is the most common cause of hardware infections, specimen contaminats, and causes of bacteremia?

S. epidermidis

What is the most common cause of UTIs in young, sexually active women?

S. saprophyticus

Pt presents with dysuria, pyruia, and bacteria in urine. What do you suspect?

UTI caused by S. saprophyticus

True/False
S. epidermidis and S. saprophytics are found in the normal flora of body sites

True

What is strains of Coagulase negative staph infections are the most common sources of infection?

Endogenous strains

S. aureus are carried in what sites?

Anterior Nares (20-30%)
Perineum
Skin
Mucous membranes

What is the only carrier of

S. aureus?

Humans

The ____ test is used to distinguish between S. aureus and Streptococcus.

Catalase Test;
S. aureus +

The Coagulase is the primary difference between

S. aureus (+) and S. epidermidis/S. saprophyticus(-)

Lysostaphin susceptibility is the primary difference between

Staphylococcus spp and Micrococcus

What is the difficulty in treating of S. aureus?

Antibiotic resitance
penicillin, MRSA, VISA, VRSA.

what is MSSA?

Methicillin Sensitive S. aurues
-treate with oxacillin or nafcillin

What is a G+, cocci, with fibrils that presents in pairs or chains (diplocci) lancet-shaped.

Streptococcaceae, specifically S. pneumoniae

How do Streptococcaceae species modify hemoglobin?

α-hemolysis-partial lysis associated with reduction of Hb produces a greenish/brownish discoloration.
β-hemolysis-complete lysis of RBCs with a clear zone surrounding colony
γ-hemolysis-no lytic activity

GAS bacteria that establishes infection by preventing phagocytosis by M protein and hyaluronic acid. Uses streptokinase

Streptococcus pyogenes

What are the Virulence Factors of S. pyogenes?

M. Protein
Streptolysin O
Streptolysin S
Strep Pyrogenic Exotoxins
Streptokinase
DNAse and hyaluronidase

What is M protein?

fibrous protein in the cell surface that protects cell from phagocytosis. Can act as an adhesion.
**S. pyogenes

What is Streptolysin O?

lyses blood cells by causing transmembrane pores.

How do you test for GAS infections?

look for antibodies formed against antigen= anti-streptolysin O (ASO) test

What is streptolysin S

lyses red and white blood cells that are responsible for beta-hemolysis on blood agar.

What are Strep pyrogenic exotixins (Spes)?

super-antigens that are involved in the development of the rash observed with scarlet fever.

what is streptokinase?

lyse blood clots, activates plaminogen, allowing rapid spread.

Clinical manifestations of the skin of S. pyogenes?

Impetigo/pyoderma
erysipelas
Cellulitis
Necrotizing fasciitis

What is an acute infection of the skin with localized pain in an area that is raised, erythematous and warm?

Erysipelas

what are common associated symptoms of Erysipelas?

LN enlargement, chiills, and fever.

S. pyrogenes is responsible for what non-skin infections?

Pharyngitis
Scarlet Fever
Strep TSS
Bacteremia

Pt. presents with pharyngitis-like symptoms, with a skin rash that first appears on upper chest then spreads to trunk, neck, and extremities. Also, appears with strawberry tongue, followed by a raspberry tongue. What are they suffering from? What bacteria has caused it?

Scarlet fever caused by s. pyogenes

Describe the clinical manifestations of Strep TSS

resembles staph TSS with hypotension, renal failure, and red rash.

Treatment of s. pyogenes

Soft tissue sepsis-clindamycin + penicillin
Debridement

What bacteria are G+, rods that form spores that are obligate anaerobes?

Clostridium genus

What bacteria causes infection by lowering oxidation-reduction potential, release alpha toxins, and use edema and gas to promote spread.

C. perfringens

What are the two wound infections caused by C. perfringens?

Clostridial cellulitis
Gas Gangrene

Infection of tissue that is already dead and produces gas

Clostridial cellulitis

invasive infection associated with toxemia, local edema, foul-smelling exudate, with various amounds of gas. That may cause septicemia, massive hemolysis and renal failure.

Gas Gangrene, due to C. perfingens

What form of food poisoning presents with diarrhea, cramps, and abdominal pain roughly 8-24 hours folloinw ingestion?

**No Vomit
C. perfringens

Loss of intestinal mucosa with bleedin into the stool can be symptom of ______

Necrotic enteritis due to C. prefringens.

How to diagnose C. perfringens infection

clinical symptoms
gram stain & culture
Nagler test (alpha toxin)

Treatment of C. perfringes

Cellulitis-remove necrotic tissue, antbiotics
Gas Gangrene-remove infected area, high does antibiotics, hyperbaric oxygen (inhibits alpha toxin)

G+ rods that produce endospores with high resistance to chemical and physical environments

Bacillus anthracis

Pathogenesis of Bacillus anthracis

spore enter through small abrasion and multiply with dramatic inflammatory response. Can occur with toxemia

pt presents with small papule that later developed into a vesicle filled with dark, bluish-black fluid. Rupure causes a black eshar.

Bacillus anthracis occurs 2-5 days after exposure.

what is the natural reservoir for Bacillus anthracis

herbivorous animals endemic in Africa and Middle East (US via imports)

Diagnosis of Bacillus anthracis

culture on blood agar, PCR

Treatment and Prevention of Bacillus anthracis

Treat-antibiotics
Prevention-sterilizaion of animal products, immunization of herbivorous animals, and humans vial cell-free filtrate.

Who receives vaccination against Bacillus anthracis?

Military and those in industrial settings

Tears contain _____ and _____ for protection

lysozyme and lactoferrin

Difference between Bacterial and Viral infections of the eye

Bacterial-milky discharge
Viral-clear exudate

What are the common causes of neonatal eye infection?

Neisseria gonorrhoeae
Chlamydia tracomatis

G-, diploccocci bacteria that often presents with PMNs

N. gonorrhoeae

G-, cocci, obligate intracellular parasite with inclusion bodies in infected host cells.

Chlamydia trachomatis

What are the major causes of bacterial conjunctivitis in everyone except neonates?

S. epidermidis
S. pyogenes
S. pneumoniae
H. influenzae
Moraxella

G-, bacillus found in normal flora of upper respiratory tract. Most commonly causes otitis media (children) and bronchitis/bronchopneumonia (elderly)

Moraxella

Viral conjunctivitis is usually caused by

adenovirus

pt presents with clouded and casularized cornea with scarred and malformed eyelids. Trichiasis (inward groth of eyelids) presents. What do you think is the dz and cause of infection?

Trachoma due to Chlamydia trachomatis

Infection of Chlamydia trachomatis

infection of conjunctival epithelial cells that cause subepithelial infiltration of lymphocytes that lead to the development of follicles.
Follicles-infected epithelial cells that contain cytoplasmic inclusion bodies.

Keratitis is caused by

HSV-1 and -2

About this deck

By: Danielle Beharie
Created: 2012-03-26
Size: 110 flashcards
Views: 23

About StudyBlue

“I have used this website for three exams, and I see a huge difference in my test results.”
Naj