Common Bacterial Infections Flashcards
Staphylococcus
Gram positive
Grape-like cocci clusturs
Most are harmless residents of skin and mucous membranes.
MRSA
Methicillin-resistant Staphylococcus Aureus
Resistent to beta lactam abx
Occur is people that have been in hospitals
Can also be community associated (CA-MRSA)
MRSA presentation
Looks like a false spider bite
Develop into deep, painful abscesses
Can cause life-threatening infxns
MRSA tx
Culture and sensitivity Septra DS 1po bid x 10 days OR Doxycycline 100mg po bid x 10 days Bactroban in the nose
Full body wash rules of 3
3 times a day for 3 days then 3 times a week for 3 weeks
Cellulitis
Red, swollen tender skin that is warm to the touch and does not pus.
Group A Streptococci Cellulitis
Typically follows unrecognized injury
Inflammation is diffuse, spreading along tissue planes
Staphylococcus Aureus Cellulitis
Usually associated with wound or penetrating trauma.
Localized abscess becomes surrounded by cellulitis.
Cellulitis Tx
Not Keflex!
Clindamycin, doxycycline or trimethoprim-sulfa
Severe cellulitis should be treated with IV abx
Cellulitis admission criteria
Animal bite on pt's face >50% of limb involved, >10% of body surface Coexisting morbidity Compromised host Need for IV abx
Abscess
When tissue in an area of cellulitis turns to pus under surface of skin.
The most common bacteria is Staph Aureus
Must be distinguished from empyemas
Abscess clinical features
Superficial
Infxns of head and neck
Can be deep seated abscess
Abscess Tx
Should be drained by I and D
If abscess has lots of cellulitis surrounding it, use antibiotic (same as cellulitis)
Abx cannot penetrate w/o drainage
Necrotizing Fasciitis
When cellulitis quickly spreads to fat and muscle .
Flesh is killed because blood supply is cut off
May also go septic
Necrotizing Fasciitis Tx
Cut ALL the dead tissue out
Keep cutting dead tissue until infxn stops spreading
Abx help, but will not cure
Use skin grafts for open muscle
Abx for anaerobes, gram- bacilli, strep, staph
Use abx for 3 weeks
Myonecrosis (Gangrene)
Pure clostridium perfringes infxn
incubates for hours to days
Local edema, pain, fever, tachy
Surgically remove infected muscle
Gangrene Tx
Surgical rescection
Consider hyperbaric chamber
Pen G and Chloramphenicol
Pyomyositis
A purulent bacterial infxn of skeletal muscles that results in pus-filled abscess
Most common in tropical areas
Usually caused by Staph A
Mainly a disease of children
Pyomyositis
Drainage and ABx for 3 wks
Pyomyositis predisposing factors
Immunodeficiency
25% report previous trauma
Erysipelas
Acute streptococcus infxn of upper dermis and superficial lymphatics
Caused by streptococcus pyogenes
Erysipelas Dx
Skin and soft tissue erythema, warmth, edema pain
Fever and leukocytosis
Hx of trauma, abrasion, skin ulceration
Has fiery red appearance w/ raised border
Erysipelas Tx
Immobilization
Elevate to reduce swelling
Draw lines to assess response to tx
2 wks of penicillin or dicloxacillin
Impetigo
Highly contagious superficial infxn
Non-bullous caused by strep A or staph A, pre-school, yellowish crusts
Bullous causes by staph A, all ages, brownish crust
Honey brown crusts =?
Impetigo
Impetigo causes
Malnutrition, diabetes, immuno-compromised
Impetigo complications
Scarlet Fever
Strawberry tongue
Urticaria
Erythema Multiforme
Impetigo Tx
Usually diagnosed by classic presentation
Soak in warm water, use wet compress to remove scabs
Abx creams: bactroban, fusidic acid, Retapamulon
Consider septra/bactrim if hx of MRSA
Superficial Folliculitis
Infxn of hair follicles Commonly caused by staph A Scalp and limb Rarely painful Heals in a week
Risk factors for folliculitis
Immunosuppression Acne or dermatitis long-term abx for acne Topical steroids Obesity Hot tub
Deep folliculitis
Starts deeper in skin surrounding hair follicle
Large swollen lump
Puss-filled blisters that break and crust
Pain, scars
PFB (pseudo folliculitis barbae)
Common problem with african americans
Persistent irritation from shaving
Curly hair curls into skin
PFB Tx
No shaving Use clippers Keep beard at 1/8 inch Cleocin T gel Erythro topical
Furuncle (Boil)
A deep folliculitis caused by staph A resulting in painful swollen areas on skin. Usually heals with scar
Furuncle Tx
May burst and heal on its own Warm compress, salts bring to a head Abx for recurrent boils Associated with poor hygiene Associated with iron deficiency anemia
Carbuncle
An abscess larger than a furuncle, connected to eachother under the skin
Usually one or more open sores
Contagious
Usually caused by staph A or Strep
Carbuncles Tx
Probably I & D and culture Oral abx for gram+ when larger than 5cm diameter or 2 cm proud Avoid squeezing and irritating NSAIDS for imflammation Monitor for sepsis
Paronychia
Seen often, a nail infection where skin meets the nail.
Acute (caused by basteria)
Chronic (caused by fungus)
Paronychia Causes
Trauma to cuticles
repeatedly washing hands
Acne medication use
diabetes, immunosuppression
Paronychia Tx
Acute: Warm soak, I&D if abscess, ABx (clind if hx of MRSA) Keflex po x 10 days
Chronic: Avoid etiological aspect
topical antifungal, steroid, remove fold surgically
Staphylococcal Scalded Skin Syndrome (SSSS)
Ritters Disease
Cause by staph A
Red, blistering skin that looks like a burn mostly in young children.
SSSS characteristics
Tissue paper wrinkling of skin followed by bullae
Rash spreads to other parts of body (arms, legs)
Top layer of skin peels in sheets
SSSS Tx
Supportive care Eradication of primary infxn Rehydration, antipyretics IV Abx for staph A - Naficillin, oxacillin, vanco
Pressure Ulcers
AKA decubitus ulcers
Any lesion caused by unrelieved pressure
Can occur anywhere in the ody
Common in hospital setting
Pressure ulcer staging
I: persistent redness
II: Partial thickness skin loss
III: FUll thickness skin loss (subQ)
IV: Full thickness skin loss (fascia)
pressure ulcer etioogy
Pressure from bones cuts off blood flow to tissue, causing necrosis
Osteomyelitis
Infection and inflammation of bone or bone marrow.
Most commonly caused by staph A
Osteomyelitis risk factors
Puncture wound to foot
Children and neonates
Higher in developing countries
Pediatric Osteomyelitis
Blood-stream sourced most common
90% are S. Aureus
Long bones generally affected
Adult Osteomyelitis
Commonly caused by immunosuppression
Open injury is most common cause
Usually S. Aureus
Leading cause of amputations
Osteomyelitis mgmt
Admit
Ortho-surg consult
Closed needle biop/drainage
Start on IV meds empirically
Osteomyelitis findings
Increased WBC, ESR, CRP
Plain film: 2-3 weeks show no changes
Abnormal bone scan in 1-2 wks
MRI works best**
Acute septic arthritis
Infxn of one or more joints, most commonly one.
Most commonly caused by S Aureus and H. Flu
Sexually active: gonorrhea
IV drugs and elderly: Pseudomonas
Acute septic arthritis causes
Direct invasion
Penetrating wound, arthroscopy
Complete destruction of articular cartilage
Considered to be a medical emergency
Acute septic arthritis diagnosis
Diagnosed by aspiration
Fever, WBC > 12k
ESR, CRP
Acute septic arthritis Tx
Same day ortho consult
IV Abx
Analgesia
Legionnaieres
Severe form of pneumonia
Most commonly affects smokers and older persons
Yersenia Pestis
Plague
Spread by fleas
Found in rodent species, re-emerging
Lyme Disease
Most common tick-bourne disease in North Hemi
Rash, may not be bulls-eye
Later symptoms involve joints, heart, CNS
Abx can treat
Lyme Dx
Western blot, Elisa
Bulls eye rash
Lyme Tx
Doxycycline or amox for 2-4 wks
Brucella
Brucellosis
Caused by consumption of unpasteurized cheese made from milk of infected animals.
Tularemia
Caused by Francisella tularenis
Tick and deer, contaminated water, inhallation
Symptoms vary, can be treated with abx
Animal BItes
Pasturella Multocida
Tx with augmentin
