Bacterial Skin Infections
Non-pharmacologic choices for primary impetigo or secondarily impetigo
- normal saline or warm tap water compresses for 10-15 min, 3-4 times per day - Address factors contributing to folliculitis in intertriginous areas by eliminating tight-fitting clothing and reducing friction, moisture and heat. - excision of cystic wall and contents, once the inflammatory stage has subsided -
pharmacological agents used for bacterial skin infections
1) cloxacillin 2) 1st generation cephalopsorin
Topical agents for bacterial skin infections
1) mupirocin 2) fusidic acid 3) ozenoxacin (topical quinolone) 4) polysporin (limited efficacy for bacterial skin infections)
in managing bacterial skin infections are first generation or third generation cephalosporins preferred?
1st generation cephalosporins are preferred over second- or third-generation cephalosporins as they have more reliable activity against gram-positive organisms.
Antibiotic therapy for human animal bites
1st line: amoxicillin/clav 2nd line for ANIMAL bites: clindamycin, metronidazole + one of a 2nd or 3rd generation cephalopsorin, doxycycline, Septra or FQ 2nd line for HUMAN bites: metronidazole + cipro or levo OR monotherapy with moxi
in order to prevent the development of bacterial resistance, the prolonged use of antibacterials >_______weeks should be avoided
2 weeks
treatment duration of erysipelas
5-10 days
what is ecthyma?
A deeper form of impetigo (caused by staph or strep) with ulceration and scarring that occurs frequently on the extremities.
what is necrotizing fasciitis caused by? - GAS - P. aeruginosa - s. aureus
GAS (group A beta-hemolytic streptococcus) (p. aeruginosa in folliculitis and s. aureus in impetigo)
patient with PURULENT cellulitis and SEVERE severity (immunocompromised and showing signs of deeper infection)
IV cefazolin IV cloxacillin IV clindamycin x5 days (or longer is slow to resolve)
association of anti-TNF therapies and SSTIs
In patients receiving anti-TNF therapies, maintain increased vigilance for skin and soft tissue infections, a known complication of these agents.
Role of mupirocin in bacterial skin infections
Used to treat localized skin infections where oral therapy is not indicated it is particularly useful for localized impetigo and folliculitis caused by s. aureus
second line treatment in adults and children with mild to moderate nonpurulent cellulitis?
adults: clindamycin and cloxacillin PO children: clindamycin PO
which of the following ingredients should be avoided due to prevalence of contact dermatitis? - bacitracin - gramicidin - polymyxin B
bacitracin
First generation cephalosporins
cefadroxil cefazolin cephalexin
CHILD patient with NON-PURULENT cellulitis with mild to moderate severity. She was prescribed cephalexin as first line therapy but after 48 hours there is no improvement which option is first line? - cefazolin IV +/- clindamycin PO - clindamycin IV
cefazolin IV +/- clindamycin PO clindamycin is a second line option (i.e., if patient has severe penicillin allergy)
which of the following acute onset skin infection has poorly circumscribed bright red erythema? - erysipelas - cellulitis
cellulitis
which of the following cases of bacterial skin infection are TOPICAL antibiotic options NOT an option? (hint: there are 2/4) - erysipelas - impetigo - bacterial folliculitis - cellulitis
cellulitis and erysipelas
first line treatment in adults and children with mild to moderate nonpurulent cellulitis?
cephalexin
which antibiotics decreases the effect of erythromycin when used concomitantly? - vancomycin - clindamycin - cefazolin
clindamycin
first line oral agents for erysipelas include all the following EXCEPT: - penicillin V PO or penicillin G IV (if severe case) - cephalexin PO or cefazolin IV (if severe case) - clindamycin PO or IV (if severe case)
clindamycin PO or IV this is actually second line option mostly used in cases where the patient has a hypersensitivity reaction to penicillin
which of the following antibiotics do not cause QT prolongation? - Ciprofloxacin - Erythromycin - Cloxacillin
cloxacillin
ADULT patient with NON-PURULENT cellulitis with mild to moderate severity. She was prescribed cephalexin as first line therapy but after 48 hours there is no improvement. all of the following are first line options EXCEPT: - cefazolin IV - clindamycin PO - cefazolin IV + probenecid PO - cloxacillin IV
cloxacillin IV (cloxacillin IV and clindamycin IV are considered second line for severe cellulitis or mild to moderate cellulitis not resolving in 48h)
two clinical forms of impetigo
crusted nonbullous
which of the following MRSA effective antibiotics can cause myalgia and rhabdomyolysis? - linezolid - vancomycin - daptomycin - septra
daptomycin (+ creatinine kinase elevation)
Antacids and sucralfate _____________absorption of ciprofloxacin
decrease
what is a cutaneous abscess?
deep cutaneous infection harbouring collections of pus that may be polymicrobial or s. aureus in origin and located independently of follicular structures
is ciprofloxacin more likely to cause diarrhea or constipation?
diarrhea
Match each skin condition with the bacteria that most commonly causes it - ecthyma (deeper form of impetigo) - impetigo (assume general) - staphylococcus aureus - GAS--streptococcus pyogenes
ecthyma: GAS impetigo: s. aureus
which of the following acute onset skin infections has higher risk of recurrence? - erysipelas - cellulitis
erysipelas
which of the following acute onset skin infections has prominent lymphatic involvement? - erysipelas - cellulitis
erysipelas
All of the following are SSTIs where s. aureus is the predominant pathogen, EXCEPT: - carbuncle - erysipelas - purulent cellulitis - impetigo
erysipelas (only SSTI where penicillin is a 1st line option) (nonpurulent cellulitis involves GAS like erysipelas)
how is erysipelas differentiated from cellulitis is they are both acute onset infections of the skin?
erysipelas is distinguished from cellulitis by more superficial cutaneous involvement and sharply delineated margins
what type of skin condition are furuncles (boil) associated with? - erysipelas - cellulitis - impetigo - folliculitis
folliculitis it is an s. aureus mediated infection of the hair follicle with extension of the suppurative material into the dermis and subQ tissue
does fusidic acid or mupirocin target gram negative or gram positive organisms?
gram positive
does clindamycin topical target gram positive or gram negative organisms?
gram positive gram positive cocci, gram -positive organism
predominant organism in suspected erysipelas
group A streptococcus
predominant organism in suspected nonpurulent cellulitis
group A streptococcus
does septra cause hypokalemia or hyperkalemia?
hyperkalemia
which patients with penicillin allergies can still be considered for cephalosporin therapy?
if they have delayed hypersensitivity reactions such as rash without hives (low risk of experiencing anaphylaxis approx 1%)
Patients with furuncles, carbuncles or abscesses with NO SYSTEMIC symptoms (tachycardia, tachypnea, leukocytosis) should be treated with what?
incision and drainage
What is folliculitis?
infection of hair follicle (variable depths lead to formation of papules and pustules)
what are carbuncles?
interconnecting furuncles in folliculitis
Does impetigo most often affect young children or older children?
it most often affects young children
which of the following drugs used for MRSA SSTIs may cause reversible myelosuppression? - septra - doxycycline - linezolid
linezolid if used for > 2 weeks monitor complete blood counts
What is necrotizing fasciitis?
mono or polymicrobial infection with resultant tissue necrosis of skin, subcuteanous tissue, fascia and muscle
safety of topical agents to treat bacterial skin infections during breastfeeding
most agents are safe (mupirocin, fusidic acid and ozenoxacin) as a general precaution, direct skin-to-skin contact of the breastfeeding infant with the treated skin area of the mother should be avoided with topical use of any medication
limb cellulitis or serious soft tissue infection that manifests with blisters and/or necrosis, "dusky/grey" appearance, severe pain, gas in soft tissue, numbness, exceptionally rapid spread - cellulitis - erysipelas - necrotizing fasciitis
necrotizing fasciitis
best treatment for the following cause of impetigo - localized flaccid vesicles and bullae that rupture easily - localized to one area - no other medications or medical conditions
oral antibacterial (cloxacillin or 1st gen ceph--cephalexin)
best treatment for the following cause of impetigo - non-bullous form (superficial erosions with honey coloured and/or hemorrhagic crusting) - localized to one area - immunosuppressed on anti-TNFa therapy for RA
oral antibacterial (cloxacillin or 1st gen ceph--cephalexin)
best treatment for the following case of folliculitis (follicular pustules with surrounding erythema) - diffuse lesions
oral antibacterial (e.g., cephalexin x7-10 days)
best treatment for the following case of folliculitis (follicular pustules with surrounding erythema) - treated for 7 days using topical mupirocin with no improvement
oral antibacterial (e.g., cephalexin x7-10 days)
Safety of oral agents to treat bacterial skin infections during pregnancy and breastfeeding
pencillins, cephalopsporins, clindamycin and erythromycin (with the exception of the estolate salt) can all be used safely if used during breastfeeding they may alter bowel flora of the infant and rarely may cause hypersensitivity
Where S. pyogenes is the suspected cause of infection (e.g., erysipelas), __________________ is the treatment of choice. - penicillin - cloxacillin - first generation cephalosporins
penicillin
match the following topical bacterials to their targeted pathogen - polymyxin B - bacitracin - gram positive - gram negative
polymyxin B: gram negative organism bacitracin: gram positive
purpose of combining probenecid with cephalosporins?
probenecid prolongs cephalosporin serum levels
predominant organism in purulent cellulitis
s. aureua
common infectious causes of cellulitis
s. aureus beta-hemolytic streptococci
common infectious causes of folliculitis
s. aureus (most common) pseudomonas aeruginosa
what does the term impetiginized mean?
secondary infection of the skin (usually s. aureus) due to underlying inflammatory skin condition such as atopic dermatitis or allergic contact dermatitis
when does orbital cellulitis need to ruled out?
sharply circumscribed painful FACIAL erythema in a CHILD
If a patient presents with symptoms and signs of a lower extremity cellulitis that is complicated by fluid-filled blisters and copious, clear, serous discharge, consider bullous erysipelas and ensure adequate coverage of ________________________ - streptococcus pyogenes - staphylococcus aureus
streptococcus pyogenes
Safety of topical agents to treat bacterial skin infections during pregnancy
there is little information available and safety in pregnancy of the topical antibiotics used for localized skin infections all are most likely safe
when should h. influenza be suspected in a child presenting with poorly circumscribed bright red erythema, edema, warmth and tenderness?
these are symptoms of cellulitis suspect h. influenzae infection in a child under 5 years of age presenting with facial cellulitis preceded by an URT prodrome
Role of FQs in treating common bacterial skin infections
they play little role in treating common bacterial skin infections unless gram negative organisms are suspected
best treatment for the following cause of impetigo - non-bullous form (superficial erosions with honey coloured and/or hemorrhagic crusting) - localized to one area - no other medications or medical conditions
topical antibacterial (e.g., fusidic acid, mupirocin or ozenoxacin x 5 days)
best treatment for the following case of folliculitis (follicular pustules with surrounding erythema) - localized - ruled out mechanical causes (occlusion or friction) of folliculitis <---IMPORTANT STEP!
topical antibacterial (e.g., mupirocin, fusidic acid, or clindamycin solution)
true or false: Elevation of the affected limb (above the level of the heart) is important in the successful treatment of cellulitis.
true
true or false: probenecid prolongs penicillin serum levels
true
true or false: silver sulfadiazine may caused delayed wound healing
true (also allergic contact dermatitis)
when is C&S of drainage/exudate required with abscesses and carbuncles?
when patient presents with SYSTEMIC symptoms such as fever, tachypnea and tachycardia and leukocytosis
Is culture and sensitivity (C&S) tests necessary for impetigo?
yes, swab exudate below crust for gram stain this will be helpful IF empiric therapy fails to work in 48 hours
pharmacological agents used for bacterial skin infections-penicillin allergic (immediate hypersensitivity reactions)
Clindamycin
patient with PURULENT cellulitis and MILD-MODERATE severity with a penicillin allergy
TMP/SMX PO or doxycycline PO x 5 days
how often daily must fusidic acid and mupirocin be applied?
BID-TID
patient with PURULENT cellulitis and SEVERE severity (immunocompromised and showing signs of deeper infection) with a penicillin allergy and MRSA RFs
MRSA coverage with IV vancomycin, linezolid or daptomycin x5 days (longer is slow to resolve)
patient with PURULENT cellulitis and MILD-MODERATE severity from a crowded homeless shelter with IV drug use
MRSA coverage with TMP/SMX or doxycycline
In the setting of cellulitis, purulence or unexpected exudate warrants consideration of and coverage for community-acquired ___________________.
MRSA infection
patient with PURULENT cellulitis and MILD-MODERATE severity
MSSA coverage with cephalexin or cloxacillin (or longer if slow to resolve)
what types of electrolyte imbalances are an issue with penicillin G ?
Na+ or K+ abnormalities
What is impetigo most commonly caused by?
Staphylococcus aureus