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