Cellulitis is a skin and subcutaneous inflammation causing localized pain, swelling, erythema, tenderness, and warmth without affecting muscles or fascia typically associated with acute infections. Cellulitis is a common infection that doesn’t lead to abscess formation, ulceration, or purulent drainage.

Erysipelas and diffuse cellulitis are caused by Streptococcal species while purulent cellulitis is caused by S. aureus which is often linked to carbuncles, furuncles, or abscesses.

Cellulitis is a common infection affecting all racial and ethnic groups with no significant difference in incidence between men and women. However, it is more prevalent in individuals > 45 years, these age groups are at higher risk for unique scenarios.

A study conducted in Utah revealed a 24.6 case incidence per 1000 person-years, with higher rates in males and individuals aged 45-64 was identified in 37.3% of patients. Visits for SSTIs increased from 32.1 to 48.1 visits per 1000 population which had reached 14.2 million by 2005. Abscess and cellulitis visits increased from 17.3 to 32.5 visits per 1000 population.

Cellulitis accounts 3% of emergency medical consultations at a UK district general hospital.

Cellulitis caused by microorganisms that infiltrating the dermis leading to inflammation. It can be caused by a breach in the skin and microscopic alterations or by the invasive nature of certain bacteria. Individuals with associated conditions like tinea pedis, toe-web intertrigo, pressure ulcers, lymphatic obstruction, or obesity that are more susceptible to recurrent cellulitis episodes.

Streptococcus pyogenes causes cellulitis and in cases with Staphylococcus aureus playing a secondary role. It rarely results from metastatic dissemination in immunocompromised individuals. Distant dissemination is associated with S. pneumoniae and marine Vibrio species.

Certain host factors like age, diabetes, immunodeficiency, cancer, and chronic kidney disease that increase the risk of severe infections. These factors including local immune function regulation and protect the host’s ability to defend against infections.

Cellulitis from lymphatic obstruction, venectomy, post-venectomy complications, and lymphadenectomy post tumor excision like mastectomy can be caused by non-group A streptococci.

Cellulitis can be managed with oral antibiotics often without long-term complications and intravenous antibiotics are effective for initial hospitalization or failure of outpatient therapy. This can escalate into severe conditions through unchecked spread leading to complications like lymphangitis, abscesses, and gangrenous or necrotizing fasciitis. Certain bacterial species can cause toxins potentially causing septic shock and mortality.

Assessment of Skin

Presence of Skin Lesions

Assessment of Systemic Signs

Functional Assessment

Cellulitis can rapidly spread which causes redness and swelling beyond the initial infection site and affects the area over a short period.

Rapidly progressing cellulitis or severe systemic symptoms may indicate a higher risk of complications.

Antibiotic treatments are effective in 90% of patients but drainage is necessary for most abscesses regardless of infection microbiology. In isolated cases the drainage may be sufficient without antibiotics. Cellulitis management is complex due to MRSA and Streptococcus pyogenes resistance but in non-severe cases it may require empirical treatment like penicillins, cephalosporins, macrolides, and clindamycin with the latter being more effective.

MRSA strains with cellulitis and abscesses exhibit clindamycin resistance while most of the macrolide resistant S. pyogenes strains remain susceptible to clindamycin and penicillin. Most of the CA-MRSA infections respond well to trimethoprim-sulfamethoxazole and tetracycline.

This is caused by staphylococci or streptococci requires hospitalization and treatment with antibiotics like cefazolin, nafcillin, clindamycin, oxacillin, and vancomycin.

Individuals allergic to penicillin should use preventive penicillin or erythromycin for cellulitis without abscesses while recurring cases should use beta-lactam antibiotics.

In mild cases the outpatient treatment can be treated with TMP-SMX or tetracyclines like doxycycline or minocycline. Both are effective for treating skin and soft tissue infections (SSTIs) but may not provide sufficient coverage against streptococci. Clindamycin may be considered depending on local MRSA sensitivities but up to 50% of MRSA strains may exhibit resistance to it in some areas according to the IDSA.

First line agents:

Effective treatment for various pathogens like Group A Streptococci infection often involves the use of specific first-line agents like penicillin. Staphylococcus aureus infections especially those causing methicillin-sensitive strains can be effectively treated with various antibiotics such as cephalexin, cefazolin, cefuroxime, cefadroxil, nafcillin, oxacillin, and dicloxacillin.

Methicillin-resistant Staphylococcus aureus infections require vancomycin while Hemophilus influenzae cases require ampicillin/sulbactam, amoxicillin clavulanate, TMP/SMX, cefuroxime, cefotaxime, and ceftriaxone.

Vibrio vulnificus infections are typically treated with doxycycline while Pasteurella multocida infections can be treated with penicillin, amoxicillin, ampicillin, and amoxicillin/clavulanate.

Aeromonas hydrophila infections can be effectively treated with levofloxacin, ofloxacin, moxifloxacin, ciprofloxacin, and TMP/SMX.

Erysipelas a condition causing streaking in superficial lymphatic vessels which is caused by group A streptococcus exotoxins and is primarily treated with amoxicillin or cephalexin which is considered as first line treatment.

Second line agents:

Second-line agents are useful for addressing specific pathogens when first-line agents are ineffective or contraindicated. If penicillin isn’t effective against Group A Streptococci the alternatives like amoxicillin, ampicillin, and cephalosporins like cephalexin or cefadroxil can be considered. Staphylococcus aureus infections particularly those causing methicillin-sensitive strains may require alternatives like amoxicillin/clavulanate or TMP/SMX.

Methicillin-resistant Staphylococcus aureus may require stronger medications like linezolid and tedizolid while Hemophilus influenzae infections might respond to fluoroquinolones like ciprofloxacin or moxifloxacin. Cephalosporins like cefotaxime or ceftazidime along with fluoroquinolones could be considered for treating Vibrio vulnificus.

Pasteurella multocida may require doxycycline or cephalosporins while cefotaxime or ceftriaxone can be used for Aeromonas hydrophila infections. Erysipelothrix rhusiopathiae can be effectively treated with erythromycin or fluoroquinolones like ciprofloxacin, moxifloxacin, levofloxacin, or ofloxacin.

Infectious Disease

Education should be given to individuals about cautious with activities that could cause this type of bacterial infection.

All type of cuts and wounds must be kept clean and covered by patient with sterile dressings to stop bacterial entry.

Provide enough education about ABH and its related causes, how it spreads, and how to stop with management strategies.

Infectious Disease

Amoxicillin:

Amoxicillin a derivative of ampicillin which has a similar antibacterial spectrum to penicillin that targeting gram-positive and gram-negative organisms.

It has enhanced bioavailability and gastric acid stability that can be effective against penicillin-resistant strains especially at higher doses.

It inhibits cell wall mucopeptide synthesis during bacterial replication and exhibiting bactericidal activity against susceptible bacteria.

Amoxicillin and clavulanate:

It is a effective antibiotic for treating bites from dogs, cats, and humans. Amoxicillin disrupts bacterial cell wall synthesis while clavulanate neutralizes beta-lactamase enzymes by preventing bacterial resistance.

Ampicillin and sulbactam:

It is a combination of a beta-lactamase inhibitor used to inhibit bacterial cell wall synthesis by providing bactericidal effects against susceptible organisms. It is effective against skin flora, enteric bacteria, and anaerobes.

It is an oral alternative to amoxicillin-clavulanate but may not be ideal for nosocomial infections due to gram-negative resistance.

Infectious Disease

Azithromycin:

It inhibits microbial growth by binding to the 50S ribosomal subunit in susceptible microorganisms and thereby halting RNA-dependent protein synthesis and treating mild to moderate microbial infections.

Erythromycin:

It is used to treat staphylococcal and streptococcal infections which inhibits bacterial growth by disrupting RNA-dependent protein synthesis potentially preventing peptidyl tRNA dissociation from ribosomes.

Clarithromycin:

It is a semisynthetic macrolide antibiotic binds to the P site of the 50S ribosomal subunit in susceptible organisms potentially inhibiting bacterial growth by dissociating peptidyl tRNA from ribosomes. Despite its similar susceptibility to erythromycin it has fewer adverse effects.

Infectious Disease

Levofloxacin:

It is used to treat pseudomonal infections and multidrug-resistant gram negative organism related infections.

Ciprofloxacin:

It inhibits bacterial DNA synthesis by targeting DNA gyrase and topoisomerases which are crucial enzymes for replication, transcription, and translation of genetic material.

Infectious Disease

Itraconazole: It is a synthetic triazole has fungistatic properties and it delays fungal cell growth which inhibits the synthesis of ergosterol.

Infectious Disease

Cephalosporins similar to penicillin’s inhibit bacterial cell wall synthesis exhibiting bactericidal properties. It is classified into first, second, third, and fourth generations they may vary in efficacy against gram-positive and gram-negative bacteria.

Cephalexin:

It targets gram-positive bacteria by causing resistance due to penicillin binding protein alterations. However, the optimal dosing intervals are not achieved due to its short half-life.

Cefazolin:

It inhibits cell wall synthesis that effectively targeting skin flora like Staphylococcus aureus but does not cover MRSA.

Ceftriaxone:

It is a third-generation cephalosporin which is effective against gram-negative bacteria but less effective against gram-positive ones, inhibits cell wall synthesis and doesn’t cover MRSA.

Cefuroxime:

It is a 2nd generation oral cephalosporin which is a bactericidal agent that inhibits cell wall synthesis.

Cefadroxil:

This is a 1st generation cephalosporin drug which inhibits the bacterial growth by preventing cell wall synthesis and effectively targeting several rapidly growing organisms but not MRSA.

Cefepime:

This drug belongs to 4th generation cephalosporins provides gram-negative coverage similar to ceftazidime but superior to gram-positive coverage like ceftriaxone but its inability to cross the blood brain barrier and prevents its use for meningitis.

Ceftazidime:

This is a 3rd generation cephalosporin drug which is effective against gram-negative bacteria like pseudomonas but less effective against gram-positive ones due to its binding capacity towards penicillin binding proteins.

Ceftaroline:

This is a beta-lactam cephalosporin drug which is effective against aerobic and anaerobic gram-positive and gram-negative bacteria including MRSA and is recommended for community acquired bacterial pneumonia and acute skin infections.

Infectious Disease

Antibiotics like metronidazole, aztreonam, clindamycin, and trimethoprim-sulfamethoxazole are effective against bacteria resistant to other antibiotics while tigecycline, daptomycin, vancomycin, and linezolid are suitable for severe cases.

Clindamycin:

It is a lincosamide which is used to treat severe skin and soft tissue staphylococcal infections including CA-MRSA by blocking peptidyl t-RNA dissociation from ribosomes which arrests RNA-dependent protein synthesis.

Vancomycin:

It is prescribed for patients who are resistant to penicillins and cephalosporins or those with resistant staphylococci infections.

Daptomycin:

It is used to treat skin and skin-structure infections caused by certain bacteria causing rapid depolarization and inhibiting protein, DNA, and RNA synthesis.

Trimethoprim and Sulfamethoxazole:

It is a combination drug which is used to inhibit bacterial growth by disrupting dihydrofolic acid synthesis and this is an alternative to vancomycin in some MRSA cases.

Infectious Disease

In incision and drainage procedure, the affected area is cleaned and then anesthesia is given to the patient, and now surgeon will do a small incision to drain the abscess.

In surgical debridement procedure, surgeons remove devitalized or necrotic tissue, foreign material, and infected debris from the affected area.

Vascular interventions may be required in cases of cellulitis associated with underlying vascular insufficiency to improve blood flow.

Infectious Disease

In the initial diagnosis phase, the physician assess symptoms related to Cellulitis which is followed by diagnostic tests.

In the next phase, Symptomatic relief should be provided to reduce pain and improve the overall health of patients.

The regular follow-up visits with the dentist is required to check the improvement of patients and newly observed complaints along with treatment response.