• Grattage test (Scratch test): Scraping a psoriatic plaque with a glass slide or fingernail reveals a characteristic sequence - first a candle-wax scaling, then a last transparent membrane (Bulkeley's membrane), then pinpoint bleeding.
• Auspitz sign: The pinpoint bleeding that appears after removing the last thin membrane - caused by dermal papillae being close to the surface with dilated capillaries.

Grattage Test and Auspitz Sign in Psoriasis

Grattage Test (Scratch/Curettage Test)

Auspitz Sign

• In psoriasis, the capillaries in the dermal papillae become elongated, tortuous, and dilated - they extend upward into club-shaped elongated papillae
• The suprapapillary epidermal plate overlying these papillae is markedly thinned
• Scraping removes this thin plate and traumatizes the exposed dilated capillaries directly below, causing pinpoint bleeding

"If the superficial silvery white (micaceous) scales are removed, then a wet surface is seen with characteristic pinpoint bleeding. This finding, called Auspitz sign, is the clinical reflection of elongated vessels in the dermal papillae together with thinning of the suprapapillary epidermis."

Figure 28-2 - Fitzpatrick's Dermatology: A = Auspitz sign; B = point of bleeding after scale removal

Specificity of Auspitz Sign

"Removal of scales in psoriasis may disclose bleeding points (Auspitz sign). This sign is common but lacks great specificity."

• Darier's disease (keratosis follicularis)
• Some cases of actinic keratosis

Histopathological Correlation

"These vessels bleed when the scale is removed, giving rise to multiple punctate bleeding points (Auspitz sign). Neutrophils form small aggregates within both the spongiotic superficial epidermis (spongiform pustule of Kogoj) and the parakeratotic stratum corneum (Munro microabscesses)."

Koebner Phenomenon (Isomorphic Response)

Definition

• Named after Heinrich Koebner, who first described it in psoriasis in 1877
• The word "isomorphic" means the new lesions are identical in morphology to the patient's existing disease lesions

Key Features in Psoriasis

• The Koebner reaction usually occurs 7 to 14 days after injury
• It is an all-or-none phenomenon - if psoriasis occurs at one site of injury, it will occur at all sites of injury
• Between 25% to 75% of patients with psoriasis may develop trauma-related Koebner phenomenon at some point during their disease
• It occurs more frequently during flares/active disease

Triggering trauma types:

• Scratches, incisions, surgical scars, burns
• Phototherapy burns (overdose of UV)
• Needle prick sites, tattoos
• Friction, pressure
• Viral exanthema (pityriasis rosea trigger)

Figure 28-3 Fitzpatrick's - A: Psoriasis at keratome biopsy sites; B: Psoriasis flare after sunburn, sparing protected areas

Diseases That Show the Koebner Phenomenon

Clinical significance

1. Diagnostic clue - helps confirm psoriasis or lichen planus when lesions appear in a linear pattern following trauma
2. Marker of disease activity - its presence indicates an active phase; absent in quiescent disease
3. Prognostic indicator - Koebnerization tends to predict more widespread or aggressive disease
4. Practical implication - patients must be advised to avoid skin trauma (scratching, tattoos, piercings, surgery during active disease) to prevent new lesion formation

Related Phenomena - Important Distinctions

Suturing of Category 3 Dog Bites

Short Answer

WHO Category 3 - Recap

Why NOT Suture Immediately

"Bite wounds should not be immediately sutured to prevent additional trauma which may help spread the virus into deeper tissues. If suturing is necessary, it should be done 24-48 hours later, applying minimum possible stitches, under the cover of rabies immunoglobulin locally."

1. Rabies virus spread - Suturing compresses and drives virus deeper into tissues along nerve endings
2. Infection risk - Bite wounds (especially punctures) are heavily contaminated; primary closure traps bacteria and promotes anaerobic infection

Exceptions - When Suturing IS Permitted

"Bite wounds of the face and scalp from any species that are less than 6 hours old may be sutured after appropriate wound preparation... Puncture wounds, wounds more than 12 hours old, and wounds infected at presentation should not be sutured."

"Primary wound closure is not recommended for animal bite wounds, with the exception of those to the face... bite wounds should not be sealed with a tissue adhesive, no matter their age or appearance."

Complete Management Protocol for Category 3 Dog Bite

1. Local Wound Care (FIRST and most important)

• Wash immediately with soap and water for ≥15 minutes under running tap (reduces rabies risk by up to 80%)
• Irrigate under pressure with saline/sterile water
• Apply virucidal agent: povidone-iodine, alcohol (40-70%), or 0.01% aqueous iodine
• For puncture wounds: use a catheter for deep irrigation
• DO NOT suture immediately

2. Rabies Post-Exposure Prophylaxis (PEP)

• Rabies Immunoglobulin (RIG) - infiltrate as much as possible around the wound; remainder given IM at a distant site
• Rabies vaccine - full course (Day 0, 3, 7, 14 ± 28 by Essen regimen)

3. Other

• Anti-tetanus prophylaxis
• Prophylactic antibiotics - amoxicillin-clavulanate (drug of choice for dog bites) - especially for hand/foot wounds, deep wounds, immunocompromised
• Observe the dog for 10 days (if available)

Antibiotic for Category 3 Dog Bite with Laceration

First-Line: Amoxicillin-Clavulanate (Co-amoxiclav / Augmentin)

Dosing

Why Amoxicillin-Clavulanate?

"Treatment failure of Pasteurella infections caused by dog and cat bites using monotherapy with erythromycin, clindamycin, penicillinase-resistant penicillins, and first-generation cephalosporins has been described." - Rosen's Emergency Medicine

Penicillin-Allergic Patients

Note: Erythromycin, first-gen cephalosporins (cephalexin), and clindamycin alone are NOT adequate for dog bites - they lack Pasteurella coverage.

When to Give Antibiotics for Dog Bites?

• ✅ Lacerations (your case)
• ✅ Hand or foot wounds
• ✅ Deep puncture wounds
• ✅ Wounds involving tendon, joint, bone, or cartilage
• ✅ Delayed presentation (>6 hours)
• ✅ Immunocompromised / asplenic / advanced liver disease
• ✅ Wounds that are primarily closed
• ✅ Facial wounds in children

If Wound is Already Infected (vs. Prophylaxis)

Complete Management Summary for Your Patient

1. Wound care - irrigate copiously with saline, debride, povidone-iodine
2. Do NOT suture primarily (or defer 24-48 h if facial)
3. Rabies PEP - RIG infiltrated at wound site + rabies vaccine series
4. Anti-tetanus prophylaxis
5. Antibiotic - Amoxicillin-clavulanate 875/125 mg BD x 5 days (oral)
6. Review at 48-72 hours for wound check and consider delayed closure if clean

Levofloxacin for Category 3 Dog Bite

Short Answer

Why Levofloxacin Falls Short Alone

"Fluoroquinolones, including moxifloxacin and levofloxacin, are very active in vitro against P. multocida and other Pasteurella spp., although published experience in humans is limited."

Accepted Role of Levofloxacin in Bite Wounds

"The combination of an antibiotic active against gram-positive cocci and anaerobes (such as clindamycin or metronidazole) with trimethoprim-sulfamethoxazole or a fluoroquinolone, which is active against many of the other potential pathogens, would appear reasonable."

"A fluoroquinolone, such as ciprofloxacin or moxifloxacin, or clindamycin combined with trimethoprim-sulfamethoxazole may be used in penicillin-allergic patients."

Comparison: Fluoroquinolones in Bite Wounds

Key point: Moxifloxacin is the preferred fluoroquinolone for bite wounds because its anaerobic coverage means it can be used as a single agent, unlike levofloxacin or ciprofloxacin.

Practical Summary

FDC Cefixime + Ofloxacin for Category 3 Dog Bite

Bottom Line Up Front

1. Poor anaerobic coverage - neither cefixime nor ofloxacin covers oral anaerobes reliably
2. Poor gram-positive (Staphylococcus aureus) coverage - cefixime (3rd-gen cephalosporin) has reduced activity against S. aureus

Breaking Down Each Component

Cefixime (3rd-generation oral cephalosporin)

"Third generation: cefixime... as for second generation but also active against Pseudomonas aeruginosa" - with less gram-positive coverage than earlier generations.

Ofloxacin (2nd-generation fluoroquinolone)

"Second-generation quinolones (e.g. ciprofloxacin, ofloxacin, norfloxacin) have good coverage of gram-negative rods and some gram-positive coverage... Third-generation quinolones (e.g. levofloxacin) are broader... Fourth-generation (e.g. moxifloxacin) [add] anaerobic coverage."

"Many fluoroquinolones (e.g. ciprofloxacin, levofloxacin, ofloxacin) display reasonable activity against anaerobes [but] other antibiotics are preferred."

Coverage Gap Analysis for Dog Bite Pathogens

Why This FDC is Popular in India (But Not for Bites)

• Typhoid / enteric fever
• Complicated UTIs
• RTIs
• Gonorrhea

What Should You Do Instead?

Can a Category 3 Dog Bite Patient Eat Meat?

Yes - absolutely allowed. There is no dietary restriction.

What the Evidence Says

"Ingestion of raw meat or other tissues from animals infected with rabies is not a source of human infection."

• Severe egg allergy (for chick embryo-based vaccines only)
• Previous severe reaction to vaccine components

Why This Myth Exists

• Meat (especially chicken/mutton)
• Spicy food
• Sour food
• Alcohol (this one actually has some basis - see below)

The Alcohol Question

What You Should Tell Your Patient

1. Complete the full rabies vaccine course (do NOT skip doses)
2. Ensure RIG was given at the wound site on Day 0
3. Keep the wound clean
4. Take the prescribed antibiotics (amoxicillin-clavulanate)
5. Anti-tetanus prophylaxis

Should We Suture a Category 3 Dog Bite Laceration?

The Core Principle: It Depends on Location, Timing, and Wound Type

Decision Table

What the Textbooks Say

"Bite wounds of the face and scalp from any species that are less than 6 hours old may be sutured after appropriate wound preparation. It is probably safe to suture most other uncomplicated dog bite wounds, although bites of the hands and feet are at high risk for infection and should rarely be sutured. Puncture wounds, wounds more than 12 hours old, and wounds infected at presentation should not be sutured."

1. Animal = dog
2. Location = face or scalp
3. Wound = simple, appropriate for single-layer closure, no devitalized tissue
4. No underlying fracture
5. Host = no systemic immunocompromising conditions

"A skilled practitioner can primarily close the wound... with a risk of post-repair wound infection of 5-15%... we recommend antibiotic prophylaxis with amoxicillin-clavulanic acid if wound closure is desired."

Alternatives to Primary Suturing

Important: Suturing + Category 3 = Mandatory RIG First

"If suturing is necessary, it should be done 24-48 hours later, applying minimum possible stitches, under the cover of rabies immunoglobulin locally."

• Give RIG infiltrated around and into the wound FIRST on Day 0
• Do not suture in a way that would prevent RIG infiltration at the wound site
• Suturing should never delay or compromise RIG administration

Quick Summary for Your Patient

• Face → Suture (after irrigation, debridement, RIG) with antibiotics cover
• Hands/feet → Do NOT suture
• Puncture wound → Do NOT suture
• Trunk/limb laceration → Can suture if < 6 h, clean, uncomplicated; otherwise DPC at 48-72 h
• All cases → RIG + vaccine + antibiotics (amoxicillin-clavulanate) regardless of suturing decision

Wound Assessment

• Location: Forearm or lower leg (extremity - NOT face/hand/foot)
• Type: Linear laceration, ~3-5 cm long
• Depth: Full-thickness - through epidermis and dermis, subcutaneous tissue visible
• Edges: Gaping, relatively clean-cut, well-demarcated
• Contamination: No gross dirt/debris visible; some loose hairs near wound edges
• Devitalized tissue: None visible - wound bed looks viable and vascular
• Signs of infection: None - no pus, no spreading erythema, no swelling

Should You Suture This? Conditionally YES - with strict conditions

Factors Favoring Suturing:

• ✅ Clean laceration with viable edges - no devitalized tissue
• ✅ Wound is gaping and full-thickness - edges won't approximate on their own
• ✅ No signs of infection
• ✅ Extremity (not hand/foot - those are high risk)
• ✅ Not a puncture wound

Factors Requiring Caution:

• ⚠️ Category 3 dog bite - contaminated with polymicrobial oral flora
• ⚠️ Location is extremity - moderate infection risk
• ⚠️ RIG must be infiltrated into this wound first before any closure

Recommended Approach

Step 1 - Right Now (Day 0)

1. Thorough irrigation - copious saline under pressure for 10-15 min
2. Povidone-iodine application
3. Debride any hair/debris from wound edges
4. Infiltrate RIG into and around the wound - this is mandatory and must NOT be compromised by early suturing
5. Start rabies vaccine (Day 0)
6. DO NOT suture yet - leave open with a non-adherent dressing

Step 2 - At 48-72 Hours (Delayed Primary Closure)

• Re-examine the wound
• If no signs of infection (no redness, no swelling, no pus, no warmth) → Suture now (delayed primary closure)
• If signs of infection appear → treat infection, leave open, allow secondary healing

Why Delay?

• Allows RIG to work in the wound tissue
• Allows monitoring for early infection
• Infection rate of sutured dog bite wounds = 5-15% vs ~5% for unsutured - the delay reduces this risk significantly

If Suturing is Done (Primary or Delayed)

• Use minimum number of sutures - do not over-tighten
• Use interrupted sutures only - allows drainage
• Avoid deep/subcutaneous buried sutures if possible - additional foreign material increases infection risk
• Cover with antibiotics: Amoxicillin-clavulanate 625 mg TDS x 5-7 days
• Review in 48 hours post-closure

Summary

Ofloxacin for UTI

Pharmacological Profile Relevant to UTI

• Mechanism: Inhibits DNA gyrase (topoisomerase II) and topoisomerase IV
• Spectrum: Excellent gram-negative coverage (E. coli, Klebsiella, Proteus, Pseudomonas with some activity), moderate gram-positive
• Urinary excretion: ~70-80% excreted unchanged in urine - achieves very high urinary concentrations
• Bioavailability: Near 100% oral absorption - IV and oral doses are equivalent
• Dosing: 200-400 mg orally every 12 hours (twice daily - unlike levofloxacin which is once daily)
• Prostate penetration: Excellent - reaches therapeutic concentrations in prostatic secretions

Efficacy by UTI Type

1. Uncomplicated Cystitis (Women)

"Fluoroquinolones remain active against most E. coli strains causing uncomplicated cystitis, although resistance is increasing in most locations and use for cystitis is discouraged."

"The FDA has stated that the risks of systemic fluoroquinolone antibacterial drugs outweigh their benefits for uncomplicated cystitis."

2. Acute Pyelonephritis

"Fluoroquinolones [dose varies by agent], women: 7 days, men: 7 days - first-line for pyelonephritis."

• Ofloxacin 200-400 mg BD x 7-14 days for outpatient pyelonephritis
• Must confirm local E. coli fluoroquinolone resistance <10-20% before empiric use
• If resistance >10% locally, give a single dose of IV ceftriaxone first, then oral fluoroquinolone

3. Complicated UTI / Catheter-Associated UTI

• Fluoroquinolones (including ofloxacin) are appropriate options
• Culture and sensitivity guided whenever possible
• Duration: 7-14 days

4. Prostatitis - Ofloxacin's BEST indication in urology

"Ofloxacin 300 mg twice daily - first-line treatment for chronic bacterial prostatitis."

Ofloxacin vs. Levofloxacin for UTI

Key Cautions with Ofloxacin/Fluoroquinolones for UTI

Practical Summary