Urinary Tract Infection

An infection of the urinary tract causes urethritis, cystitis (including trigonitis), or pyelonephritis. Urinary tract infections (UTIs) are much more common in women because of their shortened urethral length and exposure of the urinary tract to trauma and pathogens during sexual activity.

PATHOGENESIS

Most UTIs in women ascend from contamination of the urethra, acquired via instrumentation, trauma, or sexual intercourse. (A history of intercourse within the preceding 24 to 48 hours is present in up to 75% of patients with acute UTI.) Coliform organisms, especially Escherichia coli, are the most common organisms responsible for asymptomatic bacteriuria, cystitis, and pyelonephritis.

Ninety percent of first infections and 80% of recurrent infections are caused by E. coli, with between 10% and 20% resulting from Staphylococcus saprophyticus. Infection with other pathogens such as Klebsiella species (5%) and Proteus species (2%) account for most of the remaining infections. Anaerobic bacteria, Trichomonas, and yeasts are rare sources of infections except in patients with diabetes, patients who are immunosuppressed, or those requiring chronic catheterization. Infection with Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma, and Ureaplasma should all be considered when urethritis is suspected.

RISK FACTORS

• Sexual activity,
• Instrumentation,
• More virulent pathogens,
• Altered host defenses,
• Infrequent or incomplete voiding,
• Foreign body or stone,
• Obstruction, or biochemical changes in the urine (diabetes, hemoglobinopathies, pregnancy),
• Estrogen deficiency,
• Diaphragm use, and
• Spermicides

SIGNS & SYMPTOMS

• Asymptomatic (5%)
• Frequency, urgency, nocturia, or dysuria
• Pelvic pressure (cystitis)
• Fever and chills (pyelonephritis)
• Pyuria (more than fi ve white cells per high power field in a centrifuged specimen)
• Hematuria (infrequent)
• Costovertebral angle tenderness (pyelonephritis)
• Suprapubic tenderness (cystitis)

DIFFERENTIAL DIAGNOSIS

• Traumatic trigonitis
• Urethral syndrome
• Interstitial cystitis
• Bladder tumors or stones
• Vulvitis and vaginitis (may give rise to external dysuria)
• Urethral diverticulum
• Infection in the Skene’s glands
• Detrusor instability

WORKUP

• Urinalysis and Culture

MANAGEMENT

• Nonpregnant patients: single-dose therapy—amoxicillin 3 g, ampicillin 3.5 g, cephalosporin (first generation) 2 g, nitrofurantoin 200 mg, sulfisoxazole 2 g, trimethoprim (TMP) 400 mg, TMP/sulfamethoxazole 320/1600 mg, fosfomycin tromethamine (Monurol) 3 gm PO.
• Three- to 7-day therapy: amoxicillin 500 mg every 8 hours, cephalosporin (first generation) 500 mg every 8 hours, ciprofloxacin 250 mg every 12 hours, nitrofurantoin 100 mg every 12 hours, norfl oxacin 400 mg every 12 hours, ofloxacin 200 mg every 12 hours, sulfisoxazole 500 mg every 6 hours, tetracycline 500 mg every 6 hours, TMP/sulfamethoxazole 160/800 mg every 12 hours, TMP 200 mg every 12 hour.
• Contraindications: Known or suspected hypersensitivity.

Snake Bites – How Do You Treat A Snake Bites

Suspected Snake bites?

Injury resulting from snake biting a human.

Physical Finding and Clinical Presentation

• In addition to local tissue injury, envenomation may affect the renal, neurologic, gastrointestinal, vascular, and coagulation systems. Symptoms vary widely depending on type of envenomation. Not all snakebites are poisonous, and not all bites lead to envenomation. Species-specific signs and symptoms following envenomation are discussed.

CROTALIDAE (PIT VIPERS)

Local Signs and Symptoms

• Pain within 5 min
• Edema within 30 min
• Erythema of site and adjacent tissues/serous or hemorrhagic bullae, ecchymosis, and/or lymphangitis over the ensuing hours

If no edema or erythema is manifested within 8 hr after a confirmed crotalid snakebite, it is safe to assume envenomation did not occur. (Roughly 25% of cases do not involve envenomation.) In general, rattlesnake bites are more severe than those of the other snakes in the Crotalidae family.

Systemic manifestations may include:

• Mild to moderate nausea/vomiting, perioral paresthesias, metallic taste, tingling of fingers or toes (especially with rattlesnake bites), and/or fasciculations (local or generalized)
• Severe hypotension (due to increased vascular permeability), mental status change, respiratory distress, tachycardia, acute renal failure, rhabdomyolysis, and coagulopathies including intravascular hemolysis and disseminated intravascular coagulation.
  
  
  
  
  
  
  

ELAPIDAE (CORAL SNAKES):

• Local symptoms are far less pronounced (little or no pain/swelling immediately after the bite).
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• Neurologic symptoms are more common due to neurotoxins in elapid venom.
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• Systemic symptoms predominate, but onset may be delayed for up to 12 hr. Examples include:
  1. Altered mental status and cranial nerve palsies featuring ptosis, dysphagia, or dysarthria
  2. Tremors
  3. Intense salivation, nausea, vomiting, or abdominal pain
  4. Loss of DTRs and respiratory depression (late manifestations)
  
  
  
  
  
  
  

Differential Diagnosis

• Harmless snakebite
• Scorpion bite
• “Dry bite”
• Insect bite
• Cellulitis
• Laceration or puncture wound
• Necrotizing fasciitis

Workup

• An estimated 25% of venomous snakebites do not result in envenomation, but all cases of suspected envenomation should be observed for 8 hr or longer
• Check for signs of envenomation.
  1. Swelling, tenderness, redness, ecchymosis, or blebs at the bite site
  2. Elevated protime, decreased fibrinogen or platelets
  3. Systemic signs such as hypotension, bleeding complications, vomiting, diarrhea, angioedema, or neurotoxicity
• Determine if patient has indications for antivenom. Continual reassessment is indicated throughout the observation period because severity of symptoms may change.
  
  
  
  

Laboratory Tests

• For all suspected envenomations, obtain CBC (with peripheral smear and platelet count), DIC screen (PT/INR, PTT, fibrinogen, fibrin degradation products, d-dimer), ECG, serum electrolytes, BUN, Cr, and urinalysis. Serial measurements of hemoglobin, platelets, protime, and fibrinogen are needed to monitor for acute and delayed hematologic complications.
• For more severe bites, consider LFTs, sedimentation rate, creatine kinase (rule out rhabdomyolysis), ABG, and type and crossmatch.
• Other: consider chest radiograph in cases with severe envenomation or in patients over 40 years old with underlying cardiopulmonary disease; radiograph of bite site for retained fangs (poor sensitivity); head CT if concern is raised for intracranial hemorrhage

Treatment

IN THE FIELD: For a suspected snakebite:

• Transport immediately to nearest medical facility. No treatments in the field should delay travel to the nearest facility where an antivenom agent can be given if necessary.
• Immobilize affected part.
• Remove any constricting items. Applying tourniquets, incising, and applying suction to the wound is discouraged. Tourniquets cause more local tissue damage due to tissue necrosing venom seen in crotalid bites and should not delay transport to a medical facility.
• Do not apply ice; keep victim warm.
• Avoid alcohol, stimulants (caffeine), or agents that can suppress mental status.

IN THE HOSPITAL

• Record vital signs: BP, HR, T, RR, and O2 sat.
• Establish intravenous access and initiate IV hydration with crystalloid if the patient is hypotensive.
• Obtain time of bite and description of snake if possible. Crotalids have a triangle-shaped head, nostril holes (pits), and elliptical pupils. The most dangerous of the crotalids is the rattlesnake, distinguished by its telltale rattle. Elapids, like the western and eastern coral snakes of the U.S., have brightly colored red, black, and yellow stripes.
• Obtain and initiate reconstitution of appropriate antivenom. (Antivenoms are typically supplied in powder form and must be reconstituted before administration. If using older antivenoms, this process can take up to 1 hr, so it is recommended that it be initiated as soon as the patient arrives in the ED.)
  1. Inspect site of bite for fang marks and local symptoms.
  2. Delineate margins of erythema/edema with a marker.
  3. Measure circumference of bitten part at two or more proximal sites and compare with unaffected limb; repeat every 15 to 20 min; assess for extension of erythema/edema.
  4. Conduct a complete neurologic examination.
  5. Obtain past medical history; ask about allergies to horse serum in those previously treated for snakebite.
• If no signs of envenomation:
  1. Clean and immobilize affected part.
  2. Immunize against tetanus.
  3. For crotalid bites, observe patient for at least 8 hr. If, at the end of this interval, local and systemic sequelae are absent and lab values remain normal, the likelihood of significant envenomation is low, and the patient can be discharged from the acute setting. Some sources recommend observing patients with crotalid bites to the lower extremities for at least 24 hours because swelling in the larger compartments of the legs could be slower and less easily recognizable. All definitive elapid bites should be treated. If elapid bite is only suspected, the patient must be monitored for up to 18 hr as symptoms can be delayed.
• Patients who have progressive local symptoms or any systemic symptoms should be considered for antivenom. Crotalid envenomations without any progressive local or any systemic symptoms can be monitored for 12 to 24 hours, with repeat labs obtained 4 to 6 hours before discharge. If they have no new symptoms during that period of observation, they may be safely discharged. Specifically, copperhead bites often need no further interventions.
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TREATMENT OF NONNATIVE (EXOTIC) SNAKEBITES

• For bites by exotic or nonnative snakes, contact a Poison Control Center or your local zoo. (Zoos with exotic snakes are required to maintain a supply of snake-specific antivenom on their premises.)

Complications

Source: dreb,  drchy

• Allergic reactions were very frequent with horse serum antivenoms. CroFab from sheep serum should be preferentially used over equine serum if available.
• Anaphylaxis occurs within 30 min and should be treated by immediately stopping the infusion to managing the symptoms of anaphylaxis, including epinephrine SQ or IM initially and IV if needed, diphenhydramine IV, and hydrocortisone IV. If the anaphylactic symptoms can be managed and the envenomation is severe, the infusion can then be resumed.
• Delayed hematologic complications are common and can manifest up to 4 days post treatment. Most bleeding is self-limited but can rarely be severe, necessitating close follow-up.
• Serum sickness occurs 7 to 14 days after antivenom administration and is characterized by fever, rash, arthralgias, and lymphadenopathy. It can be treated with prednisone 60 mg/d PO, tapered over 7 to 10 days.
• Injuries also result from:
  1. Tourniquet placement on the field, which should be avoided
  2. Ice application (cryotherapy), which can worsen tissue damage
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