NR 511 Final Exam Study Guide

Common Infections 1. Impetigo Impetigo is a superficial bacterial infection of the skin. It is classified into primary impetigo when there is a direct bacterial invasion of previously normal skin or secondary impetigo ...

Common Infections 1. Impetigo Impetigo is a superficial bacterial infection of the skin. It is classified into primary impetigo when there is a direct bacterial invasion of previously normal skin or secondary impetigo when the infection arises at sites of minor skin trauma. The occurrence of secondary impetigo is referred to as impetiginization. Impetigo is most frequently observed in children ages 2–5 years of age, although older children of any age and adults may also be affected. The infection usually occurs in warm, humid conditions and is easily spread among individuals in close contact. Risk factors include poverty, crowding, poor hygiene, and underlying scabies. Impetigo is primarily caused by S. aureus. Group A Streptococcus (GAS) causes a minority of cases, either alone or in combination with S. aureus. Occasionally, MRSA is detected in some cases of impetigo. Variants of impetigo include nonbullous impetigo, bullous impetigo, and ecthyma. • Nonbullous impetigo—most common form of impetigo and begins as papules that progress to vesicles surrounded by erythema. Within a week, the papules eventually become pustules that enlarge, break down, and form thick, adherent crusts with a characteristic golden appearance. Lesions usually involve the face and extremities. Regional lymphadenitis may occur, although systemic symptoms are usually absent. • Bullous impetigo—Bullous impetigo is seen primarily in young children in which the vesicles enlarge to form flaccid bullae with clear yellow fluid, which later becomes darker and ruptures, leaving a thin brown crust. The trunk is more frequently affected. Bullous impetigo in an adult with appropriate demographic risk factors should prompt an investigation for previously undiagnosed human immunodeficiency virus (HIV) infection. • Ecthyma—This form of impetigo, caused by group A, beta-hemolytic Streptococcus (Streptococcus pyogenes), consists of an ulcerative form in which the lesions extend through the epidermis and deep into the dermis. Ecthyma resembles "punched-out" ulcers covered with yellow crust surrounded by raised violaceous margins. Poststreptococcal glomerulonephritis is a serious complication of impetigo (ecthyma). This condition develops within 1–2 weeks following infection. Poststreptococcal glomerulonephritis manifests with edema, hypertension, fever, and hematuria. The diagnosis of impetigo often can be made on the basis of clinical manifestations. A Gram stain and culture of pus or exudate is recommended to identify whether S. aureus and/or a beta-hemolytic Streptococcus is the cause. However, treatment may be initiated without these studies in patients with typical clinical presentations. Bullous and nonbullous impetigo can be treated with either topical or oral therapy. Topical therapy is used for patients with limited skin involvement whereas oral therapy is recommended for patients with numerous lesions. Unlike impetigo, ecthyma should always be treated with oral therapy. Benefits of topical therapy include fewer side effects and lower risk for contributing to bacterial resistance compared with oral therapy. Topical choices to treat impetigo include the following medications for 5 days. • Mupirocin three times daily • Retapamulin twice daily Extensive impetigo and ecthyma should be treated with an antibiotic effective for both S. aureus and streptococcal infections unless cultures reveal only streptococci. Dicloxacillin and cephalexin are appropriate treatments. A 7-day course of oral antibiotic treatment is recommended. If only streptococci are detected in extensive impetigo or ecthyma, oral penicillin is the preferred therapy. MRSA impetigo can be treated with doxycycline, clindamycin, or trimethoprim- sulfamethoxazole (Bactrim). Crusted lesions can be washed gently. Children can return to school 24 hours after beginning an effective antimicrobial therapy. Draining lesions should be kept covered. Quiz: Sally, aged 25, presents with impetigo that has been diagnosed as infected with staphylococcus. The clinical presentation is pruritic tender, red vesicles surrounded by erythema with a rash that is ulcerating. She has not been adequately treated recently. Which type of impetigo is this? a. Bullous impetigo b. Staphylococcal scalded skin syndrome (SSSS) c. Nonbullous impetigo d. Ecthyma 2. Staphylococcal Scalded Skin Syndrome Caused by Staphylococcus aureus, it’s a variant of bullous impetigo:Epidermal necrosis caused by bacterial exotoxins, resulting in the epithelial layer peeling off in large, sheetlike pieces; mimics scalded-skin thermal burn. This serious infection is more commonly seen in children and usually begins in the intertriginous areas. 3. Cellulitis Cellulitis is an acute infection as a result of bacterial entry via breaches in the skin barrier. As the bacteria enter the subcutaneous tissues, their toxins are released which causes an inflammatory response. ✓ Cellulitis and erysipelas is almost always a unilateral infection with the most common site of infection being the lower extremities. ✓ Cellulitis involves the deeper dermis and subcutaneous fat. ✓ Cellulitis is observed most frequently among middle-aged individuals and older adults. ✓ The vast majority of pathogens associated with cellulitis are from either Streptococcus or Staphlococcus bacteria. The most common are beta-hemolytic streptococci (groups A, B, C, G, and F), and S. aureus (gram +) ✓ Both erysipelas and cellulitis manifest with areas of skin erythema, edema, warmth and pain. Fever may be present. Additional manifestations of cellulitis and erysipelas include lymphangitis and inflammation of regional lymph nodes. Edema surrounding the hair follicles may lead to dimpling in the skin, creating an appearance reminiscent of an orange peel texture called "peau d'orange". ✓ Cellulitis may present with or without purulence ✓ patients with cellulitis tend to have a more indolent course with development of localized symptoms over a few days. ✓ Many patients with cellulitis have underlying such as tinea pedis, lymphedema, and chronic venous insufficiency. In such patients, treatment should be directed at both the infection and the predisposing condition if modifiable. ✓ Patients with cellulitis or erysipelas in the absence of abscess or purulent drainage should be managed with empiric antibiotic therapy. Patients with drainable abscess should undergo incision and drainage. I. Describe an appropriate empiric antibiotic treatment plan for cellulitis ➢ should be managed with empiric therapy for infection due to beta-hemolytic streptococci and methicillin-susceptible Staphylococcus aureus (MSSA) with: • Cephalexin 500 mg four times daily (alternative for mild penicillin allergy) • Clindamycin 300 mg to 450 mg four times daily (alternative for severe penicillin allergy) ➢ Good choices for uncomplicated cases of cellulitis that are not associated with human or animal bites include dicloxacillin or cephalexin for 10 to 14 days. ➢ If pt has severe PCN allergy rx erythromycin ➢ If caused by animal or human bite: amoxicillin-clavulanic acid (augmentin) for 2 weeks The coverage for MRSA is achieved by adding to amoxicillin one of the following: Bactrim DS twice daily Doxycycline 100 mg twice daily Minocycline 200 mg orally once, then 100 mg orally every 12 hours If clindamycin is used, no additional MRSA coverage is needed. Risk factors for community-associated methicillin-resistant S. aureus (CA-MRSA) include the following. • Antibiotic use secondary to antibiotic selective pressure. Use of cephalosporins and fluoroquinolones strongly correlates with the risk for MRSA colonization and infection. • HIV infection • Hemodialysis • Long-term care facilities Patients with drainable abscess should undergo incision and drainage. For patients undergoing incision and drainage of a skin abscess, some experts suggest antibiotic treatment under some conditions. • Single abscess ≥2 cm • Multiple lesions • Extensive surrounding cellulitis • Associated immunosuppression or other comorbidities • Systemic signs of toxicity (fever >100.5° F/38° C) • Presence of an indwelling medical device (such as prosthetic joint, vascular graft, or pacemaker) • High risk for transmission of aureus to others (such as in athletes or military personnel) Quiz: Ian, age 62, presents with a wide, diffuse area of erythematous skin on his left lower leg that is warm and tender to palpation. There is some edema involved. You suspect: a. Necrotizing fasciitis. c. Cellulitis. b. Kaposi's sarcoma. d. A diabetic ulcer. 4. Erysipelas Cellulitis and erysipelas are two of the most common skin and soft tissue infections. ✓ Erysipelas involves the upper dermis, and there is clear demarcation between involved and uninvolved tissue. ✓ An older name for erysipelas is “St. Anthony’s fire.” Despite the superficial nature of this infection, erysipelas should not be taken lightly, because it can be fatal if it is not treated promptly (especially in the very young and the elderly). ✓ Erysipelas is sometimes seen after an episode of strep throat. ✓ The most common sites of involvement are the face (especially the cheeks) and the lower legs. ✓ Erysipelas occurs in young children and older adults. ✓ Erysipelas results almost always results from a group A strep infection. ✓ erysipelas is non-purulent. ✓ Patients with erysipelas tend to have acute onset of symptoms with systemic manifestations including fever and chills ✓ Classic descriptions of erysipelas note "butterfly" involvement of the face. Involvement of the ear (Milian's ear sign) is a distinguishing feature for erysipelas, since this region does not contain deeper dermis tissue. Quiz: Which of the following types of cellulitis is a streptococcal infection of the superficial layers of the skin which does not involve the subcutaneous layers? a. Necrotizing fasciitis c. Erysipelas b. Periorbital cellulitis d. "Flesh-eating" cellulitis 5. Necrotizing fasciitis Considered as a severe case of cellulitis must refer to ER, can be a differential diagnosis of cellulitis Defined as deep infection that results in progressive destruction of the muscle fascia. The affected area may be erythematous, swollen, warm, and exquisitely tender. Pain out of proportion to exam findings may be observed. ✓ The hallmark of this infection is its rapid progression and the severity of the symptoms. The progress of the infection is measured in terms of hours instead of days, and the border can be seen to literally spread in just a few hours. ✓ This infection is caused by “flesh-eating bacteria,” and loss of life or limb is a potential complication. Quiz: Mark has necrotizing fasciitis of his left lower extremity. Pressure on the skin reveals crepitus due to gas production by which anaerobic bacteria? a. Staphylococcal aureus c. S. pyrogenes b. Clostridium perfringens d. Streptococcus 6. Mammalian bites Soft tissue trauma caused by animal and human bites have serious clinical implications because of the potential for complications. Bite wounds should be irrigated copiously with sterile saline, and grossly visible debris should be removed. Prophylactic antibiotics are administered to patients who present for evaluation of a bite wound who do not yet have signs or symptoms of infection in the following circumstances. • Deep puncture wounds (especially due to cat bites) • Wounds requiring surgical repair • Moderate to severe wounds with associated crush injury • Wounds in areas of underlying venous and/or lymphatic compromise • Wounds on the hand(s) or in close proximity to a bone or joint • Wounds on the face or in the genital area • Wounds in immunocompromised hosts Amoxicillin/clavulanate 875 mg/125 mg twice daily is the agent of choice. Alternative antibiotics include one of the following agents with activity against Pasteurella. • Doxycycline 100 mg twice daily • Bactrim DS twice daily • Penicillin VK 500 mg four times daily • Ciprofloxacin 500 mg twice daily Plus one of the following agents with anaerobic activity. • Metronidazole 500 mg three times daily • Clindamycin 450 mg three times daily First-generation cephalosporins and macrolides should be avoided. The duration of prophylactic oral antibiotics is 3–5 days, with close follow-up. Tetanus toxoid should be given to those who have completed a primary immunization series but who received the most recent booster 5 or more years ago. Patients with mild infection can be treated initially with the same prophylactic antibiotics for 5 to 14 days of therapy. ➢ Infection with Pasteurella multocida characteristically develops rapidly following cat or dog bites with erythema, swelling, and intense pain evident as early as 12 to 24 hours after the bite ➢ Wound cultures of uninfected bite wounds are not useful. Wound cultures are not indicated in clinically uninfected bite wounds as results do not correlate with likelihood of infection or the pathogen that is present in patients with subsequent infection. If a bite wound appears to be infected ➢ The laboratory requisition should note that an animal or human bite wound is the culture source because Eikenella corrodens and Pasteurella multocida are fastidious organisms. I. Identify the likely pathogen associated with cats bites, human bites and dog bites. 1. Human Bites a. Pathogens i. Staph aureus ii. Strep b. Agent of choice: Amoxicillin/clavulanate 875/125 2xday 2. Cat & Dog Bites a. Pathogens i. Pasturella multocida & capnocytophaga canimorsis b. Alternative ATB w/ activity against Pasturella i. Doxycycline 100mg 2xday ii. Bactrim DS 2xday iii. PCN VK 500mg 4xday iv. Ciprofloxacin 500mg 2xday 1. PLUS a. Metronidazole 500mg 3xday b. Clindamycin 450mg 3xday 1. Hematuria Urology - Hematuria is defined as blood in the urine and can be visible (gross) or occult (microscopic) - the ingestion of beets can color the urine red to pink, and medications such as rifampin and phenazopyridine (Pyridium) can give urine a reddish-orange color. The presence of porphyrins, hemoglobin, or myoglobin can color the urine reddish-brown. Pus in the urine is indicative of bacterial infection, such as cystitis, urethritis, or prostatitis. - Menstrual history is always important in a female patient, as well as history of recent strenuous exercise, streptococcal infection (especially poststreptococcal glomerulonephritis), or nephrolithiasis; family history (e.g., of polycystic kidney disease); and recent travel (potential exposure to parasitic infections). Gross painless hematuria is a cardinal symptom of certain malignancies such as bladder cancer. 2. Incontinence & overactive bladder - Urinary incontinence (UI) is the involuntary loss of urine from the bladder. Incontinence is so frequent in women that many consider it normal. Incontinence is also common in older men as a result of an enlarging prostate. Incontinence can affect a person’s quality of life and may be psychologically devastating. a. Stress: Failure to store due to hypermobility of bladder neck, intrinsic sphincter deficiency, neurogenic sphincter deficiency Medications: Sedatives, hypnotics, antispasmodics b. Urge: Failure to store due to urinary tract infection; vaginitis; bladder stones and tumors; cortical, subcortical, and suprasacral lesions; cerebrovascular accident; dementia; multiple sclerosis; Parkinson’s disease; spinal cord transection Medications: Diuretics, narcotics c. Overflow: Failure to empty due to underactive detrusor, outlet obstruction, diabetes mellitus Medications: Anticholinergics, disopyramide, antihistamines, calcium channel blockers d. Functional: Delirium, fecal impaction, manual dexterity and immobility Medications: diuretics, hypnotics, alcohol, narcotics, decongestants Rx: Anticholinergic/Antispasmodic Agents: ex: tolterodine (Detrol LA) or oxybutynin (Ditropan XL) for urge, overactive bladder and stress incontinence. Contraindications: Closed-angle glaucoma, Myasthenia gravis. - Tricyclic Antidepressants: Imipramine (Tofranil) amitriptyline (Elavil) for OAB and Urge incontinence - The term overactive bladder (OAB) is often used interchangeably with the term urge incontinence; however, they are different conditions. OAB is a syndrome of symptoms that include urgency, frequency, and nocturia, all of which are associated with involuntary contractions of the detrusor muscle. Urge incontinence may or may not be a feature of this syndrome; about one-third have urge incontinence. 3. Proteinuria - Proteinuria is usually indicative of a renal pathology, most often of glomerular origin. Proteinuria can be functional as a result of acute illness, emotional stress, or excessive exercise and is a benign process. It can also develop from overproduction of filterable plasma proteins, especially Bence Jones proteins associated with multiple myeloma - The most accurate way to quantify the amount of protein in the urine is a 24-hour urine collection; however, a spot urine albumin to urine creatinine ratio can be measured and is a close approximation of the 24-hour urine measurement. A 24-hour urine with more than 165 mg of protein is considered abnormal and a specimen with more than 3.5 g is indicative of a nephrotic problem. A urine albumin to urine creatinine ratio of less than 0.2 is normal and corresponds to an excretion of less than 200 mg/dL of protein. - Causes of benign, or functional, proteinuria include orthostatic proteinuria, exercise, environmental conditions, fever, and acute illnesses. Orthostatic proteinuria occurs when the protein level is elevated only when the patient has been standing but not while he or she has been reclining. Exercise-induced proteinuria may occur in athletes such as runners or boxers; it may be accompanied by elevated catecholamines, hemoglobinuria, or hematuria. Proteinuria caused by environmental conditions such as emotional stress, exposure to cold, prolonged lordotic posture, and excess in the body’s norepinephrine level will resolve spontaneously when the precipitating element is eliminated or removed. A mild, transient proteinuria may result from an albumin infusion or acute illnesses such as fever, congestive heart failure, acute pulmonary edema, head injury, or cerebrovascular accident; this type of proteinuria typically resolves as the medical condition improves. - When proteinuria is identified in a low-risk (nondiabetic or nonpregnant) patient, the urine should be tested for Bence Jones protein, the presence of which suggests multiple myeloma. 4. Cystitis & UTI - Cystitis: inflamed bladder, lower UTI: bladder/urethra - Causes: - bacterial infection (most common) - Fungal Infections - Trauma - Chemical Irritants - Foreign bodies (kidney stones) - UTI upper: kidneys and ureters - UTI lower: bladder and urethra - Common causes UTI: Gram – most common E. Coli, Gram + Staph seprophyticus 2nd most common affects young women, sexually active - Risk factors UTI: sexual intercourse, female gender, post menopause (decrease of estrogen causes a loss of protective vaginal flora increasing the risk for UTI), DM, infant boys with foreskin?, impaired bladder emptying - S/S: UTI: - suprapubic pain - urgency - dysuria (pain with urination - frequent urination Infants: fussy, fever, feed poorly Older Adults: fatigue, incontinence, dementia - symptoms not usually seens due to being systemic: fever, N/V, pain at costovertebral angle) - Dx: urinalysis pyuria (WBC in urine), urine looks cloudy; urine dipstick: leukocyte esterase, nitrites (gram – E coli converts nitrate into nitrite); Ucx is the gold-standard for dx if >100,000 from clean catch urine - If pt has pyuria (WBC in urine and culture was negative-> sterile pyuria **suggest urethritis (inflammation of urethra) Most common cause STI: Neisseria gonorrhea or Chlamydia trochamatis - Tx: Thus, both TMP-SMX and nitrofurantoin may be used as empiric therapy for uncomplicated UTI only and, in fact, may prove to be inadequate. - TMP-SMX is a sulfonamide CI with sulfa allergy - Nitrofurantoin CI in 3rd trimester, or renal function impairment. Take with food and will darken urine 5. Pyelonephritis - Inflammation of the kidney possibly due to bacterial infection. - Type of upper urinary infection: renal pelvis, tubules, or interstitial tissue; may be unilateral or bilateral. Risk factors: -female sex - indwelling catheter - Sexual intercourse - DM -urinary tract obstruction - VUR - Common pathogens: E coli, proteus, and Enterobacter (common in bowel flora) - Acute pyelonephritis usually unilaterally - S/S: - WBC in urine -WBC cast - leukocytosis (inc WBC in blood) - fever - N/V, chills - flank pain at cosovertebral angle Dx: urinalysis: positive for bacteria, proteinuria, leukocyte esterase, urinary nitrites, hematuria, pyuria, and specifically white blood cell (WBC) casts (reflecting the passage of neutrophils through the renal tubules) Urine Cx: demonstrates greater than 100,000 cfu/mL, allowing for identification of the causative organism. -Tx: abx and hydration First-line therapy ciprofloxacin (Cipro) 500 mg two times daily for 7 days, or levofloxacin (Levaquin) 750 mg daily for 5 days. In second-line therapy, trimethoprim-sulfamethoxazole (TMP-SMX) (Bactrim DS, Septra DS) taken orally for 14 days may be as effective as amoxicillin-clavulanate for 14 days in young women with their first pyelonephritis and without anatomical abnormalities. However, given the prevalence of sulfonamide and ampicillin resistance among common uropathogens, TMP-SMX and amoxicillin are likely to be ineffective in cases of recurrent or moderate to severe pyelonephritis (except in cases of Enterococcus infection, which calls for the addition of amoxicillin [Amoxil] 500 mg PO three times daily). Nitrofurantoin should be avoided because it does not achieve adequate tissue levels. Other effective choices are third generation cephalosporins (e.g., cefixime, cefpodoxime, ceftriaxone), aminoglycosides (e.g., gentamicin, tobramycin), or aztreonam, with fluoroquinolones reserved for antibiotic-resistant organisms, hence the critical need for early urine culture to guide pharmacotherapy. 6. Urethritis - Infections of the lower urinary tract can occur in the urethra, bladder, and prostate. Infection of the urethra (urethritis) and infection of the urinary bladder (cystitis) usually occur together. - Common causes: E. coli, chlamydia or gonorrhea, trichomonas, HSV - Pus in the urine is indicative of bacterial infection, such as cystitis, urethritis, or prostatitis. - Suprapubic tenderness is indicative of a bladder etiology, whereas urethral discharge indicates a urethritis. - Acute cystitis and urethritis produce gross hematuria and are more common in women. - Hematuria is also often present in lower and upper UTI, but not in vaginitis or urethritis. - Urethritis in men is rare; if left untreated or treated inadequately, it can lead to complications such as urethral strictures, periurethral abscess, urethral diverticuli, and fissures. - Vaginal discharge in women and urethral discharge in men may suggest sexually transmitted diseases (STDs). Purulent urethral discharge (Neisseria gonorrhoeae) or whitish-mucoid discharge (Chlamydia trachomatis) should be treated aggressively with the appropriate antibiotic therapy. ............................................CONTINUED.....................................