DIAGNOSIS & TREATMENT - PART 5 potx

Viral Encephalitis■ Essentials of Diagnosis • Most common agents include enterovirus, Epstein-Barr virus,and viruses of herpes simplex, measles, rubella, rubeola, vari-cella, West Nile f

Varicella (Acute Chickenpox, Zoster [Shingles])

■ Essentials of Diagnosis

• Acute varicella: fever, malaise with eruption of pruritic, centripetal,papular rash, vesicular and pustular before crusting; lesions in allstages at any given time; “drop on rose petal” is the first lesion

• Incubation period 14–21 days

• Bacterial infection, pneumonia, and encephalitis may complicate

• Reactivation varicella (herpes zoster): dermatomal distribution,vesicular rash with pain often preceding eruption

• Immune globulin or antivirals for exposed susceptible suppressed or pregnant patients

immuno-• Acyclovir early for immunocompromised or pregnant patients,severe disease (eg, pneumonitis, encephalitis), or ophthalmicdivision of trigeminal nerve involvement with zoster

• Corticosteroids combined with antiviral agent with rapid tapermay diminish postherpetic neuralgia in older patients with zoster

Mumps (Epidemic Parotitis)

■ Essentials of Diagnosis

• Painful, swollen salivary glands , usually parotid; may be unilateral

• Incubation period 12–24 days

• Orchitis or oophoritis, meningoencephalitis, or pancreatitis mayoccur

• Cerebrospinal fluid shows lymphocytic pleocytosis in encephalitis with hypoglycorrhachia

meningo-• Diagnosis confirmed by isolation of virus in saliva or appearance

of antibodies after second week

■ Differential Diagnosis

• Parotitis or enlarged parotids due to other causes (eg, bacteria,sialolithiasis, cirrhosis, diabetes, starch ingestion, Sjögren’s syn-drome, sarcoidosis, tumor)

• Aseptic meningitis, pancreatitis, or orchitis due to other causes

Viral Encephalitis

■ Essentials of Diagnosis

• Most common agents include enterovirus, Epstein-Barr virus,and viruses of herpes simplex, measles, rubella, rubeola, vari-cella, West Nile fever

• Fever, malaise, stiff neck, nausea, altered mentation

• Signs of upper motor neuron lesion: exaggerated deep tendonreflexes, absent superficial reflexes, spastic paralysis

• Increased cerebrospinal fluid protein with lymphocytic sis, occasional hypoglycorrhachia

pleocyto-• Isolation of virus from blood or cerebrospinal fluid; serology itive in paired specimens 3– 4 weeks apart

pos-• Brain imaging shows temporal lobe abnormalities in herpeticencephalitis

■ Differential Diagnosis

• Other encephalitides (postvaccination, Reye’s syndrome, toxins)

• Lymphocytic choriomeningitis

• Primary or secondary neoplasm

• Bacterial meningitis or brain abscess

■ Treatment

• Vigorous supportive measures with attention to elevated centralnervous system pressures

• Mannitol in selected patients

• Acyclovir for suspected herpes simplex encephalitis; other specificantiviral therapy is under study

paral-• Cerebrospinal fluid lymphocytic pleocytosis with slight elevation

of protein

• Virus recovered from throat washings or stool

■ Differential Diagnosis

• Other aseptic meningitides

• Postinfectious polyneuropathy (Guillain-Barré syndrome)

• Amyotrophic lateral sclerosis

Lymphocytic Choriomeningitis

■ Essentials of Diagnosis

• History of exposure to mice or hamsters

• “Influenza-like” prodrome with fever, chills, headache, malaise,and cough followed by headache, photophobia, or neck pain

• Kernig and Brudzinski signs positive

• Cerebrospinal fluid with lymphocytic pleocytosis and slight crease in protein

in-• Serology for arenavirus positive 2 weeks after onset of toms; virus recovered from blood and cerebrospinal fluid

symp-• Illness usually lasts 1–2 weeks

■ Differential Diagnosis

• Other aseptic meningitides

• Bacterial or granulomatous meningitis

Dengue (Breakbone Fever, Dandy Fever)

to torso

• Dengue hemorrhagic fever is a severe form in which intestinal hemorrhage is prominent and patients often present withshock

Colorado Tick Fever

■ Essentials of Diagnosis

• A self-limited acute viral (coltivirus) infection transmitted by

Dermacentor andersoni tick bites

• Onset 3–6 days following bite

• Abrupt onset of fever, chills, myalgia, headache, photophobia

• Occasional faint rash

• Second phase of fever after remission of 2–3 days common

• Imbedded ticks, especially in children’s scalps, may cause paresis

■ Differential Diagnosis

• Borrelliosis

• Influenza

• Adult Still’s disease

• Other viral exanthems

• Guillain-Barré syndrome (if paralysis present)

■ Treatment

• Supportive for uncomplicated cases

• With paresis, removal of tick results in prompt resolution ofsymptoms

■ Essentials of Diagnosis

• A rhabdovirus encephalitis transmitted by infected saliva

• History of animal bite (bats, bears, skunks, foxes, raccoons; dogsand cats in developing countries)

• Paresthesias, hydrophobia, rage alternating with calm

• Convulsions, paralysis, thick tenacious saliva and muscle spasms

• Thorough, repeated washing of bite and scratch wounds

• Postexposure immunization, both passive and active

• Observation of healthy biting animals, examination of brains ofsick or dead biting animals

• Treatment is supportive only; disease is almost uniformly fatal

■ Essentials of Diagnosis

• Caused by an orthomyxovirus transmitted via the respiratory route

• Abrupt onset of fever, headache, chills, malaise, dry cough, coryza,and myalgias; constitutional signs out of proportion to catarrhalsymptoms

• Epidemic outbreaks in fall or winter, with short incubation period

• Virus isolated from throat washings; serologic tests positive aftersecond week of illness

• Complications include bacterial sinusitis, otitis media, and monia

pneu-• Myalgias occur early in course, rhabdomyolysis late

■ Differential Diagnosis

• Other viral syndromes

• Primary bacterial pneumonia

• Meningitis

• Dengue in returned travelers

• Rhabdomyolysis of other cause

■ Treatment

• Yearly active immunization of persons at high risk (eg, chronicrespiratory disease, pregnant women, cardiac disease, health careworkers, immunosuppressed); also for all over 50

• Chemoprophylaxis for epidemic influenza A effective with tadine; zanamivir and oseltamivir effective against influenza Aand B

aman-• Antivirals reduce duration of symptoms and infectivity if givenwithin 48 hours

• Avoid salicylates in children because of association with Reye’ssyndrome

Infectious Mononucleosis (Epstein-Barr Virus Infection)

■ Essentials of Diagnosis

• An acute viral illness due to EBV, usually occurring up to age 35but any age possible

• Transmitted by saliva; incubation period is 5–15 days or longer

• Fever, severe sore throat, striking malaise, lymphadenopathy

• Maculopapular rash, splenomegaly common

• Leukocytosis and lymphocytosis with atypical large lymphocytes

by smear; positive heterophil agglutination test (Monospot) byfourth week of illness; false-positive rapid plasma reagin test(RPR) in 10%

• Clinical picture much less typical in older patients

• Complications include splenic rupture, hepatitis, myocarditis,thrombocytopenia, and encephalitis

■ Differential Diagnosis

• Other causes of pharyngitis

• Other causes of hepatitis

• Toxoplasmosis

• Rubella

• Acute HIV, CMV, or rubella infections

• Acute leukemia or lymphoma

lymph-• Ampicillin apt to cause rash

• Avoid vigorous abdominal activity or exercise

RICKETTSIAL INFECTIONS

Rocky Mountain Spotted Fever (Rickettsia rickettsii)

■ Essentials of Diagnosis

• Exposure to tick bite in endemic area

• Influenzal prodrome followed by chills, fever, severe headache,myalgias, occasionally delirium and coma

• Red macular rash with onset between second and sixth days offever; first on extremities, then centrally, may become petechial

or purpuric

• Leukocytosis, proteinuria, hematuria

• Serologic tests positive by second week of illness, but diagnosismay be made earlier by skin biopsy with immunologic staining

Despite the name, Rocky Mountain spotted fever is far more common

in the southeastern United States.

Reference

Thorner AR et al: Rocky Mountain spotted fever Clin Infect Dis 1998;27:1353.[PMID: 9868640]

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Q Fever (Coxiella burnettii)

■ Essentials of Diagnosis

• Infection following exposure to sheep, goats, cattle, or fowl

• Acute or chronic febrile illness with severe headache, cough, andabdominal discomfort

• Pulmonary infiltrates by chest x-ray; leukopenia

• Serologic confirmation by third to fourth weeks of illness

• Granulomatous hepatitis and culture-negative endocarditis inoccasional cases

BACTERIAL INFECTIONS Streptococcal Pharyngitis

■ Essentials of Diagnosis

• Abrupt onset of sore throat, fever, malaise, nausea, headache

• Pharynx erythematous and edematous with exudate; cervicaladenopathy

• Strawberry tongue

• Throat culture or rapid antigen detection confirmatory

• If erythrotoxin (scarlet fever) is produced, scarlatiniform rash redand papular with petechiae and fine desquamation; prominent inaxilla, groin, behind knees

• Glomerulonephritis, rheumatic fever may complicate

exu-• If equivocal, await culture or antigen confirmation

• If history of rheumatic fever, continuous antibiotic prophylaxisfor 5 years

Streptococcal Skin Infection

• Other causes of infectious cellulitis (eg, staphylococcal, E coli)

• Toxic shock syndrome

• Beriberi (in setting of thiamin deficiency)

■ Treatment

• Penicillin for culture-proved streptococcal infection

• Staphylococcal coverage (dicloxacillin) for empiric therapy oruncertain diagnosis

Pneumococcal Infections

■ Essentials of Diagnosis

• Pneumonia characterized by initial chill, severe pleuritis, feverwithout diurnal variation; signs of consolidation and lobar infil-trate on x-ray ensue rapidly

head-• Endocarditis, empyema, pericarditis, and arthritis may also plicate, with empyema most common

com-• Predisposition to bacteremia in children under 24 months of age

or in asplenic or immunocompromised adults (eg, AIDS, elderly)

• Blood culture prior to antibiotics

• Third-generation cephalosporin for severe disease; add empiricvancomycin for meningitis pending culture results

• Adults over 50 with any serious medical illness, patients withsickle cell disease, and asplenic patients should receive pneumo-coccal vaccine

• Penicillin unreliable pending results of susceptibility testing

Staphylococcal Soft Tissue or Skin Infections

■ Essentials of Diagnosis

• Painful, pruritic erythematous rash with golden crusts or discharge

• Folliculitis, furunculosis, carbuncle, abscess, and cellulitis all seen

• Culture of wound or abscess is diagnostic; Gram-stained smear

positive for large gram-positive cocci (Staphylococcus aureus) in

Thestrup-Pedersen K: Bacteria and the skin: clinical practice and therapy update

Br J Dermatol 1998;139(Suppl)53:1 [PMID: 9990405]

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Staphylococcus aureus-Associated Toxic

Shock Syndrome

■ Essentials of Diagnosis

• Abrupt onset of fever, vomiting, diarrhea, sore throat, headache,myalgia

• Toxic appearance, with tachycardia and hypotension

• Diffuse maculopapular erythematous rash with desquamation onthe palms and soles; nonpurulent conjunctivitis

• Association with tampon use; culture of nasopharynx, vagina,rectum, and wounds may yield staphylococci, but blood culturesusually negative

• Usually caused by toxic shock syndrome toxin-1 (TSST-1)

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Clostridial Myonecrosis (Gas Gangrene)

■ Essentials of Diagnosis

• Sudden onset of pain, swelling in an area of wound contamination

• Severe systemic toxicity and rapid progression of involved tissue

• Brown or blood-tinged watery exudate with surrounding skin coloration

dis-• Gas in tissue by palpated or auscultated crepitus or x-ray

• Clostridium perfringens in anaerobic culture or smear of exudate

is the classic—but not the only—cause

• Immediate surgical debridement and exposure of infected areas

• Hyperbaric oxygen of uncertain benefit

• Intravenous penicillin with clindamycin

• Tetanus prophylaxis

■ Pearl

In a patient severely symptomatic and extremely toxic with the clinical picture noted, a relatively low-grade fever is virtually diagnostic of gas gangrene.

Reference

Chapnick EK: Necrotizing soft-tissue infections Infect Dis Clinics North Am1996;10:835.[PMID: 8958171] )

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Tetanus (Clostridium tetani)

■ Essentials of Diagnosis

• History of nondebrided wound or contamination may or may not

be obtained

• Jaw stiffness followed by spasms (trismus)

• Stiffness of neck or other muscles, dysphagia, irritability, reflexia; late, painful convulsions precipitated by minimal stim-uli; fever is low-grade

• Active immunization preventive

• Passive immunization with tetanus immune globulin and current active immunization for all suspected cases

con-• Chlorpromazine or diazepam for spasms or convulsions, with ditional sedation by barbiturates as necessary

ad-• Vigorous supportive care with particular attention to airway andlaryngospasm

Botulism (Clostridium botulinum)

■ Essentials of Diagnosis

• Sudden onset of cranial nerve paralysis, diplopia, dry mouth, phagia, dysphonia, and progressive muscle weakness

dys-• Fixed and dilated pupils in 50%

• In infants: irritability, weakness, and hypotonicity

• History of recent ingestion of home-canned, smoked, or packed foods

vacuum-• Demonstration of toxin in serum or food

• Guillain-Barré syndrome or variant

• Inorganic phosphorus poisoning

■ Treatment

• Removal of unabsorbed toxin from gut

• Specific antitoxin (CDC Poison Control Hotline 800-292-6678)

• Vigilant support, including attention to respiratory function

Anthrax (Bacillus anthracis)

■ Essentials of Diagnosis

• History of industrial or agricultural exposure (farmer, veterinarian,tannery or wool worker); a potential agent in biological warfare

• Persistent necrotic ulcer on exposed surface

• Regional adenopathy, fever, malaise, headache, nausea and iting

vom-• Inhalation of spores causes severe tracheobronchitis and monia with dyspnea and cough

pneu-• Hematologic spread with profound toxic and cardiovascular lapse may complicate either cutaneous or pulmonary form

col-• Confirmation of diagnosis by culture or specific fluorescent body test, but clinical picture highly suggestive

anti-■ Differential Diagnosis

• Skin lesions: staphylococcal or streptococcal infection

• Pulmonary disease: tuberculosis, fungal infection, sarcoidosis,lymphoma with mediastinal adenopathy, plague

■ Treatment

• Therapy for post exposure prophylaxis is oral doxycycline or oralciprofloxacin

• Optimal therapy for confirmed disease due to a susceptible strain

is oral amoxacillin or oral doxycycline for 60 days

• Mortality rate is high despite proper therapy, especially in nary disease

Diphtheria (Corynebacterium diphtheriae)

■ Essentials of Diagnosis

• An acute infection spread by respiratory secretions

• Sore throat, rhinorrhea, hoarseness, malaise, relatively sive fever (usually < 37.8 °C)

unimpres-• Tenacious gray membrane at portal of entry

• Toxin-induced myocarditis and neuropathy may complicate, due

Pertussis (Bordetella pertussis)

■ Essentials of Diagnosis

• An acute infection of the respiratory tract spread by respiratorydroplets

• History of declined DTP vaccination

• Two-week prodromal catarrhal stage of malaise, cough, coryza,and anorexia; seen predominantly in infants under age 2

• Paroxysmal cough ending in high-pitched inspiratory “whoop”(whooping cough)

• Absolute lymphocytosis with extremely high white counts sible

pos-• Culture confirms diagnosis

• Active immunization preventive (as part of DTP)

• Erythromycin with immune globulinin selected patients

• Treat secondary pneumonia and other complications

impli-8

Meningococcal Meningitis (Neisseria meningitidis)

■ Essentials of Diagnosis

• Fever, headache, vomiting, confusion, delirium, or seizures; cally epidemic in young adults; onset may be astonishingly abrupt

typi-• Petechial or ecchymotic rash of skin and mucous membranes

• May have positive Kernig and Brudzinski signs

• Purulent spinal fluid with gram-negative intracellular and cellular cocci by Gram-stained smear

extra-• Culture of cerebrospinal fluid, blood, or petechial aspirate firms diagnosis

con-• Disseminated intravascular coagulation and shock may complicate

■ Differential Diagnosis

• Meningitis due to other causes

• Petechial rash due to rickettsial, viral, or other bacterial infection

• Idiopathic thrombocytopenic purpura

■ Treatment

• Active immunization available for selected susceptible groups(military recruits, college dormitory residents)

• Penicillin, ceftriaxone, or chloramphenicol

• Mannitol and corticosteroids for elevated intracranial pressure

• Ciprofloxacin (single dose) or rifampin (2 days) therapy for mate exposures

inti-■ Pearl

The most common bacterial meningitis in which organisms are not seen

on cerebrospinal fluid Gram stain (50% of cases).

Reference

Salzman MB et al: Meningococcemia Infect Dis Clin North Am 1996;10:709 [PMID: 8958165]

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Legionnaire’s Disease

■ Essentials of Diagnosis

• Caused by Legionella pneumophila and a common cause of

community-acquired pneumonia in some areas

• Seen in patients who are immunocompromised or have chroniclung disease

• Malaise, dry cough, fever, headache, pleuritic chest pain, toxicappearance, purulent sputum

• Chest x-ray with patchy infiltrates often unimpressive early; sequent development of effusion or multiple lobar involvementcommon

sub-• Purulent sputum without organisms seen by Gram stain; sis confirmed by culture or special silver stains or direct fluores-cent antibodies, urinary antigen

Reference

Breiman RF et al: Legionnaires’ disease: clinical, epidemiological, and publichealth perspectives Semin Respir Infect 1998;13:84 [PMID: 9643385]

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Enteric Fever (Typhoid Fever)

■ Essentials of Diagnosis

• Caused by several salmonella species; in “typhoid fever,” serotype

Salmonella typhi is causative and accompanied by bacteremia

• Transmitted by contaminated food or drink; incubation period is5–14 days

• Gradual onset of malaise, headache, sore throat, cough, followed

by diarrhea or, with S typhi, constipation; stepladder rise of fever

to maximum of 40 °C over 7–10 days, then slow return to normalwith little diurnal variation

• Rose spots, relative bradycardia, splenomegaly, abdominal tention and tenderness

dis-• Leukopenia; blood, stool, and urine cultures positive for S typhi

(group D) or other salmonellae

• Ciprofloxacin or second-generation cephalosporin pending ceptibility results

sus-• Cholecystectomy may be necessary for relapsed cases

• Complications in one-third of untreated patients include intestinalhemorrhage or perforation, cholecystitis, nephritis, and meningitis

Salmonella Gastroenteritis (Various Salmonella Species)

■ Essentials of Diagnosis

• The most common form of salmonellosis

• Nausea, headache, meningismus, fever, high-volume diarrhea,usually without blood, and abdominal pain 8–48 hours after in-gestion of contaminated food or liquid

• Positive fecal leukocytes

• Culture of organism from stool; bacteremia less common

■ Differential Diagnosis

• Viral gastroenteritis, especially enterovirus

• Dysenteric illness (shigella, campylobacter, amebic)

• Enterotoxigenic E coli infection

• Inflammatory bowel disease

■ Treatment

• Rehydration and potassium repletion

• Antibiotics (ciprofloxacin or ceftriaxone ) essential in those withsickle cell anemia or immunosuppression

• In others, antimicrobials reduce symptoms by 1–2 days