Infectious Disorders

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Background



  • Elevation in body temperature as a result of cytokine-induced displacement of the hypothalamic set point.


  • Regulated through the hypothalamus.


  • Pyrogens can be exogenous or endogenous substances.



    • Endogenous pyrogens: interleukin 1 (IL-1), interleukin 6 (IL-6), tumor necrosis factor á (TNF-á).


    • Exogenous cytokines: derived from bacterial toxins, bacterial products, or microorganisms.


  • Results in elevated core temperature, shivering, and core vasoconstriction.



Fever in Neonate

Andrea M. Kline-Tilford



  • Temperature ≥38.0°C (100.4°F); rectal.


  • Neonates, birth to 28 days, are at greater risk for significant bacterial infection (SBI).


  • At birth, presence of maternal IgG cells; however, absence of immunologic memory and adaptive immunity.


  • B and T cells are at normal levels, but are less efficient than adult cells.


  • Complete evaluation required when a neonate develops fever (e.g., full septic workup/evaluation).



    • Complete blood count (CBC) with differential, blood culture, urinalysis (UA), and urine culture (specimen obtained through catheterization).


    • Lumbar puncture.


  • Immune system rapidly develops in the first 3 months of life.


  • Neonates often lack focal examination findings in the presence of an SBI.


  • Most commonly, SBI in neonates results from bacteremia, meningitis, pneumonia, or urinary tract infection (UTI).


  • Common SBI pathogens in neonates:



    • Group B streptococcus.


    • Listeria monocytogenes.


    • Salmonella.


    • Escherichia coli.


    • Neisseria meningitides.


    • Streptococcus pneumoniae.


    • Haemophilus influenzae type B.


    • Staphylococcus aureus.


  • Other common pathogens resulting in serious infection/illness in the neonate:



    • Respiratory syncytial virus (RSV).


    • Varicella-zoster virus.


    • Candida species.


  • If nasal congestion, evaluation is needed for RSV, parainfluenza, and influenza.


  • Plan is individualized; however, admission indicated in negative evaluation.


  • If nontoxic, empiric antibiotics may be delayed until laboratory evaluation is collected and results are available.


  • Recommended empiric antibiotic coverage in neonates includes ampicillin and gentamicin or ampicillin and cefotaxime.


  • Acyclovir, in addition to empiric antibiotics, if one of the following: seizures, cerebrospinal fluid (CSF) pleocytosis, primary maternal herpes simplex virus (HSV) infection, prolonged maternal rupture of membranes, mucocutaneous lesion, or fetal scalp electrode use.



    • Continue until CSF HSV polymerase chain reaction (PCR) results are available.


    • Recent evidence suggests acyclovir therapy for any infant <4 weeks of age with fever.


  • If laboratory evaluation is suggestive of UTI, full laboratory evaluation is still warranted. Admission and initiation of ampicillin and gentamicin are indicated.



  • Discharge if cultures are negative at 48 to 72 hours and the neonate is stable and afebrile. Close with primary care provider is needed, typically 48 hours after discharge.



Fever without a Source

Andrea M. Kline-Tilford



Fever of Unknown Origin

Meghan Shackelford



Etiology



  • Most common causes of fever of unknown origin (FUO) are infectious disease and connective tissue disorders.


  • Neoplastic disorders are less common and typically have manifestations other than fever.


  • Generally caused by a common disorder with an unusual presentation.



    • Sepsis, meningitis, urosepsis, toxic shock syndrome (TSS), and pneumonia should be considered during investigation of fever.


    • Meningitis should always be considered when evaluating an infant/child with FUO. See Table 11.2 for common pathogens in meningitis.



Evaluation



  • History.



    • Fever identification: touch, thermometry device, and site of temperature measurement.


    • Fever history is an important consideration.


    • Presentation of fever with sweating could indicate heat intolerance or hyperthyroid disease.


    • Lack of response to nonsteroidal anti-inflammatory drugs (NSAIDs) can indicate a noninflammatory condition causing the FUO (e.g., dysautonomia, ectodermal dysplasia).









      TABLE 11.1 Examples of Criteria Approaches to FWS






















































      Boston


      Milwaukee


      Philadelphia


      Rochester


      Age


      28-89 d


      28-56 d


      29-60 d


      ≤60 d


      Temperature


      ≥38.0°C


      ≥38.0°C


      ≥38.2°C


      ≥38.0°C


      History


      No immunizations or antibiotics in prior 48 hr.


      No evidence of dehydration.


      Not defined.


      Not defined.


      Term infant.


      No perinatal antibiotic administration.


      Absence of underlying disease.


      Not hospitalized longer than mother.


      Appearance/Physical Examination


      Well-appearing.


      No signs of focal infection (e.g., otitis media, soft tissue).


      Well-appearing.


      No evidence of dehydration.


      No signs of focal infection (e.g., otitis media, soft tissue).


      Well-appearing.


      Unremarkable physical examination.


      Well-appearing.


      No signs of focal infection (e.g., otitis media, soft tissue).


      Laboratory Results


      Serum WBC <20,000/mm3.


      CSF <10 WBC/mm3.


      UA <10 WBC/hpf.


      Chest radiograph: no focal infiltrate (if obtained).


      Serum WBC <15,000/mm3.


      CSF <10 WBC/mm3.


      UA <5-10 WBC/hpf; no bacteria, leukocyte, and nitrite negative.


      Chest radiograph: no focal infiltrate (if obtained).


      Serum WBC <15,000/mm3.


      Band to neutrophil ratio <0.2.


      CSF <8 WBC/mm3.


      CSF Gram stain negative. UA <10 WBC/hpf.


      Urine Gram stain negative.


      Chest radiograph: no focal infiltrate. Stool: no blood, few or no WBCs on smear (if obtained).


      Serum WBC <5,000/mm3 >15,000/mm3.


      Band neutrophils <1,500/mm3.


      CSF: not applicable; no lumbar puncture indicated.


      UA <10 WBC/hpf Stool WBC ≤5/hpf (if obtained).


      Low-Risk Management Strategy


      Home/outpatient.


      Empiric antibiotics.


      Follow-up evaluation required.


      Home with reliable caretaker.


      Follow-up evaluation required.


      Ceftriaxone 50 mg/kg IM with reevaluation in 24 hr.


      Home/outpatient.


      No antibiotics.


      Follow-up evaluation required.


      Home/outpatient.


      No antibiotics.


      Follow-up evaluation required.


      High-Risk Management Strategy


      Hospitalize.


      Antibiotic therapy.


      Not defined.


      Hospitalize.


      Antibiotic therapy.


      Hospitalize.


      Antibiotic therapy.


      hpf, high-powered field; WBC, white blood cell; IM, intramuscular










      TABLE 11.2 Most Common Pathogens in Meningitis by Age Group

























      Age


      Pathogens


      Symptoms


      Neonates-28 d of life


      Group B streptococcus E. coli.


      L. monocytogenes


      Strep. pneumoniae


      H. influenzae type b


      Staph. aureus


      Herpes simplex virus (HSV)


      Also consider viral etiology.


      Lethargy


      Poor feeding


      Fever or hypothermia


      Vomiting


      Apnea


      1-3 mo of age


      C. trachomatis


      Strep. pneumoniae


      N. meningitidis


      Group B streptococcus (late-onset GBS infection)


      Pertussis


      Consider viral etiology.


      Fever


      Nuchal rigidity


      Change in mental status


      Change in LOC


      + Kernig sign


      + Brudzinski sign


      3 mo-2 y of age


      N. meningitidis


      Strep. pneumoniae


      Moraxella catarrhalis


      Group A streptococcus


      Salmonella


      Mycoplasma pneumoniae


      M. tuberculosis


      Mostly bacterial; low incidence of viral.


      Fever


      Headache


      Nuchal rigidity


      Change in LOC


      + Kernig sign


      + Brudzinski sign


      Erythematous


      rash, if toxic shock syndrome present.


      2-18 y of age


      N. meningitidis


      Strep. pneumoniae Chlamydia


      M. tuberculosis


      Mostly bacterial; low incidence of H. influenzae.


      Fever


      Headache


      Nuchal rigidity


      Change in LOC


      + Kernig sign


      + Brudzinski sign


      Erythematous rash if toxic shock syndrome present.


      LOC, loss of consciousness



    • Evaluate other clinical manifestations that accompany the fever, such as urine output, feeding intolerance, vomiting, pain, headache.


  • Diagnostic evaluation.



    • CBC, blood culture, UA and urine culture, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), complete metabolic panel (CMP); consider lactate if the child appears septic.


    • Consider chest radiography.


    • Tuberculosis testing, human immunodeficiency virus (HIV) evaluation, or immune evaluation.


Management



  • Based on age and presentation at time of fever.


  • If a child is ill-appearing or in septic shock, the evaluation is more comprehensive.


  • Neonates to 28 days with temperature >38.0°C rectal (see “Fever in Neonate” for more detail).


  • Infants 1 to 3 months of age:



    • The most common differential for this age group includes bacteremia, meningitis, and UTI.


    • In the ill-appearing infant, cultures should be obtained, including blood, urine, and CSF culture. A WBC count with differential should also be obtained. IV antibiotics should be started and the child is admitted to the hospital. A chest radiography is optional in this age group.


    • If meningitis is suspected, ampicillin and cefotaxime are indicated with acyclovir.


  • Infant >3 months of age:



    • Vancomycin and ceftriaxone are antibiotics of choice.


    • If treating pneumonia, cefotaxime and ampicillin or clindamycin are recommended.


  • Children 3 months to 2 years of age:



    • This age group has fever typically related to a bacterial etiology.


    • Differential diagnosis: meningitis, pneumonia, toxic shock, and urosepsis. Toxic shock typically presents with an erythematous rash.


    • In the ill-appearing child, cultures should be sent in addition to WBC count with differential and hospital admission is warranted.


    • Antibiotic choices for meningitis include vancomycin and ceftriaxone.


    • If treating pneumonia, ampicillin, cefuroxime, or ceftriaxone can be used with clindamycin or vancomycin for empiric treatment.


    • If the child is well-appearing, discharge home with outpatient follow-up.


  • Children 2 to 18 years of age:



    • Toxic shock, meningitis, and pneumonia are common etiologies.


    • If the child is ill-appearing and hemodynamically unstable, blood, urine, and CSF cultures should be obtained, along with CBC count and differential. IV antibiotics should be started and hospital admission is warranted.


    • If treating pneumonia, azithromycin with cefuroxime or ceftriaxone, and clindamycin or vancomycin are antibiotics of choice.


    • If meningitis is suspected, ceftriaxone and vancomycin are initiated.


    • See Table 11.3 for common infectious diseases by body system.


    • See Table 11.4 for examples of cephalosporin coverage.


    • See Box 11.1 for helpful cephalosporin mnemonics.









      TABLE 11.3 Common Infectious Organisms and Disease/System Involved






























      Organism


      Disease/System Process


      Gram-positive cocci (aerobic):


      Staph. aureus


      Staph. epidermis


      Other Staphylococcus species


      Nosocomial: wound, ventilator


      Neonatal


      UTI


      (typically hospital-associated infections)


      Gram-positive enterococcus (aerobic):


      Strep. gordoni


      Strep. pneumoniae


      Strep. mutans


      Strep. viridans


      Endocarditis


      Sepsis


      Meningitis


      Urinary tract infection


      Gram-positive enterococcus (aerobic):


      Staph. pyogenes


      Toxic shock syndrome


      Necrotizing fasciitis


      Gram-positive cocci (anaerobic):


      Peptostreptococcus


      Peritonitis; can occur anywhere (e.g., soft tissue, CNS, chest, bone)


      Gram-negative cocci:


      N. meningiditis


      M. cattarhalis


      Meningitis


      Myocarditis


      Otitis media


      Sinusitis


      Gram-positive bacilli:


      L. monocytogenes


      C. difficile


      C. botulinum


      Sepsis (L. monocytogenes); primarily <2 mo of age


      Meningitis (L. monocytogenes); primarily <2 mo of age


      Antibiotic or hospital-acquired diarrhea (C. difficile)


      Flaccid paralysis


      (C. botulinum)


      Gram-negative bacilli:


      E. coli


      Enterobacter


      P. mirabilis


      K. pneumoniae


      Wound infection


      UTI


      Meningitis


      Bacteremia


      Health care-associated infections (especially


      Klebsiella; increasing resistance also)


      Gram-negative bacilli:


      P. aeruginosa


      Bacteremia


      Sepsis


      Health care-associated infections


      Encephalitis


      Meningitis


      Pneumonia



    • See Box 11.2 for examples of organisms requiring double antibiotic coverage.


    • Refer to an antimicrobial reference (e.g., Sanford Guide) for additional information on appropriate antibiotic coverage for pathogens (Tables 11.5 and 11.6).











TABLE 11.4 Examples of Cephalosporin Generations



























First Generation


Second Generation


Third Generation


Fourth Generation


Cefazolin


Cephalexin


Cefadroxil


Cephradine


Cefaclor


Cefuroxime


Cefprozil


Loracarbef


Cephamycins; give resistance to β-lactamases.


Different from other second-generation cephalosporins. Similar activity, though, have activity against anaerobic bacteroides.


Cefdinir


Cefixime


Cefotaxime


Ceftriaxone


Cefpiramide


Cefepime


Cefluprenam


Cefozopran


Cefpirome


Spectrum of Activity


Good gram-positive cocci coverage (e.g., Streptococci, Staphylococci, Enterococci).


Not effective against methicillin-resistant Staph. aureus or penicillin-resistant


Strep. pneumoniae.


Some gram-negative coverage (e.g., E. coli, P. mirabilis, and K. pneumoniae).


Poor activity H. influenzae and M. catarrhalis.


Almost comparable to first-generation agents against Streptococci; slight loss of activity against Staphylococci.


Do not provide coverage against MRSA.


Gram-negative aerobe coverage: M. catarrhalis, P. mirabilis, H. influenzae, Klebsiella, N. gonorrheae.


No coverage against


Enterococci or Pseudomonas.


Limited gram-positive coverage.


Cefotaxime, ceftriaxone, and ceftizoxime have the best gram-positive coverage of third generation cephalosporins including Staph. aureus (methicillin-sensitive), group A and B streptococci, viridans streptococci.


Enhanced β-lactamase stability; activity against gram-negative bacteria.


Known to induce gram-negative bacteria resistance.


Gram-negative bacteria: H. influenzae, M. catarrhalis, N. meningitidis, Proteus, Klebsiella, Serratia, Providencia, Citrobacter, E. coli.


None are effective against Listeria, or methicillin-resistant Staphylococci or Enterococci.


No coverage for Pseudomonas.


Cefotaxime and ceftriaxone have coverage against oral anaerobes.


Broadest spectrum of activity.


Similar grampositive coverage as first-generation cephalosporins.


Gram-positive cocci: group A and B streptococci, Strep. pneumoniae, Staph. aureus (methicillin susceptible).


Gram-negative bacteria: improved activity compared with third generation.


Excellent coverage for Pseudomonas and Enterobacteriaceae.


Limited anaerobic coverage.


Uses


Uncomplicated skin/soft tissue infections, uncomplicated UTIs, group A streptococcal pharyngitis, surgical prophylaxis. Does NOT provide good coverage for acute otitis media.


Do not cross the blood-brain barrier; NOT a good choice for CNS infections (e.g., meningitis). Cefazolin is used most frequently.


Otitis media, acute sinusitis, upper and lower respiratory tract infections, uncomplicated UTIs.


Do not cross bloodbrain barrier; not a good choice for CNS infections.


Meningitis: gram-negative bacilli; upper respiratory tract infections, otitis media, pyelonephritis, skin and soft tissue infections.


Lyme disease (Ceftriaxone).


Gonorrhea (Ceftriaxone).


Good penetration into CSF (cefotaxime, ceftazadime, ceftriaxone).


Antipseudomonal cephalosporin; ceftazadime.


Nosocomial pathogens; especially cefepime and cefpirome.


Crosses blood-brain barrier/CNS penetration: cefepime.





Fever and Neutropenia

Meghan Shackelford



Etiology



  • Bacteremia is the most common etiology.


  • Common sites of infection include the gastrointestinal (GI) tract (e.g., oral and intestinal mucositis, diarrhea), upper and lower respiratory tracts, urinary tract, skin, and soft tissues.


  • Diarrhea is most commonly caused by Clostridium difficile and Salmonella.


  • Gram-positive and gram-negative organisms must be considered.



    • Gram-positive pathogens are coagulase-negative staphylococci, viridans streptococci, and Staph. aureus (including MRSA).


    • Gram-negative organisms are gram-negative bacilli, E. coli, Klebsiella, Pseudomonas, Acinetobacter, and Enterobacter.


  • Candida and other fungal species can develop after prolonged use of broad-spectrum antibiotic therapy.



    • Other opportunistic fungi include Aspergillus, Phycomycetes, and Cryptococcus.


  • Viral etiologies in these children include HSV, varicella-zoster virus, as well as respiratory viruses.



Clinical Presentation



  • A complete history is essential in determining whether neutropenia and fever are linked to chemotherapy and an infectious process or are of a hemolytic etiology.


  • Important history includes antimicrobial prophylaxis, infectious exposures, chronic steroid therapy, history of infections or bacterial colonization, fever-causing medications, type of chemotherapeutic agents received, recent blood product transfusion, presence of invasive lines/devices, previous chemotherapy.


  • Skin breakdown is a portal of infection for an immunocompromised patient.


  • Monitoring for pancreatitis and pneumonia and evaluation of subtle vital sign changes such as tachycardia assist in diagnosis and prompt, accurate treatment.


Diagnostic Evaluation



  • Laboratory evaluation: CBC with differential and platelet count, CMP, including BUN (blood urea nitrogen)/creatinine, AST (aspartate aminotransferase)/ALT (alanine transaminase), and total bilirubin; blood, urine, body fluid, and, sometimes, CSF cultures.


  • Imaging may be indicated: computed tomography (CT) or ultrasound if concern for fluid collections, effusions, or acute changes; chest radiography if respiratory symptoms.


  • If a central venous catheter is present, a blood culture should be obtained and sent from each lumen.



    • Removal of the central line may be indicated.


  • In the absence of a central venous catheter, a peripheral culture should be obtained using sterile technique.


  • Lumbar puncture if altered mental status.


  • C. difficile toxin assay if diarrhea is present.


Management



  • Broad-spectrum antibiotics are administered quickly to the neutropenic patient with fever. Treatment varies according to individual patient according to specific guidelines.


  • Two categories: high-risk and low-risk.



    • High-risk patients have neutropenia expected to last >7 days, are clinically unstable, and have comorbidities.


    • Low-risk patients have neutropenia expected to last <7 days and are clinically stable with no comorbidities.


  • Low-risk outpatient: Ciprofloxacin and amoxicillin-clavulanate PO are recommendations for treatment, followed by observation for 4 to 24 hours after initiation of antibiotics.


  • Low-risk inpatient: Zosyn, carbapenem, ceftazidime, or cefepime based on suspected organism, severity of infection, and preference.


  • High-risk patient: hospital admission and antibiotic therapy with Zosyn, carbapenem, ceftazidime, or cefepime. For patients with minimal response or signs of decline, therapy should be adjusted for clinical, radiographic, and/or culture data. Vancomycin or linezolid should be used for cellulitis or pneumonia. An aminoglycoside and carbapenem should be used for pneumonia or a gram-negative bacteremia. Flagyl should be used if the patient has abdominal symptoms or suspected C. difficile infection.




    • Infectious disease consult is warranted for the high-risk patient, especially if not responsive to therapy.


  • Antifungal therapy is reserved for neutropenic patients with fever persisting for 4 to 7 days after starting broad-spectrum antibiotics.



    • Amphotericin B is often the initial recommendation; however, should be considered with caution because of significant toxicity risk.



Health Care Associated Infections

Jill S. Thomas


Central Line-Associated Bloodstream Infections


Background



  • A health care-associated infection is an infection that is not present upon hospital admission but develops within 48 hours of admission in an acute care setting.


  • Infections not present at discharge but apparent within 10 days after discharge are also considered to be of nosocomial origin.



Etiology/Types



  • Migration of skin organisms at the insertion site, leading to colonization of the catheter tip.


  • Direct catheter or catheter hub contamination; infusate contamination.


  • Hematogenous seeding of catheters by other sites of infection.


  • Common causative organisms include coagulase-negative staphylococci, gram-negative bacteria, Staph. aureus, and Candida species.


Clinical Presentation



Diagnostic Evaluation



  • Two quantitative blood cultures, with at least one drawn peripherally.


  • Qualitative blood cultures can be used with continuously monitored differential time to positivity.


  • Catheter tip cultures, CBC with differential, CRP, ESR.


  • Urine, sputum, respiratory viral cultures as indicated to evaluate for other infectious sources.


Management



  • Empiric antibiotic coverage with broad-spectrum gram-positive and gram-negative bacterial coverage with adjustment of coverage on determination of isolate’s sensitivities.


  • Consideration of central line removal with subsequent replacement of intravenous access.


Ventilator-Associated Events, Including Pneumonia



Clinical Presentation



  • Fever, leukopenia, or leukocytosis.


  • Increased respiratory secretions or change in sputum character.


  • New-onset or worsening apnea, tachypnea, dyspnea, wheezing, rales, rhonchi, cough, bradycardia, oxygenation.


  • Two or more serial chest radiographs with new or progressive and persistent infiltrate, consolidation, cavitation, or pneumatoceles (in infants <1 year of age).




Diagnostic Evaluation



  • Chest radiography.


  • CBC with differential, CRP, ESR.


  • Blood and bacterial cultures, and Gram staining from endotracheal aspirate.


  • Bronchoalveolar lavage, using protected-specimen brush collection specimen.


  • Pleural fluid or lung biopsy.


  • Evaluation for viral etiology with respiratory viral culture/viral panel.


Management



  • Increase oxygen and other ventilator settings.


  • Hemodynamic support, as indicated support.


  • Broad-spectrum antibiotic administration.


Catheter-Associated Urinary Tract Infection



Etiology/Types



  • Symptomatic UTI; asymptomatic bacteriuria.


Common Causative Organisms



  • E. coli, P. aeruginosa, Candida species, Enterococcus species, K. pneumoniae.


Clinical Presentation



  • Fever.


  • Urinary urgency, frequency, dysuria.


  • Costovertebral pain or suprapubic tenderness.


  • Associated with a positive urine culture, pyuria, positive dipstick for leukocyte esterase and/or nitrate.


  • Infants may present with hypothermia, apnea, bradycardia, lethargy, vomiting.


  • See www.cdc.gov/nhsn/PDFs/pscManual/17pscNosInfDef_current.pdf for delineation of CDC catheter-associated urinary tract infection criteria.


Diagnostic Evaluation



  • UA and urine culture with Gram stain.


  • CBC with differential, CRP.


Management



  • Antibiotic administration.


  • Analgesia and higher-level support if urosepsis.


Nosocomial Respiratory Syncytial Virus



Background



  • RSV is one of the most common etiologies of pediatric nosocomial respiratory tract infections in the pediatric intensive care unit (PICU) and is the most common nosocomial infection overall on pediatric wards.


  • Incubation period ranges from 2 to 8 days; median hospitalization for RSV disease is approximately 5 days; 10 days for nosocomial RSV disease.


  • Children with underlying morbidities and risk for severe disease, increased risk for prolonged hospitalization, and risk for mortality.


  • Hand washing and barrier devices are greatest tools in disease transmission prevention.


  • For more information, see RSV bronchiolitis in Section 3.


Surgical Site Infection



Etiology/Types



  • Superficial incisional primary or secondary SSI.


  • Deep incisional primary or secondary SSI.


  • Organ/space SSI.


Common Causative Organisms (Pediatrics)



  • Staph. aureus, coagulase-negative staphylococci, P. aeruginosa.


Clinical Presentation



Diagnostic Evaluation



  • Wound culture or tissue biopsy.


  • CBC with differential, ESR, CRP.


  • Radiography, magnetic resonance imaging (MRI), CT, as indicated.


Management



  • Antibiotic administration.


  • Surgical drainage (include cultures).


  • Implant removal, as indicated.


Invasive Fungal Infections in Pediatric Patients: Aspergillus, Mucor, and Pneumocystis

Daniel K. Choi



Etiology/Types



  • Three major groups of fungus.



    • Yeasts: round/oval, unicellular, and reproduce via budding. Examples include the Candida species.


    • Molds: long, floppy, fluffy colonies that have long tubular structures called hyphae. Reproduce by forming spore-forming structures called conidia. Examples include Aspergillus and Mucor species.


    • Dimorphs: change from yeast to mold and back, and grow in environment as molds.


  • Fungus is ubiquitous in the environment, preferring warm/damp environments to grow/reproduce (e.g., respiratory tract, endotracheal tubes, plastic in central venous catheters).



Clinical Presentation



  • Skin rashes.


  • Persistent fever in an immunocompromised patient.


  • In the oncology population, fever for >4 days in a neutropenic patient is suggestive of fungal infection.


  • Persistent cough and/or other sinopulmonary symptoms.


  • Purulent sinusitis/sinus pain is suggestive of Mucor infection.


  • Persistent tachypnea and lower oxygen saturations are suggestive of Pneumocystis jirovecii pneumonia (formerly known as Pneumocystis carinii pneumonia [PCP]) infection.


  • Patients often appear asymptomatic.


Diagnostic Evaluation



  • Blood culture, urine culture; specify the specimen for fungal culture as well, as it is not universal across institutions.



    • Note that fungal cultures often take days to start growing.


  • Samples should have calcofluor white testing (formerly ordered as KOH) to test for yeast elements.


  • Suspicion for Pneumocystis jirovecii/P. carinii pneumonia can be tested via silver staining, confirmed by PCR testing.


  • Biopsy-proven infection is the gold standard, but is often difficult to obtain (except for skin biopsies).



    • Respiratory tract biopsies can be done via bronchoalveolar lavage, surgical biopsy, induced sputum culture, endotracheal tube culture.


  • Candida species will grow from urine and blood cultures.


  • Chest radiograph with diffuse “fluffy” infiltrates is suggestive of Pneumocystis jirovecii/P. carinii pneumonia.


  • CT of the sinuses/chest/abdomen/pelvis with contrast often indicated.



    • Fungal imaging varies widely, from single nodules to diffuse/necrotic tissue.


  • In some instances, MRI of the soft tissue is indicated.


  • Galactomannan antigen testing is helpful for Aspergillus species, but has variable sensitivity and specificity; must be interpreted with caution.


Management



  • Consultation with a pediatric infectious disease specialist is indicated.


  • Broad-spectrum coverage for invasive fungal infections is usually with an IV formulation of an echinocandin (e.g., micafungin) or polyene class (e.g., amphotericin B).


  • Azoles (e.g., voriconazole) do have activity against invasive species, although often have multiple drug interactions.


  • In localized Mucor infection, aggressive debridement (particularly in the sinuses) is indicated to prevent CNS extension.


  • For confirmed PCP infection, treatment with IV trimethoprim-sulfamethoxazole (i.e., Bactrim). For patients who cannot tolerate trimemethoprim-sulfamethoxazole, IV pentamidine is another option.


  • Treatments are often for a minimum of 6 to 8 weeks, and longer as needed under the supervision of pediatric infectious disease specialist.



  • Trimethoprim-sulfamethoxazole prophylaxis should strongly be considered for patients who are at risk for continued immunosuppression.


Viral and Bacterial Infections

Jill S. Thomas


Multidrug-Resistant Organisms



  • Increased prevalence of microorganisms resistant to one or more antimicrobial agents in the acute care setting leads to increased length of stay, mortality, and hospital costs.


  • Have created management challenges due to limited antibiotic selection and limited new antibiotic development.


  • Requires commitment to antibiotic stewardship by health care providers (Table 11.5).


Meningococcemia

Elizabeth Rosner



Etiology



  • N. meningitidis is an encapsulated, gram-negative, oxidase-positive diplococcus.


  • Five clinically important serotypes are A, B, C, W-135, and Y.



    • W-135 accounts for approximately 75% of invasive disease in the United States.


    • Serotype B accounts for the majority of disease in infants <1 year of age.








TABLE 11.5 Multiresistant Organisms







































Name


Definition


Clinical Presentation


Diagnoses


Management


Methicillin-resistant Staph. aureus (MRSA)


Strains of Staph. aureus resistant to β-lactams, found in community and health care settings.


Skin and soft tissue infections, wounds, bacteremia, pneumonia, osteomyelitis, and sepsis.


Blood and/or fluid culture.


Vancomycin, clindamycin, trimethoprim-sulfamethoxazole, linezolid.


Drug-resistant Strep. pneumoniae (DRSP)


Pneumococcal infections resistant to β-lactams; found in community and health care settings.


Otitis media, sinusitis, pneumonia, and bacteremia.


Culture of primary site and blood culture.


Vancomycin, clindamycin, high-dose β-lactam, and fluoroquinolones.


Vancomycin-resistant enterococcus (VRE)


Any bacteria belonging to the genus Enterococcus resistant to vancomycin and often resistant to ampicillin.


UTI, intra-abdominal infections, and nosocomial infections.


Culture of primary site and blood culture with Gram stain.


Linezolid or daptomycin.


H. influenzae, nontypable


Community-acquired pathogen. Intrinsic efflux resistance mechanisms of the nontypable strain limit the activity of macrolides, azolides, and ketolides.


Otitis media, sinusitis, pneumonia.


Culture of primary site, blood culture with Gram stain.


Amoxicillin-clavulanate, extended-spectrum cephalosporins.


Extended-spectrum β-lactamase (ESBL) producing E. coli and K. pneumoniae


Plasmid mediated enzymes capable of inactivating a variety of β-lactams, including penicillins, third-generation cephalosporins, and aztreonam.


ESBLs are commonly found in E. coli and K. pneumoniae; however, may be found in other gram-negative pathogens.


UTIs, nosocomial infections.


Culture of primary site and blood culture with susceptibility.


Broad-spectrum antibiotics. Treatment options include carbapenems.





Clinical Presentation



  • Initially may present with nonspecific symptoms of fever, malaise, vomiting, diarrhea, headache, and myalgias.


  • Later symptoms include limb pain, difficulty walking, maculopapular rash, signs of meningitis, including photophobia, nuchal rigidity, lethargy, and seizures.


  • In fulminant meningococcemia, purpura, limb ischemia, shock, coma, and death can occur in as little as a few hours (Figure 11.1).


Diagnostic Evaluation



  • Blood and CSF cultures identifying N. meningitidis are the definitive diagnosis.



    • May not be able to obtain CSF in unstable patients.


  • PCR from the blood and CSF can also be used to detect the organism.


  • CBC, coagulation studies, and blood gas analysis should also be obtained.






FIGURE 11.1 • Meningococcemia. Gangrene in a child with sepsis from acute meningococcemia.


Management



  • Intravenous ceftriaxone at meningitic doses (100 mg/kg/day) as soon as possible for 5 to 7 days.



    • Cefotaxime is also acceptable.


    • Once the organism has been identified, it may be acceptable to switch to penicillin G.


    • In a penicillin-allergic patient, use either chloramphenicol or meropenem.


  • Fluid resuscitation up to and beyond 60 mL/kg as fast as possible until perfusion improves.


  • Hemodynamic support with agents such as dopamine, epinephrine, and/or norepinephrine may be necessary for fluid-refractory shock.


  • Correct for metabolic and electrolyte derangements.


  • Intubation and mechanical ventilation for severe shock, sepsis, and subsequent multiple organ dysfunction, especially acute respiratory distress syndrome (ARDS).


  • Treatment of seizures with antiepileptics, as indicated.



Sexually Transmitted Infections

Jill S. Thomas


Sexually Transmitted Infections



  • Sexually transmitted infections (STIs) refer to a variety of clinical syndromes caused by pathogens that can be acquired and transmitted through sexual activity.


  • Part of the management of any patient with an STI is counseling about prevention and referral of partner.



Herpes Simplex Virus (HSV)



Etiology/Types



  • HSV-1.


  • HSV-2: believed to cause the majority of genital HSV infections.


Clinical Presentation



  • Asymptomatic or may have vesicular lesions, ulcers, leucorrhea, dysuria, inguinal adenopathy.


Diagnostic Evaluation



  • Viral cell culture.


  • PCR (greater sensitivity than viral cultures).


  • HSV type-specific serological assay.


Management



  • Antiviral therapy with acyclovir, famciclovir, or valacyclovir.


  • Length of therapy dependent on initial presentation or recurrence of infection.


Gonorrhea



Clinical Presentation



  • General: urinary frequency, urgency, and burning with urination.


  • Females: may have inflammation of the Bartholin and Skene glands, cervical mucoid discharge, or may remain asymptomatic until complications occur.


  • Males: penile discharge.


Diagnostic Evaluation



  • Test endocervical, vaginal, urethral (male only), and urine specimens.


  • Bacterial culture with Gram stain, nucleic acid hybridization tests, and nucleic acid amplification tests (NAATs) detect N. gonorrhoeae.


  • Culture and antimicrobial susceptibility testing if treatment failure is suspected.


  • Evaluate for other STIs, including chlamydia, syphilis, and HIV.


Management



  • Intramuscular ceftriaxone plus azithromycin or doxycycline.



Chlamydia



Etiology/Types



  • Chlamydia trachomatis.


Clinical Presentation



  • Asymptomatic infection common among men and women.


  • Women may present with vaginitis, urethritis, cervicitis, endometriosis, salpingitis, PID. May experience vaginal discharge or dysuria.


Diagnostic Evaluation



  • Urine, endocervical, vaginal, urethral (men), rectal, and oropharyngeal swabs.


  • NAATs are the test of choice.


  • Cell culture, direct immunofluorescence, enzyme immunoassay (EIA), and nucleic acid hybridization tests available for endocervical specimens.


  • Urethral swab specimens from men.


  • U.S. Preventive Services Task Force recommends routine chlamydia screening for all women ≤25 years of age who are sexually active.



Management



  • Azithromycin or doxycycline as per CDC recommendations.



Syphilis



Etiology/Types



  • Primary: develops 10 to 90 days after exposure.


  • Secondary: develops 4 to 10 weeks after primary infection.


  • Tertiary: develops 2 to 19 years after primary infection in untreated individuals.


Clinical Presentation



  • Primary: presents with an ulcer or painless chancre at the infected site.


  • Secondary: myalgias, mucocutaneous lesions, lymphadenopathy, influenza-like symptoms, cranial nerve dysfunction, altered mental status, or skin rash involving soles of the feet and palms of the hands.


  • Tertiary: cardiac or gummatous lesions.


  • Latent infections lack clinical symptoms.


Diagnostic Evaluation



  • Darkfield examinations and direct fluorescent antibody (DFA) detection of T. pallidum in lesion exudate or tissue are the definitive methods for diagnosing early syphilis.


  • Dual serological testing using a nontreponemal test (Venereal Disease Research Laboratory and rapid plasma reagin tests) and treponemal test (fluorescent treponemal antibody absorption tests, the Treponema pallidum passive particle agglutination assay, EIA), study of choice for latent, secondary, and tertiary syphilis.

Jan 30, 2021 | Posted by in NURSING | Comments Off on Infectious Disorders
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