Week 36: Infectious Disease – Bacterial, et al

Up to 30% of meningococcemia patients will present with this picture and no immediate evidence of meningitis or sepsis.

Antibiotics should not be held while waiting for a lumbar puncture. There have been multiple studies looking at antibiotics effects of lumbar puncture results.  Here is a link to 3 articles looking at this.

Dexamethasone should also be started as it decreases neurological complications from step pneumoniae meningitis.

Botulism presents as a descending paralysis/anticholinergic syndrome. Autonomic dysfunction with orthostatic hypotension is common. Ileus and urinary retention may occur. Antitoxin, intensive care unit admission, and early intubation are often indicated.

Localized tetanus reflects a local neuromuscular process with pain and spasm. It is likely due to a partial immunity. Immune globulin is indicated. Although mortality is lower, it can progress to generalized tetanus, and admission is warranted.

HTIG prophylaxis (250 units IM) is recommended for unimmunized and underimmunized patients with wounds at high risk for tetanus (>6 hours old, >1 cm deep, contaminated, stellate, denervated, ischemic, infected).²⁷ When tetanus toxoid and HTIG are given concurrently, separate injection sites should be used. The only contraindication to tetanus and diphtheria toxoids is a history of a neurologic or severe hypersensitivity reaction to a previous dose. Adverse reactions to tetanus toxoid and tetanus-diphtheria toxoids occur commonly and may be the result of the preservative thimerosal. The most common side effects are minor: local swelling, pain, erythema, pruritus, fever, nausea, vomiting, malaise, and nonspecific rash.

The surgical dressing must be removed to ensure there is no nasal packing or other foreign body present that could serve as a precipitant of toxic shock syndrome (fever, hypotension, diffuse erythroderma, multisystem organ dysfunction). Toxic shock syndrome is commonly associated with postsurgical dressings as well as vaginal foreign bodies (classically, extended-use tampons). Toxic shock syndrome toxin-1 (TSST-1) producing strains of S. aureuscause the infection, with the toxin serving as a superantigen that leads to overstimulation of T-lymphocytes and subsequent massive, unregulated cytokine release. Patients often report a prodrome of flu-like symptoms including headache, myalgias, vomiting, and diarrhea.

Antibiotics (A) prevent recurrence but do not affect the outcome of the acute illness. However, starting an antistaphylococcal antibiotic early is standard practice. There is evidence that the addition of clindamycin or linezolid offers an additional benefit of decreasing production of TSST-1. A wound culture (C) has limited utility in this scenario. A blood culture may be useful but should be obtained after the nidus of infection is removed. All diagnostic testing, including imaging (B), should be performed after searching for and removing the likely source of toxin.

The two most important ancillary tests in the evaluation of fever in the adult patient, and especially in elder patients who frequently have atypical presentations, are urinalysis and chest radiography. Chest radiographs are often helpful in the diagnosis of pulmonary infection but may be difficult to interpret in the patient with chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), or other chronic lung disease. The urinalysis, although not foolproof, is highly accurate for urinary tract infection, especially in men. Although the white blood cell count is almost universally used in the evaluation of febrile patients, it lacks sensitivity and specificity to be of discriminatory value. Cultures are ordered in selected patients; however, the delay in obtaining results precludes any influence in emergency evaluation and treatment. Other tests that have relevance in select patients with fever include Gram’s stain, cerebrospinal fluid (CSF) analysis, thyroid function studies, ultrasonography, and computed tomography (CT) of the abdomen or head.

Most cases of necrotizing fasciitis are caused by polymicrobial infection with gram-negative, gram-positive, andanaerobic bacteria. Commonly identified organisms include S. aureus, beta-hemolytic streptococci, enterococci, enterobacteria, and anerobes such as Bacteroides and Clostridium species. Necrotizing fasciitis is characterized by deep tissue infection involving subcutaneous fat, fascia, and muscle layers, as opposed to cellulitis, where infection does not extend past the dermal layer. Infection may begin by direct bacterial invasion of subcutaneous tissue via breaks in the skin from an abscess or wound, or via spread from a perforated viscous such as colon, rectum, or anus. The hallmark of necrotizing fasciitis is pain out of proportion to physical exam. Early recognition is critical as necrotizing fasciitis is rapidly progressive and has a high mortality rate. General surgery should be consulted as soon as necrotizing fasciitis is suspected. It is treated with surgical debridement, intravenous broad-spectrum antibiotics, and hemodynamic support.

Necrotizing fasciitis of the perineal, perianal, or scrotal is called Fournier’s gangrene.

Sepsis affects both myocardial function and peripheral vascular tone. The systemic vascular resistance is usually markedly depressed. Cardiac output is generally increased because of a compensatory tachycardia that can at least partially overcome the ventricular dilation and depressed ejection fraction. The myocardial effects are typically reversible.

The febrile neonate is a child 28 days and younger who presents with a fever. These children are at very high risk of serious bacterial infections including urinary tract infection, pneumonia, meningitis, and bacteremia. Risk factors for serious bacterial infection in a neonate include prematurity, low birth weight, premature or prolonged rupture of membranes, meconium aspiration, or maternal group B streptococcus infection. The evaluation of a neonate with a fever includes CBC, urinalysis, blood culture, urine culture, and a lumbar puncture in order to obtain CSF for cell count, gram stain, and culture. If the child has respiratory symptoms, a chest X-ray should be performed. If the child has diarrhea, stool testing should also be performed. The most common pathogens involved in serious bacterial infections, including meningitis and bacteremia, in neonates are Listeria monocytogenes, Group B streptococcus, and Escherichia coli. These children can become critically ill very rapidly; therefore, initial management should include a fluid bolus of 20 mL/kg and broad-spectrum antibiotics to cover for the most common pathogens in this age group. The most appropriate antibiotics to use in neonates with a fever are ampicillin and cefotaxime. Ampicillin will cover Listeria monocytogenes while cefotaxime will cover Group B streptococcus and Escherichia coli. If there is a history of maternal infection with herpes simplex virus, acyclovir should be added to the empiric broad-spectrum treatment. These patients universally need to be admitted to the hospital for IV antibiotics and observation until all cultures have returned.

Most cases of necrotizing fasciitis are caused by polymicrobial infection with gram-negative, gram-positive, andanaerobic bacteria. Commonly identified organisms include S. aureus, beta-hemolytic streptococci, enterococci, enterobacteria, and anerobes such as Bacteroides and Clostridium species. Necrotizing fasciitis is characterized by deep tissue infection involving subcutaneous fat, fascia, and muscle layers, as opposed to cellulitis, where infection does not extend past the dermal layer. Infection may begin by direct bacterial invasion of subcutaneous tissue via breaks in the skin from an abscess or wound, or via spread from a perforated viscous such as colon, rectum, or anus. The hallmark of necrotizing fasciitis is pain out of proportion to physical exam. Early recognition is critical as necrotizing fasciitis is rapidly progressive and has a high mortality rate. General surgery should be consulted as soon as necrotizing fasciitis is suspected. It is treated with surgical debridement, intravenous broad-spectrum antibiotics, and hemodynamic support.

Necrotizing fasciitis of the perineal, perianal, or scrotal is called Fournier’s gangrene.

That’s correct!

Sepsis is defined as meeting systemic inflammatory response criteria (SIRS) plus a suspected infection. Severe sepsis is sepsis plus organ dysfunction. Septic shock is sepsis plus hypotension not responsive to a fluid challenge. This patient has SIRS (elevated heart rate and elevated temperature), renal dysfunction (new creatinine elevation), but a normal blood pressure; thus, he meets the definition for severe sepsis.