Harrison's Internal Medicine Chapter 132. Infections Caused by Listeria monocytogenes
Infections Caused by Listeria monocytogenes: Introduction
Listeria monocytogenes is a food-borne pathogen that can cause serious infections, particularly in pregnant women and immunocompromised individuals. A ubiquitous saprophytic environmental bacterium, L. monocytogenes is also a pathogen with a broad host range. Humans are probably accidental hosts for this microorganism. L.
The innate and acquired immune responses to L. monocytogenes have been studied extensively in mice. Shortly after IV injection, most bacteria are found in Kupffer cells in the liver, with some organisms in splenic macrophages. Listeriae that survive the bactericidal activity of initially infected macrophages grow in the cytosol and spread from cell to cell. In the liver, the result is infection of hepatocytes. Neutrophils are crucial to host defense during the first 24 h of infection, while influx of activated macrophages from the bone marrow is critical subsequently.
Tham khảo sách 'respiratory disease and infection - a new insight http edited by bassam h. mahboub and mayank vats', y tế - sức khoẻ, y học thường thức phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả
Adaptive immune responses (it takes them days to respond to a primary invasion)
such as infection by any pathogen, lead to production of antibodies and cell-mediated
responses which recognize foreign pathogens and destroy them as a function of
specific immune cell types. The response to a second round of infection is often more
rapid than to the primary infection because of the activation of memory B and T cells.
Harrison's Internal Medicine Chapter 82. Infections in Patients with Cancer
Infections in Patients with Cancer: Introduction Infections are a common cause of death and an even more common cause of morbidity in patients with a wide variety of neoplasms. Autopsy studies show that most deaths from acute leukemia and half of deaths from lymphoma are caused directly by infection. With more intensive chemotherapy, patients with solid tumors have also become more likely to die of infection.
Harrison's Internal Medicine Chapter 138. Moraxella Infections
The gram-negative coccus Moraxella catarrhalis is a component of the normal bacterial flora of the upper airways and has been increasingly recognized as a cause of otitis media, sinusitis, and bronchopulmonary infection. Over the past several decades, this organism has been variously designated as Micrococcus catarrhalis, Neisseria catarrhalis, and Branhamella catarrhalis.
Bacteriology and Immunity
On Gram's staining, M.
Harrison's Internal Medicine Chapter 127. Treatment and Prophylaxis of Bacterial Infections
Treatment and Prophylaxis of Bacterial Infections: Introduction
The development of vaccines and drugs that prevent and cure bacterial infections was one of the twentieth century's major contributions to human longevity and quality of life. Antibacterial agents are among the most commonly prescribed drugs of any kind worldwide. Used appropriately, these drugs are lifesaving.
The diagnosis of diphtheria is based on clinical signs and symptoms plus laboratory confirmation. Respiratory diphtheria should be considered in patients with sore throat, pharyngeal exudates, and fever. Other symptoms may include hoarseness, stridor, or palatal paralysis. The presence of a pseudomembrane should prompt consideration of diphtheria. Once a clinical diagnosis of diphtheria is made, diphtheria antitoxin should be administered as soon as possible.
Laboratory diagnosis is based either on cultivation of C. diphtheriae or toxigenic C.
Nosocomial and Device-Related Infections The fact that 25–50% or more of nosocomial infections are due to the combined effect of the patient's own flora and invasive devices highlights the importance of improvements in the use and design of such devices. Intensive education and "bundling" of evidence-based interventions (Table 125-2) can reduce infection rates through improved asepsis in handling and earlier removal of invasive devices, but the maintenance of such gains requires ongoing efforts.
The epidemic of mad cow disease, centered in the United Kingdom, and associated human cases of variant Creutzfeldt-Jakob disease (Chap. 378) caused by disinfection-resistant prion agents have led to revised recommendations for decontaminating surgical instruments, especially those used for operations on the central nervous system or in patients with dementing illness of unknown etiology.
The process of diagnosing and treating wound infections begins with a careful assessment of the surgical site in the febrile postoperative patient.
Vascular device–related infection is suspected on the basis of the appearance of the catheter site or the presence of fever or bacteremia without another source in patients with vascular catheters. The diagnosis is confirmed by the recovery of the same species of microorganism from peripheral-blood cultures (preferably two cultures drawn from peripheral veins by separate venipunctures) and from semiquantitative or quantitative cultures of the vascular catheter tip.
Adenovirus can be isolated from HSCT recipients at rates varying from 5 to 18%. Although hemorrhagic cystitis, pneumonia, gastroenteritis, and fatal disseminated infection have been reported, adenovirus infection, which (like CMV infection) usually occurs in the first or second month after transplantation, is often asymptomatic. A role for cidofovir therapy has been suggested, but the efficacy of this agent is unproven.
Infections with parvovirus B19 (presenting as anemia or occasionally as pancytopenia) and enteroviruses (sometimes fatal) can occur.
Harrison's Internal Medicine Chapter 139. Haemophilus Infections
Haemophilus influenzae was first recognized in 1892 by Pfeiffer, who erroneously concluded that the bacterium was the cause of influenza. The bacterium is a small (1- by 0.3-µm) gram-negative organism of variable shape; hence, it is often described as a pleomorphic coccobacillus. In clinical specimens such as cerebrospinal fluid (CSF) and sputum, it frequently stains only faintly with phenosafranin and therefore can easily be overlooked.
Hib strains cause systemic disease by invasion and hematogenous spread from the respiratory tract to distant sites such as the meninges, bones, and joints. The type b polysaccharide capsule is an important virulence factor affecting the bacterium's ability to avoid opsonization and cause systemic disease.
Nontypable strains cause disease by local invasion of mucosal surfaces. Otitis media results when bacteria reach the middle ear by way of the eustachian tube. Adults with chronic bronchitis experience recurrent lower respiratory tract infection due to nontypable strains.
The level of suspicion of infections with certain organisms should depend on the type of cancer diagnosed (Table 82-3). Diagnosis of multiple myeloma or CLL should alert the clinician to the possibility of hypogammaglobulinemia. While immunoglobulin replacement therapy can be effective, in most cases prophylactic antibiotics are a cheaper, more convenient method of eliminating bacterial infections in CLL patients with hypogammaglobulinemia.
More common than tunnel infections are exit-site infections, often with erythema around the area where the line penetrates the skin. Most authorities (Chap. 129) recommend treatment (usually with vancomycin) for an exit-site infection caused by a coagulase-negative Staphylococcus. Treatment of coagulasepositive staphylococcal infection is associated with a poorer outcome, and it is advisable to remove the catheter if possible. Similarly, many clinicians remove catheters associated with infections due to P.
Typhlitis Typhlitis (also referred to as necrotizing colitis, neutropenic colitis, necrotizing enteropathy, ileocecal syndrome, and cecitis) is a clinical syndrome of fever and right-lower-quadrant tenderness in an immunosuppressed host. This syndrome is classically seen in neutropenic patients after chemotherapy with cytotoxic drugs.
Urinary Tract Infections Urinary tract infections (UTIs) account for as many as 40–45% of nosocomial infections; up to 3% of bacteriuric patients develop bacteremia. Although UTIs contribute only 10–15% to prolongation of hospital stay and to extra costs, these infections are important reservoirs and sources for spread of antibiotic-resistant bacteria in hospitals. Almost all nosocomial UTIs are associated with preceding instrumentation or indwelling bladder catheters, which create a 3–10% risk of infection each day.
Table 125-3 Controlling Antibiotic Resistance: Approaches to Consider
Conduct surveillance for antibiotic resistance.
Perform molecular typing (e.g., pulsed-field gel electrophoresis) when rates increase.
For clonal expansion (e.g., single-strain outbreaks): Stress hand hygiene (alcohol hand rub and universal gloving); monitor adherence and give feedback.
For polyclonal expansion (e.g., multistrain outbreaks): Stress antibiotic prudence (consider antibiotic rotation for ICUs); monitor adherence and give