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Clostridium difficile Infection

Clostridium difficile infection ( CDI ), also known as pseudomembranous colitis or C. difficile –associated diarrhea, refers to gastrointestinal (GI) colonization with C. difficile resulting in a diarrheal illness. It is a common cause of antibiotic-associated diarrhea and the most common cause of healthcare-associated infections in the United States, accounting for 12% of these infections. An increase in inpatient and outpatient acquisition of CDI has been…

Tetanus (Clostridium tetani)

Etiology Tetanus is an acute, spastic paralytic illness caused by a neurotoxin produced by Clostridium tetani. Thus, tetanus can be considered more as a toxin-mediated process than an acute infectious process, since there are few, if any, symptoms elicited by the presence of replicating microorganisms or host inflammatory response. Unlike other pathogenic clostridia species, C. tetani is not a tissue-invasive organism and instead causes illness through…

Botulism (Clostridium botulinum)

There are 3 naturally occurring forms of human botulism, characterized by mode of acquisition: infant botulism (intestinal toxemia), foodborne botulism , and wound botulism . Infant botulism is the most common form in the United States. Under rare circumstances of altered intestinal anatomy, physiology, and microflora, older children and adults may contract infant-type botulism ( adult intestinal toxemia ).Two other forms, both human-made, also occur: inhalational…

Bartonella

The spectrum of disease resulting from human infection with Bartonella species includes the association of bacillary angiomatosis and cat-scratch disease with Bartonella henselae. There are more than 30 validated species of Bartonella , but 6 major species are responsible for most human disease: B. henselae, B.quintana, B. bacilliformis, B. elizabethae, B. vinsonii, and B. clarridgeiae ( Table 236.1 ). The remaining Bartonella spp. have been found…

Legionella

Legionellosis comprises legionnaires disease ( Legionella pneumonia), other invasive extrapulmonary Legionella infections, and an acute flulike illness known as Pontiac fever. In contrast to the syndromes associated with invasive disease, Pontiac fever is a self-limited illness that develops after aerosol exposure and may represent a toxic or hypersensitivity response to Legionella. Etiology Legionellaceae are aerobic, non–spore-forming, nonencapsulated, gram-negative bacilli that stain poorly with Gram stain when…

Brucella

Human brucellosis is caused by organisms of the genus Brucella and continues to be a major public health problem worldwide. Humans are accidental hosts and acquire this zoonosis from direct contact with an infected animal (cattle, sheep, camels, goats, and pigs) or consumption of products of an infected animal. Although brucellosis is widely recognized as an occupational risk among adults working with livestock, much of the…

Tularemia (Francisella tularensis)

Tularemia is a zoonosis caused by the gram-negative bacterium Francisella tularensis. Tularemia is primarily a disease of wild animals; human disease is incidental and usually results from tick or deer fly bites or contact with infected live or dead wild animals. The illness caused by F. tularensis is manifest by multiple clinical syndromes, the most common consisting of an ulcerative lesion at the site of inoculation…

Pseudomonas, Burkholderia, and Stenotrophomonas

Pseudomonas aeruginosa Thomas S. Murray Robert S. Baltimore Keywords bacteremia biofilm burn wound sepsis conjunctivitis cystic fibrosis ecthyma gangrenosum immunosuppressed neutropenia urinary tract infection ventilator-associated pneumonia Etiology Pseudomonas aeruginosa is a gram-negative rod and is a strict aerobe. It can multiply in a great variety of environments that contain minimal amounts of organic compounds. Strains from clinical specimens do not ferment lactose, are oxidase positive, and may produce…

Aeromonas and Plesiomonas

Aeromonas and Plesiomonas are gram-negative bacilli that include species capable of causing enteritis and, less frequently, skin and soft tissue infections and invasive disease. They are common in fresh water and brackish water and colonize animals and plants in these environments. Aeromonas Ameneh Khatami Adam J. Ratner Etiology Aeromonas is a member of the Aeromonadaceae family and includes 2 major groups of isolates: the nonmotile psychrophilic organisms that…

Yersinia

The genus Yersinia is a member of the family Enterobacteriaceae and comprises more than 14 named species, 3 of which are established as human pathogens. Yersinia enterocolitica is by far the most common Yersinia species causing human disease and produces fever, abdominal pain that can mimic appendicitis, and diarrhea. Yersinia pseudotuberculosis is most often associated with mesenteric lymphadenitis. Yersinia pestis is the agent of plague and…

Campylobacter

Campylobacter , typically Campylobacter jejuni and Campylobacter coli , are found globally and are among the most common causes of human intestinal infections. Clinical presentation varies by age and underlying conditions. Etiology Twenty-six species and 9 subspecies of Campylobacter are recognized (as of December 2014). Most of these have been isolated from humans, and many are considered pathogenic. The most significant of these are C. jejuni…

Cholera

Cholera is a dehydrating diarrheal disease that rapidly leads to death in the absence of immediate initiation of appropriate treatment. Worldwide, 1.3 billion people are at risk for cholera, resulting in an estimated 1 to 4 million cases and 95,000 deaths annually. Cholera is highly prone to producing outbreaks, and the ongoing outbreaks in Yemen and Haiti emphasize how cholera and potentially other infectious diseases can…

Escherichia coli

Escherichia coli is an important cause of intraintestinal and extraintestinal infections. Intraintestinal infections present as different diarrheal illnesses. Extraintestinal infections include disease of the urinary tract (see Chapter 553 ) and bloodstream ( Chapter 129, Chapter 202, Chapter 203 ). Intraintestinal pathogenic E. coli , also called enteric E. coli , produce diarrheal diseases. E. coli causing extra- and intraintestinal infections are highly specialized with unique…

Shigella

Shigellosis , infection by Shigella species , is acute invasive enteric infection clinically manifested by diarrhea that is often bloody. The term dysentery describes a syndrome of bloody diarrhea with fever, abdominal cramps, rectal pain, and mucoid stools. Bacillary dysentery is a term often used to distinguish dysentery caused by Shigella from amebic dysentery caused by Entamoeba histolytica . Etiology Four species of Shigella are responsible…

Salmonella

Salmonellosis is a common and widely distributed food-borne disease that is a global major public health problem affecting millions of individuals and resulting in significant mortality. Salmonellae live in the intestinal tracts of warm- and cold-blooded animals. Some species are ubiquitous, whereas others are specifically adapted to a particular host. The sequencing of the Salmonella enterica serovar Typhi (previously called Salmonella typhi ) and Salmonella typhimurium…

Pertussis ( Bordetella pertussis and Bordetella parapertussis )

Pertussis is an acute respiratory tract infection; the term pertussis means “intense cough” and is preferable to whooping cough, because most infected individuals do not “whoop.” Etiology Bordetella pertussis is the cause of epidemic pertussis and the usual cause of sporadic pertussis. Bordetella parapertussis is an occasional cause of sporadic pertussis that contributes significantly to total cases of pertussis in Eastern and Western Europe, but increasingly…

Moraxella catarrhalis

Moraxella catarrhalis is an unencapsulated gram-negative diplococcus and is a human-specific pathogen that colonizes the respiratory tract beginning in infancy. Patterns of colonization and infection with M. catarrhalis are changing in countries where pneumococcal conjugate vaccines are used widely. The most important clinical manifestation of M. catarrhalis infection in children is otitis media . Etiology Moraxella catarrhalis has long been considered to be an upper respiratory…

Chancroid (Haemophilus ducreyi)

Chancroid is a sexually transmitted disease characterized by painful genital ulceration and inguinal lymphadenopathy. Etiology and Epidemiology Chancroid is caused by Haemophilus ducreyi, a fastidious gram-negative bacillus. It is prevalent in many developing countries but occurs sporadically in the developed world. Most Western cases occur in returning travelers (90% are male) from endemic areas or occasionally in localized urban outbreaks associated with commercial sex workers. Chancroid…

Haemophilus influenzae

Effective vaccines to prevent Haemophilus influenzae type b (Hib) disease, introduced in the United States and most other countries, have resulted in a dramatic decrease in the incidence of infections caused by this organism. However, mortality and morbidity from Hib infection remain a problem worldwide, primarily in developing countries. Occasional cases of invasive disease caused by non–type b organisms continue to occur but are infrequent. Nontypeable…

Kingella kingae

Kingella kingae is being increasingly recognized as the most common etiology of septic arthritis, osteomyelitis, and spondylodiscitis in young children. Etiology Kingella kingae is a fastidious, facultative anaerobic, β-hemolytic member of the Neisseriaceae family that appears as pairs or short chains of gram-negative coccobacilli with tapered ends ( Fig. 220.1 ). Epidemiology K. kingae is asymptomatically carried in the posterior pharynx. Colonization usually starts after age…