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Helicobacter pylori and Other Gastric Helicobacter Species

Reviewed for currency January 14, 2021 Reviewed for currency January 14, 2021 Helicobacter pylori (formerly known as Campylobacter pylori or pyloridis ) was first isolated from humans in 1982. This highly motile, curved, gram-negative rod lives within the mucus layer overlying the gastric mucosal epithelium. H. pylori is commonly found in the human stomach, and when present, it is usually the single dominant species. Essentially all…

Campylobacter jejuni and Related Species

Revised July 1, 2020 Campylobacteriosis refers to the group of infections caused by gram-negative bacteria of the genus Campylobacter. Among the most common bacterial infections of humans in all areas of the world, Campylobacter spp. cause both diarrheal and systemic illnesses and may be associated with long-term sequelae. Infection of domesticated animals with Campylobacter is widespread. The name Campylobacter is derived from the Greek campylos, meaning…

Other Pathogenic Vibrios

Vibrio species are ubiquitous in estuarine waters in the temperate zones. Plankton blooms and temperature upshifting in the spring are followed by rapid outgrowth of most vibrios. Molluscan shellfish, which are filter feeders, acquire vibrios as part of their normal microbiota during the warmer months. Shellfish contamination by these vibrios thus occurs as a consequence of the normal climate-associated changes in Vibrio prevalence in coastal waters.…

Vibrio cholerae

Cholera is an acute and often severe watery diarrheal disease that is among the most rapidly fatal infectious diseases of humans. Previously well individuals infected with Vibrio cholerae, the comma-shaped gram-negative rod that causes this disease, can die from dehydration in less than a day. Two epidemiologic features of cholera also distinguish it from other diarrheal diseases. First, cholera can appear in explosive epidemics, particularly among…

Moraxella catarrhalis, Kingella , and Other Gram-Negative Cocci

Over the past 3 decades Moraxella (Branhamella) catarrhalis has emerged as an important and common human respiratory tract pathogen. In this chapter M. catarrhalis is discussed. In addition, Kingella and other gram-negative cocci, including Neisseria other than N. meningitidis and N. gonorrhoeae , and other Moraxella , which are less common causes of human infection, are considered. Acinetobacter is discussed in Chapter 222 , and Oligella…

Neisseria gonorrhoeae (Gonorrhea)

Reviewed for currency November 8, 2020 Gonorrhea is a common bacterial infection that is transmitted almost exclusively by sexual contact or perinatally and primarily affects the mucous membranes of the urethra and cervix and, less frequently, those of the rectum, oropharynx, and conjunctivae. Ascending genital infection in women leads to endometritis and salpingitis—collectively called pelvic inflammatory disease (PID)—the predominant complication and one of the most common…

Neisseria meningitidis

Revised December, 2019 Definition and History Neisseria meningitidis (the meningococcus) is the cause of epidemic cerebrospinal fever, clusters and sporadic cases of acute bacterial meningitis, mild bacteremia to devastating septicemia, pneumonia, and, less commonly, septic arthritis, pericarditis, chronic bacteremia, conjunctivitis, epiglottitis, otitis, sinusitis, urethritis, and proctitis. Historically, half a million cases of invasive meningococcal disease occur worldwide each year, but incidence is declining owing to the…

Whipple Disease

Reviewed for currency January 14, 2021 Whipple disease (WD) is a rare systemic infectious disorder caused by the actinomycete Tropheryma whipplei. This chronic disease, first described by Whipple as “intestinal lipodystrophy,” preferentially affects middle-aged white men, who may present with weight loss, arthralgia, diarrhea, and abdominal pain. Various other clinical patterns, such as involvement of the heart, lung, or central nervous system (CNS), are frequent. In…

Erysipelothrix rhusiopathiae

Erysipelothrix rhusiopathiae is a thin, pleomorphic, nonsporulating gram-positive rod. First isolated from mice by Robert Koch in 1878 and from swine by Louis Pasteur in 1882, it was established as the etiologic agent of swine erysipelas in 1886 by Löffler and as a human pathogen in 1909 when Rosenbach isolated it from a patient with localized cutaneous lesions. Rosenbach coined the term erysipeloid to avoid confusion…

Bacillus Species and Related Genera Other Than Bacillus anthracis

Microbiology Bacteria of the genus Bacillus are well adapted to their normal environment of soil. This includes Bacillus anthracis, discussed elsewhere in this text (see Chapter 207 ). These gram-positive or gram-variable, aerobic or facultatively anaerobic, rod-shaped bacilli have rounded or squared-off ends, form endospores, tolerate extremes of temperature and moisture, and are ubiquitous. They are found in superficial lake and ocean sediment, even in deep…

Bacillus anthracis (Anthrax)

Anthrax has never been a cause of the massive loss of life associated with cholera, plague, or smallpox, but it has played a prominent role in the history of infectious diseases. While much of the industrialized world is focused on anthrax as an agent of bioterrorism, anthrax remains a significant cause of animal deaths as well as more limited numbers of human cases in much of…

Listeria monocytogenes

Definition Listeria monocytogenes is a gram-positive bacillus and zoonotic and foodborne pathogen found worldwide that causes listeriosis. Listeriosis spans the clinical spectrum from self-limited febrile gastroenteritis in immunocompetent people to more severe and invasive disease that mostly affects pregnant women, newborn infants, older adults, and individuals with cell-mediated immunodeficiencies. It is a rare but important pathogen because of the populations it infects and its high rates…

Other Coryneform Bacteria, Arcanobacterium haemolyticum, and Rhodococci

Coryneform Bacteria Other Than Corynebacterium diphtheriae Corynebacterium was proposed as a genus by Lehmann and Neumann in 1896, who derived the name from the Greek koryne, which means “club,” and bacterion, meaning “little rod.” The coryneforms are a diverse group of organisms. Corynebacterium diphtheriae serves as the type species, leading to the term diphtheroids to describe other bacteria sharing similar morphologic features. Also known as coryneform…

Corynebacterium diphtheriae (Diphtheria)

A primary series of vaccination with diphtheria toxoid affords protective immunity in children and adults. To counter the effect of waning immunity, booster doses should be administered every 10 years to older children and adults who have completed the primary vaccination series. Close contacts and Corynebacterium diphtheriae carriers should be treated with a course of antibiotics until microbiologic clearance is documented and should also undergo primary…

Streptococcus anginosus Group

The Streptococcus anginosus (milleri) group is a subgroup within the viridans-group streptococci that includes three separate streptococcal species: S. anginosus, S. constellatus, and S. intermedius. These viridans-group streptococci are part of the normal flora of the human oropharynx and urogenital and gastrointestinal tracts, but tend to be more virulent than other viridans streptococci and are known to cause serious infections. Microbiologically, members of this group are…

Viridans Streptococci, Nutritionally Variant Streptococci, and Groups C and G Streptococci

Overview The viridans group streptococci (VGS) are a diverse group of organisms and are the predominant microbiota in the oropharynx and gastrointestinal (GI) tract. The viridans streptococci cause a significant percentage of all cases of infective endocarditis (IE). Streptococcus mutans is responsible for dental caries. Several typing schemes for the VGS have been proposed. There are at least 30 recognized species of VGS, which are classified…

Streptococcus agalactiae (Group B Streptococci)

Reviewed for currency January 14, 2021 Historical Perspective Group B streptococci (GBS; Streptococcus agalactiae ) were reported as human pathogens in 1938 by Fry, who described three cases of fatal puerperal sepsis. Infections in humans were reported infrequently until the 1960s, when it became evident that disease was occurring more commonly. By the 1970s, GBS emerged as the predominant pathogens causing septicemia and meningitis in neonates…

Enterococcus Species, Streptococcus gallolyticus Group, and Leuconostoc Species

Revised January 7, 2021 Historical Background The first time that the term entérocoque was used appears to have been in an article in the French literature in 1899. The article was referring to a diplococcus found in the gastrointestinal (GI) tract that had the potential to become pathogenic for humans. The first clinical and pathologic description of an enterococcal infection was published the same year (1899)…

Streptococcus pneumoniae

Revised July 1, 2020 Long recognized for causing asymptomatic colonization and as a prominent cause of pneumonia, bacteremia, meningitis, sinusitis, and otitis media, Streptococcus pneumoniae is likely the most common cause of serious bacterial respiratory infection in both children and adults worldwide. Antimicrobials and vaccines have substantially reduced the incidence of, and morbid outcomes from, pneumococcal infection. However, acquisition of antibiotic resistance, the more limited impact…

Nonsuppurative Poststreptococcal Sequelae: Rheumatic Fever and Glomerulonephritis

Reviewed for currency November 8, 2020 Rheumatic Fever Acute rheumatic fever (ARF) is a disease characterized by nonsuppurative inflammatory lesions involving primarily the heart, joints, subcutaneous tissues, and central nervous system. In its classic form, ARF is acute, febrile, and largely self-limited. However, damage to heart valves may occur, and such damage may be chronic and progressive and lead to severe cardiac failure, total disability, and…