Forms Of Bacterial Infections
Bacteria are associated with many illnesses and conditions. Some of the more common ones are listed below.
Upper respiratory tract infections. Upper respiratory tract infections are a leading cause of time lost from work and school (Madoff 2004). Bacteria account for up to 25% of upper respiratory tract infections. Group A streptococci are responsible for 95% of the cases of strep throat in the United States (Goldmann 2003; O'Brien 2002). Strep throat is most common in children and adolescents (aged 3 years to 18 years). Other pathogens include Haemophilus influenzae (Echave 2003; Robinson 2001).
Otitis media. Middle ear infections are the most common bacterial infections in children in the United States. By the age of 3 years, two-thirds of American children have had at least one episode of otitis media, and the other third has had three or more episodes. S. pneumoniae is the most frequent cause (Leibovitz 2004).
Lower respiratory tract infections. Common lower respiratory tract infections include acute, chronic, and health care–associated pneumonia and bronchitis (Garcia Ordonez 1999; Hedlund 1995). S. pneumoniae is the most frequent cause of community-acquired lung infections and pneumonia. Lower respiratory tract infections can occur in both healthy and immunocompromised individuals.
Tuberculosis (TB). An estimated 15 million people in the United States are infected with Mycobacterium tuberculosis (Dai 1998; Skamene 1991). Of these, however, far fewer will actually develop clinically evident disease. Whether TB infection will progress to disease depends on a person's nutritional status. TB occurs disproportionately in poorer populations. Infection is more likely to occur in people aged 15 to 25 years, those older than age 60 years, people with HIV, or people who have been incarcerated for longer than 6 months (Fleischmann 2002). In prisons in particular, overcrowding and the frequent movement of prisoners between cells is a factor in the spread of infection (Lobacheva 2005). It is important to note that the antibiotics used as first-line treatments in TB, such as Isoniazid, are known to cause vitamin B6 deficiencies (NIH 2005).
Infectious diarrhea is a leading cause of morbidity and mortality worldwide (Marignani 2004; Reinert 1993). In the United States, 100 million people are affected by acute diarrhea every year. Most diarrhea is viral (not bacterial) in origin, but bacteria remain an important cause. Nearly half of patients with acute diarrhea must restrict activities, 10% consult physicians, 250,000 require hospitalization, and approximately 3000 die. Common bacterial pathogens that cause diarrhea include Campylobacter species, Salmonella, Shigella, and E. coli O157:H7.
Campylobacter jejuni. Campylobacter jejuni (C. jejuni) is the most common cause of bacterial diarrhea in the United States. The Centers for Disease Control and Prevention (CDC) estimates that more than 1 million Americans are affected yearly. Previously, most cases of bacterial diarrhea were caused by Salmonella, but the increased use of antibiotics in poultry- and cattle-feed has been linked to the increasing incidence of drug-resistant C. jejuni (Butzler 2004; Moore 2005; Takkinen 2003). Transmission is via exposure to contaminated food (especially chicken) and water, or contact with infected animals (especially cats and puppies) (Kasper 2004).
Salmonella. Salmonellosis is the second most frequent cause of bacterial disease in the United States. In 2002, more than 44,000 cases were reported to the CDC. Mild infections often are undiagnosed or unreported, so incidence may be 30 or more times greater than reported (Gold 2000). Infections with Salmonella species include diarrhea, fever, and abdominal cramps (Murray1998). The elderly, infants, and people with impaired immune systems are at greater risk of severe disease. Transmission is via exposure to contaminated food (especially eggs) or water, or contact with infected animals (reptiles) (Conte 2002; Howard1994).
Shigella. Shigella species infection causes a watery or bloody diarrhea with abdominal pain, fever, and malaise. An estimated 448,240 cases occur in the United States yearly. Groups at highest risk in the United States are children in child care centers, individuals in custodial institutions, and international travelers (Gold 2000; Madoff 2004).
Escherichia coli O157:H7. E. coli O157:H7 is associated with a severe diarrheal disease called hemolytic uremic syndrome. It has caused several nationally prominent outbreaks of food poisoning. An estimated 73,000 cases are reported in the United States annually (Conte 2002). Transmission is through contaminated hamburger meat, apple cider, and fruits and vegetables (Madoff 2004).
Helicobacter pylori. Helicobacter pylori (H. pylori) is the most common chronic infection in humans (Basso 2004; Go 2002). Acute infection causes abdominal pain, weight loss, nausea, and vomiting. H. pylori is the major cause of gastritis and peptic ulcers in adults and children (Zambon 2002). H. pylori impairs absorption of nutrients, altering the balance of iron, vitamin B12, folic acid, alpha-tocopherol, vitamin C, and beta-carotene.
Skin infections include impetigo, boils, carbuncles, cellulitis, and complications from burns (Gelfand 1984; Gold 2000). Common pathogens include Staphylococcus aureus, group A streptococci, and Pseudomonas aeruginosa (Baggett 2004; Toshkova 2001; Wysocki 2002). Impetigo, a skin infection caused mostly by group A streptococci, can cause severe kidney inflammation, sometimes resulting in kidney failure.
Health Care–Associated Infection
Hospital-acquired and health care–related infections are an increasing threat to patient safety and health in the United States (Weinstein 1991; Weinstein 1998). In the United States, infections encountered in the hospital or a health care facility affect more than 2 million patients, cost $4.5 billion, and contribute to 88,000 deaths in hospitals annually (Malone 2002; Tasota 1998).
Urinary tract infections (UTIs) are the most common, followed by pneumonias, skin and soft tissue infections, and invasive bloodstream infections. Surgical wound infections account for 20% to 30% of cases, but contribute to as many as 57% of extra hospital days and 42% of extra costs. Staphylococcus epidermidis, S. aureus, Enterococcus faecium, Enterococcus faecalis, E. coli, Enterobacter species, and P. aeruginosa are common pathogens in wound infections (Goldmann 1996; Weinstein 1991).