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Abbreviation for osteogenesis imperfecta.


osteogenesis imperfecta.


Abbreviation for osteogenesis imperfecta.


(in'deks?) (in'di-sez?) plural.indexes, indices [L. index, pointer]
1. The forefinger.
2. The ratio of the measurement of a given substance to that of a fixed standard.

addiction severity index

A structured assessment tool that evaluates the impact of addictive behavior on seven areas of living: alcohol use, drug use, employment, family relationships, illegal activities, physical health, and psychological health.

alveolar index

Gnathic index.

ankle-brachial index

Abbreviation: ABI
A measure of the adequacy of blood flow to the arteries of the legs. It is used to gauge the severity of peripheral vascular disease.

Patient care

The index is obtained by measuring the systolic blood pressure in the upper and lower extremities after the patient has been lying on his or her back for about 5 min and then repeating the measurements after the patient walks for 5 min. There are several ways to obtain an ABI. The most accurate test results are obtained by measuring the blood pressure in both arms using a blood pressure cuff and Doppler ultrasound and recording the higher of these two pressures. The measurement is repeated in each leg, with measurement of blood pressures at both the posterior tibial and dorsalis pedis arteries. The pressure that should be recorded is the pressure found during the first return of a pulse to the cuffed limb. The blood pressure in each leg is divided by the blood pressure in the higher pressure of the two arms to obtain an ABI for each lower extremity. An ABI above 0.9 is normal, except when it exceeds 1.3 (an indicator of severe peripheral arterial obstruction). Severe obstruction is also indicated by an ABI of less than 0.5. Moderate peripheral arterial disease is suggested by an ABI of 0.8. A drop in the ABI after exercise also strongly suggests peripheral arterial disease. Patients with mild or moderately abnormal ABIs are usually treated with antiplatelet medications, an exercise regimen, and cholesterol-lowering drugs or diet. Those who smoke are encouraged to quit. Patients with severe disease may need angiography and, in some instances, arterial bypass surgery or stenting.

apnea-hypopnea index

Abbreviation: AHI
The number of times in an hour when a sleeping person either stops breathing completely or has limited airflow. Each episode must last at least 10 sec. The AHI is one indicator of obstructive sleep apnea, although it is recognized as an imperfect diagnostic tool. An AHI of 30 or more events in an hour indicates severe sleep apnea; 15 to 29 events suggests moderate apnea; and 5 to 14 events indicates mild apnea.

Barthel index

See: Barthel index

bispectral index

Abbreviation: BIS
An electroencephalographic measure of the effect of sedative and hypnotic drugs on an anesthetized patient. It is used (along with clinical assessment of the patient) to determine the level of central nervous system depression. The index ranges from zero (completely unresponsive to stimulation) to 100 (awake and alert). At levels below 60, most patients are adequately sedated for surgery.
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body mass index

Abbreviation: BMI
An index for estimating obesity. The BMI can be obtained by dividing weight in kilograms by height in meters squared, or according to the following formula: BMI = (Weight/2.205) / (Height/39.37)2 . In adults, a BMI greater than 30 kg/m2 indicates obesity; a BMI greater than 40 kg/m2 indicates morbid obesity; and a BMI less than 18.5 kg/m2 indicates a person is underweight. The lowest overall death rate is found in people with a BMI of 20 to 24.9 kg/m2.
Synonym: Quetelet index See: illustration

burn scar index

A rating scale developed to assess hypertrophic burn scars and their rate of development or resolution. It is available at Burnsurgery.org.
Synonym: Vancouver scar index; Vancouver scar scale

cardiac index

The cardiac output (expressed in liters per minute) divided by the body surface area (expressed in square meters).

cephalic index

The biparietal diameter of the skull divided by its occipitofrontal diameter, all multiplied by 100.

cerebral index

The ratio of greatest transverse diameter to the greatest anteroposterior diameter of the cranium.

chemotherapeutic index

The ratio of the toxicity of a drug, expressed as the maximum tolerated dose per kilogram of body weight to the minimal curative dose per kilogram of body weight. This index is used in judging the safety and effectiveness of drugs.

clinical risk index for babies

Abbreviation: CRIB
An index of the severity of illness, used to estimate the likelihood of mortality in very low birth weight infants who are cared for in a neonatal intensive care unit.

color index

An outmoded method of expressing the amount of hemoglobin present in each red cell.

Cumulative Index to Nursing and Allied Health Literature

See: Cumulative Index to Nursing and Allied Health Literature

dental index

A system of numbers for indicating comparative size of the teeth.

DMF index

The index of dental health and caries experience based on the number of decayed, missing, and filled (DMF) teeth or tooth surfaces.

dynamic gait index

Abbreviation: DGI
A semiquantitative tool used to evaluate a patient's ability to modify gait by changing task demands, esp. in patients with dizziness and balance deficits. This test is used to identify patients, esp. older adults, who are predisposed to falling. Patients are graded on their ability to vary speed, turn their heads, turn their bodies, step over and around obstacles, climb stairs, turn while walking, pick objects up from the floor, and perform alternate step-ups on a stool.

exposure index

A relative value indicating the quantity of ionizing radiation received by a digital radiographic image receptor. Although vendors currently use many kinds of exposure indices, e.g., Sensitivity Numbers, standardization is being developed by physicists' organizations.

fatigue index

The difference between the muscle power generated during peak exertion and the power that can be generated after repeated loading and unloading of the muscle.

Frenchay Activities Index

A formal interview for patients who have suffered a stroke to compare their functional abilities preceding and following the stroke. The patient describes how employment, meal preparation and clean up, gardening, shopping, and other activities of daily living have been altered by the stroke.

gas exchange index

One of several measurements of the efficiency of respiration, esp. of the extent of intrapulmonary shunting in respiratory failure. Among the commonly used gas exchange indices is the alveolar-arterial oxygen tension difference (a measurement derived from an analysis of the oxygen tension of an arterial blood gas compared with the atmospheric oxygen content).

glycemic index

A ratio used to describe the ability of a food to increase blood glucose levels as compared with consumption of either glucose or white bread as the standard. Foods with a low glycemic index result in a slower rise and lower maximum elevation of blood glucose levels than foods with a higher glycemic index. Consumption of low glycemic index foods can contribute to blood glucose regulation in patients with diabetes mellitus. Another use for the index is to identify the choice of food that will raise blood sugar levels after, e.g., endurance exercise.

gnathic index

A measure of the degree of projection of the upper jaw by finding the ratio of the distance from the nasion to the basion to that of the basion to the alveolar point and then multiplying by 100. Synonym: alveolar index

human development index

A measure of national quality of life used by the United Nations Development Program. It consists of three elements: life expectancy at birth, mean years and expected years of schooling, and the gross national income at purchasing power parity per capita.

Insall-Salvati index

See: Insall-Salvati index

International Sensitivity Index

Abbreviation: ISI
A laboratory standard for thromboplastins, the reagents used to determine the prothrombin time (PT). Because thromboplastin contents vary, PT results performed on the same sample of blood in different laboratories can be markedly different, even though the patient's actual level of anticoagulation is a constant. The ISI is used to calculate the international normalized ratio, a standardized measure of anticoagulation, thus enabling health care professionals working with different laboratories to compare results and adjust anticoagulant doses according to a single set of guidelines.

Karnofsky Index

See: Karnofsky Index

labeling index

The rate at which cells take up identifiable chemicals that they use in cell division. The index is a measure of the rate of the reproduction of the cells, as in fetal tissue development or the growth of cancers.

leukopenic index

A test formerly used to determine hypersensitivity to foods, in which the white blood cell count is checked 90 min after the consumption of a suspected allergen. A precipitous decrease in the white blood cell count within 90 min after ingestion of the test food was thought to indicate that the food was incompatible with that person.

life satisfaction index

Abbreviation: LSI
A self-reporting instrument to measure personal fulfillment or contentment, esp. with one's social relationships, occupation, maturation, or aging. A total of five rating scales are used.


See: McMurtry index

Index Medicus

A publication of the National Library of Medicine that lists biomedical and health sciences journal articles by title, subject, field, and country of publication. The major national and international medical and biological journals are indexed.

Mentzer Index

See: Mentzer index

mitotic index

The number of mitoses seen in a biopsy specimen per square millimeter of tissue examined. Mitoses in tissue are indicative of malignancy. The higher the mitotic index, the more rapidly a tumor is dividing and the worse the prognosis.

nasal index

The greatest width of the nasal aperture in relation to a line from the lower edge of the nasal aperture to the nasion.

notch width index

The width of the femoral intercondylar notch divided by the width of the femoral condyles.

opsonic index

A ratio of the number of bacteria that are ingested by leukocytes contained in the serum of a normal individual compared with the number ingested by leukocytes in the study patient's blood serum.

oral hygiene index

Abbreviation: OHI
A popular indicator developed in 1960 to determine oral hygiene status in epidemiological studies. The index consists of an oral debris score and a calculus score. Six indicator teeth are examined for soft deposits and calculus. Numerical values are assigned to the six indicator teeth according to the extraneous deposits present. The scores are added and divided by the number of surfaces examined to calculate the average oral hygiene score.

Oswestry Disability Index

Abbreviation: ODI
A questionnaire that requires a patient to rate the effect of back pain on 10 different activities, each having six levels of disability. The test was designed to assess patients with failed back surgery, but it is widely used for nonsurgical patients with other spinal conditions.
Synonym: Oswestry disability score

oxygenation index

Abbreviation: OI
A measure of the efficiency of oxygen exchange by the lungs. The index is used in critical care medicine to assess the severity of acute lung injury and to gauge the effectiveness of ventilator management strategies. Mathematically it is represented as the product of the fractional concentration of inspired oxygen and the mean airway pressure, divided by the arterial oxygen concentration.

Pearl index

See: Pearl index

pelvic index

The ratio of pelvic conjugate and transverse diameters multiplied by 100.

periodontal (Ramfjord) index

An extensive consideration of the periodontal status of six teeth by evaluating gingival condition, depth of gingival sulcus or pocket, appearance of plaque or calculus, attrition, tooth motility, and extent of tooth contact.

phagocytic index

The average number of bacteria ingested by each leukocyte after incubation of the leukocytes in a mixture of serum and bacterial culture.

physiological cost index

Abbreviation: PCI
The metabolic expenditure per unit of distance traveled. It is expressed as the number of heartbeats per meter traveled and is calculated by subtracting the resting heart rate from the exercise heart rate divided by the distance traversed.

Pneumonia Severity Index

, pneumonia severity index
A diagnostic scoring system for predicting the level of care a patient with pneumonia will require. It includes demographic factors (such as the patient's age, whether he or she resides in a nursing home); findings on physical examination (such as altered mental status, fever, tachycardia, and low blood pressure); laboratory data (including serum pH, glucose and sodium levels); and the presence of other illnesses (such as heart, lung, brain, liver, or kidney disease). Synonym: pneumonia PORT score.

ponderal index

The ratio of an individual's height to the cube root of his or her weight; used to determine body mass.
See: body mass index

proliferative index

Abbreviation: PI
The proportion of cells within a tumor specimen that are actively reproducing. In general, as the number of replicating cells in a tumor increases, the cancer behaves more aggressively and the prognosis for the patient worsens.

index of refraction

1. The ratio of the angle made by the incident ray with the perpendicular (angle of incidence) to that made by the emergent ray (angle of refraction).
2. The ratio of the speed of light in a vacuum to its speed in another medium. The refractive index of water is 1.33; that of the crystalline lens of the eye is 1.413.
Synonym: refractive index

refractive index

Index of refraction.

rapid shallow breathing index

Abbreviation: f/TV; RSBI.
The ratio of the respiratory rate (f) and the tidal volume (TV) of a patient treated with mechanical ventilation while breathing on a T-piece (or at minimal levels of positive airway pressure or pressure support). Levels less than 105/min/L indicate that a patient may be able to be weaned successfully from the ventilator and breathe unassisted.

Reid index

See: Reid index

respiratory index

Abbreviation: RI
Alveolar/arterial gradient.

respiratory disturbance index

A measurement of the number of disordered breathing cycles during sleep. Sleep disordered breathing, which includes both apneas and hypopneas, results in daytime fatigue. It is also associated with an increased prevalence of cardiovascular disease.

sacral index

The sacral breadth multiplied by 100 and divided by the sacral length.

satiety index

The relative degree to which different foods of the same caloric value satisfy hunger.

saturation index

In hematology, the amount of hemoglobin present in a known volume of blood compared with the normal amount.

Science Citations Index

Abbreviation: SCI.
An electronic database of scientific journal articles published and referred to by other authors.

The Index is a proprietary product of the Thomson Corporation.

shock index

1. The systolic blood pressure divided by the heart rate.
2. The heart rate divided by the systolic blood pressure.

sulcus bleeding index

Abbreviation: SBI.
A sensitive measure of gingival condition that involves probing of all sulci. The score is based on six defined criteria. It is calculated by counting the number of sulci with bleeding, dividing by the total number of sulci, and multiplying by 100.

sunscreen protective factor index

In preparations for protecting the skin from the sun (using sunscreens), the ratio of the amount of exposure needed to produce a minimal erythematous response with the sunscreen in place divided by the amount of exposure required to produce the same reaction without the sunscreen. This index assesses the ability of sunscreens to block (short-wavelength) ultraviolet B rays but does not measure the protective effect of sunscreens against (long-wavelength) ultraviolet A radiation.
See: erythema dose

therapeutic index

The maximum tolerated dose of a drug divided by the minimum curative dose.

thoracic index

The ratio of the thoracic anteroposterior diameter to the transverse diameter.

Vancouver scar index

Burn scar index.

ventilation index

Abbreviation: VI.
1. A calculation used to determine the severity of respiratory illness (acute lung injury and/or respiratory distress syndrome) in critically ill patients. The VI is the partial pressure of arterial CO2 multiplied by the peak airway pressure multiplied by the rate of ventilation, all divided by 1000.

Symbolically, the ventilation index is calculated as follows: VI = [RR x (PIP - PEEP) × PaCo2]/1000.

2. In environmental science, a measure of air pollution based on the speed of the wind and the height of the column of air in which smoke or other pollutants mix.

vital index

The ratio of the number of births to the number of deaths in a population over a stated period of time.

Western Ontario McMaster Osteoarthritis Index

See: Western Ontario McMaster Osteoarthritis Index

oxygenation index

Abbreviation: OI
A measure of the efficiency of oxygen exchange by the lungs. The index is used in critical care medicine to assess the severity of acute lung injury and to gauge the effectiveness of ventilator management strategies. Mathematically it is represented as the product of the fractional concentration of inspired oxygen and the mean airway pressure, divided by the arterial oxygen concentration.
See also: index


(in-fek'shon) [L. infectio, discoloration, dye]
A disease caused by microorganisms, esp. those that release toxins or invade body tissues. Worldwide, infectious diseases such as malaria, tuberculosis, hepatitis viruses, and diarrheal illnesses produce more disability and death than any other cause. Infection differs from colonization of the body by microorganisms in that during colonization, microbes reside harmlessly in the body or perform useful functions for it, e.g., bacteria in the gut that produce vitamin K. By contrast, infectious illnesses typically cause bodily harm.


The most common pathogenic organisms are bacteria (including mycobacteria, mycoplasmas, spirochetes, chlamydiae, and rickettsiae), viruses, fungi, protozoa, and helminths. Life-threatening infectious disease usually occurs when immunity is weak or suppressed (such as during the first few months of life, in older or malnourished persons, in trauma or burn victims, in leukopenic patients, and in those with chronic illnesses such as diabetes mellitus, renal failure, cancer, asplenia, alcoholism, or heart, lung, or liver disease). Many disease-causing agents, however, may afflict vigorous persons, whether they are young or old, fit or weak. Some examples include sexually transmitted illnesses (such as herpes simplex or chlamydiosis), respiratory illnesses (influenza or varicella), and food or waterborne pathogens (cholera, schistosomiasis).


Systemic infections cause fevers, chills, sweats, malaise, and occasionally, headache, muscle and joint pains, or changes in mental status. Localized infections produce tissue redness, swelling, tenderness, heat, and loss of function.


Pathogens can be transmitted to their hosts by many mechanisms, namely, inhalation, ingestion, injection or the bite of a vector, direct (skin-to-skin) contact, contact with blood or body fluids, fetomaternal contact, contact with contaminated articles (fomites), or self-inoculation.

In health care settings, infections are often transmitted to patients by the hands of professional staff or other employees. Hand hygiene before and after patient contact prevents many of these infections.


The body's defenses against infection begin with mechanisms that block entry of the organism into the skin or the respiratory, gastrointestinal, or genitourinary tract. These defenses include chemicals, e.g., lysozymes in tears, fatty acids in skin, gastric acid, and pancreatic enzymes in the bowel; mucus that traps the organism; clusters of antibody-producing B lymphocytes, e.g., tonsils, Peyer's patches; and bacteria and fungi (normal flora) on the skin and mucosal surfaces that destroy more dangerous organisms. In patients receiving immunosuppressive drug therapy, the normal flora can become the source of opportunistic infections. Also, one organism can impair external defenses and permit another to enter; e.g., viruses can enhance bacterial invasion by damaging respiratory tract mucosa.

The body's second line of defense is the nonspecific immune response, inflammation. The third major defensive system, the specific immune response, depends on lymphocyte activation, during which B and T cells recognize specific antigenic markers on the organism. B cells produce immunoglobulins (antibodies), and T cells orchestrate a multifaceted attack by cytotoxic cells. See: B cell; T cell; inflammation for table


Once pathogens have crossed cutaneous or mucosal barriers and gained entry into internal tissues, they may spread quickly along membranes such as the meninges, pleura, or peritoneum. Some pathogens produce enzymes that damage cell membranes, enabling them to move rapidly from cell to cell. Others enter the lymphatic channels; if they can overcome white blood cell defenses in the lymph nodes, they move into the bloodstream to multiply at other sites. This is frequently seen with pyogenic organisms, which create abscesses far from the initial entry site. Viruses or rickettsiae, which reproduce only inside cells, travel in the blood to cause systemic infections; viruses that damage a fetus during pregnancy (such as rubella and cytomegalovirus) travel via the blood.


Although many infections (such as those that cause characteristic rashes) are diagnosed clinically, definitive identification of infection usually occurs in the laboratory. Carefully collected and cultured specimens of blood, urine, stool, sputum, or other body fluids are used to identify pathogens and their susceptibilities to treatment.


Many infections, like the common cold, are self-limited and require no specific treatment. Understanding this concept is crucial because the misuse of antibiotics does not help the affected patient and may damage society by fostering antimicrobial resistance, e.g., in microorganisms such as methicillin-resistant Staphylococcus aureus. Many common infections, such as urinary tract infections or impetigo, respond well to antimicrobial drugs. Others, like abscesses, may require incision and drainage.

acute infection

An infection that appears suddenly and may be of brief or prolonged duration.

airborne infection

An infection caused by inhalation of pathogenic organisms in droplet nuclei.

apical infection

An infection located at the tip of the root of a tooth.

autochthonous infection

Infection caused by organisms normally present in the patient's body. It may occur when host defenses are compromised, or when resident flora are introduced into an abnormal site.

bacterial infection

Any disease caused by bacteria. Bacteria exist in a variety of relationships with the human body. They colonize body surfaces and provide benefits, e.g., by limiting the growth of pathogens and by producing vitamins for absorption (in a symbiotic relationship). Bacteria can coexist with the human body without producing harmful or beneficial effects (in a commensal relationship). Bacteria may also invade tissues, damage cells, trigger systemic inflammatory responses, and release toxins (in a pathogenic or infectious relationship).
See: bacterium for table

bladder infection

See: urinary tract infection

blood-borne infection

An infection transmitted through contact with the blood (cells, serum, or plasma) of an infected individual. The contact may occur sexually, through injection, or via a medical or dental procedure in which a blood-contaminated instrument is inadvertently used after inadequate sterilization. Examples of blood-borne infections include hepatitis B and C and AIDS.
needle-stick injury;

breakthrough infection

An infection that occurs despite previous vaccination.

chronic infection

An infection having a protracted course.

concurrent infection

The existence of two or more infections at the same time.
See: superinfection

cross infection

The transfer of an infectious organism or disease from one patient in a hospital to another.

cryptogenic infection

An infection whose source is unknown.

cytomegalovirus infection

Abbreviation: CMV infection
A persistent, latent infection of white blood cells caused by cytomegalovirus (CMV). Approx. 60% of people over 35 have been infected with CMV, usually during childhood or early adulthood; the incidence appears to be higher in those of low socioeconomic status. Primary infection is usually mild in people with normal immune function, but CMV can be reactivated and cause overt disease in pregnant women, AIDS patients, or those receiving immunosuppressive therapy following organ transplantation. CMV has been isolated from saliva, urine, semen, breast milk, feces, blood, and vaginal secretions of those infected; it is usually transmitted through contact with infected secretions that retain the virus for months to years.

During pregnancy, the woman can transmit the virus transplacentally to the fetus with devastating results. Approx. 10% of infected infants develop CMV inclusion disease, marked by anemia, thrombocytopenia, purpura, hepatosplenomegaly, microcephaly, and abnormal mental or motor development; more than 50% of these infants die. Most fetal infections occur when the mother is infected with CMV for the first time during this pregnancy, but they may also occur following reinfection or reactivation of the virus. Patients with AIDS or organ transplants may develop disseminated infection that causes retinitis, esophagitis, colitis, meningoencephalitis, pneumonitis, and inflammation of the renal tubules.


CMV is transmitted from person to person by sexual activity, during pregnancy or delivery, during organ transplantation, or by contaminated secretions; rarely, (5%) blood transfusions contain latent CMV. Health care workers caring for infected newborns or immunosuppressed patients are at no greater risk for acquiring CMV infection than are those who care for other groups of patients (approx. 3%). Pregnant women and all health care workers should strictly adhere to standard infection control precautions.


Primary infection in the healthy is usually asymptomatic, but some people develop mononucleosis-type symptoms (fever, sore throat, swollen glands). Symptoms in immunosuppressed patients are related to the organ system infected by CMV and include blurred vision progressing to blindness; severe diarrhea; and cough, dyspnea, and hypoxemia. Antibodies seen in the blood identify infection but do not protect against reactivation of the virus.


Antiviral agents such as ganciclovir and foscarnet are used to treat retinitis, colitis, and pneumonitis in immunosuppressed patients; chronic antiviral therapy has been used to suppress CMV, but this protocol has not been effective in preventing recurrence of CMV or development of meningoencephalitis. Ganciclovir has limited effect in congenital CMV. No vaccine is available.

Patient care

Health care providers can help prevent CMV infections by advising pregnant women and the immunocompromised to avoid exposure to contact with people who have confirmed and or suspected cases of CMV. The virus spreads from one person to another as a result of exposure to blood (as in transfusions) and other body fluids including feces, urine, and saliva. Contact with the diapers or drool of an infected child may result in infection of a person who has previously been unexposed to the infection. CMV is the most common congenital infection, affecting about 35,000 newborns each year. CMV infection that is newly acquired during the first trimester of pregnancy can be esp. hazardous to the developing fetus. As a result, young women who have no antibodies to CMV should avoid providing child care to infected youngsters. In the U.S., nurses who have failed to advise infected patients of the risk that CMV may pose to others have been judged to be negligent by the courts. Parents of children with severe congenital CMV require support and counseling. Although CMV infection in most nonpregnant adults is not harmful, it can cause serious illnesses or death in people with HIV/AIDS, organ transplants, and those who take immunosuppressive or cancer chemotherapeutic drugs. Infected immunosuppressed patients with CMV should be advised about the uses of prescribed drug therapies, the importance of completing the full course of therapy, and adverse effects to report for help in managing them. Family caregivers for infected people should be taught to observe standard precautions when handling body secretions. Since asymptomatic people may have and secrete the virus, standard precautions should be maintained by health care professionals at all times when such secretions are present or being handled.

deep neck infection

An infection that enters the fascial planes of the neck after originating in the oral cavity, pharynx, or a regional lymph node. It may be life-threatening if the infection enters the carotid sheath, the paravertebral spaces, or the mediastinum. Death may also result from sepsis, asphyxiation, or hemorrhage. Aggressive surgical therapy is usually required because antibiotics alone infrequently control the disease.
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diabetic foot infection

A polymicrobial infection of the bones and soft tissues of the lower extremities of patients with diabetes mellitus, typically those patients who have vascular insufficiency or neuropathic foot disease. Eradication of the infection may require prolonged courses of antibiotics, surgical débridement or amputation, or reconstruction or bypass of occluded arteries. Synonym: diabetic foot ulcer See: illustration

droplet infection

An infection acquired by the inhalation of a microorganism in the air, esp. one added to the air by sneezing or cough.

focal infection

Infection occurring near a focus, such as the cavity of a tooth.

fungal infection

Pathological invasion of the body by yeast or other fungi. Fungi are most likely to produce disease in patients whose immune defenses are compromised.
See: table

fungal infection of nail

Infection of a nail by one of a number of fungi. Systemic therapy with antifungal drugs may eradicate the infection.

health-care associated infection

Abbreviation: HAI
Nosocomial infection.

hospital-acquired infection

Nosocomial infection.

inapparent infection

An infection that is asymptomatic or is not detected.

local infection

An infection that has not spread but remains contained near the entry site.

low-grade infection

A loosely used term for a subacute or chronic infection with only mild inflammation and without pus formation.

nosocomial infection

An infection acquired in a hospital, nursing home, or other health care setting. Patients in burn units and surgical intensive care units have the highest rates of nosocomial infections. Synonym: health-care associated infection; hospital-acquired infection

Patient care

Hospital-acquired infections result from the exposure of debilitated patients to the drug-altered environment of the hospital, where indwelling urinary catheters, intravenous lines, and endotracheal tubes enter normally sterile body sites and allow microbes to penetrate and multiply. Over 2 million nosocomial infections occur in the U.S. annually. Antibiotic-resistant organisms such as Enterobacter spp., Pseudomonas spp., staphylococci, enterococci, Clostridium difficile, and fungi often are responsible for the infectious outbreaks that result. Standard precautions and infection control procedures limit the incidence of nosocomial infections.

opportunistic infection

Abbreviation: OI
1. Any infection that results from a defective immune system that cannot defend against pathogens normally found in the environment. Common types include bacterial (Pseudomonas aeruginosa), fungal (Candida albicans), protozoan (Pneumocystis jirovecii), and viral (cytomegalovirus). Opportunistic infections are seen in patients with impaired defenses against disease, such as those with cystic fibrosis, poorly controlled diabetes mellitus, acquired or congenital immune deficiencies, or organ transplants.
2. An infection that results when resident flora proliferate and infect a body site in which they are normally present or at some other location. In healthy humans, the millions of bacteria in and on the body do not cause infection or disease. Host defenses and interaction with other microorganisms prevent excess growth of potential pathogens. A great number of factors, many poorly understood, may allow a normal bacterial resident to proliferate and cause disease.

pocket infection

Infection of the tissues beneath the skin into which an implanted device, such as a pacemaker or defibrillator, has been surgically inserted.

protozoal infection

An infection with a protozoon, e.g., malaria.

pyogenic infection

An infection resulting from pus-forming organisms.

reproductive tract infection

Abbreviation: RTI
Any infection of the reproductive organs. The most common causes are sexually transmitted diseases, but infections may also result from bacterial overgrowth or occasionally when instruments used in medical procedures introduce microorganisms. In women RTIs can cause pelvic pain, subfertility, infertility, or damage to the developing fetus. RTIs in men include epididymitis, prostatitis, and urethritis.

risk for infection

An immunocompromised state.

secondary infection

An infection made possible by a primary infection that lowers the host's resistance, e.g., bacterial pneumonia following influenza.

slow virus infection

An infection caused by a virus that remains dormant in the body for a prolonged period before causing signs and symptoms of illness. Such viruses may require years to incubate before causing diseases. Examples include progressive multifocal leukoencephalopathy and subacute sclerosing panencephalitis.

subacute infection

An infection intermediate between acute and chronic.

subclinical infection

An infection that is immunologically confirmed but does not produce obvious symptoms or signs.

surgical site infection

An infection that occurs within thirty days of an operation, either at the suture line, just beneath it, or in internal organs and spaces that were operated upon.
Synonym: surgical wound infection

surgical wound infection

Surgical site infection.

systemic infection

An infection in which the infecting agent or organisms circulate throughout the body.

terminal infection

An often fatal infection appearing in the late stage of another disease.

transfusion-associated bacterial infection

Transfusion-transmitted bacterial infection.

transfusion-transmitted bacterial infection

Abbreviation: TTBI.
Illness in a transfusion recipient that develops after the infusion of contaminated blood or blood products, esp. platelets. It usually results from colonization of the blood product during handling or storage or, less frequently, from an unsuspected infection in the blood donor. Coagulase-negative staphylococci are often responsible. Other bacteria that sometimes cause TTBI include Pseudomonas species, Anaplasma, Babesia, and Rickettsia.

Viruses may also be transmitted from blood donors to transfusion recipients. They may include cytomegalovirus, encephalitis viruses, and, rarely, hepatitis viruses or human immunodeficiency virus.

Synonym: transfusion-associated bacterial infection

upper respiratory infection

Abbreviation: URI
An imprecise term for any infection involving the nasal passages, pharynx, and bronchi. The cause is usually bacterial or viral, and, occasionally, fungal.

urinary tract infection

Abbreviation: UTI
Infection of the kidneys, ureters, or bladder by microorganisms that either ascend from the urethra (95% of cases) or that spread to the kidney from the bloodstream (5%). About 7 million Americans visit health care providers each year because of UTIs. These infections commonly occur in otherwise healthy women, men with prostatic hypertrophy or bladder outlet obstruction, children with congenital anatomical abnormalities of the urinary tract, and patients with urinary stasis related to incomplete bladder emptying, neurogenic bladder or indwelling bladder catheters. See: clean-catch method; cystitis; pyelonephritis; urethritis


Escherichia coli causes about 80% of all UTIs. In young women, Staphylococcus saprophyticus is also common. In men with prostate disease, enterococci are often responsible. The small remaining percentage of infections may be caused by Klebsiella species, Proteus mirabilis, Staphylococcus aureus, Pseudomonas aeruginosa, or other virulent organisms.


The presenting symptoms of UTI vary enormously. Young patients with bladder infections may have pain with urination; urinary frequency or urgency, or both; pelvic or suprapubic discomfort; low-grade fevers; or a change in the appearance or odor of their urine (cloudy, malodorous, or rarely bloody). Older patients may present with fever, lethargy, confusion, delirium, or coma caused by urosepsis. Patients with pyelonephritis often complain of flank pain, prostration, nausea, vomiting, diarrhea, and high fevers with shaking chills. UTI may also be asymptomatic, esp. during pregnancy. Asymptomatic UTI during pregnancy is a contributing factor to maternal pyelonephritis, or fetal prematurity and stillbirth.


Urinalysis (obtained either as a clean catch or catheterized specimen) and subsequent urinary culture are used to determine the presence of UTI, the suspect microorganism, and the optimal antibiotic therapy. A dipstick test may identify leukocyte esterase and nitrite in a urinary specimen, strongly suggesting a UTI. The presence of more than 8 to 10 white blood cells per high-power field of spun urine also strongly suggests UTI, as does the presence of bacteria in an uncentrifuged urinary specimen.


Sulfa drugs, nitrofurantoin, cephalosporins, or quinolones may be used for the outpatient treatment of UTIs while the results of cultures are pending. Patients sick enough to be hospitalized may also be treated with intravenous aminoglycosides, medicine to treat nausea and vomiting, and hydration. The duration of therapy and the precise antibiotics used depend on the responsible organism and the underlying condition of the patient. Patients with anatomical abnormalities of the urinary tract, e.g., children with ureteropelvic obstruction or older men with bladder outlet obstruction, may sometimes require urological surgery.

Risk Factors

The following conditions predispose sexually active women to development of UTI: the use of a contraceptive diaphragm, the method of sexual intercourse, (greatly prolonged or cunnilingus), and failure to void immediately following intercourse.

Prevention of UTI in Young Women

Fluid intake should be increased to and maintained at to six to eight glasses daily. Although cranberry and other fruit juices are often recommended for patients with UTI, there is little objective evidence to show they have an impact. The urinary tract anesthetic phenazopyridine and sitz baths may provide relief from perineal discomfort. The anal area should be wiped from front to back or wipe the front first to prevent carrying bacteria to the urethral area; the bladder should be emptied shortly before and after intercourse; the genital area should be washed before intercourse; if vaginal dryness is a problem, water-soluble vaginal lubricants should be used before intercourse; a contraceptive diaphragm, cap, shield, or sponge should not remain in the vagina longer than necessary. An alternative method of contraception should be considered.

Patient care

Instructing the patient should emphasize self-care and prevention of recurrences. The antibiotic regimen should be explained, and the patient should be aware of signs and symptoms and, when they occur, should report them promptly to the primary caregiver.

yeast infection

A colloquial term for vulvovaginal candidiasis.
Superficial Fungal Infections
DiseaseCausative OrganismsStructures InfectedMicroscopic Appearance
Epidermophytosis (e.g., dhobie itch)Epidermophyton, (e.g., floccosum)Inguinal, axillary, and interdigital folds; hairs not affectedLong, wavy, branched, and segmented hyphae and spindle-shaped cells in stratum corneum
Favus (tinea favosa)Trichophyton schoenleiniiEpidermis around a hair; all parts of body; nailsVertical hyphae and spores in epidermis; sinuous branching mycelium and chains in hairs
Ringworm (tinea, otomycosis)Microsporum (e.g., audouinii)Horny layer of epidermis and hairs, chiefly of scalpFine septate mycelium inside hairs and scales; spores in rows and mosaic plaques on hair surface
Trichophyton (e.g., tonsurans)Hairs of scalp, beard, and other parts; nailsMycelium of chained cubical elements and threads in and on hairs; often pigmented
Thrush and other forms of candidiasisCandida albicansTongue, mouth, throat, vagina, and skinYeastlike budding cells and oval thick-walled bodies in lesion
Systemic Fungal Infections
AspergillosisAspergillus fumigatusLungsY-shaped branching of septate hyphae
BlastomycosisBlastomyces brasiliensis, B. dermatitidisSkin and lungsYeastlike cells demonstrated in lesion
CandidiasisCandida albicansEsophagus, lungs, peritoneum, mucous membranesSmall, thin-walled, ovoid cells
CoccidioidomycosisCoccidioides immitisRespiratory tractNonbudding spores containing many endospores, in sputum
CryptococcosisCryptococcus neoformansMeninges, lungs, bone, skinYeastlike fungus having gelatinous capsule; demonstrated in spinal fluid
HistoplasmosisHistoplasma capsulatumLungsOval, budding, uninucleated cells

opportunistic infection

Abbreviation: OI
1. Any infection that results from a defective immune system that cannot defend against pathogens normally found in the environment. Common types include bacterial (Pseudomonas aeruginosa), fungal (Candida albicans), protozoan (Pneumocystis jirovecii), and viral (cytomegalovirus). Opportunistic infections are seen in patients with impaired defenses against disease, such as those with cystic fibrosis, poorly controlled diabetes mellitus, acquired or congenital immune deficiencies, or organ transplants.
2. An infection that results when resident flora proliferate and infect a body site in which they are normally present or at some other location. In healthy humans, the millions of bacteria in and on the body do not cause infection or disease. Host defenses and interaction with other microorganisms prevent excess growth of potential pathogens. A great number of factors, many poorly understood, may allow a normal bacterial resident to proliferate and cause disease.
See also: infection