There are several risk factors that increase the likelihood of developing bacteremia from any type of bacteria. These include:

- HIV infection

- Diabetes Mellitus

- Chronic hemodialysis

- Solid organ transplant

- Stem cell transplant

- Treatment with glucocorticoids

- Liver failure

Gram negative bacterial species are responsible for approximately 24% of all cases of healthcare-associated bacteremia and 45% of all cases of community-acquired bacteremia. In general, gram negative bacteria enter the bloodstream from infections in the respiratory tract, genitourinary tract, gastrointestinal tract, or hepatobiliary system. Gram-negative bacteremia occurs more frequently in elderly populations (65 years or older) and is associated with higher morbidity and mortality in this population.

"E.coli" is the most common cause of community-acquired bacteremia accounting for approximately 75% of cases. E.coli bacteremia is usually the result of a urinary tract infection. Other organisms that can cause community-acquired bacteremia include "pseudomonas aeruginosa", "klebsiella pneumoniae", and "proteus mirabilis". "Salmonella" infection, despite mainly only resulting in gastroenteritis in the developed world, is a common cause of bacteremia in Africa. It principally affects children who lack antibodies to Salmonella and HIV+ patients of all ages.

Among healthcare-associated cases of bacteremia, gram negative organisms are an important cause of bacteremia in the ICU. Catheters in the veins, arteries, or urinary tract can all create a way for gram negative bacteria to enter the bloodstream. Surgical procedures of the genitourinary tract, intestinal tract, or hepatobiliary tract can also lead to gram negative bacteremia. "Pseudomonas" and "enterobacter" species are the most important causes of gram negative bacteremia in the ICU.

After exposure to "B. pseudomallei" (particularly following a laboratory accident) combined treatment with co-trimoxazole and doxycycline is recommended. Trovafloxacin and grepafloxacin have been shown to be effective in animal models.

Person-to-person transmission is exceedingly unusual; and patients with melioidosis should not be considered contagious. Lab workers should handle "B. pseudomallei" under BSL-3 isolation conditions, as laboratory-acquired melioidosis has been described.

In endemic areas, people (rice-paddy farmers in particular) are warned to avoid contact with soil, mud, and surface water where possible. Case clusters have been described following flooding and cyclones and probably relate to exposure. Other case clusters have related to contamination of drinking water supplies. Populations at risk include patients with diabetes mellitus, chronic renal failure, chronic lung disease, or an immune deficiency of any kind. The effectiveness of measures to reduce exposure to the causative organism have not been established. A vaccine is not yet available.

Its precise cause is unknown, but an insult to the blood vessels taking blood from and to the lungs is believed to be required to allow the anti-GBM antibodies to come into contact with the alveoli. Examples of such an insult include:

exposure to organic solvents (e.g. chloroform) or hydrocarbons,

exposure to tobacco smoke,

certain gene mutations ("HLA-DR15"),

infection (such as influenza A),

cocaine inhalation,

metal dust inhalation,

bacteraemia,

sepsis,

high-oxygen environments, and

treatment with antilymphocytic treatment (especially monoclonal antibodies).

Etiology uncertain. Wissler suggested an allergic reaction to bacteraemia as the pathogenic factor.

Goodpasture syndrome (GPS) is a rare autoimmune disease in which antibodies attack the basement membrane in lungs and kidneys, leading to bleeding from the lungs and kidney failure. It is thought to attack the alpha-3 subunit of type IV collagen, which has therefore been referred to as Goodpasture's antigen. Goodpasture syndrome may quickly result in permanent lung and kidney damage, often leading to death. It is treated with immunosuppressant drugs such as corticosteroids and cyclophosphamide, and with plasmapheresis, in which the antibodies are removed from the blood.

The disease was first described by an American pathologist Ernest Goodpasture of Vanderbilt University in 1919 and was later named in his honor.

Children and adolescents are most frequently affected; age in the reported cases varied from 5 to 17 years.

Any acute factors that affect neurotransmitter, neuroendocrine or neuroinflammatory pathways can precipitate an episode of delirium in a vulnerable brain. Clinical environments can also precipitate delirium, and optimal nursing and medical care is a key component of delirium prevention. Some of the most common precipitating factors are listed below:

- Metabolic

- Malnutrition

- Dehydration, electrolyte imbalance

- Anaemia

- Hypoxia

- Hypercapnoea

- Hypoglycaemia

- Endocrine disorders (e.g., SIADH, Addison’s disease, hyperthyroidism, hypercalcaemia)

- Infection

- Especially respiratory and urinary tract infections

- Medication

- Anticholinergics, dopaminergics, opioids, steroids, recent polypharmacy

- General Anesthetic

- Vascular

- Stroke/Transient ischaemic attack

- Myocardial infarction, arrhythmias, decompensated heart failure

- Physical/psychological stress

- Pain

- Iatrogenic event, esp. post-operative, mechanical ventilation in ICU

- Chronic/terminal illness, esp. cancer

- Post-traumatic event (e.g., fall, fracture)

- Immobilisation/restraint

- Severe constipation/fecal impaction

- Urinary retention

- Other

- Substance withdrawal (esp. alcohol, benzodiazepines)

- Substance intoxication

- Traumatic head injury

The highest rates of delirium (often 50% to 75% of people) is seen among those who are critically ill in the intensive care unit (ICU) As a result, this was referred to as "ICU psychosis" or "ICU syndrome", terms largely abandoned for the more widely accepted term ICU delirium. Since the advent of validated and easy-to-implement delirium instruments for ICU patients such as the Confusion Assessment Method for the ICU (CAM-ICU) and the Intensive Care Delirium Screening Checkllist (IC-DSC)., of the hundreds of thousands of ICU patients who develop delirium in ICUs every year, it has been recognized that most of them belong to the hypoactive variety, which is easily missed and invisible to the managing teams unless actively monitored using such instruments. The causes of delirium in such patients depend on the underlying illnesses, new problems like sepsis and low oxygen levels, and the sedative and pain medicines that are nearly universally given to all ICU patients. Outside the ICU, on hospital wards and in nursing homes, the problem of delirium is also a very important medical problem, especially for older patients.

The most recent area of the hospital in which delirium is just beginning to be monitored routinely in many centers is the Emergency Department, where the prevalence of delirium among older adults is about 10%. A systematic review of delirium in general medical inpatients showed that estimates of delirium prevalence on admission ranged from 10 to 31%. About 5% to 10% of older adults who are admitted to hospital develop a new episode of delirium while in hospital. Estimates of the prevalence of delirium in nursing homes are between 10% to 45%.