What Is a Nosocomial Infection?
The problem of nosocomial infections has existed since the hospitals were established. However, the scientific understanding of nosocomial infections and the need to reduce the incidence of nosocomial infections have been gradually recognized, deepened and resolved in the development of modern science. The history of nosocomial infections can be summarized in three stages:
- Western Medicine Name
- Hospital Infection
- Other name
- Nosocomial infection
- Affiliated Department
- Internal Medicine-
- Contagious
- Contagious
| Qin Ailan | (Chief physician) | Department of Infectious Diseases, the First Affiliated Hospital of Soochow University |
| Li Xinfang | (Attending physician) | Department of Infection Management, Fourth People's Hospital of Suzhou City |
- Nosocomial infections refer to infections acquired by hospitalized patients in the hospital, including infections that occur during hospitalization and infections that occur after being discharged from the hospital, but do not include infections that have started before admission or are in the incubation period at the time of admission. Nosocomial infections are also acquired by hospital staff. In a broad sense, the objects of nosocomial infections include inpatients, hospital staff, outpatients and outpatients, visitors and family members of patients. These people can be referred to as nosocomial infections in the hospital area. 3. Visitors and family members of patients stay in the hospital for a short period of time. There are many and complicated factors to obtain the infection. It is often difficult to determine whether the infection comes from the hospital. Therefore, in fact, the objects of hospital infection are mainly inpatients and hospital staff.
Hospital Infectious Diseases
- The problem of nosocomial infections has existed since the hospitals were established. However, the scientific understanding of nosocomial infections and the need to reduce the incidence of nosocomial infections have been gradually recognized, deepened and resolved in the development of modern science. The history of nosocomial infections can be summarized in three stages:
- Before the era of bacteriology and before the 19th century, it was thought that purulent infections after trauma were inevitable, because at that time people did not recognize the microorganisms in nature and could not take preventive measures. For example, Holmes discovered puerperium fever in 1843, which was a well-known and dangerous disease in Europe. The hospital was once called the "place of death" for it.
- After the era of bacteriology, people gradually became aware of microorganisms after the 19th century. The British surgeon Lister first clarified the relationship between bacteria and infection, and put forward the concept of disinfection. French microbiologist Pasteur found microorganisms in the air under a microscope and used methods such as heat disinfection to reduce their number to control infection. Not long after, aseptic technology was developed, and the era of steam sterilizer sterilization began.
- The era of antibiotics. In 1928, Fleming in the United Kingdom discovered penicillin and made it successfully in the 1940s. Since then, it has entered the era of antibiotics. Penicillin has played a special role in preventing and treating infections. Weakened the hospital's emphasis on sterilization technology. Until the 1970s, medical staff turned their attention to aseptic technology and combined with the application of antibiotics, they are effectively solving the problem of infection and nosocomial infection.
Classification of nosocomial infections
Nosocomial infections by infection site
- Nosocomial infections can occur in various organs and parts of the body, which can be divided into nosocomial infections in the respiratory system, nosocomial infections in the surgical site, nosocomial infections in the urinary system, nosocomial infections in the blood system, nosocomial infections in skin and soft tissues, and so on.
Nosocomial infections by pathogen
- Nosocomial infections can be divided into bacterial infections, viral infections, fungal infections, mycoplasma infections, chlamydia infections, and protozoal infections, among which bacterial infections are the most common. Each type of infection can be classified according to the specific name of the pathogen, such as Coxsackie virus infection, Pseudomonas aeruginosa infection, and Staphylococcus aureus infection.
Nosocomial infections by pathogen source
- 1. Endogenous infection: also known as self-infection, refers to a hospital infection that occurs due to the invasion of a patient's own inherent pathogens in the hospital caused by various reasons. Pathogens are usually normal flora residing in patients, which are usually non-pathogenic, but when an individual's immune function is impaired, their health is poor, or their resistance is reduced, they can become conditional pathogens and become infected.
- 2. Exogenous infection: also known as cross-infection, refers to the infection caused by patients in hospitals caused by non-inherent pathogens. Pathogens come from individuals outside the patient's body, the environment, and the like. Including direct transmission from individual to individual and indirect infection caused by goods and environment.
Causes of nosocomial infections
- Any infection is a pathological process that occurs when the pathogenic microorganism interacts with the host under certain conditions. Nosocomial infections are no exception. On the one hand, pathogens look for all opportunities and ways to invade the human body, and excrete metabolites during their growth and reproduction, which damage the host's cells and tissues. On the other hand, the human body activates its various immune defense mechanisms. Try to kill the invading pathogens and expel them together with toxic products. The strength and increase and decrease of the two forces determine the development and outcome of the entire infection process.
- There are patients with various diseases in the hospital, and their immune defense functions have different degrees of damage and defects. At the same time, during the hospitalization period, patients received various diagnosis and treatment measures, such as tracheal intubation, urinary tract intubation, endoscope, major surgery and radiation therapy, chemotherapy, etc. Immune Function. Coupled with the intensive staff in the hospital, patients with various infectious diseases may discharge pathogens into the hospital environment at any time. As a result, the air in the hospital was severely polluted and became a place where microorganisms gathered. Bacteria, viruses, fungi and other microorganisms can exist in the air, object surfaces, appliances, and equipment of the hospital. In this way, all kinds of patients who have low resistance, but also live in an environment with concentrated microorganisms, are always at risk of hospital infection.
Nosocomial infections
Nosocomial infections
- Medical personnel have insufficient knowledge of nosocomial infections and their hazards; they cannot strictly implement aseptic technique and disinfection and quarantine systems; inadequate hospital rules and regulations have caused the source of infection to spread. In addition, there is a lack of effective monitoring of the effects of disinfection and sterilization, which cannot effectively control the occurrence of nosocomial infections.
Objective factors of nosocomial infection
- With the development of medicine, more and more invasive operations are performed in medical activities, such as arteriovenous intubation, urinary catheters, tracheotomy, tracheal intubation, inhalation devices, monitoring instrument probes, etc. The introduction of external microorganisms into the body at the same time damages the body's defense barrier, making it easy for pathogens to invade the body; for the treatment needs, the extensive use of hormones or immunosuppressants, after receiving chemotherapy and radiotherapy, causes the patient's own immune function to decline and become susceptible The development and popularization of a large number of antibiotics has caused the disorder of the normal flora in patients, the increase of drug-resistant strains, resulting in a prolonged course of disease and increased opportunities for infection. With the advancement of medical technology, certain incurable diseases in the past can be cured or prolonged survival. Therefore, the proportion of chronic diseases, malignant diseases, and elderly patients in hospitalized patients has increased, and these patients' resistance to infection is quite low, resulting in increased hospital infections.
Nosocomial infection
- Pathogenesis of endogenous infections: Endogenous infections play an important role in nosocomial infections, especially for some special populations, such as patients with low immune function, organ transplantation, and large-scale use of broad-spectrum highly effective antibacterial drugs. However, the pathogenesis of nosocomial infections in different patients may not be exactly the same. For example, Chinese scholars Xiaoguang Xia and other scholars [1] serial studies of intestinal nosocomial infections in burn patients. It was found that intestinal bacteria began to shift in 1-3 hours after burns, reached mesenteric lymph nodes in 30-60 minutes, reached liver and spleen in 90 minutes, and peaked throughout the body in 12-24 hours. This is mainly due to the stress response of the intestinal mucosa after large-scale burns, increased permeability, bleeding, ulcers, reduced IgA secretion, and reduced colonization resistance; meanwhile, macrophages can take in proliferating bacteria and cannot kill them. To make it a tool for carrying and spreading bacteria through walls. Therefore, the occurrence of early sepsis in burn patients is closely related to the intestinal mucosal damage barrier and the rapid increase of endotoxin in the portal vein. Other scholars have studied the pathogenesis of pneumonia in hospitals. It is believed that the pathogen mainly originates from the patient. For example, the colonization bacteria of the patient's nasopharynx enter the lower respiratory tract with various operations, or it may be due to the increase of the pH value in the patient's stomach, which causes the colonization of G-bacteria and the reverse colonization of the gastric fluid to the mouth Pneumonia caused by pharynx, trachea, and inhalation, or pneumonia caused by direct inhalation of gastric juice; At the same time, some exogenous factors such as various intubation, talk about damage to respiratory mucosa, contamination of the ventilator threaded tube, contamination The backflow of condensed water and the contamination of the hands of medical staff are also important factors that promote the displacement of nasopharyngeal and tracheal colonizing bacteria in patients and cause pneumonia.
- Pathogenesis of exogenous infection: The pathogen of exogenous infection comes from the outside of the patient, enters the patient through different routes, and then the infection occurs. For example, microorganisms enter the patient's body through various contaminated devices, contaminated implants, and medical staff's hands, and then adhere, aggregate, and colonize in different parts of the patient, and infection occurs when the patient's immunity decreases.
Clinical manifestations of nosocomial infection
- Nosocomial infections in different parts often have different clinical manifestations, such as nosocomial infections
- Symptoms or signs: Fever without other causes (> 38 ° C); white blood cells decreased (<4000WBC / mm3) or white blood cells increased (12000 WBC / mm3); elderly people aged 70 years without sudden mental changes for other reasons. New appearance of purulent sputum or sputum changes or increased respiratory secretions or increased suction frequency; new or worsening cough or dyspnea or shortness of breath; wet snoring or bronchial breathing sounds; gas exchange disorders [such as oxygen Saturation decreases (PaO2 / FiO2 240), oxygen demand increases, or mechanical ventilation demand increases];
- Radiological examination: new or progressive and continuous infiltration; lung consolidation; cavity formation.
- Nosocomial infections and urinary tract infections have the following manifestations
- Symptoms or signs: recent fever (> 38 ° C); bladder irritation such as urgency, frequent urination, and dysuria; dysuria or pubic tenderness.
- Laboratory tests: urine leukocyte esterase and / or nitrate test positive (using dipstick test paper); pyuria (non-centrifugal urine 10 WBC / mm3 or 3 WBC / high power field); non-centrifugal urine Gram The pathogen was seen in the staining; The same bacteria (Gram-negative bacteria or Staphylococcus spp.) Were cultured at least 2 times in the non-urinary urinary (extracted by catheterization or suprapubic puncture), and the number of colonies was 102cfu / ml; previously Has been treated with effective antibacterial drugs for urinary tract infections, the number of bacterial colonies in urine culture is 105cfu / ml, and there is only a single pathogenic bacterium (gram-negative bacillus or staphylococcus saprophytic)
Epidemiological characteristics of nosocomial infection (three distributions)
- Population distribution of nosocomial infections: Investigation found that nosocomial infections are related to age, high infection rates among infants and the elderly, and mainly related to low resistance of infants and the elderly; most surveys found that nosocomial infections are not related to gender; The incidence of nosocomial infections varies among patients with underlying diseases, with malignancies being the highest, followed by hematological diseases; patients with and without risk factors have different rates of nosocomial infections, and patients with risk factors have a high incidence of nosocomial infections.
- Regional distribution of nosocomial infections: There is a large difference in the rate of nosocomial infections in different departments. It is generally believed that the intensive care unit (ICU) has the highest incidence, followed by oncology and hematology, and burns. The incidence of nosocomial infections is different in different grades, natures and beds. The higher the level, the higher the incidence of nosocomial infections; larger hospitals are higher than small hospitals; teaching hospitals are higher than non-teaching hospitals, mainly because the patients treated by the former are more ill, have more risk factors and invasive procedures. (3) The incidence of nosocomial infections varies from region to region. It is generally believed that poor countries are higher than developing countries and developing countries are higher than developed countries. Data released by the World Health Organization in 2002 show that the prevalence survey results of 55 hospitals in 14 countries funded by them show that the average is 8.7% Of hospitalized patients developed an infection. The participating hospitals represented four WHO regions (Europe, Eastern Mediterranean, Southeast Asia, and Western Pacific). The highest rates of nosocomial infections were in the Eastern Mediterranean and Southeast Asia (11.8% and 10.0%, respectively), and in Europe and the Western Pacific, 7.7% and 9.0%, respectively.
- Time distribution of nosocomial infections: Seasonal changes in nosocomial infections are not significant, and there have been reports of higher rates in winter and lower rates in summer.
Nosocomial infection transmission characteristics
- The spread of nosocomial infection includes three links, namely the source of infection, the route of transmission and the susceptible population. This is in terms of exogenous infections, but endogenous infections are different. Its transmission process is the source of the infection, the translocation pathway, and the susceptible ecological environment, which needs to be described from a microecological perspective.
- Source of infection: refers to the natural survival, reproduction, and elimination of the host by pathogenic microorganisms. Including infected patients; carriers or self-infected; environmental bacteria storage source; animal infection source.
- Transmission route: refers to the way that pathogens are excreted from the source of infection and invaded the susceptible population. Including contact transmission; air transmission; water and food transmission; iatrogenic transmission; biological vector transmission.
- Susceptible population: includes: (i) impaired immune function; (ii) infants and the elderly; (iii) malnutrition; (ii) immunosuppressive therapy; (ii) long-term use of broad-spectrum antibacterial drugs; (ii) long hospital stay; (ii) surgery Elderly; Patients undergoing various interventional procedures.
Nosocomial infection
- The harm of nosocomial infection is not only manifested in increasing the morbidity and mortality of patients, increasing patient suffering and workload of medical staff, reducing bed turnover, but also causing significant economic losses to patients and society. It is reported that the additional fatality rate from nosocomial infections is 4% to 33%, and the highest fatality rate is HAP. Studies in Argentina show that UTI, catheter-associated BSI (CA-BSI) bloodstream infection, and VAP increase mortality by 5%, 25%, and 35%, respectively. It is also reported that more than 2 million hospital infections occur each year in the United States, causing an additional cost of 4 billion U.S. dollars and 80,000 deaths; the United Kingdom estimates that 100,000 hospital infections occur each year, causing 5,000 deaths and an additional expenditure of 1.6 billion Euros. These are all Refers to a direct loss. Studies in developed countries show that the additional cost of nosocomial infections is $ 1,000 to $ 4,500 (average of $ 1,800), but in pediatric wards, especially neonatal wards, the additional cost can exceed $ 10,000. [2-5]
Hospital infection prevention and control
- Strengthen the management of nosocomial infections;
- Strengthen the management of infection sources;
- (3) Monitoring of nosocomial infections;
- Strengthen the management of clinical antibacterial drugs;
- Strengthen the supervision and management of hospital sterilization;
- Strengthen the cleaning and disinfection of medical staff's hands;
- Strengthen hospital hygiene monitoring;
- Strengthen the monitoring and management of iatrogenic transmission factors;
- Strict visit and escort system;
- Strengthening the management of disposable sterile medical supplies for clinical use;
- Strengthen nosocomial infection management in key departments, key links, high-risk populations and major infection sites;
- Implement protective isolation for vulnerable groups;
- Summarize and report clinically isolated pathogens and their sensitivity to antibacterial drugs in time;
- Carry out publicity and education on nosocomial infections.