Nosocomial infection

Introduction to hospital infection Nosocomial infections (nosocomialinfections) are infections that occur during hospitalization, infections that occur before hospitalization, positive incubation periods during hospitalization, or inpatients after hospitalization. Conversely, infections acquired during hospitalization are not discharged after hospitalization. The person who is ill should be counted as a hospital infection. Infections that occur when the newborn passes through the birth canal, such as group B streptococcal infection, are hospital infections; fetal infections transmitted through the placenta, such as congenital syphilis, rubella, cytomegalovirus infection, herpes simplex, toxoplasmosis, etc. are all outside the hospital infection. Infections that are already present during hospitalization may be considered as nosocomial infections due to expansion or complications during hospitalization unless the pathogen has changed and the infection has occurred during hospitalization. This infection is based on epidemiological data. Involved in hospitalization, this situation should be used as a hospital infection, infection with unknown incubation period and occurrence within 48 to 72 hours after hospitalization should be regarded as nosocomial infection, unless epidemiological and clinical data indicate that the infection is outside the hospital. . basic knowledge The proportion of illness: 0.02% Susceptible people: no special people Mode of infection: contact spread droplets spread blood transmission Complications: sepsis

Infection in hospital

Bacteria (25%):

The vast majority (more than 95%) of hospital infections are caused by bacteria, of which 60% to 65% are Gram-negative bacilli, mainly Escherichia coli, Klebsiella, Proteus and other Enterobacteriaceae bacteria, Pseudomonas aeruginosa and The situation of septicemia caused by the infection of Enterobacter genus and Enterobacter agglomerans has been reported in recent years. The outbreaks of infections in neonatal wards, typhoid bacillus and dysentery bacilli have occasionally occurred, and pathogens causing nosocomial infections are often Antibiotic resistance.

Staphylococcus aureus (S. aureus), Staphylococcus epidermidis (S. albicans) and other coagulase-negative staphylococci and enterococci are common Gram-positive cocci in hospital infections. Staphylococcus aureus resistance is still very serious. More than 90% of strains producing penicillinase, methicillin-resistant Staphylococcus aureus are also increasing, accounting for 60% or more of clinical isolates of staphylococci in some large hospitals, and can cause outbreaks in certain wards of hospitals Epidemic, in patients with indwelling venous catheters, venous catheters and ventricular drainage tubes, the presence of Staphylococcus aureus is more common, showing an upward trend, and Staphylococcus aureus can also cause infections in orthopedic artificial devices, artificial heart valves, etc. Enterococcus mainly causes urinary tract infections. And wound infection, in recent years, with the wide application of cephalosporins, various enterococci infections have an increasing trend, group B hemolytic streptococcus is the main pathogen of neonatal meningitis and sepsis, group A hemolytic streptococcus Can cause postoperative wound infection.

Legionella pneumophila and other Legionella are common pathogens of pulmonary infection in hospitals. It is reported that the incidence of Legionella pneumophila pneumonia accounts for about 3% to 10% of hospital-acquired pneumonia, and faster-growing mycobacteria, such as birds. Mycobacteria, M. chelonei and M. fortuitum can cause sternal osteomyelitis, pericarditis and endocarditis, as well as other surgical wound infections and muscles after cardiac surgery. Infection caused by injection, Campylobacter fetus is one of the pathogens of diarrhea.

Bacteroides is the most common pathogen of anaerobic infection, which can cause abdominal and pelvic infections after gastrointestinal and gynecological surgery. Clostridium, digestive and actinomycetes can cause infections in the mouth and respiratory system, such as inhalation. Pneumonia, necrotizing pneumonia, lung abscess, empyema, etc., sepsis and endocarditis caused by Bacteroides, Propionibacterium are not uncommon, and the enteritis caused by antibiotics is caused by Clostridium difficile, the latter Can be distributed in the hospital.

Fungus (25%):

Candida, Aspergillus and some other conditions Pathogenic fungi are common pathogens of double infection, mostly in patients with antibiotics and corticosteroids, and in patients with neutropenia. 80% of Candida species are Candida albicans. In recent years, Candida tropicalis, Candida krusei has an increasing trend. In addition to the pathogens of pulmonary infection and digestive tract infections in hospitals, Candida can also cause mucosal skin rosary in patients with sepsis and immunodeficiency when intravenously intubating. Bacterial disease, Aspergillus is one of the common pathogens in the infection of patients with acute non-lymphocytic leukemia. Aspergillus lung infection is not uncommon. In addition, cryptococcal meningitis can also occur in immunodeficient patients due to bandages and tubular shape. Gypsum contamination can cause Rhizopus and Aspergillus cellulitis.

Virus (20%):

The virus is also an important pathogen of nosocomial infections. Common viral infections in the hospital include respiratory syncytial virus and parainfluenza virus-induced respiratory infections, influenza, rubella, viral hepatitis, etc. Newborns are most susceptible to rhinoviruses. Odd virus B can cause neonatal infection and epidemics. The diarrhea caused by rotavirus and Novak factor occurs mostly in infants and the elderly. Herpes simplex virus, cytomegalovirus and herpes-varicella virus can all be in the hospital. Formed popular.

Other (15%):

Conjunctivitis and pneumonia caused by Chlamydia trachomatis are found in neonates. Ureaplasma and Gardnarella vaginalis can be colonized in kidney transplant patients, which are also susceptible to Pneumocystis and Toxoplasma, malaria transmission during transfusion, amoeba, Infestation of Aphis sinensis and A. faecalis is common in mentally ill or intelligently low-lying children, and A. elegans can also be spread by organ transplantation.

Intra-hospital infection prevention

The attention of health administrative leaders at all levels and the medical staff of all levels, well-organized organizations and publicity and education play an important role in controlling infections in hospitals.

(1) General measures Because hospital infections have serious adverse effects on the recovery of patients' health and cause huge economic losses, controlling hospital infections should be taken seriously by all health administrators and medical workers. All hospitals should have full-time epidemiology. The hospital infection prevention team consisting of physicians, public health nurses and laboratory technicians often checks the ward medical records, laboratory results and X-ray examinations; once infectious diseases are discovered, the source of infection and the route of transmission should be traced, and effective prevention measures should be formulated. And at any time to modify and improve, the hospital staff, including all medical staff and non-medical staff, such as cooks, industrious personnel, etc. to carry out health publicity and education, so that everyone can master the basic knowledge of hospital infections, to prevent cross-infection between patients, It also prevents patients from getting infections from workers and workers infected in hospitals. Employees should strictly abide by and implement the disinfection and isolation system. Simple and easy hand washing measures should not be forgotten. Wash hands before and after contact with patients, so that everyone can recognize Hand washing is an important measure to prevent infection in hospitals.

A new physical examination should be carried out for new employees in the hospital, including tuberculin test, determination of hepatitis B antigen and antibody, and determination of rubella virus antibodies, etc., and all relevant units should be given measles, mumps vaccine for workers under 30 years old. , tetanus and diphtheria toxoid injection, contact with pregnant women of all ages, men and women susceptible to vaccination should be vaccination, influenza vaccine can be considered in some cases, the staff of the cerebral ward is very rare, so the flow of vaccine Or the significance of drug prevention is still difficult to affirm, pregnant workers should avoid rubella, hepatitis B and cytomegalovirus, pregnant women should not be vaccinated against rubella, should avoid contact with rubella patients, should also avoid exposure to blood or blood products of hepatitis B patients It is not possible to work in a ward with a cytomegalovirus-infected child. Workers who work in the ward for a long time should regularly carry out bacterial culture of the nose and hands. If there is a drug infected with Staphylococcus aureus, it should be actively treated with mupirocin ( It is mainly suitable for carriers of Staphylococcus aureus in the nose. Those who continue to carry Staphylococcus aureus should stop working in the ward.

Bacterial contamination of the hospital environment has a certain significance for the occurrence of nosocomial infections; therefore, it should be sampled and tested regularly in the ward environment, according to the detection of bacteria, appropriate measures, disinfectant and modern disinfection technology application, proper disposal of waste and kitchen, The improvement of the toilet hygiene code can reduce the environmental pollution caused by bacteria.

The hospital infection prevention team should frequently search for patients. Patients with infectious diseases or hospital staff should be found in the early stage for timely treatment. Those who need to be isolated should take corresponding measures according to the isolation routine, but unnecessary isolation or complicated isolation measures should be avoided. And release the isolation on schedule.

(B) specific measures In order to reduce the incidence of urinary tract infections, try to avoid catheterization, urine culture is not an indication of catheterization, clean urine collection of specimens can meet the requirements of urine culture, retaining catheterization needs to be strictly controlled, If there is an indication for application, a sterile closed drainage system is required. Strict aseptic technique should be used when inserting the catheter and the device with a closed drainage system. The collection bag should be fixed below the patient's position to avoid urine reversal. Flow, and discharge urine on time, keep the catheter for a shorter period of time. The catheter should be checked frequently for leaks during the placement of the catheter. Antibiotics or other antibiotics can not prevent urinary tract infection. Occurrence, which will lead to the emergence of drug-resistant bacterial infections, antibiotics should be given before the removal of the catheter to prevent post-cold urinary tract infection or post-cold bacteremia. In recent years, it has been reported to apply silver-coated catheterization. Tube can reduce the incidence of bacteriuria, some scholars believe that intermittent catheterization is more physiological, eliminating the adverse effects of foreign body (catheter), and bacteriuria or urinary tract The incidence of infection is much lower than that of those who retain catheterization. Intermittent catheterization is used for patients with neurogenic bladder and spinal cord injury.

The fine operation of the surgeon during surgery, reducing tissue trauma, reducing dead space, and stopping bleeding can reduce the incidence of postoperative infection. Ultraviolet irradiation in the operating room can reduce the infection rate of clean surgery, and air laminar flow can reduce airborne infection. The preventive application of antibacterial drugs has preventive effects on certain surgical infections, such as transvaginal hysterectomy, some orthopedic surgery, revascularization, biliary tract and colon surgery, etc., and application of antibacterial drugs before and after surgery for 24 to 48 hours. It can prevent the occurrence of postoperative infection.

Eliminate or prevent bacteria that may cause disease from colonizing the oropharynx. It is an important measure to prevent pulmonary infection in hospitals. The disinfection of aspirator or nebulizer, the frequent replacement of respiratory treatment equipment, and the operation of certain respiratory treatments should be Strengthening hand washing or glove operation can prevent exogenous bacteria from colonizing the oropharynx. The gastrointestinal tract is often the main source of endogenous respiratory colonization bacteria, especially gastric acid reduction caused by various causes and intestinal flora. In patients with dysregulation, therefore, patients with gastric bleeding should stop using antacids or H2 receptor blockers, and use sucralfate to prevent gastric bleeding without changing the pH of the stomach, thereby preventing bacterial colonization and reducing hospital lungs. The occurrence of infection, in addition to selective decontamination of digestive SDD (SDD) is a new measure to prevent colonization of foreign bacteria in the respiratory tract in recent years, reportedly reduced respiratory infections caused by Gram-negative bacteria The incidence rate shortens the hospitalization time of patients in the intensive care unit. The intermittent inhalation of intermittent antibacterial drugs has a certain effect on eliminating the colonization of oropharyngeal bacteria. Early ambulation, to be analgesics relieve pain wound so as not to interfere with coughing or deep breathing, difficulty swallowing for critically ill patients should be fed by nasogastric tube, to prevent the occurrence of aspiration pneumonia.

In order to prevent infection of intravenous infusion, strict hand washing and mastery of aseptic operation should be carried out. When placing high-nutrient infusion tube or intravenous rehydration for patients who are prone to infection, sterile gloves should be used. For venipuncture, a smaller needle should be used. Use peripheral veins to avoid the use of femoral veins. Add polymyxin, an ointment made of neomycin and bacitracin or an iodophor ointment at the catheter joint. Add a filter membrane to the infusion catheter to prevent bacteria from passing through the catheter. Into, venous incision is generally not used, but only as the last intravenous rehydration method, daily inspection and cleaning of the venipuncture site during rehydration, once local skin infection or phlebitis occurs, the tube should be removed in time, and the infusion tube, needle and patient blood Bacterial and fungal culture, the maintenance time of each infusion site should not exceed 48 ~ 72h.

(3) Treatment of nosocomial infections In view of the fact that in-hospital infections occur in patients with low immune function, in addition to the use of antibacterial drugs with strong bactericidal action and high curative effect on pathogens, attention should be paid to improving the patient's constitution and enhancing the patient's immune function. Reported that varicella-bearing immunoglobulin can prevent varicella and herpes zoster. The endotoxin monoclonal antibody HA-IA can reduce the mortality of Gram-negative bacilli sepsis, but its clinical efficacy is still difficult to evaluate. Immunization such as rubella, measles, Mumps, hepatitis B and other vaccines may be used in some hospital staff or susceptible patients, but may not have been promoted and applied. In addition, active treatment of patients with primary disease, such as controlling diabetes, chemotherapy for leukemia patients, etc. Helps control of infections in hospitals.

Hospital infection complications Complications sepsis

Intra-hospital infections can present complications of various systems, and the performance is complex and variable. The most serious complication is death.

Symptoms of infection in the hospital Common symptoms Gram-negative bacilli infection Bacterial infection Wound infection Pulmonary infection bacteria Urine sepsis Coma shock

(1) Infection in the hospital : After the bacteria or acne pathogens that are colonized in the gastrointestinal tract contaminate the urethral orifice, they can invade the bladder by means of a catheter or through a thin layer of liquid between the catheter and the mucosa of the urethra to reach the bladder through the catheter. The cavity is the most common way of bacterial invasion. The bacteria enter the catheter lumen after contaminating the catheter, drainage tube and urine collector. The cross-contamination of the retention catheter system caused by the staff's hand is in the spread of bacterial infection. In addition, bacteria can still enter the urinary tract through contaminated irrigating solution and various drug solutions, cystoscopes that are not strictly sterilized, and the chance of bacteriuria after a catheterization is 1% to 5%. Urinary catheter without closed disinfection collection device, after 48h, bacteriuria can be seen in 90% of patients; in closed disinfection collection devices, bacteriuria is only seen in 20% to 25% of patients, the incidence of infection is guided The urinary catheter is placed for a longer period of time, and the chance of bacteriuria is 5% to 10% per day. After 2 weeks, more than 50% of patients will develop infection.

(2) Surgical wound infection : Staphylococcus aureus is an important pathogen of wound infection. Infection usually occurs 3 to 8 days after operation. Contact infection is more important than air transmission during surgery. Cross infection between patients in postoperative ward may come from The carrier's carriers are generally transmitted by contact. Some Staphylococcus aureus wound infections may come from the patients themselves. Coagulase-negative staphylococci, streptococcus and enterococci are also common pathogens for wound infections. Gram-negative bacilli are very infectious. Less in the operating room, mostly in the ward, wound infection caused by Gram-negative bacilli accounts for about 60% of all wound infections, including Pseudomonas aeruginosa, Escherichia coli, etc.; except for the source of pathogens, colonization of the patient's intestines Bacteria in the respiratory tract can also be used as pathogenic bacteria for wound infections, such as intra-abdominal and wound infections after gastrointestinal surgery and abdominal puncture wounds, which are mainly caused by endogenous fragile bacilli and aerobic gram-negative bacilli. Anaerobic bacteria such as Bacteroides are also common pathogens for infection after gynecological surgery.

(3) Lower respiratory tract infection : The pathogen of pharyngeal colonization may come from the gastrointestinal tract of the patient, or may be obtained by cross-infection between patients or by the hands of hospital staff. Respirators, sprayers, humidifiers, etc. As a medium for bacterial transmission, some therapeutic devices with liquid reservoir devices can create conditions for the growth of Gram-negative bacilli, patients with tracheotomy lose their pharyngeal defense function; and non-sterile or traumatic suction during treatment, contaminated rinsing liquid, treatment of antibiotics, long-term bed rest in the elderly, intermittently inhaled secretions and contaminated intermittent pressurized respirators are all factors contributing to the development of lung infection, about 20 after chest and upper abdominal surgery % of patients have clinically significant infections, and half of the patients have X-ray evidence showing that some postoperative pulmonary complications, smoking, and original lung lesions, and surgery time of more than 2 hours will increase the incidence of postoperative infection, pneumonia It occurs 2 to 4 days after surgery, and Gram-negative bacteria are the most common pathogens, accounting for 60-80%, especially Enterobacteriaceae and Pseudomonas aeruginosa such as Klebsiella. Bacillus is more common, and can also be influenza bacillus, Staphylococcus aureus, pneumococcal, Legionella pneumophila, etc., when the humoral immune function is low, it is easy to cause pneumonia caused by capsule bacteria (influenza, pneumococci), cellular immune function Low patients can easily cause Aspergillus, Candida, Pneumocystis carinii, cytomegalovirus, herpes zoster virus, Chlamydia trachomatis, atypical mycobacteria, Legionella pneumophila and other lung infections, coma, shock and other patients Anaerobic bacteria (digestive cocci, digestive streptococci, Fusobacterium, etc.) or anaerobic bacteria mixed with aerobic bacteria may occur due to inhalation of oral secretions. Respiratory syncytial virus is the most important cause of lower respiratory tract infection in infants at 2 years of age. The pathogens have high morbidity and mortality.

(D) sepsis : the incidence of sepsis in hospitals is 0.3% to 2.8%, primary sepsis (the lesions of the primary infection are not obvious or by intravenous infusion, endovascular examination and hemodialysis caused by sepsis) account for about half of sepsis Others are from urinary surgical wounds, lower respiratory tract and skin infections.

(5) Digestive system infections: 1. pseudomembranous colitis, 2. viral hepatitis, 3. gastroenteritis.

(6) Skin infections Skin infections in hospitals account for about 5% of all hospital infections, including pyoderma caused by Staphylococcus aureus, rickets, impetigo, etc., hemolytic streptococcus pyoderma and herpes zoster. The incidence of skin infection caused by Staphylococcus aureus is high, which often causes epidemics. When most infants are hospitalized in the baby room for more than 4 days, there are Staphylococcus aureus colonization in the umbilicus, nose and skin. The colonization rate can reach 25%, but it is not necessarily the disease. 30% of the baby room staff can also have Staphylococcus aureus in the nose. Staphylococcus aureus can also be found in bed utensils, clothes, floors, tables and chairs, etc. Staphylococcus aureus spreads through contact in the infant compartment, and the hands of the staff play an important role in cross-infection, and airborne transmission is less common.

(7) Central nervous system infections Central nervous system infections often occur after craniocerebral surgery and cerebrospinal fluid shunt. The pathogens are more common with Enterobacteriaceae, Pseudomonas aeruginosa, Staphylococcus aureus, Epiphylococcus, and Acinetobacter. , even can be Candida albicans, high mortality.

Hospital infection check

Mainly for pathogen examination and culture and drug sensitivity experiments.

Diagnosis of hospital infection

Identification of infections and non-infectious diseases that cause inflammation in other ways, such as:

(1) An inflammatory reaction caused by injury or an inflammation caused by abiotic (such as rational, chemical) stimulation.

(2) There is only colonization of bacteria in open wounds or secretions between skin and mucous membranes, but no clinical symptoms and signs.

(3) Infections caused by placenta in infants, such as herpes simplex virus, varicella virus, toxoplasma, etc., and indications of infection within 48 hours after birth.

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