Nosocomial infections

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Nosocomial infections

  1. 1. NOSOCOMIAL INFECTIONS Prof. Dr. N. Ribarova, MD
  2. 2. <ul><li>Definition : Nosocomial infection (NI) is every infectious process, appearing during hospital stay, despite its clinical picture, carrier status and time of manifestation - during hospital treatment or after discharge. </li></ul>
  3. 3. <ul><li>Infections that develop in outpatient departments, day clinics or other closed human groups such as in nursing houses or orphanages and are associated to medical or dental procedures are nosocomial too. </li></ul>
  4. 4. <ul><li>Acute infectious diseases that were in incubation period before hospital admittance are not considered as a NI. </li></ul>
  5. 5. <ul><li>Diseases, caused by opportunistic microorganisms, without determined incubation period, are regarded as a NI, in case they developed 48-72 hours after patient's admittance in the hospital ward. </li></ul>
  6. 6. <ul><li>Nosocomial infections are topic of the day of contemporary health care. Their importance is determined by the relatively large number of patients with NI - 2-15 %of all admitted patients and significantly higher lethality - up to 80 %. Besides the health costs, there are considerable damages of economic, social and ethical character. </li></ul>
  7. 7. <ul><li>Short historical review: The problem with NI emerged with the appearance and development of hospital institutions. The foun-dations of contemporary manage-ment of NI was laid by Hungarian doctor J. Semmelweis, 1846. N.I.Pirogov (1810-1881) recom-mended a system of &quot;segregation&quot; to stop NI. J. Lister (1827-1921) is the founder of antiseptics (usage of pulverized carbolic acid and gauzes with carbolic acid during operations). </li></ul>
  8. 8. <ul><li>With the invention of sulfonamides, and later antibiotics, new opportunities for antimicrobial therapy of NI appeared. However soon disappointment appeared because of bacterial antibiotic resistance. The selection of resistant microorganisms in the course of antibiotic and other current chemotherapy, combined with the outburst of various diagnostic and therapeutic interventions lead to changes in the nature of NI. </li></ul>
  9. 9. <ul><li>Etiology: A typical feature of contemporary NI is that their etiological agents are opportunistic microorganisms that are a part of patient's own microbial flora. </li></ul><ul><li>Up to 50 % of NI in the last decades are caused by Gram-negative microorganisms from the family Enterobacteriaceae, genus Escherichia, Klebsiella, Enterobacter, Serratia, Proteus, Providencia; genus Pseudomonas and Acinetobacter from the group of Gram-negative non-fermenting aerobes. </li></ul>
  10. 10. <ul><li>Gram-positive cocci from genus Staphylococcus and Streptococcus cause 20-50 % of NI, various viruses - about 15-20 %, the rest NI are caused by non-spore rising anaerobes, fungi, opportunistic bacteria and rarely by protozoa. </li></ul>
  11. 11. <ul><li>The NI etiology is highly influenced by the changes in microbial population, caused by broad and not always reasonable antibiotic administration. Therefore in the &quot;high risk&quot; hospital wards (neonatology, obstetrics, general surgery, urology, intensive care units) circulate the so-called &quot;hospital&quot; strains, that are highly virulent, invasive and with multiple resistance to the used antibiotics and disinfection solutions. </li></ul>
  12. 12. <ul><li>NI etiological agents are characterized by significant stability in surrounding environment. Gram-positive cocci can stand dehydration for long periods on surfaces, while Gram-negative survive in humid conditions for months. </li></ul>
  13. 13. <ul><li>Pathogenesis: The polietiology of NI creates prerequisites for various changes in the host organism. </li></ul>
  14. 14. <ul><li>Entry site for the infection can be the skin and mucous membranes, respiratory and digestive system, the urogenital tract. Very often the etiology agent is a part of the own bacterial flora (in cases with endogenous infection). Typical for NI is the creation of additional, uncommon entry sites of the infection as a result of multiple diagnostic and therapeutic invasive procedures. </li></ul>
  15. 15. <ul><li>The incubation period of NI varies from few hours to 30 and more days according to the nosology unit. </li></ul>
  16. 16. <ul><li>Classification scheme of J.Gamer (1970), according to which NI are separated into 7 groups based on clinical criteria: </li></ul><ul><li>Infections of respiratory system </li></ul><ul><li>Infections of digestive system </li></ul><ul><li>Infections of urogenital system </li></ul><ul><li>Infections of cardiovascular system </li></ul><ul><li>Infections of skin and subcutaneous tissues </li></ul><ul><li>Infections of sensory organs </li></ul><ul><li>Other infections (classic acute infectious diseases) </li></ul>
  17. 17. <ul><li>Sources of infection: </li></ul><ul><li>Sick or carriers among the medical staff, students, residents, mothers of sick children </li></ul><ul><li>New patients, carriers or patients in incubation period of an infectious disease </li></ul><ul><li>New patients with mixed or undistinguished infection </li></ul><ul><li>Patients with evident infection or in carrier state </li></ul>
  18. 18. <ul><li>In current NI 30-50 % of cases represent endogenous infection (autoinfection). It is caused by microorganisms belonging to patient's own intestinal or skin flora that reached normally sterile areas or were activated by administered therapy (antibiotics, corticosteroids, cytostatics). </li></ul>
  19. 19. <ul><li>From an epidemiological standpoint as a source for infection most important is the medical personnel that become carriers of highly virulent, strongly invasive and with multiple resistance &quot;hospital&quot; strains of microorganisms. </li></ul>
  20. 20. <ul><li>Mechanisms to pass the infection: The mechanisms are various. Practically in hospital environment all 4 mechanisms to pass an infection are possible (airborne, blood, fecal-oral and contact). There are various factors for transmitting the infection with predominance of the contact mechanism. Most important are the staffs' hands, medical equipment and instruments. </li></ul>
  21. 21. <ul><li>Population susceptibility and immunity: Typical for the current epidemic process of NI is that large number of hospital population is vulnerable to infections. </li></ul>
  22. 22. <ul><li>Various etiology leads to different in terms of intensive immunity. Infections, caused by opportunistic bacterial flora, the developed humoral and cell-mediated (phagocytic) immunity is of short duration. Recurrences of the infection are possible. </li></ul>
  23. 23. <ul><li>Characteristics of the epidemiology process: Current NI represent a problem for economically developed countries. </li></ul>
  24. 24. <ul><li>NI prolong hospital stay, raise treatment's cost, decrease the utilization of hospital services and effectiveness of health care system, cause suffering, disability and premature death. Ultimately they significantly affect national economy. </li></ul>
  25. 25. <ul><li>Among the registered NI most common are the infections of upper respiratory tract -40%, followed by pulmonary NI - 13%, surgical wound infections - 12 %, urogenital infections - 10 %, cutaneous NI - 8 %, intestinal infections - 6 %. </li></ul>
  26. 26. <ul><li>Nowadays major prerequisites for the appearance and development of NI are the following: </li></ul><ul><li>Constantly increasing stream of patients in health care institutions as a result of population aging, chronic diseases, accessibility of medical care, broadened health culture. </li></ul><ul><li>Hospital overpopulation </li></ul><ul><li>Concentration of multiple sources of infection and circulation of &quot;hospital strains&quot; of microorganisms </li></ul>
  27. 27. <ul><li>Various artificial ways for additional contamination - diagnostic and therapeutic manipulations and interventions </li></ul><ul><li>Status of the sanitary care and hygiene, management, culture of medical care </li></ul>
  28. 28. <ul><li>The intensity of epidemiological process of NI is manifested by sporadic cases and epidemic outbreaks, and rarely by epidemics. </li></ul>
  29. 29. <ul><li>Antiepidemic measures: </li></ul><ul><li>2. Regarding the patient </li></ul><ul><li>- Well-timed and proper diagnosis </li></ul><ul><li>- Effective sanitary preparation before </li></ul><ul><li>admittance to the ward </li></ul><ul><li>- Specific therapy </li></ul><ul><li>3. Regarding the people in contact </li></ul><ul><li>- Microbiological, clinical and other tests </li></ul><ul><li>- Active immunization </li></ul><ul><li>- Specific means for passive prophylactics </li></ul><ul><li>4. Regarding the surrounding environment </li></ul><ul><li>- Disinfection, Sterilization </li></ul>
  30. 30. <ul><li>Measures for Prophylactics: </li></ul><ul><li>Detection, registration and report of NI </li></ul><ul><li>Improvement of hospital equipment and utilities for treating patients </li></ul><ul><li>Antiseptics and aseptics of all medical procedures </li></ul><ul><li>Clinical and microbial service and antimicrobial therapy </li></ul><ul><li>Organization and management of activities for prophylactics and treatment of NI, for training of the medical staff about NI. </li></ul>

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