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Nosocomial infection
Lecture 21
Question | Answer |
---|---|
nosocomial infections | important cause of morbidity and mortality, 5-10% people hospitalized in US develop an infection |
impact of nosocomial infections | risk of death doubles, length of hospital stay is prolonged, expensive and contribute to rising health care costs |
expansion of definition of nosocomial | infection not present when they enter hospital, most become evident at 72 hrs or more with a few exceptions |
endemic infections | occuring as part of the background or normal rate of infection in a specified population |
epidemic infections | occuring as part of an outbreak defined as a significant increase in the usual rate of infection in the specified population |
prevalence rate | a measurement of infections total number of cases in the defined population at a specific time/time period |
crude/overall mortality rate | measurement of the worst outcome of infection in the population in general ratio of patients who die to overall number of patients |
attributable mortality rate | a measurement of the worst outcome from infection in those with the infection ratio of those who die to those who have the condition in the population |
device associated incidence rate | measurement of infections related to medical devices ratio of the number of new cases of device related infections to the number of days of device utilization in the population at risk |
information sources upon which infections stats are based | combination of clinical findings, lab evidence, and supportive data |
two conditions that are not infections | 1. colonization: superficial microbes on skin, mucous membranes, open wounds, or secretions that are not causing clinical symptoms 2. inflammation: tissue response to injury or stimulation by non-infectious agents such as chemicals or physical stress |
goals of hospital epidemiology | infection control, quality improvement, controlling costs |
targeted surveillance | used for a special patient population, diagnostic and therapeutic procedures, and specific pathogens |
methods of disease spread | direct, indirect, droplet, airborne, vector borne |
Current guidelines | 2 tiered: 1. standard: gloves when touching body fluids, mucous membranes, or non-intact skin, gowns and face masks when splashing liquids or aerosols present, 2. transmission based: supplement standards. Divided into contact, airborne, and droplet |
Contact precautions | using gloves when making contact with skin/inanimate objects that have been in direct contact with patient, gowns when it's likely that workers clothing will come into contact with the patient or items in the room. Used with antibiotic resistant bacteria |
airborne precautions | patients in room with - pressure ventilation, patients must remain in room, doors and windows to room kept closed, hospital workers wear N95 TB respirator |
droplet precautions | wear a mask, keep a certain distance from patient, use a private room |
main nosocomial organisms in 2009 | staph aureus, clostridium difficile, vancomycin resistant enterococcus, gram- rods (ESBL enterobacteriaceae, KPC klebsiella, acinetobacter from iraq, pseudomonas aeruginosa) |
MRSA implications | all other penicillins and cephalosporins are not very effective |
MRSA major hospital problem | known patient carriers are placed in isolation ARO precautions: gown, gloves, and wash hand before and after entering room |
VRSA | due to overuse, patient must be in strict isolation, government agencies get involved |
VISA | treatment failure, affect people more than VRSA, harder to detect in lab testing |
prevention of S. aureus infection | in infants the cord is treated with triple antimicrobial disinfectant dye after delivery (purple) |
spread of staph aureus | primarily by hand, autoinfection common in community |
reduction of surgical infection | brief, high dose regimen of antibiotics during time of certain types of surgery can lower infection rate, fewer people in OR, post surgery isolate infected patients, handwashing with chlorohexidine or iodophor soaps, wear protective clothing |
attempts to lower MRSA nosocomial infections | screen all high risk persons coming into the hospital for MRSA (nasal swab plus culture or PCR. High risk=nurisng home patients, prisoners, past MRSA patients, those going into ICUs, those with long/complicated stays |
VRE | emerged in early 90's, now >20% are resistant |
resistance and treatment | E. faecium: resistant to ampicillin, VRE now common in HAI |
Clostridium difficile | widespread in environment, intestinal flora of 2-4% of adults, produces 2 toxins (A: enterotoxin, B:potent cytotoxin). Nosocomial infections in 0.5-3% of hospitalized patients |
New strain of C. difficile | hyper producer of toxins, toxin repressor gene is not functional and toxin is 10-100 times higher than in normal strains |
treatment for C. difficile PMC | stop offending antibiotic which is altering the normal flora, use vancomycin or metronizadole, surgery to remove part of colon may be required. Early diagnosis important (current tests miss 10-20%), isolate patients, wash hands with soap and water |