Safety and Effectiveness of a Laboratory Intervention to Effectively NOT Treat Asymptomatic Bacteriuria

Overview

This is an observational cohort study of 1000 consecutive patients on medical and surgical wards at the Mount Sinai Hospital in Toronto who have a mid-stream urine culture ordered. When these cultures are ordered or received in the laboratory, a message is posted that the specimen will not be processed in the laboratory unless a call is received to say that the patient has local urinary symptoms. The goal is to establish whether not processing mid-stream urine cultures is safe.

The clinical information system for Mount Sinai Hospital will be programmed such that, whenever a mid-stream urine sample is received in the microbiology laboratory from medical and surgical wards, the specimen will be held rather than processed. The system will reflex a result the specimen (either at a set time twice daily, or at the time the specimen is accessioned) with a message saying: "The great majority of positive urine cultures from inpatients without an indwelling urinary catheter represent asymptomatic bacteriuria and are no longer routinely processed. If you strongly suspect that your patient has developed a urinary tract infection or if you have mislabeled this specimen, please call the Microbiology laboratory within 48 hours to request processing of this urine culture". Any urine being held in the microbiology laboratory will automatically generate an email alert to the study coordinator. Within 24 hours of receipt of the urine culture, the coordinator will confirm that the specimen was a midstream urine specimen, interview the patient, determine if they have had any symptoms of a urinary tract infection, and collect information on what other symptoms of infection were present when the culture was ordered, why the culture was ordered, and whether antibiotic therapy was started empirically. All patients whose urines have not been processed will have a second follow-up visit/call at 72-96 hours to ensure that urinary symptoms have not developed or worsened. If symptoms develop/worsen, the study coordinator will have the investigator follow up. All patients will have a follow-up telephone call/visit 28-35 days after the specimen is obtained to identify any intercurrent infections (including C. difficile infection), and any potential complications/adverse effects from antibiotics. Permission will be obtained to contact family or other attending physicians to clarify any information if necessary. Data collected for each patient will include: age, gender, underlying medical conditions, reason for hospitalization, date of admission to hospital, service at admission and at the time urine specimen obtained, date urine specimen obtained, whether or not urine culture processed, urine culture results and date reported (if the urine culture was processed), urinalysis results (if ordered), why the urine culture was ordered, whether the patient had fever, hypothermia, dysuria, urgency, frequency, costophrenic angle tenderness, increased incontinence, presence/absence of delirium, presence/absence of any other behavior changes, whether the patient was capable of reporting urinary tract symptoms, duration of each symptom, whether or not empiric antibiotics were ordered (name, dose, duration) at the time the specimen was ordered and what the indication for antibiotics was, what the whether or not antibiotics ordered empirically were stopped if the urine culture was reported as negative; whether empiric antibiotics were appropriate to the pathogen (if the urine was cultured), whether the antibiotic regimen was changed in response to culture results (urine or other); what the final diagnosis from the most responsible physician was regarding the episode for which the urine culture was ordered; whether the episode met NHSN criteria for any infection, whether the patient developed any adverse events potentially associated with antibiotics (includes solicited: nausea, vomiting, diarrhea (including CDI), rash, vaginitis, any allergic reaction) and unsolicited - if the unsolicited are known to be adverse events associated with the antibiotic in question (eg. Stevens-Johnson syndrome with Septra, achilles tendon rupture with fluoroquinolones). Data will be collected by chart review, and by interview with the patient/next of kin. For each patient in whom a serious adverse event occurs, a case summary will be prepared. Based on the case summary, hospital chart, and study notes, two internists/infectious disease physicians, otherwise unrelated to the study will be asked independently to assess whether the serious adverse event was associated with the failure to process a urine culture (if one was not processed), or associated with antibiotic prescribed for asymptomatic bacteruria. If the two physicians disagree, a third physician will review, and the three will meet to arrive at a consensus. If consensus cannot be achieved, the event will be recorded as associated with not performing the culture or with the antibiotic if 2 physicians of the 3 agree.