Machine learning and machine teaching in histopathology.

An artificial intelligence (AI) platform was trained by a consultant histopathologist to classify whole slide images (WSIs) of large bowel biopsies. Six medical students viewed WSIs of five large bowel biopsy cases and assigned the WSIs to one of the nine diagnostic categories. Then the students compared their answers with those generated by the AI. This training was repeated for a total of six rounds of five cases, and the accuracy of the students was recorded for each round. Each case had one or more WSIs. The student with the best final accuracy was asked to describe the morphological features that they had deduced. All the students improved during their training, from a mean accuracy of 13.7% in the first round to a mean accuracy of 77.1% in the sixth round (p = 0.0011). The student-deduced diagnostic features were mainly accurate. Some students learned more quickly than others.

Extended spectrum beta-lactamase testing of community Enterobacteriaceae in the west of Australia: poor performance of phenotypic methods.

Expanded spectrum ß-lactamase (ESBL) producing organisms have long been recognised in institutions worldwide. Recently, community isolates producing ESBL have been reported overseas and in eastern Australia. We tested 571 consecutive Enterobacteriaceae urinary isolates from Western Australia and the Northern Territory phenotypically by calibrated dichotomous sensitivity (CDS) methods in two periods (2007 and 2012). Eleven ESBL-producing isolates from 2012 and 39 banked strains were genotyped by PCR. Twenty-six (4.6%) strains produced ESBL by CDS. Only 57.7% of CDS-confirmed ESBL strains had an initial reduced cephalosporin zone. Vitek 2 identified only nine (34.6%) CDS-ESBL strains. There was no significant change in ESBL strain prevalence over the two periods by CDS, but our laboratory information system showed a steady increase from 2007-2012 in ESBL strain prevalence (identified by multiple methods) at a rate of 0.02% per month to reach 2% by 2012. Genotyping of 50 CDS-confirmed isolates demonstrated ESBL genes in 44 (88%), mainly CTX-M genes. Twenty-five ESBL strains contained more than one ß-lactamase gene, up to a maximum of three genes. There is a rising prevalence of ESBL strains in our communities. CDS and Vitek-2 testing is neither sensitive nor specific in detecting ESBL enzymes. Routine laboratories need access to genotyping to identify and monitor ESBLs in the community.

Staphylococcus aureus colonization among healthcare workers at a tertiary care hospital.

We describe the epidemiology of Staphylococcus aureus colonization among 200 healthcare workers. The prevalence of S. aureus was 28%, and the prevalence of methicillin-resistant S. aureus (MRSA) was 2%. The incidence of MRSA colonization was extremely low. This study suggests that the risk of MRSA transmission to healthcare workers is low in a hospital where MRSA is endemic.

Outbreak management and implications of a nosocomial norovirus outbreak.

BACKGROUND: Noroviruses are enterically transmitted and are a frequent cause of gastroenteritis, affecting 23 million people annually in the United States. We describe a norovirus outbreak and its control in a tertiary care hospital during February-May 2004. METHODS: Patients and health care workers met the case definition if they had new onset of vomiting and/or diarrhea during the outbreak period. Selected stool samples were tested for norovirus RNA. We also determined outbreak costs, including the estimated lost revenue associated with unit closures, sick leave, and cleaning expenses. RESULTS: We identified 355 cases that affected 90 patients and 265 health care workers and that were clustered in the coronary care unit and psychiatry units. Attack rates were 5.3% (7 of 133) for patients and 29.9% (29 of 97) for health care workers in the coronary care unit and 16.7% (39 of 233) for patients and 38.0% (76 of 200) for health care workers in the psychiatry units. Thirteen affected health care workers (4.9%) required emergency department visits or hospitalization. Detected noroviruses had 98%-99% sequence identity with representatives of a new genogroup II.4 variant that emerged during 2002-2004 in the United States (e.g., Farmington Hills and other strains) and Europe. Aggressive infection-control measures, including closure of units and thorough disinfection using sodium hypochlorite, were required to terminate the outbreak. Costs associated with this outbreak were estimated to be $657,644. CONCLUSIONS: The significant disruption of patient care and cost of this single nosocomial outbreak support aggressive efforts to prevent transmission of noroviruses in health care settings.