Systematic review of antibiograms: A National Laboratory System approach for improving antimicrobial susceptibility testing practices in Michigan.

OBJECTIVES: Public health surveillance is often dependent on sentinel testing performed in clinical microbiology laboratories, and recognition of emerging/ unusual antimicrobial resistance is especially challenging. We obtained cumulative antibiograms from hospitals to determine whether clinical laboratories recognized unusual resistance or reported antimicrobials inappropriate for various bacterial species, as measured before and after public health laboratory (PHL) educational and technical-support interventions. METHODS: We compared cumulative antibiogram data from 81 clinical laboratories servicing 86 hospitals in Michigan from 2000 through 2005 with a standardized checklist derived from Clinical and Laboratory Standards Institute (CLSI) antimicrobial susceptibility testing (AST) documents. We considered the reporting of unlikely percent-susceptible results and/or inappropriate antimicrobials serious errors, and we calculated error rates for each data year. We used CLSI-recommendation compliance as a measure to determine whether laboratories were implementing changes. RESULTS: Ninety-five of 239 (28%) cumulative antibiograms examined had one or more serious errors. The annual number of cumulative antibiograms with serious errors did not change radically (range: 10-13); however, when expressed as a percentage of cumulative antibiograms received, the occurrence of these errors declined from 59% in 2000 to 19% in 2005. The reporting of misleading or dangerous antimicrobial-organism combinations occurred less frequently than the reporting of unlikely percent-susceptible results. Compliance with new CLSI recommendations did not improve significantly. CONCLUSIONS: AST is complex and nuanced. PHL programs can provide resources, guidance, and technical support to help clinical microbiologists differentiate questionable AST results from true emerging antimicrobial resistance.

Association of Group B Streptococcus colonization and bovine exposure: a prospective cross-sectional cohort study.

BACKGROUND: While Group B Streptococcus (GBS) human colonization and infection has long been suspected as originating from cows, several investigators have suggested that ongoing interspecies GBS transmission is unlikely due to genotyping data demonstrating that human and bovine-derived GBS strains represent mostly distinct populations. The possibility of ongoing transmission between humans and their livestock has not been systematically examined. METHODOLOGY/PRINCIPAL FINDINGS: To examine ongoing interspecies transmission, we conducted a prospective cross-sectional cohort study of 68 families and their livestock. Stool specimens were collected from 154 people and 115 livestock; GBS was detected in 19 (12.3%) humans and 2 (1.7%) animals (bovine and sheep). Application of multilocus sequence typing (MLST) identified 8 sequence types (STs or clones), with STs 1 and 23 predominating. There were 11 families in which two members submitted stools and at least one had GBS colonization. In 3 of these families, both members (consisting of couples) were colonized, yielding a co-colonization rate of 27% (95% CI: 7%-61%). Two of these couples had strains with identical MLST, capsule (cps) genotype, susceptibility, and RAPD profiles. One couple co-colonized with ST-1 (cps5) strains also had a bovine colonized with the identical strain type. On multivariate analysis of questionnaire data, cattle exposure was a predictor of GBS colonization, with each unit increase in days of cattle exposure increasing the odds of colonization by 20% (P = 0.02). These results support interspecies transmission with additional evidence for transmission provided by the epidemiological association with cattle exposure. CONCLUSIONS/SIGNIFICANCE: Although GBS uncommonly colonizes livestock stools, increased frequency of cattle exposure was significantly associated with human colonization and one couple shared the same GBS strains as their bovine suggesting intraspecies transmission. These results set the framework for GBS as a possible zoonotic infection, which has significant public health implications.

Drug-resistant Neisseria gonorrhoeae in Michigan.

The increasing prevalence of quinolone-resistant Neisseria gonorrhoeae (QRNG) in the United States is a cause for concern. Detecting resistance is complicated by the widespread use of molecular tests that do not provide isolates for susceptibility testing. The Michigan Department of Community Health developed a sentinel surveillance program to detect antimicrobial drug resistance in N. gonorrhoeae. Sentinel surveillance from 11 laboratories submitted 1,122 isolates for antimicrobial drug susceptibility testing and detected 2 clusters of QRNG from January 2003 to September 2004. These clusters were epidemiologically distinct: one involved young, heterosexual youth, and the other involved older men who have sex with men. This finding led to changes in local treatment recommendations that limited spread of resistant strains. Development of the sentinel program, collection of data, and epidemiologic analysis of the clusters are discussed.