Frances P. Downes

Comparison of Prevalence and Antimicrobial Susceptibilities of Campylobacter spp. Isolates from Organic and Conventional Dairy Herds in Wisconsin

ABSTRACT The prevalence and antimicrobial susceptibilities of Campylobacter spp. isolates from bovine feces were compared between organic and conventional dairy herds. Thirty organic dairy herds, where antimicrobials are rarely used for calves and never used for cows, were compared with 30 neighboring conventional dairy farms, where antimicrobials were routinely used for animals for all ages. Fecal specimens from 10 cows and 10 calves on 120 farm visits yielded 332 Campylobacter isolates. The prevalence of Campylobacter spp. in organic and conventional farms was 26.7 and 29.1%, and the prevalence was not statistically different between the two types of farms. Campylobacter prevalence was significantly higher in March than in September, higher in calves than in cows, and higher in smaller farms than in large farms. The rates of retained placenta, pneumonia, mastitis, and abortion were associated with the proportion of Campylobacter isolation from fecal samples. The gradient disk diffusion MIC method (Etest) was used for testing susceptibility to four antimicrobial agents: ciprofloxacin, gentamicin, erythromycin, and tetracycline. Two isolates were resistant to ciprofloxacin, and none of isolates was resistant to gentamicin or erythromycin. Resistance to tetracycline was 45% (148 of 332 isolates). Tetracycline resistance was found more frequently in calves than in cows (P = 0.042), but no difference was observed between organic and conventional farms. When we used Campylobacter spp. as indicator bacteria, we saw no evidence that restriction of antimicrobial use on dairy farms was associated with prevalence of resistance to ciprofloxacin, gentamicin, erythromycin, and tetracycline.

Assessing the Risk of Laboratory-Acquired Meningococcal Disease

ABSTRACT Neisseria meningitidis is infrequently reported as a laboratory-acquired infection. Prompted by two cases in the United States in 2000, we assessed this risk among laboratorians. We identified cases of meningococcal disease that were possibly acquired or suspected of being acquired in a laboratory by placing an information request on e-mail discussion groups of infectious disease, microbiology, and infection control professional organizations. A probable case of laboratory-acquired meningococcal disease was defined as illness meeting the case definition for meningococcal disease in a laboratorian who had occupational exposure to an N. meningitidis isolate of the same serogroup within 14 days of illness onset. Sixteen cases of probable laboratory-acquired meningococcal disease occurring worldwide between 1985 and 2001 were identified, including six U.S. cases between 1996 and 2000. Nine cases (56%) were serogroup B; seven (44%) were serogroup C. Eight cases (50%) were fatal. All cases occurred among clinical microbiologists. In 15 cases (94%), isolate manipulation was performed without respiratory protection. We estimated that an average of three microbiologists are exposed to the 3,000 meningococcal isolates seen in U.S. laboratories yearly and calculated an attack rate of 13/100,000 microbiologists between 1996 and 2001, compared to 0.2/100,000 among U.S. adults in general. The rate and case/fatality ratio of meningococcal disease among microbiologists are higher than those in the general U.S. population. Specific risk factors for laboratory-acquired infection are likely associated with exposure to droplets or aerosols containing N. meningitidis. Prevention should focus on the implementation of class II biological safety cabinets or additional respiratory protection during manipulation of suspected meningococcal isolates.

Newborn Screening for Spinal Muscular Atrophy by Calibrated Short-Amplicon Melt Profiling

BACKGROUND The management options for the autosomal recessive neurodegenerative disorder spinal muscular atrophy (SMA) are evolving; however, their efficacy may require presymptom diagnosis and continuous treatment. To identify presymptomatic SMA patients, we created a DNA-based newborn screening assay to identify the homozygous deletions of the SMN1 (survival of motor neuron 1, telomeric) gene observed in 95%-98% of affected patients. METHODS We developed primers that amplify a 52-bp PCR product from homologous regions in the SMN1 and SMN2 (survival of motor neuron 2, centromeric) genes that flank a divergent site at site c.840. Post-PCR high-resolution melt profiling assessed the amplification product, and we used a unique means of melt calibration to normalize profiles. Samples that we had previously characterized for the numbers of SMN1 and SMN2 copies established genotypes associated with particular profiles. The system was evaluated with approximately 1000 purified DNA samples, 100 self-created dried blood spots, and >1200 dried blood spots from newborn screening tests. RESULTS Homozygous deletion of SMN1 exon 7 produced a distinctive melt profile that identified SMA patients. Samples with different numbers of SMN1 and SMN2 copies were resolved by their profiles. All samples with homozygous deletions were unambiguously recognized, and no normal sample was misidentified as a positive. CONCLUSIONS This assay has characteristics suitable for population-based screening. A reliable screening test will facilitate the identification of an SMA-affected cohort to receive early intervention to maximize the benefit from treatment. A prospective screening trial will allow the efficacy of treatment options to be assessed, which may justify the inclusion of SMA as a target for population screening.

Use of multiple‐locus variable number tandem repeat analysis and phage typing for subtyping ofSalmonella Enteritidis from sporadic human cases in the United States

Aims:  To investigate the genetic diversity among S. Enteritidis isolates from different geographic regions to evaluate the relationship between phage types (PTs) and variable number tandem repeat analysis (VNTR) loci.

Delayed Detection of an Increase in Resistant Acinetobacter at a Detroit Hospital

OBJECTIVE To study an increase of antimicrobial-resistant Acinetobacter baumannii and to assess reasons for the delayed detection of this increase. DESIGN Review of medical, laboratory, and infection control records. Plasmid profile analysis of available A baumannii isolates. SETTING A 340-bed trauma and intensive care hospital in Detroit, Michigan. RESULTS The number of hospitalized patients with resistant A baumannii increased during late 1989 and early 1990: 4 in September, 10 in October, 12 in November, 18 in December, and 23 in January (chi square for trend = 14.6, p = .0001). Forty-four (66%) of the 67 patients culture-positive for resistant A baumannii had respiratory tract colonization or infection. Of 11 resistant isolates, 6 had a similar plasmid profile and 5 had no plasmids. Under the hospitals targeted surveillance system, only positive cultures from blood or wounds were investigated; this largely respiratory increase of resistant A baumannii went unrecognized until January 1990. CONCLUSIONS Antimicrobial resistance in A baumannii is an important concern. Such resistance is not necessarily plasmid mediated. Targeted surveillance for this and other agents of nosocomial infection should be used with caution, particularly in hospitals with many debilitated patients.

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.

From Newborn Screening to Population Health Research: Implementation of the Michigan BioTrust for Health

In June 2009, the Michigan Department of Community Health launched the Michigan BioTrust for Health to improve preservation and utility of residual dried blood spots from newborn screening (NBS) for biomedical research while maintaining public support and integrity of NBS. In this article, we chronicle implementation of the BioTrust and document its impact on NBS. Overall, the percentage of new parents who consent to possible future research use of their childrens dried blood spots through the BioTrust has remained consistent with previous public opinion surveys. No significant increase in refusal of NBS has been observed despite increased publicity. There was, however, a slight increase in requests to destroy samples following completion of NBS, indicating readily accessible opt-out information. Given adequate training and cooperation of birthing hospital staff, as well as outreach education for parents and health-care providers, we conclude it is possible to implement a biobanking initiative without adversely impacting NBS.

A comprehensive Laboratory Services Survey of State Public Health Laboratories.

In November 2004, the Association of Public Health Laboratories (APHL) conducted a Comprehensive Laboratory Services Survey of State Public Health Laboratories (SPHLs) in order to establish the baseline data necessary for Healthy People 2010 Objective 23-13. This objective aims to measure the increase in the proportion of health agencies that provide or assure access to comprehensive laboratory services to support essential public health services. This assessment addressed only SPHLs and served as a baseline to periodically evaluate the level of improvement in the provision of laboratory services over the decade ending 2010. The 2004 survey used selected questions that were identified as key indicators of provision of comprehensive laboratory services. The survey was developed in consultation with the Centers for Disease Control and Prevention National Center for Health Statistics, based on newly developed data sources. Forty-seven states and one territory responded to the survey. The survey was based on the 11 core functions of SPHLs as previously defined by APHL. The range of performance among individual laboratories for the 11 core functions (subobjectives) reflects the challenging issues that have confronted SPHLs in the first half of this decade. APHL is now working on a coordinated effort with other stakeholders to create seamless state and national systems for the provision of laboratory services in support of public health programs. These services are necessary to help face the threats raised by the specter of terrorism, emerging infections, and natural disasters.

The evolving Public Health Laboratory System.

Charles Darwins On the Origin of Species celebrated its 150th anniversary in 2009.1 In this publication that has shaped our understanding of biology, the author proposes that organisms evolve increasingly complex independent and interdependent systems to survive and flourish in an ever-changing environment. The evolution of public health laboratories (PHLs) can be compared with that of multi-celled organisms. PHL history tracks the progress from simply having laboratory testing available for public health programs to the development and fine-tuning of laboratory networks requiring special linkages and shared efforts to provide populations with comprehensive laboratory testing for rapid diagnosis, surveillance, and disease-control efforts. The evolution, from a PHL to the new definition of a PHL system that includes public and private laboratories, is reflected by a new focus on the relationships between laboratories, which complement the technical capabilities—similar to the increasingly complex interactions of multi-celled organisms responding to a changing environment.