March 2012

News read or heard lately

Gonococcal infections and laboratory capacity for culture, AST

Investing in rebuilding defenses against gonococcal infections, including local and regional laboratory capacity for culture and antimicrobial susceptibility testing, is paramount in controlling the spread and reducing the consequences of cephalosporin-resistant strains, say the authors of an editorial in the Feb. 9 New England Journal of Medicine, “The emerging threat of untreatable gonococcal infection” (366;6:485–487).

Susceptibility to cephalosporins has been decreasing rapidly, write Gail A. Bolan, MD, of the CDC’s Division of STD Prevention; P. Frederick Sparling, MD, of the Department of Medicine, University of North Carolina School of Medicine; and Judith N. Wasserheit, MD, MPH, of the Departments of Global Health, Medicine, and Epidemiology, University of Washington.

One of the priorities now is to be vigilant for cases in which cephalosporin treatment has failed, the authors write. They say the shift from culture-based methods, which are necessary for antimicrobial susceptibility testing, to nucleic acid amplification tests, “which cannot currently detect the genetic markers of cephalosporin-resistant gonorrhea, makes it more difficult to identify treatment failures.”

“Patients who return with persistent or recurrent symptoms shortly after treatment should be retested for gonorrhea by culture, and isolates should be submitted for antimicrobial-susceptibility testing,” they write.

Clinicians need protocols for transporting culture specimens to laboratories, and they need to know which laboratories are able to perform gonococcal culture testing, say Drs. Bolan, Sparling, and Wasserheit. They add: “Health plans that restrict coverage to only one type of test per visit should instead allow reimbursement for both gonococcal nucleic acid-amplification tests and cultures when patients are being evaluated for reinfection or cure.”

The Gonococcal Isolate Surveillance Project is designed to monitor trends in minimum inhibitory concentrations and to inform treatment recommendations. “Yet GISP samples less than 2% of all reported gonorrhea cases and cannot provide results quickly enough,” caution the authors, who say, “A surveillance infrastructure for resistant gonorrhea must be implemented at the local level to be more timely and effective.”

The authors say that reduced susceptibility to cephalosporins results from the combined effects of several chromosomal gene mutations, including mutations in penA, the gene that encodes penicillin-binding protein 2; penB, which affects drug entry through an outer membrane protein channel (PorB1b), and mtrR, a repressor of the MtrCDE-encoded pump.

Product label change for Tysabri includes anti-JCV antibody status

The FDA has approved a product label change for Tysabri (natalizumab), an immunomodulator used to treat multiple sclerosis or Crohn’s disease, identifying anti-JC virus (JCV) antibody status as a risk factor for developing progressive multifocal leukoencephalopathy (PML). The new label says that anti-JCV antibody negative status indicates exposure to the JC virus has not been detected.

The label update was based on analysis of data from a quantitative risk stratification algorithm from Biogen Idec and Elan Corp., co-marketers of Tysabri. Patients in the analysis who were anti-JCV antibody positive were found to be at a higher risk for developing PML. Patients who were anti-JCV antibody positive and had received prior immunosuppressant therapy and treatment with Tysabri for more than two years had the highest risk of developing PML.

The U.S. label update follows European Commission approval of anti-JCV antibody status as an additional factor to aid in stratifying patients at risk for developing PML in the summary of product characteristics for Tysabri in the European Union.

The FDA on Jan. 20 cleared the Stratify JCV Antibody ELISA test and has granted Quest Diagnostics a de novo classification petition for the Stratify JCV antibody ELISA testing service. The FDA recommends considering carefully the risks and benefits of continuing treatment with Tysabri in patients who are anti-JCV antibody positive and have one or more of the other known risk factors for developing PML.

AACC names Vukovljak EVP

Lana Vukovljak on Feb. 27 became executive vice president of the American Association for Clinical Chemistry. She succeeds Richard Flaherty, who retired on Dec. 31, 2011 after 20 years with the association.

Vukovljak previously was chief executive officer of the American Association of Diabetes Educators.

Ambry reports exome test results

Ambry Genetics reported specific results from one of three recent diagnoses using its Clinical Diagnostic Exome sequencing test. Four individuals with rare genetic conditions for which the cause could not be identified were diagnosed successfully with the test. Three were diagnosed at Kennedy Krieger Institute in Baltimore and one was diagnosed at a large university hospital in New York City.

One case at Kennedy Krieger involved two brothers, ages 22 and 24, with profound intellectual disability and autism, the cause of which had been unknown. The Clinical Diagnostic Exome test revealed that their condition is a form of autosomal recessive intellectual disability caused by mutations in the ELP2 gene, which was recently discovered and for which routine testing was not available.

Exons make up about 1.5 percent of the genome. Traditional genetic testing analyzes one or a few specific genes at a time. Exome sequencing targets the exons of nearly all genes.

Needlestick safety—before and after preventive legislation

The Needlestick Safety and Prevention Act has contributed to the decline in percutaneous injuries among U.S. hospital workers, say Elayne Phillips, BSN, PhD; Mark Conaway, PhD; and Janine Jagger, MPH, PhD, of the University of Virginia, in correspondence published in the Feb. 16 issue of the New England Journal of Medicine (366;7:670–671).

To determine whether the legislation, signed into law in November 2000, has had an effect, the authors used a historical, prospective study design, with the use of the multihospital sharps-injury database of the International Healthcare Worker Safety Center at the University of Virginia. They selected the 1995–2005 period, which included 23,908 injuries that took place in 85 hospitals in 10 states.

Prelegislation, there was a trend toward increasing rates of injuries, followed by a drop of about 38 percent in 2001 when the legislation took effect. “Subsequent injury rates, through 2005, remained well below pre-NSPA rates,” they write.

Drs. Phillips, Conaway, and Jagger say prelegislation safety conditions may have resulted in injury rate reductions, such as OSHA’s bloodborne pathogens standard, which had been in effect since 1991. “However,” they say, “the significant decrease in these rates did not occur until after the year of its passage, suggesting that this particular legislation had an independent effect.”