Luciana Borio

Pneumocystis carinii Dihydropteroate Synthase but Not Dihydrofolate Reductase Gene Mutations Correlate with Prior Trimethoprim-Sulfamethoxazole or Dapsone Use

Recent studies of the human Pneumocystis carinii dihydropteroate synthase (DHPS) gene suggest that P. carinii is developing resistance to sulfamethoxazole (SMX) and dapsone. To explore whether P. carinii is also developing resistance to trimethoprim (TMP), the human P. carinii dihydrofolate reductase (DHFR) gene was cloned, DHFR and DHPS genes in 37 P. carinii isolates from 35 patients were sequenced, and the relationship between TMP-SMX or dapsone use and gene mutations was analyzed. The DHFR gene sequences were identical in all isolates except 1 with a synonymous substitution. In contrast, the DHPS gene sequences showed mutations in 16 of the 37 isolates; prior sulfa/sulfone prophylaxis was associated with the presence of these mutations (P<.001). In addition to suggesting that there is less selective pressure on DHFR than on DHPS, this study reinforces the hypothesis that mutations in the DHPS gene are likely involved in the development of sulfa resistance in P. carinii.

Management of Anthrax

From 3 October 2001 through 16 November 2001, in the United States, there were 18 confirmed cases of inhalational and cutaneous anthrax, an additional 4 suspected cases of cutaneous anthrax, and 5 deaths due to inhalational anthrax. Although the number of cases was relatively small, this experience brought bioterrorism and its potential to sharp focus as thousands of people began receiving prophylactic antibiotics after possible exposure to anthrax spores. These events have resulted in a substantial impact on the health care system, including the rewriting of pneumonia guidelines, new emphasis on identification of microbial etiology, substantial infusion of funds for bioterrorism-related research, and a sudden mandate for regional disaster and public health planning. This article provides clinicians with clinically relevant information about the diagnosis and management of anthrax.

The use of oral washes to diagnose Pneumocystis carinii pneumonia: A blinded prospective study using a polymerase chain reaction-based detection system

Pneumocystis carinii pneumonia (PCP) can be diagnosed by direct microscopic examination of induced sputum or by bronchoalveolar lavage (BAL). However, many institutions have little diagnostic success with induced sputum, and BAL is invasive and expensive. This prospective, blinded study assessed oral washes as a more convenient specimen than either sputum or BAL fluid and used a dissociation-enhanced lanthanide fluoroimmunoassay time-resolved fluorescent hybridization polymerase chain reaction (PCR) detection system that is feasible for clinical laboratories. The study assessed 175 oral washes, each paired with either an induced sputum that was positive for Pneumocystis or a BAL sample. The PCR test based on the Pneumocystis major surface glycoprotein primers had a sensitivity of 91% and a specificity of 94%, compared with a test based on mitochondrial large subunit rRNA primers, which had a sensitivity of 75% and a specificity of 96%. These results suggest that oral washes can provide a useful sample for diagnosis of PCP when a sensitive PCR detection system is used.

Scientists urge DHS to improve Bioterrorism Risk Assessment.

In 2006, the Department of Homeland Security (DHS) completed its first Bioterrorism Risk Assessment (BTRA), intended to be the foundation for DHSs subsequent biennial risk assessments mandated by Homeland Security Presidential Directive 10 (HSPD-10). At the request of DHS, the National Research Council established the Committee on Methodological Improvements to the Department of Homeland Securitys Biological Agent Risk Analysis to provide an independent, scientific peer review of the BTRA. The Committee found a number of shortcomings in the BTRA, including a failure to consider terrorists as intelligent adversaries in their models, unnecessary complexity in threat and consequence modeling and simulations, and a lack of focus on risk management. The Committee unanimously concluded that an improved BTRA is needed to provide a more credible foundation for risk-informed decision making.