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 In this new feature, a panel of IDSA members identifies and
critiques important new infectious diseases studies in the current
literature that have a significant impact on the practice of infectious
diseases medicine.
For more from Clinical Infectious Diseases and The Journal of Infectious Diseases, see the "In the IDSA Journals" section of IDSA News.
Two Studies on Screening Patients for MRSA Reach Conflicting Conclusions
Sara E. Cosgrove, MD, MS
In the March 12 issue of the Journal of the American Medical Association,
Harbarth et al. found no differences in the rates of nosocomial MRSA
infection or MRSA surgical site infection when surgical patients in one
institution were screened for MRSA carriage on admission. In contrast,
in a study in the March 18 issue of Annals of Internal Medicine,
Robicsek et al. showed a reduction in hospital-associated MRSA
infections when all admitted patients at three hospitals were screened
for MRSA.
It is important to note that both studies had an intervention
component that went beyond obtaining cultures and placing MRSA carriers
in contact isolation; rather, both had arms in which rapid testing for
MRSA with direct feedback to providers about results occurred, both had
good compliance with contact isolation and both employed decolonization
strategies with mupirocin and chlorhexidine baths for MRSA carriers.
Thus, in the positive Robicsek study, understanding the independent
benefit of obtaining MRSA surveillance cultures relative to other
interventions is challenging. On the other hand, the negative result in
the Harbarth study may be partially attributed to the fact that almost
one third of patients did not have MRSA surveillance culture data
available before surgery to allow for adjustments in antimicrobial
prophylaxis.
Although both groups used advanced analytic techniques to minimize
potential confounding factors, neither study is a cluster-randomized
trial where different units or institutions are randomized to receive a
particular intervention, which would be the most robust study design to
avoid confounding. Harbarth et al. used a crossover design with
concomitant control units in each intervention period which strengthens
the results. There was no control group in the Robicsek study..
In summary, these studies provide differing results with regard to
the effect that screening patients for MRSA carriage has on prevention
of subsequent MRSA infection in hospitals, demonstrating that
successful approaches to MRSA prevention differ among patient
populations and institutions. (Harbarth et al., JAMA. 2008;299:1149-1157. Robicsek et al., Ann Intern Med. 2008;148:409-18.)
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Airborne Varicella-Zoster Virus from Patients With Shingles?
Jason B. Weinberg, MD
Two reports in the March 1 issue of The Journal of Infectious Diseases highlight the potential for herpes zoster (HZ) to serve as a source for varicella outbreaks via airborne transmission.
In the first, Lopez et al. describe an outbreak of varicella in a
long-term care facility in which the index case patient was an
individual with HZ, suggesting possible airborne transmission from
isolated cutaneous disease. Despite seemingly appropriate precautions
(lesions were covered for the duration of the rash), high
concentrations of varicella zoster virus (VZV) DNA were detected in
environmental samples, and three other individuals in the facility
became infected. Identical VZV strains were detected in all
environmental isolates and in isolates from case patients.
In a second article in the same issue, Mehta et al. demonstrated the
presence of VZV DNA in the saliva of all 54 patients with acute herpes
zoster tested. Together, these two studies indicate that contrary to
current opinion, aerosolized VZV may be transmitted from patients with
herpes zoster.
In an accompanying editorial, Bauer notes that the potential for
airborne transmission raises questions about the overall effectiveness
of current isolation guidelines for HZ patients. These guidelines are
primarily focused on covering cutaneous lesions but do not recommend
respiratory isolation of all HZ patients, and probably need
modification. (Lopez et al., J Infect Dis. 2008; 197:646-53. Mehta et al., J Infect Dis. 2008;197:654-657. Breuer, J Infect Dis. 2008;197:635-637.)
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Circumcision Lowers Rates of HPV in Men
Melinda M. Pettigrew, PhD
Human papillomavirus (HPV) was detected in the glans penis or corona
sulcus in 46 percent of uncircumcised men and 29 percent of circumcised
men in this study in the March 15 issue of The Journal of Infectious Diseases.
Uncircumcised men also were 2.5 times more likely to have high-risk HPV
types and 3.5 times more likely to have more than one HPV type. This
study is noteworthy because the authors sampled multiple genital sites
and controlled for potential confounders. These data add significantly
to our knowledge of HPV in men. The study suggests male circumcision
may prevent genital warts and penile cancer in men and may reduce HPV
transmission and related cancers in the sex partners of HPV infected
men. Male circumcision may provide an important tool for HPV prevention
in addition to condoms and vaccines. Prospective studies are needed to
clarify the role of circumcision in HPV incidence, transmission, and
cancer. (Hernandez et al., J Infect Dis. 2008;197:787-94.)
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PIs Associated with Elevated Fibrinogen Levels
Sabrina R. Kendrick, MD
Use of protease inhibitors (PI) was associated with higher
fibrinogen levels, while use of non-nucleoside reverse transcriptase
inhibitors (NNRTI) were associated with lower fibrinogen levels in a
study in the March 30 issue of AIDS. Elevated fibrinogen levels may contribute to the elevated risk of coronary artery disease in HIV-infected patients.
The analysis sought to identify factors associated with elevated
fibrinogen levels in HIV infected patients compared to controls.
Subjects were drawn from a study to evaluate the correlates of changes
in fat distribution and other atherosclerosis markers.
After adjusting for adipose tissue volume, which is associated with
fibrinogen levels, the authors found patients on PI drugs had 11
percent higher fibrinogen levels compared with those not on PIs.
Elevation was seen with all PIs studied and suggested a class effect,
which may contribute to atherosclerosis risk.
PIs and C-reactive protein were independently associated with
elevated fibrinogen levels, suggesting that PIs may directly alter
fibrinogen levels independent of acute inflammation as a mechanism.
The results should be interpreted with some caution, however,
because the study’s cross-sectional design was unable to prove
causality between antiretroviral therapy, alteration in fibrinogen
levels, and subsequent cardiovascular events. Also, the present study
did not assess effects of more recently introduced PI drugs. (Madden et al., AIDS. 2008; 22:707-715.)
Negligible Public Health Risk from Cardiovascular Complications of HAART
In contrast, all three classes of antiretroviral therapy provided a
survival benefit and no significant increase in the rate of
cardiovascular events in a large, 11-year retrospective cohort of
HIV-infected patients at US Veterans Affairs facilities, published in
the March issue of the Journal of Acquired Immune Deficiency Syndromes. (Bozzette et al., JAIDS. 2008;47:338-341.)
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