Journal of clinical microbiology
-
J. Clin. Microbiol. · Dec 2011
Comparative StudyEvaluation of the impact of direct plating, broth enrichment, and specimen source on recovery and diversity of methicillin-resistant Staphylococcus aureus isolates among HIV-infected outpatients.
We compared recovery of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) from nasal and groin swab specimens of 600 HIV-infected outpatients by selective and nonselective direct plating and broth enrichment. Swabs were collected at baseline, 6-month, and 12-month visits and cultured by direct plating to mannitol salt agar (MSA) and CHROMagar MRSA (CM) and overnight broth enrichment with subculture to MSA (broth). MRSA isolates were characterized by pulsed-field gel electrophoresis (PFGE), staphylococcal cassette chromosome mec (SCCmec) typing, and PCR for the Panton-Valentine leukocidin. ⋯ Broth enrichment had a greater impact on recovery of MRSA from the groin than from the nose compared to both CM (P ≤ 0.001) and MSA (P ≤ 0.001). Overall, 19% of MRSA-colonized patients would have been missed with nasal swab specimen culture only. USA500/Iberian and USA300 were the most common MRSA strains recovered, and USA300 was more likely than other strain types to be recovered from the groin than from the nose (P = 0.05).
-
J. Clin. Microbiol. · Dec 2011
Galactomannan antigenemia after infusion of gluconate-containing Plasma-Lyte.
We demonstrated that sodium gluconate was the factor causing false-positive galactomannan (GM) antigenemia of Plasma-Lyte hydration solution. Infusion of sodium gluconate-containing solution but not gluconate-free Plasma-Lyte resulted in positive serum GM antigenemia. Serum GM concentrations also correlated with the volume and in vitro concentrations of GM within gluconate-containing solutions of infused Plasma-Lyte.
-
J. Clin. Microbiol. · Nov 2011
Viral-bacterial interactions and risk of acute otitis media complicating upper respiratory tract infection.
Acute otitis media (AOM) is a common complication of upper respiratory tract infection whose pathogenesis involves both viruses and bacteria. We examined risks of acute otitis media associated with specific combinations of respiratory viruses and acute otitis media bacterial pathogens. Data were from a prospective study of children ages 6 to 36 months and included viral and bacterial culture and quantitative PCR for respiratory syncytial virus (RSV), human bocavirus, and human metapneumovirus. ⋯ The risk was higher for the presence of bocavirus and H. influenzae together (OR, 3.61; 95% CI, 1.90 and 6.86). Acute otitis media risk differs by the specific viruses and bacteria involved. Acute otitis media prevention efforts should consider methods for reducing infections caused by respiratory syncytial virus, bocavirus, and adenovirus in addition to acute otitis media bacterial pathogens.
-
J. Clin. Microbiol. · Oct 2011
Comparative StudyExtended multilocus variable-number tandem-repeat analysis of Clostridium difficile correlates exactly with ribotyping and enables identification of hospital transmission.
PCR ribotyping is currently used in many countries for epidemiological investigation to track transmission and to identify emerging variants of Clostridium difficile. Although PCR ribotyping differentiates over 300 types, it is not always sufficiently discriminatory for epidemiological investigations particularly for common ribotypes, e.g., ribotypes 027, 106, and 017. Multilocus variable-number tandem-repeat analysis (MLVA) is a highly discriminatory molecular subtyping method that has been applied to a number of bacterial species for high-level subtyping. ⋯ Although these schemes are good genotyping methods with the ability to discriminate between isolates, they do not identify the ribotype. We show here that increasing the number of VNTR loci to 15, creating the extended MLVA (eMLVA) scheme, we have successfully subtyped all clinically significant ribotypes while still clustering isolates in concordance with PCR ribotyping. The eMLVA scheme developed here provides insight into the genetic diversity of the C. difficile population at both global and cross-infection clusters in patient levels, with the possibility of replacing PCR ribotyping.
-
J. Clin. Microbiol. · Oct 2011
Unbiased parallel detection of viral pathogens in clinical samples by use of a metagenomic approach.
Viral infectious diseases represent a major threat to public health and are among the greatest disease burdens worldwide. Rapid and accurate identification of viral agents is crucial for both outbreak control and estimating regional disease burdens. Recently developed metagenomic methods have proven to be powerful tools for simultaneous pathogen detection. ⋯ Using the metagenomic data, 11 draft genomes of the abundantly detected viruses in the samples were reconstructed with 21.84% to 98.53% coverage. Our results show the power of the short-read-based metagenomic approach for accurate and parallel screening of viral pathogens. Although there are some inherent difficulties in applying this approach to clinical samples, including a lack of controls, limited specimen quantity, and high contamination rate, our work will facilitate further application of this unprecedented high-throughput method to clinical samples.