Steven E. Seifried

Short Communication: Methicillin-Resistant Staphylococcus aureus Infections in Children and Young Adults Infected with HIV

The epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) infections, in particular with Panton-Valentine leukocidin (PVL)-positive strains, has not been well characterized in children and young adults with HIV infection. It is not known if PVL-positive strains of MRSA cause an increased morbidity in this population compared to PVL-negative strains. The purpose of this study was to retrospectively analyze the epidemiology of PVL-positive and PVL-negative MRSA infections in children and young adults with HIV from 2000 to 2007. Molecular typing was performed by polymerase chain reaction (PCR) for detection of the PVL genes. Staphylococcus Cassette Chromosome (SCC) mec and spa typing were performed on all PVL-positive isolates. The number of HIV patients with MRSA infection increased significantly between 2000 and 2007 ( p=0.0015). Twenty seven (87%) of the 31 MRSA isolates were from skin and soft tissue infections (SSTI). Clindamycin resistance was observed in 19% of the MRSA isolates. PVL-positive isolates bearing the type IV SCC mec element comprised 16 of 31 (52%) MRSA isolates. All the PVL-positive isolates belonged to the USA300 pulsed-field type. There was no difference in the mean CD4 count and HIV viral load between patients with PVL-positive and PVL-negative MRSA infections. PVL-positive MRSA infections were associated with more SSTI ( p=0.043) but not with increased morbidity or a higher risk of complications compared to PVL-negative MRSA infections in children and young adults with HIV.

Panton-Valentine leukocidin-positive methicillin-resistant Staphylococcus aureus infections in children with cancer.

New strains of methicillin‐resistant Staphylococcus aureus (MRSA) which frequently carry the Panton–Valentine leukocidin (PVL) genes have been recognized to cause invasive infections in otherwise healthy children and adults. However, the epidemiology of PVL‐positive MRSA infections has not been described in children or adults with cancer.

Staphylococcus aureus bacteremia in pediatric patients with cancer.

The epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S.aureus (MSSA) in children with cancer has not been well studied. A total of 10 MRSA and 42 MSSA isolates from bacteremic episodes were collected from cancer patients from 2000 through 2007. Seventeen patients (33%) suffered from complications. Thirty-eight (73%) of the bacteremic episodes were catheter-related. Methicillin resistance was associated with increased catheter removal (P = 0.003), but no increase in complications or adverse outcomes was seen.

Increasing prevalence of nasal and rectal colonization with methicillin-resistant Staphylococcus aureus in children with cancer†‡

Infections with methicillin‐resistant Staphylococcus aureus (MRSA), in community‐settings, especially with strains carrying the Panton‐Valentine Leukocidin (PVL) genes, have increased markedly in recent years. Colonization with S. aureus is a risk factor for infection. However, there are few studies that examine colonization and infection with PVL‐positive strains of MRSA in cancer patients.

Association between angiotensin-converting enzyme gene polymorphisms and QT duration in a multiethnic population in Hawaii

OBJECTIVES Recent studies have suggested that heart-rate corrected QT interval (QTc) in normal populations may be influenced by genetic factors. We report findings of a study of the relationship between QTc, increased QTc (> 440 ms) and angiotensin-converting enzyme (ACE) genotype in a multiethnic, population-based study completed in rural Hawaii. METHODS Blood samples were obtained while fasting and after an oral glucose challenge from 1452 individuals between 1997 and 2000. The clinical examination included an electrocardiogram. Medical histories, behavioral and socio-demographic information were obtained during the interview. Ethnicity was estimated by self-report. The insertion/deletion (I/D) polymorphism in intron 16 of the ACE gene was determined by polymerase chain reaction (PCR) from a random sample of 588 participants. Multiple linear and logistic regression was used to test for associations between QTc and ACE gene polymorphisms. RESULTS The overall crude prevalence of increased QTc was 21.2%. The prevalence of increased QTc was lowest among those with ACE DD genotype, and highest among those with ACE insertion/insertion (II) genotype. The adjusted odds ratio for increased QTc was 2.29 (95% CI 1.02-5.12) and 3.61 (95% CI 1.60-8.13) for ID and II genotypes, respectively, compared to the DD genotype. The test for trend was highly significant (p < 0.001). CONCLUSIONS The ACE insertion allele was associated with increased prevalence of prolonged QTc independent of ethnicity, age, gender, and BMI. These findings may implicate the ACE gene as an important genetic risk factor for cardiovascular disease morbidity and mortality.

No Evidence of Human Leukocyte Antigen Gene Association With Rheumatic Fever Among Children in Samoa

Human leukocyte antigens (HLAs) have been implicated in rheumatic fever pathogenesis. This pilot whole genome association study compares genotypes of Samoan children with rheumatic fever to unaffected siblings and unrelated healthy controls. No risk-related genotypes were associated with HLA genes. Thirteen Regions of Interest were identified as candidates for further study.

A probe-based method for confirmation of methicillin-resistant Staphylococcus aureus and detection of Panton-Valentine leukocidin and tst virulence genes.

Probe-based detection of mecA, lukS/F-PV (Panton-Valentine leukocidin), and tst virulence genes in 435 isolates of Staphylococcus aureus had comparable sensitivity and specificity to end-point polymerase chain reaction as a reference standard.

Aerobic Microorganisms Identified Over a Fourteen-Month Period from the Upper Respiratory Tract of Captive Hawaiian Monk Seals (Monachus schauinslandi)

Infectious disease is a growing concern for the overall declining Hawaiian monk seal (HMS) (Monachus schauinslandi) population. Recently, the HMS population in the main Hawaiian Islands (MHI) is increasing, and this may result in additional rehabilitation and release events. A key aspect for population health assessment is to identify the “normal” bacteria flora (e.g., the upper respiratory tract). Our current knowledge for the HMS flora is based on microbial isolates from stranding or mortality events rather than on healthy animals. This 14-mo study includes 52 oral and 55 nasal sampling events from the two healthy resident HMSs at the Waikiki Aquarium in Honolulu, Hawaii. Extensive culturing, Gram stains, phenotypic (e.g., biochemical), and genotypic (16S rRNA sequencing) characterization were used to identify aerobic microorganisms from the upper respiratory tract. The study detected 30 species of Gram negative bacteria, 18 species of Gram positive bacteria, and two species of yeast. The “normality” of the bacterial population was established over the study time period by consistent recovery of identical bacterial species from upper respiratory tract samplings. These results may provide a baseline for normal aerobic bacterial flora in these seals. These results may also allow for comparison to other HMSs in facilities and their wild conspecifics, and have implications for diagnosis of infection in diseased animals.

Mass Spectrometric Protocol for the Analysis of UV-Crosslinked Protein-Nucleic Acid Complexes

Publisher Summary This chapter describes the mass spectrometric protocol for the analysis of UV-crosslinked protein–nucleic acid complexes. It presents a protocol that combines developed methods for UV-light-induced photochemical crosslinking of proteins to nucleic acids with MALDI, and ESI mass spectrometry to locate and identify the particular amino acid and nucleotide residues that covalently bind to each other. The chapter explains the application of some of the stages in this analytical scheme to two different systems of protein–nucleic acid complexes, the phage T4 gene 32 protein UV-laser cross-linked to the oligonucleotide photoaffinity-labeled with 4-thiouridinediphosphate. In the first stage, the nucleic acid binding protein and its nucleic acid substrate or a photoactivatable analogue thereof are incubated under proper conditions to form the protein–nucleic acid complex. The sample is subsequently irradiated with UV light for a given period of time to create photochemically crosslinked protein–nucleic acid complexes.