Phyllis Della-Latta

Transfusion of red blood cells after prolonged storage produces harmful effects that are mediated by iron and inflammation

Although red blood cell (RBC) transfusions can be lifesaving, they are not without risk. In critically ill patients, RBC transfusions are associated with increased morbidity and mortality, which may increase with prolonged RBC storage before transfusion. The mechanisms responsible remain unknown. We hypothesized that acute clearance of a subset of damaged, stored RBCs delivers large amounts of iron to the monocyte/macrophage system, inducing inflammation. To test this in a well-controlled setting, we used a murine RBC storage and transfusion model to show that the transfusion of stored RBCs, or washed stored RBCs, increases plasma nontransferrin bound iron (NTBI), produces acute tissue iron deposition, and initiates inflammation. In contrast, the transfusion of fresh RBCs, or the infusion of stored RBC-derived supernatant, ghosts, or stroma-free lysate, does not produce these effects. Furthermore, the insult induced by transfusion of stored RBC synergizes with subclinical endotoxinemia producing clinically overt signs and symptoms. The increased plasma NTBI also enhances bacterial growth in vitro. Taken together, these results suggest that, in a mouse model, the cellular component of leukoreduced, stored RBC units contributes to the harmful effects of RBC transfusion that occur after prolonged storage. Nonetheless, these findings must be confirmed by prospective human studies.

Assessment of two hand hygiene regimens for intensive care unit personnel

ObjectiveTo compare skin condition and skin microbiology among intensive care unit personnel using one of two randomly assigned hand hygiene regimens: a 2% chlorhexidine gluconate (CHG)-containing traditional antiseptic wash and a waterless handrub containing 61% ethanol with emollients (ALC). DesignProspective, randomized clinical trial. SettingTwo critical care units (medical and surgical) in a large, metropolitan academic health center in Manhattan. SubjectsFifty staff members (physicians, nurses, housekeepers, respiratory therapists) working full time in the intensive care unit. InterventionsOne of two hand hygiene regimens randomly assigned for four consecutive weeks. Measurements and Main Results The two outcomes were skin condition (measured by two tools: Hand Skin Assessment form and Visual Skin Scaling form) and skin microbiology. Samples were obtained at baseline, on day 1, and at the end of wks 2 and 4. Participants in the ALC group had significant improvements in the Hand Skin Assessment scores at wk 4 (p = 0.04) and in Visual Skin Scaling scores at wks 3 (p = 0.01) and 4 (p = 0.0005). There were no significant differences in numbers of colony-forming units between participants in the CHG or ALC group at any time period. The ALC regimen required significantly less time than the CHG regimen (mean: 12.7 secs and 21.1 secs, respectively;p = 0.000) and resulted in a 50% reduction in material costs. ConclusionsChanges in hand hygiene practices in acute care settings from the traditional antiseptic wash to use of plain, mild soap and an alcohol-based product should be considered. Further research is needed to examine the association between use of antiseptic products for hand hygiene of staff and reductions in nosocomial infection rates among patients.

Outbreak of Extended-Spectrum Beta-Lactamase–Producing Klebsiella Pneumoniae in a Neonatal Intensive Care Unit Linked to Artificial Nails

BACKGROUND From April to June 2001, an outbreak of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae infections was investigated in our neonatal intensive care unit. METHODS Cultures of the gastrointestinal tracts of patients, the hands of healthcare workers (HCWs), and the environment were performed to detect potential reservoirs for ESBL-producing K. pneumoniae. Strains of K. pneumoniae were typed by pulsed-field gel electrophoresis using XbaI. A case-control study was performed to determine risk factors for acquisition of the outbreak clone (clone A); cases were infants infected or colonized with clone A and controls (3 per case) were infants with negative surveillance cultures. RESULTS During the study period, 19 case-infants, of whom 13 were detected by surveillance cultures, harbored clone A. The overall attack rate for the outbreak strain was 45%; 9 of 19 infants presented with invasive disease (n = 6) or developed invasive disease (n = 3) after colonization was detected. Clone A was found on the hands of 2 HCWs, 1 of whom wore artificial nails, and on the designated stethoscope of a case-infant. Multiple logistic regression analysis revealed that length of stay per day (odds ratio [OR], 1.05; 95% confidence interval [CI95], 1.02 to 1.09) and exposure to the HCW wearing artificial fingernails (OR, 7.87; CI95, 1.75 to 35.36) were associated with infection or colonization with clone A. CONCLUSION Short, well-groomed, natural nails should be mandatory for HCWs with direct patient contact

An outbreak of methicillin-resistant Staphylococcus aureus in a neonatal intensive care unit.

OBJECTIVE To describe the epidemiologic and molecular investigations that successfully contained an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) in a neonatal intensive care unit (NICU). DESIGN Isolates of MRSA were typed by pulsed-field gel electrophoresis (PFGE) and S. aureus protein A (spa). SETTING A level III-IV, 45-bed NICU located in a childrens hospital within a medical center. PATIENTS Incident cases had MRSA isolated from clinical cultures (eg, blood) or surveillance cultures (ie, anterior nares). INTERVENTIONS Infected and colonized infants were placed on contact precautions, cohorted, and treated with mupirocin. Surveillance cultures were performed for healthcare workers (HCWs). Colonized HCWs were treated with topical mupirocin and hexachlorophene showers. RESULTS From January to March 2001, the outbreak strain of MRSA, PFGE clone B, was harbored by 13 infants. Three (1.3%) of 235 HCWs were colonized with MRSA. Two HCWs, who rotated between the adult and the pediatric facility, harbored clone C. One HCW, who exclusively worked in the childrens hospital, was colonized with clone B. From January 1999 to November 2000, 22 patients hospitalized in the adult facility were infected or colonized with clone B. Spa typing and PFGE yielded concordant results. PFGE clone B was identified as spa type 16, associated with outbreaks in Brazil and Hungary. CONCLUSIONS A possible route of MRSA transmission was elucidated by molecular typing. MRSA appears to have been transferred from our adult facility to our pediatric facility by a rotating HCW. Spa typing allowed comparison of our institutions MRSA strains with previously characterized outbreak clones.

Genetic Organization of Transposase Regions Surrounding blaKPC Carbapenemase Genes on Plasmids from Klebsiella Strains Isolated in a New York City Hospital

ABSTRACT Carbapenem-resistant Klebsiella strains carrying Klebsiella pneumoniae carbapenemases (KPC) are endemic to New York City and are spreading across the United States and internationally. Recent studies have indicated that the KPC structural gene is located on a 10-kb plasmid-borne element designated Tn4401. Fourteen Klebsiella pneumoniae strains and one Klebsiella oxytoca strain isolated at a New York City hospital in 2005 carrying either blaKPC-2 or blaKPC-3 were examined for isoforms of Tn4401. Ten of the Klebsiella strains contained a 100-bp deletion in Tn4401, corresponding to the Tn4401a isoform. The presence of this deletion adjacent to the upstream promoter region of blaKPC in Tn4401a resulted in a different −35 promoter sequence of TGGAGA than that of CTGATT present in isoform Tn4401b. Complete sequencing of one plasmid carrying blaKPC from each of three nonclonal isolates indicated the presence of genes encoding other types of antibiotic resistance determinants. The 70.6-kb plasmid from K. pneumoniae strain S9 carrying blaKPC-2 revealed two identical copies of Tn4401b inserted in an inverse fashion, but in this case, one of the elements disrupted a group II self-splicing intron. In K. pneumoniae strain S15, the Tn4401a element carrying blaKPC-2 was found on both a large 120-kb plasmid and a smaller 24-kb plasmid. Pulsed-field gel electrophoresis results indicate that the isolates studied represent a heterogeneous group composed of unrelated as well as closely related Klebsiella strains. Our results suggest that endemic KPC-positive Klebsiella strains constitute a generally nonclonal population comprised of various alleles of blaKPC on several distinct plasmid genetic backgrounds. This study increases our understanding of the genetic composition of the evolving and expanding role of KPC-producing, healthcare-associated, gram-negative pathogens.

Multicenter evaluation of the Candida albicans/Candida glabrata peptide nucleic acid fluorescent in situ hybridization method for simultaneous dual-color identification of C. albicans and C. glabrata directly from blood culture bottles

ABSTRACT We evaluated the performance of the Candida albicans/Candida glabrata peptide nucleic acid fluorescent in situ hybridization (PNA FISH) method, a rapid two-color assay for detection of C. albicans and C. glabrata, in a multicenter study. The assay is designed for use directly from positive blood culture bottles in a FISH format. Intact, fixed cells are labeled fluorescent green (C. albicans) or fluorescent red (C. glabrata) by rRNA hybridization of fluorophore-labeled PNA probes. Results are available <3 h after cultures signal positive. An evaluation of 197 routine blood culture bottles newly positive for yeast by Gram staining was performed at five hospitals. The sensitivities of detection for C. albicans, and C. glabrata were 98.7% (78/79) and 100% (37/37), respectively, and the specificity for both components of the assay was 100% (82/82). The assay was also evaluated with 70 fungal reference strains and was challenged in the BacT/ALERT microbiological detection system with spiked blood culture bottles. These results support the use of the assay for rapid, simultaneous identification of C. albicans and C. glabrata in positive blood culture bottles. This rapid assay may aid in the selection of initial antifungal drugs, leading to improved patient outcomes.

Risk factors for late onset gram-negative sepsis in low birth weight infants hospitalized in the neonatal intensive care unit.

Background: Gram-negative bloodstream infections (BSIs) cause 20–30% of late onset sepsis in neonatal intensive care unit (NICU) patients and have mortality rates of 30–50%. We investigated risk factors for late onset Gram-negative sepsis in very low birth weight (<1500 g) NICU patients. Methods: We performed a case-control study as part of a larger 2-year clinical trial that examined the effects of hand hygiene practices on hospital-acquired infections. In this substudy, a case was a very low birth weight infant with a hospital-acquired Gram-negative BSI; control subjects, matched on study site and hand hygiene product, were chosen randomly from the patients who did not have Gram-negative BSIs. Potential risk factors were analyzed by Mantel-Haenszel methods and conditional logistic regression. Results: There were 48 cases of Gram-negative BSI. In multivariate analysis, we found that the following variables were significantly associated with Gram-negative BSI: central venous catheterization duration of >10 days; nasal cannula continuous positive airway pressure use; H2 blocker/proton pump inhibitor use; and gastrointestinal tract pathology. Conclusions: These analyses provide insights into potential strategies to reduce Gram-negative BSIs. Catheters should be removed as possible and H2 blockers/proton pump inhibitors should be used judiciously in NICU patients. The association between nasal cannula continuous positive airway pressure and Gram-negative BSIs requires further investigation. The association of gastrointestinal tract pathology with Gram-negative BSIs identifies a high risk group of neonates who may benefit from enhanced preventative strategies.

Vancomycin-resistant Enterococcus faecium meningitis successfully managed with linezolid : Case report and review of the literature

Enterococci cause serious illness in immunocompromised patients and severely ill, hospitalized patients. Resistance to vancomycin has increased in frequency during the past few years. Limited therapeutic options are available for vancomycin-resistant enterococcal infections and the optimum therapy has not been established. We report a case of nosocomial vancomycin-resistant Enterococcus faecium meningitis in the setting of hyperinfection with Strongyloides stercoralis that was successfully treated with linezolid. We also review the previously reported cases of vancomycin-resistant E. faecium meningitis.

Epidemiology of nontuberculous mycobacteria in patients without HIV infection, New York City.

The incidence appears to be increasing.

Prevalence of methicillin-sensitive and methicillin-resistant Staphylococcus aureus in pregnant women.

OBJECTIVE: To estimate the extent of Staphylococcus aureus vaginal-rectal colonization among pregnant women as severe S aureus infections have emerged in pregnant and postpartum women and infants. METHODS: We conducted a prospective surveillance study for methicillin-sensitive S aureus and methicillin-resistant S aureus on all routine de-identified vaginal-rectal prenatal group B streptococcus (GBS) screening cultures submitted to the microbiology laboratory of a tertiary-care facility from January to July 2005. Standard microbiologic techniques and molecular analyses were used to detect community-associated methicillin-resistant S aureus strains. As opposed to health care–associated methicillin-resistant S aureus isolates, community-associated methicillin-resistant S aureus isolates were defined as those possessing the type IV or type V staphylococcal chromosomal cassette mec element and usually lacking a multidrug-resistant phenotype. RESULTS: A total of 2,963 GBS screening cultures were analyzed, from which 743 (25.1%, 95% confidence interval [CI] 23.5–26.7%) GBS isolates and 507 (17.1%, 95% CI 15.7–18.5%) S aureus isolates were identified. Group B streptococcus colonization was significantly associated with S aureus colonization (prevalence odds ratio 2.1, 95% CI 1.7–2.5, P<.001). Of the S aureus isolates, 14 (2.8%, 95% CI 1.4–4.2%) were methicillin-resistant, and 13 of these were determined to be community-associated methicillin-resistant S aureus. CONCLUSION: The prevalence of S aureus colonization identified in GBS screening cultures from pregnant women was substantial and associated with GBS co-colonization. Although we do not advocate routine screening of pregnant women for methicillin-sensitive S aureus and methicillin-resistant S aureus colonization, we recommend continued monitoring of both methicillin-sensitive S aureus and methicillin-resistant S aureus infections in this population and their infants. LEVEL OF EVIDENCE: II-3