Risk factors for Pneumocystis pneumonia with acute respiratory failure among kidney transplant recipients.

PURPOSE: One of the rare life-threatening fungal infections is pneumocystis pneumonia (PCP). Immunocompromised patients are the main vulnerable population. We investigate the risk factors associated with the development of severe PCP infection with acute respiratory failure after kidney transplantation. MATERIALS AND METHODS: This is a retrospective, single-center, case-control study. PCP patients who are kidney transplant recipients and required high-flow oxygen support or mechanical ventilation between March 2009 and February 2017 were included in the study. The comparison was conducted between the non-severe and severe PCP groups. To identify associated risk factors, we performed univariate and multivariate logistic regression. RESULTS: Among the total 2,330 kidney transplant recipients, 50 patients (2.1%) were diagnosed with PCP. Of these, 27 patients (54.0%) had severe PCP and 7 patients (14.0%) died, all of them were severe PCP patients. In the severe PCP group, the time from transplantation to PCP diagnosis (23.4 ± 24.9 months vs. 13.7 ± 9.9 months, p = 0.090) was insignificantly faster than in the non-severe PCP group. According to multiple logistic regression analysis, the significant risk factors associated with severe PCP were as follows, age (odds ratios (OR) 1.07; 95% confidence intervals (CI): 1.01-1.13; p = 0.027), time from transplantation to PCP diagnosis (odds ratios (OR) 0.92; 95% confidence intervals (CI): 0.86-0.99; p = 0.024), lymphopenia (OR 6.48; 95% CI: 1.05-40.09; p = 0.044), and history of acute rejection within 1 year (OR 8.28; 95% CI: 1.29-53.20; p = 0.026). CONCLUSION: Patients who have lymphopenia at the time of hospital admission or have been recently treated with acute rejection are more likely to progress to severe PCP, requiring intensive monitoring and aggressive treatment.

Deterministic Migration-Based Separation of White Blood Cells.

Functional and phenotypic analyses of peripheral white blood cells provide useful clinical information. However, separation of white blood cells from peripheral blood requires a time-consuming, inconvenient process and thus analyses of separated white blood cells are limited in clinical settings. To overcome this limitation, a microfluidic separation platform is developed to enable deterministic migration of white blood cells, directing the cells into designated positions according to a ridge pattern. The platform uses slant ridge structures on the channel top to induce the deterministic migration, which allows efficient and high-throughput separation of white blood cells from unprocessed whole blood. The extent of the deterministic migration under various rheological conditions is explored, enabling highly efficient migration of white blood cells in whole blood and achieving high-throughput separation of the cells (processing 1 mL of whole blood less than 7 min). In the separated cell population, the composition of lymphocyte subpopulations is well preserved, and T cells secrete cytokines without any functional impairment. On the basis of the results, this microfluidic platform is a promising tool for the rapid enrichment of white blood cells, and it is useful for functional and phenotypic analyses of peripheral white blood cells.

Comparisons of Fit Factors Between Two Quantitative Fit Testers (PortaCount vs. MT).

This study evaluated the consistency between two quantitative fit test devices with different methods of ambient aerosol counting. Three types of respirators (N95, half mask, and full facepiece) were worn by 50 participants (male, n = 25; female, n = 25), PortaCount (Pro+ 8038) and MT (05U) were connected to one probe to one mask, and fit factors (FFs) were measured simultaneously with the original and modified protocols. As a result of comparing MT FFs with PortaCount FFs as references and by applying for the pass/fail criteria (FF = 100), the consistency between the two devices for half masks and full facepieces was very high. N95 was somewhat weaker than the two type of respirators in the consistency; however, the correlation between the two devices was very strong (p < 0.0001). The results showed that an FF of 100 as measured by PortaCount was likely to be measured as 75 by the MT. Therefore, when performing the fit test for N95 using the MT and pass level of FF 100, a certain level of adjustment is necessary, whether end-user or putting a scaling factor by manufacturer.

Development of Korean Head forms for Respirator Performance Testing.

BACKGROUND: Protection from yellow dust and particulate matter is ensured by the use of respirators among the Korean citizens and workers. However, the manikins used to test the performance of the same were manufactured considering western facial specifications owing to which they do not represent Korean facial characteristics. METHODS: Analysis of the data from the 6th 3D anthropometric survey of Koreans (Size Korea; 2010-2013) of 4,583 people aged 7 to 69 years was performed to obtain their facial dimensions. We subsequently clustered 44 facial measurements using Design X software, followed by the creation of the cluster centroid. RESULTS: Three 3D head forms were developed-small, medium, and large, and their images were stored in ".stl" format for 3D printing. The facial widths and lengths of the three head forms were 127.1 mm × 90.6 mm, 143.2 mm × 104.0 mm, and 149.1 mm × 120.2 mm, respectively. CONCLUSION: We developed manikin head forms according to the facial dimensions of the Korean population, which was essential in evaluating respiratory protective equipment. These head forms can be used to test the performance of respirators considering the facial dimensions of the Korean population.

Effect of storage in juice with or without pulp and/or calcium lactate on the subsequent survival of Escherichia coli O157:H7 in simulated gastric fluid.

A study was conducted to evaluate the effect of storing Escherichia coli O157:H7 in fruit or vegetable juices with or without pulp and/or calcium lactate, on the bacterial resistance to a simulated gastric fluid (SGF, pH 1.5). Apple, carrot, orange, and tomato juices containing pulp or freed from pulp by filtration were used in this study. Calcium lactate at about 1.4 g/l was added to juices to obtain calcium supplemented juices. Juices with or without pulp and/or calcium lactate were inoculated with E. coli O157:H7 and then were stored at 7 degrees C for 0, 1, 2, or 4 days. The acid resistance of cells stored in juices with or without pulp and/or calcium lactate was determined by incubating in SGF for 90 or 240 min at 37 degrees C. Cells stored in apple juice for 4 days, carrot juice for 2 days, and orange juice for 4 days with pulp only had greater acid resistance, while all cells stored in tomato juice with pulp had greater acid resistance than cells stored in juice without pulp. The D-values of cells stored in supplemented apple and orange juices with calcium lactate declined 1.7-3.5 fold, whereas D-values of cells stored in supplemented tomato juice decreased by about 1.4-fold when compared to cells stored in juice without calcium lactate after exposure in SGF. These results indicate that storing E. coli O157:H7 in juices with pulp had little or no effect on the acid resistance of cells during subsequent exposure in SGF. Calcium lactate supplemented into juices could dramatically decrease the ability of E. coli O157:H7 to survive in SGF, possibly reducing the risk of foodborne illness by juice products.

The education and practice program for medical students with quantitative and qualitative fit test for respiratory protective equipment.

Tuberculosis infection is prevalent in Korea and health care workers are vulnerable to tuberculosis infection in the hospital. The aims of this study were to develop and validate an education program that teaches senior medical students how to wear and choose the proper size and type of respiratory protective equipment (RPE), which may help reduce the risk of contracting Mycobacterium tuberculosis (MTB) from patients. Overall, 50 senior medical students participated in this education program. Methods of choosing the proper type of RPE, performing a fit check of the RPE, and choosing a suitable mask size were taught by certified instructors using the real-time quantitative fit test (QNFT). The validity of education program was evaluated with qualitative fit test (QLFT) before and after the education as pass or fail. The education program was effective, as shown by the significantly pass rate (increased 30 to 74%) in the QLFT after the education program (p<0.05). Among study participants, changing mask size from medium to small significantly increased the pass rate (p<0.001). Incorporation of this program into the medical school curriculum may help reduce risk of MTB infection in medical students working in the hospital.

Assessing real-time performances of N95 respirators for health care workers by simulated workplace protection factors.

To assess performances of N95 respirators for Health Care Workers (HCWs) in a simulated health-care setting, we measured the Simulated Workplace Protection Factors (SWPFs) in real-time from the volunteers. A total of 49 study subjects, wearing 3 M respirator Model N95 1860 and 1860S, were fit tested using the OSHA Exercise Regimen. The test subjects were asked to perform simulated scenarios, including patient assessments, suction, and intravenous injection (IV) treatment. Two TSI PortaCount instruments continuously measured concentrations in the respirator and the room concentration. For Quantitative Fit Testing (QNFT), 36 out of 49 (73.5%) passed the fit factor (FF) criteria set at 100 and 13 (26.5%) failed. The results of QNFT were found to have a low correlation with SWPF, with R(2)=0.32. The geometric means (GM) and geometric standard deviations (GSD) of SWPF were 68.8 (1.1) for those subjects who passed and 39.6 (1.3) for those who failed. Real-time assessments of SWPF showed that lower SWPFs were; moving head up and down, and bending at the waist. This study identifies the needs for providing different sizes of respirators for HCWs and the importance of performing fit tests for HCWs regularly. And particular movements were identified as attributing factors affecting more on SWPFs.

Speech perception in older listeners with normal hearing:conditions of time alteration, selective word stress, and length of sentences.

BACKGROUND AND OBJECTIVES: Deficits of the aging auditory system negatively affect older listeners in terms of speech communication, resulting in limitations to their social lives. To improve their perceptual skills, the goal of this study was to investigate the effects of time alteration, selective word stress, and varying sentence lengths on the speech perception of older listeners. SUBJECTS AND METHODS: Seventeen older people with normal hearing were tested for seven conditions of different time-altered sentences (i.e., ±60%, ±40%, ±20%, 0%), two conditions of selective word stress (i.e., no-stress and stress), and three different lengths of sentences (i.e., short, medium, and long) at the most comfortable level for individuals in quiet circumstances. RESULTS: As time compression increased, sentence perception scores decreased statistically. Compared to a natural (or no stress) condition, the selectively stressed words significantly improved the perceptual scores of these older listeners. Long sentences yielded the worst scores under all time-altered conditions. Interestingly, there was a noticeable positive effect for the selective word stress at the 20% time compression. CONCLUSIONS: This pattern of results suggests that a combination of time compression and selective word stress is more effective for understanding speech in older listeners than using the time-expanded condition only.

Successful containment of carbapenem-resistant Enterobacteriaceae by strict contact precautions without active surveillance.

BACKGROUND: Carbapenem-resistant Enterobacteriaceae (CRE) are a growing problem worldwide. Guidelines focus on carbapenemase-producing organisms, and little is known about whether strict adherence to infection control measures is effective for CRE without carbapenemase. During 2009, CRE increased markedly in a tertiary hospital, and enhanced infection control measures without active surveillance were adopted. METHODS: Beginning in April 2010, enhanced antimicrobial stewardship, strict contact precautions, and cohort isolation were adopted. After September 2010, hand hygiene performance was prospectively monitored by active surveillance, and results were monthly fed back to medical personnel. Available carbapenem-resistant Escherichia coli (ECO) and carbapenem-resistant Klebsiella pneumoniae (KPN) isolated during 2008-2010 were characterized. Imipenem and meropenem minimal inhibitory concentrations were confirmed by E-test (AB biodisk, Solna, Sweden). Phenotypic screening assays and polymerase chain reaction (PCR) amplification of known ß-lactamase and carbapenemase genes were performed. RESULTS: From 3,511 ECO and 2,279 KPN, 44 (0.76%) were CRE (3 ECO, 41 KPN). CRE incidence rates rose from 1.61 in 2008 to 5.49 in 2009; they rose further to 9.81 per 100,000 patient days in early 2010. After adoption of strict infection control measures, CRE frequency fell back in 2011 and remained at baseline afterward. Phenotypic screening and PCR showed AmpC ß-lactamase and extended spectrum ß-lactamases with or without loss of porins; carbapenemases were not detected. CONCLUSION: Enhanced infection control measures, even without active surveillance, seem effective to prevent further spread of CRE in a low-prevalence setting with mainly carbapenemase-nonproducing CRE.

Outcome of cefazolin prophylaxis for total knee arthroplasty at an institution with high prevalence of methicillin-resistant Staphylococcus aureus infection.

OBJECTIVES: The aim of this study was to evaluate the outcome of cefazolin prophylaxis for total knee arthroplasty (TKA) in a hospital with a high prevalence of methicillin-resistant Staphylococcus aureus (MRSA) infection. METHODS: Since July 1, 2006, we have applied a 'care bundle' to TKA to prevent surgical site infection (SSI) without using vancomycin as antimicrobial prophylaxis, in accordance with the 1999 Hospital Infection Control Practices Advisory Committee guidelines. All patients undergoing TKA from July 1, 2006 to September 30, 2009 were enrolled. We reviewed data on SSI collected prospectively as part of routine infection control surveillance. RESULTS: Of 1323 TKAs, an SSI developed in 14 (1.06%) cases, which is comparable to the percentage obtained in other previous reports. When stratified by the National Nosocomial Infection Surveillance risk index, SSI rates were 0.86% (8/926), 1.30% (5/384), and 7.69% (1/13) in risk categories 0, 1, and 2, respectively. Of 14 SSIs, four (29%) were classified as superficial incisional, two (14%) as deep incisional, and eight (57%) as organ-space SSI. CONCLUSIONS: Our data suggest that antimicrobial prophylaxis using only cefazolin can maintain low SSI rates if other important infection management measures are employed, even where there is a high prevalence of MRSA infection.