A Systematic Review of the Protective Effect of Prior SARS-CoV-2 Infection on Repeat Infection.

We systematically reviewed studies to estimate the risk of SARS-CoV-2 reinfection among those previously infected with SARS-CoV-2. For this systematic review, we searched scientific publications on PubMed and MedRxiv, a pre-print server, through August 18, 2021. Eligible studies were retrieved on August 18, 2021. The following search term was used on PubMed: ((("Cohort Studies"[Majr]) AND ("COVID-19"[Mesh] OR "SARS-CoV-2"[Mesh])) OR "Reinfection"[Majr]) OR "Reinfection"[Mesh]. The following search term was used on MedRxiv: "Cohort Studies" AND "COVID-19" OR "SARS-CoV-2" AND "Reinfection". The search terms were broad to encompass all applicable studies. There were no restrictions on the date of publication. Studies that did not describe cohorts with estimates of the risk of SARS-CoV-2 reinfection among those with previous infection were excluded. Studies that included vaccinated participants were either excluded or limited to sub-groups of non-vaccinated individuals. To identify relevant studies with appropriate control groups, we developed the following criteria for studies to be included in the systematic analysis: (1) baseline polymerase chain reaction (PCR) testing, (2) a uninfected comparison group, (3) longitudinal follow-up, (4) a cohort of human participants, i.e. not a case report or case series, and (5) outcome determined by PCR. The review was conducted following PRISMA guidelines. We assessed for selection, information, and analysis bias, per PRISMA guidelines. We identified 1,392 reports. Of those, 10 studies were eligible for our systematic review. The weighted average risk reduction against reinfection was 90.4% with a standard deviation of 7.7% (p-value: <0.01). Protection against SARS-CoV-2 reinfection was observed for up to 10 months. Studies had potential information, selection, and analysis biases. The protective effect of prior SARS-CoV-2 infection on re-infection is high and similar to the protective effect of vaccination. More research is needed to characterize the duration of protection and the impact of different SARS-CoV-2 variants.

Methicillin resistance in Staphylococcus aureus infections among patients colonized with methicillin-susceptible Staphylococcus aureus.

OBJECTIVES: We have noticed that patients colonized with methicillin-susceptible Staphylococcus aureus (MSSA) rarely get methicillin-resistant S. aureus (MRSA) infections. The purpose of this study was to compare the odds of a Staphylococcus aureus (SA) infection being an MRSA infection in MSSA carriers, MRSA carriers and non-carriers of SA. METHODS: Hospitalizations of adult patients at the Cleveland Clinic Health System from 2008 to 2015 were screened to identify those where the patient was tested for SA colonization. The first such hospitalization was identified. Among these 90 891 patients, those who had an SA infection during the hospitalization were included. SA carrier status (MRSA, MSSA, or non-carrier), was defined based on the first nasal SA test result. The association of carrier status and MRSA infection was examined. RESULTS: The mean (±standard deviation (SD)) age of the 1999 included patients was 61 (17) years, and 1160 (58%) were male. Thirty percent, 26%, and 44%, were MRSA carriers, MSSA carriers and non-carriers, respectively. Of the 601 SA infections in MRSA carriers (reference group), 552 (92%) were MRSA infections compared with 42 (8%) of 516 in MSSA carriers (odds ratio (OR) 0.008, 95% confidence interval (CI) 0.005-0.012, p <0.0001) and 430 (49%) of 882 in non-carriers (OR 0.072, 95% CI 0.051-0.100, p <0.0001), after controlling for age, sex, hospital length of stay and calendar year. CONCLUSION: Among patients with SA infection, the odds of the infection being an MRSA infection are 125-times lower in an MSSA carrier than in an MRSA carrier.

Propionibacterium acnes endocarditis: a case series.

OBJECTIVES: Propionibacterium acnes remains a rare cause of infective endocarditis (IE). It is challenging to diagnose due to the organism's fastidious nature and the indolent presentation of the disease. The purpose of this study was to describe the clinical presentation and management of P. acnes IE with an emphasis on the methods of diagnosis. METHODS: We identified patients from the Cleveland Clinic Infective Endocarditis Registry who were admitted from 2007 to 2015 with definite IE by Duke Criteria. Propionibacterium acnes was defined as the causative pathogen if it was identified in at least two culture specimens, or identified with at least two different modalities: blood culture, valve culture, valve sequencing or histopathological demonstration of microorganisms. RESULTS: We identified 24 cases of P. acnes IE, 23 (96%) of which were either prosthetic valve endocarditis or IE on an annuloplasty ring. Invasive disease (71%) and embolic complications (29%) were common. All but one patient underwent surgery. Propionibacterium acnes was identified in 12.5% of routine blood cultures, 75% of blood cultures with extended incubation, 55% of valve cultures, and 95% of valve sequencing specimens. In 11 of 24 patients (46%), no causative pathogen would have been identified without valve sequencing. CONCLUSIONS: Propionibacterium acnes almost exclusively causes prosthetic valve endocarditis and patients often present with advanced disease. The organism may not be readily cultured, and extended cultures appear to be necessary. In patients who have undergone surgery, valve sequencing is most reliable in establishing the diagnosis.

Epidemiology and risk factors for infections in myelodysplastic syndromes.

We conducted a case-control study to describe the epidemiology and risk factors for infections requiring hospitalization in patients with myelodysplastic syndromes (MDS). Of 497 patients identified, 103 patients developed 201 episodes of infection. The probability of acquiring an infection 1 year from date of MDS diagnosis was 15% (95% confidence interval [CI] 12-18%). Patients developing infections had decreased survival compared to those who did not (P = 0.007). Significant risk factors for infection were higher risk MDS (hazard ratio [HR] = 2.7, 95% CI = 1.7-4.1, P < 0.0001), nadir absolute neutrophil count <500/mL (HR = 1.8, 95% CI = 1.2-2.7, P < 0.007), chronic obstructive pulmonary disease (HR = 2.6, 95% CI = 1.4-4.9, P < 0.003), history of other malignancy (HR 2.0, 95% CI = 1.3-3.1, P < 0.003), and autoimmune disease (HR 2.9, 95% CI = 1.4-6.0, P < 0.005). Age, nadir platelet count <20,000/mL, diabetes mellitus, and MDS treatment were not significant risk factors. Pneumonia was the most common infection, and bacteria the predominant pathogens.

Immuno-flow cytometry for the rapid identification of Staphylococcus aureus and the detection of methicillin resistance.

Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) can be reliably differentiated by flow cytometry when labeled with nucleic acid dyes. The purpose of this study was to determine if this differentiation can be achieved while labeling with a S. aureus-specific anti-staphylococcal protein A antibody instead of nucleic acid dyes. A total of 103 S. aureus isolates were incubated for 4 h at 37°C in Mueller Hinton broth with and without oxacillin, then stained with anti-staphylococcal protein A antibody, and analyzed by flow cytometry using the Micro PRO™ instrument. Dot plots (side scatter vs. fluorescence intensity) of isolates exposed to oxacillin were examined to define two gates encompassing the majority of MSSA and MRSA signal events, respectively. The ratio of signal event counts in the two gates was called the gate signal count ratio (GSCR), and its performance was evaluated using receiver operating characteristic (ROC) curves. The GSCR could differentiate MRSA from MSSA with 98% sensitivity and 100% specificity using a cut-off of 0.6868 when the two gates were defined as follows: gate 1, fluorescence intensity 2-10, side scatter 5-70; gate 2, fluorescence intensity 7-700, side scatter 70-500. MRSA and MSSA can be accurately detected and differentiated by flow cytometry after 4 h of oxacillin exposure when labeled with anti-staphylococcal protein A antibody.

Effect of the influenza A (H1N1) live attenuated intranasal vaccine on nitric oxide (FE(NO)) and other volatiles in exhaled breath.

For the 2009 influenza A (H1N1) pandemic, vaccination and infection control were the main modes of prevention. A live attenuated H1N1 vaccine mimics natural infection and works by evoking a host immune response, but currently there are no easy methods to measure such a response. To determine if an immune response could be measured in exhaled breath, exhaled nitric oxide (FE(NO)) and other exhaled breath volatiles using selected ion flow tube mass spectrometry (SIFT-MS) were measured before and daily for seven days after administering the H1N1 2009 monovalent live intranasal vaccine (FluMist®, MedImmune LLC) in nine healthy healthcare workers (age 35 ± 7 years; five females). On day 3 after H1N1 FluMist® administration there were increases in FE(NO) (MEAN±SEM: day 0 15 ± 3 ppb, day 3 19 ± 3 ppb; p < 0.001) and breath isoprene (MEAN±SEM: day 0 59 ± 15 ppb, day 3 99 ± 17 ppb; p = 0.02). MS analysis identified the greatest number of changes in exhaled breath on day 3 with 137 product ion masses that changed from baseline. The exhaled breath changes on day 3 after H1N1 vaccination may reflect the underlying host immune response. However, further work to elucidate the sources of the exhaled breath changes is necessary.

Histoplasmosis in solid organ transplant recipients: 10 years of experience at a large transplant center in an endemic area.

BACKGROUND: Many clinical scenarios have been encountered by patients who developed histoplasmosis after receiving a solid organ transplant at a large transplant center in an endemic area. METHODS: Cases of posttransplantation histoplasmosis were identified by use of multiple methods, including reviews of microbiology test results, transplant databases, and billing codes. Data were obtained retrospectively. Descriptive statistics were used. RESULTS: During the 1997-2007 study period, 3436 patients received a solid organ transplant, and 38 patients were identified as having posttransplantation histoplasmosis. Of these 38 patients, 9 were excluded from our study because the diagnosis was solely clinical. Of the remaining 29 patients, 14 had posttransplantation histoplasmosis (incidence, 1 case per 1000 person-years); 14 showed histologic evidence of histoplasmosis in the recipient or donor tissue, which was encountered unexpectedly at the time of transplantation; and 1 had histoplasmosis before receiving the transplant. Of the 14 patients who developed histoplasmosis after transplantation, 5 were heart transplant recipients, 3 were lung transplant recipients, 3 were kidney transplant recipients, 1 was a liver transplant recipient, 1 was a pancreas transplant recipient, and 1 was a kidney-pancreas transplant recipient. The median time from transplantation to diagnosis was 17 months (interquartile range, 8.1-46 months), and the median time from onset of symptoms to diagnosis 3 weeks (interquartile range, 1.9-6.5 weeks). All recipients had disseminated disease. The most common treatment was amphotericin B and itraconazole. All were cured, or still on treatment, but symptom-free. Of the 14 patients who had an explanted organ or donor tissue that showed histologic evidence of histoplasmosis, 13 (93%) were lung transplant recipients, and 1 (7%) was a liver transplant recipient. None of these patients developed active histoplasmosis, but all received prophylactic treatment. Finally, 1 patient had histoplasmosis before transplantation; he was treated with itraconazole 3 months before and after transplantation, and he did well. CONCLUSIONS: In conclusion, posttransplantation histoplasmosis is rare (1 case per 1000 transplant-person-years; 95% confidence interval, 0.6-1.7), even in endemic areas. Prognosis is good but requires protracted therapy. Patients with latent infection did not develop posttransplantation histoplasmosis when prophylaxis was used.

Echocardiographic evaluation of diastolic function in asymptomatic type 2 diabetes.

INTRODUCTION: Diabetes mellitus is an established risk factor for congestive cardiac failure in which the diastolic function is impaired earlier than the systolic function and majority of these patients maybe asymptomatic without signs of overt heart failure. METHODS: A cross sectional hospital based study was done which included 100 asymptomatic patients with type 2 diabetes without evidence of coronary artery disease, congestive heart failure, thyroid or overt renal disease. LVDD was evaluated by Doppler echocardiography, which included the valsalva maneuver to unmask the pseudonormal pattern of left ventricular filling. The prevalence of LVDD and the associated risk factors were assessed. RESULTS: LVDD was found in 71 subjects (71%), of whom 60 had impaired relaxation and 11 had a pseudonormal pattern of ventricular filling. Systolic function was normal in all subjects, and there was no correlation between LVDD and indexes of metabolic control. It was also found that age > or =45 years was associated with an almost three times higher risk for the development of diastolic dysfunction in type 2 diabetes. Females were at a two times higher risk of developing diastolic dysfunction than when compared to men. Duration of diabetes > or = two years was associated with a two times higher risk for developing diastolic dysfunction. CONCLUSIONS: LVDD is much more common than previously reported in subjects with well-controlled type 2 diabetes who are free of clinically detectable heart disease. The high prevalence of this phenomenon in this high-risk population suggests that screening for LVDD in type 2 diabetes should include procedures such as the valsalva maneuver to unmask a pseudonormal pattern of ventricular filling.

Protease-sparing regimen in a real-life practice with naïve patients: an equal opportunity approach?

PURPOSE: Proven clinical efficacy of protease-sparing regimens (PSR) has been shown. Concerns exist about broad applicability of these regimens in advanced naïve patients. Recent reports have associated a rise in liver enzymes with nevi rapine; however, no data exist with efavirenz. METHOD: 17 consecutive antiretroviral-naïve HIV patients were started on a PSR with efavirenz plus two nucleoside reverse transcriptase inhibitors. Baseline liver enzymes, serum CD38, CD4, and HIV viral load data were collected. Correlation between change in viral load and immune reconstitution on therapy were compared to baseline laboratory values. RESULTS: All patients had a mean viral load decrease of >2 logs, including patients with low initial CD4% or high viral load, and there was no increase of liver enzymes observed at a median follow-up of 42 weeks (range 17-78). There was a perfect correlation between the change in viral load and the initial viral load (p <.0001, r = 1.00) including patients with viral load > or =100,000 copies/mL and CD4 count< or =50 (n = 5). Even patients with low initial CD4 had a significant percentage increase in CD4 count (p <.0002, r = 0.7880). CD38% showed a positive correlation with change in viral load (p =.046, r = 0.522). CONCLUSION: All patients experienced a mean viral load decrease of >2 logs (88% less than 400 copies/mL and 35% less than 20 copies/mL). There were no observed increases in liver enzymes. Patients with low CD4 counts, high initial viral load, or high CD38 expression still experienced a significant change in viral load.

Conversion of ammonia to dinitrogen in wastewater by Nitrosomonas europaea.

Because Nitrosomonas europaea contains ammonia-oxidizing enzyme, nitrite reductase, and nitrous oxide reductase, the conversion of ammonia to dinitrogen was tried with different reaction conditions. In aerobic reaction conditions, ammonium was converted to nitrite (NO2-), while under oxygen-limiting or oxygen-free conditions, NO2(-)-N formed from ammonia oxidation by N. europaea was reduced to N2O and dinitrogen with 22% conversion. During denitrification, optimal pH for the production of N2O and dinitrogen was found to be 7.0-8.0. Dinitrogen was not produced in acidic pH <7.0. A low partial oxygen pressure as well as oxygen-free conditions are favorable for high production of dinitrogen.

Two-dimensional echocardiographic diagnosis of left-atrial thrombus in rheumatic heart disease. A clinicopathologic study.

Two-dimensional echocardiographic studies were performed in 293 patients with rheumatic heart disease who underwent open-heart mitral valve surgery during an 18-month period. Diagnostic confirmation of a left atrial thrombus was based on direct inspection of the left atrium during surgery and histopathologic examination. Two-dimensional echocardiographic recordings were reviewed. Of the 293 patients, 33 had left atrial thrombi by two-dimensional echocardiographic criteria. This diagnosis was confirmed at surgery and histopathologic study in 30 (specificity 98.8%). A thrombus was not found in three patients. In 21 other patients, left atrial thrombi were present but were not detected by two-dimensional echocardiography (sensitivity 58.8%). Ten of these 21 had thrombi in the left atrial cavity. In 11 patients, thrombi were located in the left atrial appendage, all of which were missed by two-dimensional echocardiography. Excluding these 11 left atrial appendage thrombi, the sensitivity of two-dimensional echocardiography for detecting left atrial cavity thrombi was 75.0%.

Left atrial rhythm in man: an experimental study.

Ten patients with atrial septal defect of the secondum variety undergoing diagnostic haemodynamic study were subjected to electrical stimulation of the endocardium of the left atrium using a bipolar pacing electrode catheter. The polarity, frontal plane P wave axis and P wave configuration were analysed from ten scalar 12 lead electrocardiogram (ECG), recorded at 25-50 mm/sec during sinus rhythm and left atrial stimulation. While four patients demonstrated the "dome and dart" appearance of P waves in V1, nine out of ten patients revealed upright P waves in V1 during left atrial pacing; one patient showed inverted P waves in V1-V6. Four patients had negative "P" waves in L1 and only five of ten patients had inverted "P" waves in L1 and V6. All the criteria of left atrial rhythm were present in only one patient. It appears that the "P" waves change during left atrial pacing are variable and that the typical findings of left atrial rhythm are not obtained in all cases. This study was planned because trans-septal left atrial stimulation in the genesis of left atrial rhythm has not been widely reported.