The cooperation between orf virus and Staphylococcus aureus leads to intractable lesions in skin infection

A large amount of evidence shows that different kinds of microorganisms can jointly cope with environmental pressures including cell hosts. For example, in many cases, it has been found that secondary or mixed infection of animals caused by ORFV (an epitheliophilic Parapoxvirus) and bacteria (such as Staphylococcus aureus or Streptococcus) shows a mutual aid mode that indirectly leads to the deterioration of the disease. However, the lack of research on the co-pathogenic mechanism, including how to hijack and destroy the cell host in the pathological microenvironment, has hindered the in-depth understanding of the pathogenic process and consequences of this complex infection and the development of clinical treatment methods. Here, we summarized the current strategies of trapping cell hosts together, based on the previously defined ORFV-Host (O-H) system. The opportunistic invasion of S. aureus destroyed the delicate dynamic balance of the O-H, thus aggravating tissue damage through bacterial products (mediated by Agr), even causing sepsis or inducing cytokine storms. In fact, the virus products from its adaptive regulatory system (VARS) weaken the immune attacks and block molecular pathways, so that S. aureus can settle there more smoothly, and the toxins can penetrate into local tissues more quickly. This paper focuses on the main challenges faced by cell hosts in dealing with mixed infection, which provides a starting point for us to deal with this disease in the future.

Secondary infections in COVID-19: Antemortem and postmortem culture study

Background

Secondary bacterial infections during COVID-19 hospitalization have been reported in about 6-15% of patients.

Aims

To study the secondary bacterial infections that affected the COVID-19 patients during their hospitalisation and to unearth the bacteriological profile of samples obtained after their demise.

Settings and Design

This prospective study was carried out at a COVID-19 dedicated, apex tertiary care centre in North India from July 2020 to April 2021.

Methods and Materials

Samples of 268 patients were considered for the study. Nasopharyngeal swab specimen, blood, and tissue (lung) were collected from the deceased body as early as possible and processed.

Statistical Analysis

Statistical analyses were performed using STATA version 11.1 (Stata Corp., College Station, TX, USA).

Results

A total of 170 samples were received from patients before their death, which included blood, urine, respiratory samples, pus, and cerebrospinal fluid. Forty-four pathogens were isolated, which consisted of Acinetobacter baumannii (43.1%), Klebsiella pneumoniae (36.3%), Escherichia coli (11.3%), and Pseudomonas aeruginosa (4.5%), Enterococcus faecium (4.5%). Two hundred fifty-eight samples were collected from the deceased bodies wherein the nasopharyngeal sample was highest, followed by tissue and blood. A total of 43 pathogens were isolated among them which included A. baumannii (44.1%), followed by K. pneumoniae (25.5%), E. coli (20.9%), P. aeruginosa (6.97%) and Enterobacter cloacae (2.3%). All these isolates were highly resistant to antimicrobials.

Conclusions

In our study, bacterial profiles in antemortem and postmortem samples were found to be similar, suggesting that resistant pathogens may be the cause of mortality in COVID-19 infected hospitalised patients.

The Association of Procalcitonin and C-Reactive Protein with Bacterial Infections Acquired during Intensive Care Unit Stay in COVID-19 Critically Ill Patients

In COVID-19 patients, procalcitonin (PCT) and C-reactive protein (CRP) performance in identifying bacterial infections remains unclear. Our study aimed to evaluate the association of PCT and CRP with secondary infections acquired during ICU stay in critically ill COVID-19 patients. This observational study included adult patients admitted to three COVID-19 intensive care units (ICUs) from February 2020 to May 2022 with respiratory failure caused by SARS-CoV-2 infection and ICU stay ≥ 11 days. The values of PCT and CRP collected on the day of infection diagnosis were compared to those collected on day 11 after ICU admission, the median time for infection occurrence, in patients without secondary infection. The receiver operating characteristic curve (ROC) and multivariate logistic model were used to assess PCT and CRP association with secondary infections. Two hundred and seventy-nine patients were included, of whom 169 (60.6%) developed secondary infection after ICU admission. The PCT and CRP values observed on the day of the infection diagnosis were larger (p < 0.001) than those observed on day 11 after ICU admission in patients without secondary infections. The ROC analysis calculated an AUC of 0.744 (95%CI 0.685-0.803) and 0.754 (95%CI 0.695-0.812) for PCT and CRP, respectively. Multivariate logistic models showed that PCT ≥ 0.16 ng/mL and CRP ≥ 1.35 mg/dL were associated (p < 0.001) with infections acquired during ICU stay. Our results indicated that in COVID-19 patients, PCT and CRP values were associated with infections acquired during the ICU stay and can be used to support, together with clinical signs, rather than predict or rule out, the diagnosis of these infections.

Secondary infections in critically ill patients with COVID-19: A retrospective single-center study

Background

Patients infected with COVID-19 admitted to the intensive care unit (ICU) may have a higher incidence of developing secondary infections. These infections can further deteriorate the hospital course and increase mortality. Therefore, the objectives of this study were to investigate the incidence, associated risk factors, outcomes, and pathogens associated with secondary bacterial infections in critically ill patients with COVID-19.

Methods

All adult COVID-19 patients admitted to the intensive care unit requiring mechanical ventilation from October 1, 2020 until December 31, 2021 were screened for inclusion in the study. A total of 86 patients were screened and 65 who met the inclusion criteria were prospectively entered into a customized electronic database. The database was then retrospectively analyzed to investigate secondary bacterial infections.

Results

Of the 65 patients included, 41.54% acquired at least one of the studied secondary bacterial infections during the course of their ICU stay. The most common secondary infection (59.26%) seen was hospital-acquired pneumonia followed by acquired bacteremia of unknown origin (25.92%) and catheter-related sepsis (14.81%). Diabetes mellitus (P = <.001), cumulative dose of corticosteroids (P = 0.001), were associated with an increased risk of secondary bacterial infection. The most commonly isolated pathogen in patients with secondary pneumonia was Acinetobacter baumannii. Staphylococcus aureus was the most common organism associated with a bloodstream infection and catheter-related sepsis.

Conclusion

The incidence of secondary bacterial infections was high in critically ill patients with COVID-19 and was associated with a longer duration of admission to the hospital and ICU and a higher mortality. Diabetes mellitus and cumulative dose of corticosteroids were associated with significantly increased risk of secondary bacterial infection.

Baricitinib Treatment of Coronavirus Disease 2019 Is Associated With a Reduction in Secondary Infections

We performed a secondary analysis of the National Institutes of Health-sponsored Adaptive COVID-19 Treatment Trial (ACTT-2) randomized controlled trial and found that baricitinib was associated with a 50% reduction in secondary infections after controlling for baseline and postrandomization patient characteristics. This finding provides a novel mechanism of benefit for baricitinib and supports the safety profile of this immunomodulator for the treatment of coronavirus disease 2019.

The impact of COVID-19 pandemic on healthcare associated infections: A teaching hospital experience

Coronavirus disease-19 (COVID-19) is a global pandemic, with a high capability of contagious distribution, where national secondary and co-infections characterization are lacking. The objective of this study was to assess the impact of the COVID-19 pandemic on infection rates among patients admitted to the intensive care units at King Abdullah University Hospital, profiling the drug resistance rates nationally. This is a cross-sectional study of COVID-19 associated infections that was conducted at a teaching hospital, in the north of Jordan. It included all COVID-19 patients who were admitted to intensive care units during the first and second pandemic waves. Data on age, gender, length of stay, co-morbidities, co-infections and sensitivity to antibiotics were retrospectively collected from the hospital information database. Statistical analyses were performed using SPSS software. A total of 589 COVID-19 patients were included, of whom 20% developed bacterial associated infections. The ratio of bacterial co-infection to secondary infections was 1:8. Gram-negative bacteria, Acinetobacter baumannii (40.1%), Eschericia coli (17.5%), Klebsiella pneumonia (6.8%), and Pseudomonas aeruginosa (5.1%) were the most abundant isolated species. The detection rates of E coli (ESBL), K pneumonia (ESBL), A baumannii (CRO), P aeruginosa (CRO), S aureus (MRSA) were 52%, 67%, 97%, 44%, and 67%, respectively.

Immunomodulators for severe coronavirus disease-2019 in transplant patients: Do they increase the risk of secondary infection?

BACKGROUND

Current guidelines recommend immunomodulators, tocilizumab or baricitinib, for the management of severe coronavirus disease-2019 (COVID-19) in patients with increasing oxygen requirements. Given their immunosuppressive effects, there is a concern for higher rates of infection among transplant recipients.

METHODS

A retrospective cohort study of transplant patients with severe COVID-19 between April 2020 and January 2022 was performed at the Mayo Clinic. The primary outcome was incidence of secondary infections after COVID-19 diagnosis. Secondary outcomes were 90-day mortality, ventilatory days, and thromboembolic events.

RESULTS

A total of 191 hospitalized transplant patients were studied, including 77 (40.3%) patients who received an immunomodulator. Overall, 89% were solid organ transplant recipients, with kidney as the most common transplanted organ (50.3%). The majority (89.0%) required oxygen supplementation on admission, and 39.8% of these patients required mechanical ventilation during the hospital course. There was no significant difference in the incidence of secondary infections between those who received or did not receive an immunomodulator (p = .984). Likewise, there was no difference in 90-day mortality between patients who received or did not receive an immunomodulator (p = .134). However, higher mortality was observed among patients that developed a secondary infection (p < .001).

CONCLUSION

The use of immunomodulators in transplant patients with severe COVID-19 was not significantly associated with an increased risk of secondary infections. Secondary infections were associated with higher risk of all-cause mortality. Future studies of larger cohorts are needed to explore the effect of immunomodulators on survival among transplant patients with COVID-19.

Association between Vitamin D Status and Secondary Infections in Patients with Severe COVID-19 Admitted in the Intensive Care Unit of a Tertiary-Level Hospital in Turkey

There are several studies showing that the vitamin D status can determine risk of COVID-19 infections, severity and mortality from coronavirus disease 2019 (COVID-19). However, the association between vitamin D (25(OH)D) and secondary infections in the prognosis of COVID-19 patients has not been reported yet. The aim was to investigate whether the vitamin D status affects the rates of secondary infections in patients with severe COVID-19 hospitalized in the intensive care unit (ICU) of a tertiary-level hospital in Turkey. The data of 194 patients with diagnosis of severe COVID-19 who were admitted to the ICU from March 2020 to June 2021 and older than 18 years were evaluated in this retrospective study. The patients were divided into two groups according to total serum 25(OH)D level as normal group (≥20 ng/mL) and low group (<20 ng/mL). The 25(OH)D level was low in 118 (60.8%) and normal in 76 (39.2%) patients. The mean age of the low group was significantly higher than that of the normal group (67.02 ± 14.47 vs. 61.70 ± 14.38; p = 0.013). The systolic and diastolic blood pressure as well as the Glasgow coma scale score of the low group were significantly lower than that of the normal group (p = 0.004, 0.002 and 0.001, respectively). The intubation rate and APACHE (Acute Physiology and Chronic Health Evaluation) score of the low group was significantly higher than that of the normal group (p = 0.001). The platelets number and blood pH decreased, and the neutrophil/lymphocyte ratio, procalcitonin, lactate, urea, creatinine and lactate dehydrogenase concentrations increased significantly in the low group (p < 0.05). The mortality rate was 79.7% in the low group and 22.4% in the normal group (p < 0.001). Microbiological growth was observed in 68.6% of the normal group and 52.6% of the normal group (p = 0.025). The number of cultures with resistant bacteria was significantly higher in the low group (25.9%) than that in the normal group (17.5%) (p = 0.035). The severe COVID-19 patients hospitalized with vitamin D deficiency may have increased risks of poor prognosis and mortality due to secondary infections in the ICU.

Secondary Bacterial Infections in Mucormycosis-COVID-19 Cases: Experience during the Second COVID-19 Wave in India

In the second wave of COVID-19 in India, there was a new challenge in the form of mucormycosis. Coinfection with mucormycosis was perilous as both conditions required a prolonged hospital stay, thus serving as an ideal platform for secondary infections. Using a retrospective observational study, we studied secondary infections and their impact on the outcome in COVID-19 patients with mucormycosis. The outcome in these patients was evaluated and compared with COVID-19 patients with mucormycosis but without any secondary infection. SPSS V-20 was used for data analysis. Fifty-five patients tested positive for mucormycosis (55/140; 39.28). Twelve out of these 55 (21.8%) developed secondary infections during their hospital stay. Bloodstream infection was the most common (42.86%) secondary infection. The Gram-negative (GN) organisms were more common (11/16; 68.75%) compared with the Gram-positives (GP) (5/16; 31.25%). But the most common isolate was Enterococcus faecium (5/16; 31.25%). A high percentage of microorganisms isolated were multidrug-resistant (15/16; 93.75%). Two out of five (40%) isolates of Enterococcus faecium were vancomycin-resistant (VRE). High resistance to carbapenems was noted in the GN isolates (9/11; 81.81%). The comparison of length of stay in both subgroups was statistically significant (P value <0.001). When compared, the length of stay in people with adverse outcomes was also statistically significant (P value <0.001). Procalcitonin (PCT) had a positive predictive value for the development of secondary bacterial infections (P value <0.001). Antimicrobial stewardship and strict infection control practices are the need of the hour. IMPORTANCE Although our knowledge about COVID-19 and secondary infections in patients is increasing daily, little is known about the secondary infections in COVID-19-mucormycosis patients. Thus, we have intended to share our experience regarding this subgroup. The importance of this study is that it brings to light the type of secondary infections seen in COVID-19-mucormycosis patients. These secondary infections were partially responsible for the mortality and morbidity of the unfortunate ones. We, as health care workers, can learn the lesson and disseminate the knowledge so that in similar situations, health care workers, even in other parts of the world, know what to expect.

Metatranscriptomic Analysis Reveals Disordered Alterations in Oropharyngeal Microbiome during the Infection and Clearance Processes of SARS-CoV-2: A Warning for Secondary Infections

This study was conducted to investigate oropharyngeal microbiota alterations during the progression of coronavirus disease 2019 (COVID-19) by analyzing these alterations during the infection and clearance processes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The diagnosis of COVID-19 was confirmed by using positive SARS-CoV-2 quantitative reverse transcription polymerase chain reaction (RT-qPCR). The alterations in abundance, diversity, and potential function of the oropharyngeal microbiome were identified using metatranscriptomic sequencing analyses of oropharyngeal swab specimens from 47 patients with COVID-19 (within a week after diagnosis and within two months after recovery from COVID-19) and 40 healthy individuals. As a result, in the infection process of SARS-CoV-2, compared to the healthy individuals, the relative abundances of Prevotella, Aspergillus, and Epstein-Barr virus were elevated; the alpha diversity was decreased; the beta diversity was disordered; the relative abundance of Gram-negative bacteria was increased; and the relative abundance of Gram-positive bacteria was decreased. After the clearance of SARS-CoV-2, compared to the healthy individuals and patients with COVID-19, the above disordered alterations persisted in the patients who had recovered from COVID-19 and did not return to the normal level observed in the healthy individuals. Additionally, the expressions of several antibiotic resistance genes (especially multi-drug resistance, glycopeptide, and tetracycline) in the patients with COVID-19 were higher than those in the healthy individuals. After SARS-CoV-2 was cleared, the expressions of these genes in the patients who had recovered from COVID-19 were lower than those in the patients with COVID-19, and they were different from those in the healthy individuals. In conclusion, our findings provide evidence that potential secondary infections with oropharyngeal bacteria, fungi, and viruses in patients who have recovered from COVID-19 should not be ignored; this evidence also highlights the clinical significance of the oropharyngeal microbiome in the early prevention of potential secondary infections of COVID-19 and suggests that it is imperative to choose appropriate antibiotics for subsequent bacterial secondary infection in patients with COVID-19.

Hospital-acquired bloodstream infections in patients deceased with COVID-19 in Italy (2020-2021)

INTRODUCTION

In hospitalized patients with COVID-19, bloodstream infections (BSI) are associated with high mortality and high antibiotic resistance rates. The aim of this study was to describe BSI etiology, antimicrobial resistance profile and risk factors in a sample of patients deceased with COVID-19 from the Italian National COVID-19 surveillance.

METHODS

Hospital charts of patients who developed BSI during hospitalization were reviewed to describe the causative microorganisms and their antimicrobial susceptibility profiles. Risk factors were analyzed in univariate and multivariate analyses.

RESULTS

The study included 73 patients (71.2% male, median age 70): 40 of them (54.8%) received antibiotics and 30 (41.1%) systemic steroids within 48 h after admission; 53 (72.6%) were admitted to intensive care unit. Early steroid use was associated with a significantly shorter interval between admission and BSI occurrence. Among 107 isolated microorganisms, the most frequent were Enterococcus spp., Candida spp., Acinetobacter baumannii, and Klebsiella pneumoniae. Median time from admission to BSI was shorter for Staphylococcus aureus compared to all other bacteria (8 vs. 24 days, p = 0.003), and longer for Enterococcus spp., compared to all other bacteria (26 vs. 18 days, p = 0.009). Susceptibility tests showed a high rate of resistance, with 37.6% of the bacterial isolates resistant to key antibiotics. Resistance was associated with geographical area [adjusted odds ratio (AOR) for Central/South Italy compared to North Italy: 6.775, p = 0.002], and with early use of systemic steroids (AOR 6.971, p = 0.018).

CONCLUSIONS

In patients deceased with COVID-19, a large proportion of BSI are caused by antibiotic-resistant bacteria. Early steroid use may facilitate this occurrence.

Invasiveness of Ventilation Therapy Is Associated to Prevalence of Secondary Bacterial and Fungal Infections in Critically Ill COVID-19 Patients

Superinfections are a fundamental critical care problem, and their significance in severe COVID-19 cases needs to be determined. This study analyzed data from the Lean European Open Survey on SARS-CoV-2-Infected Patients (LEOSS) cohort focusing on intensive care patients. A retrospective analysis of patient data from 840 cases of COVID-19 with critical courses demonstrated that co-infections were frequently present and were primarily of nosocomial origin. Furthermore, our analysis showed that invasive therapy procedures accompanied an increased risk for healthcare-associated infections. Non-ventilated ICU patients were rarely affected by secondary infections. The risk of infection, however, increased even when non-invasive ventilation was used. A further, significant increase in infection rates was seen with the use of invasive ventilation and even more so with extracorporeal membrane oxygenation (ECMO) therapy. The marked differences among ICU techniques used for the treatment of COVID-19-induced respiratory failure in terms of secondary infection risk profile should be taken into account for the optimal management of critically ill COVID-19 patients, as well as for adequate antimicrobial therapy.

Secondary infections in COVID-19 patients: A two-centre retrospective observational study

INTRODUCTION

We sought to evaluate secondary infections (SIs) in patients admitted to the intensive care unit (ICU) for COVID-19 with respect to incidence, causative pathogens, and clinical outcomes.

METHODOLOGY

In this two-centre retrospective study, we analysed 146 patients (96 males, 50 females; median age, 64 years) admitted to the ICU with COVID-19 between March 26 and December 31, 2020. Inclusion criteria were an ICU admission for at least 48 hours and age beyond 18 years. Patients with and without SIs were compared and the impacts of SIs and carbapenem resistance on mortality were analysed.

RESULTS

During ICU admission, 84 episodes of SIs developed in 58 patients (39.7%). A total of 104 isolates were recovered, with Gram-negative bacteria most frequent accounting for 74%. At least one carbapenem-resistant pathogen (n = 61) was recovered in 41 patients (70.1%). In multivariate analysis, the use of ECMO and an elevated procalcitonin level were significantly associated with the development of SIs. The mortality rate and the incidence of carbapenem resistance did not differ significantly in COVID-19 patients with and without SIs (p = 0.059 and p = 0.083, respectively).

CONCLUSIONS

The incidences of SIs and carbapenem resistance among COVID-19 patients were alarming, emphasizing stricter infection control measures in the ICU setting.

Secondary infections worsen the outcome of COVID-19 in patients with hematological malignancies: A report from the ITA-HEMA-COV

The impact of secondary infections (SI) on COVID-19 outcome in patients with hematological malignancies (HM) is scarcely documented. To evaluate incidence, clinical characteristics, and outcome of SI, we analyzed the microbiologically documented SI in a large multicenter cohort of adult HM patients with COVID-19. Among 1741 HM patients with COVID-19, 134 (7.7%) had 185 SI, with a 1-month cumulative incidence of 5%. Median time between COVID-19 diagnosis and SI was 16 days (IQR: 5-36). Acute myeloid leukemia (AML) and lymphoma/plasma cell neoplasms (PCN) were more frequent diagnoses in SI patients compared to patients without SI (AML: 14.9% vs. 7.1%; lymphoma/PCN 71.7% vs. 65.3%). Patients with SI were older (median age 70 vs. 66 years, p = 0.002), with more comorbidities (median Charlson Comorbidity Index 5 vs. 4, p < 0.001), higher frequency of critical COVID-19 (19.5% vs. 11.5%, p = 0.046), and more frequently not in complete remission (75% vs. 64.7% p = 0.024). Blood and bronchoalveolar lavage were the main sites of isolation for SI. Etiology of infections was bacterial in 80% (n = 148) of cases, mycotic in 9.7% (n = 18) and viral in 10.3% (n = 19); polymicrobial infections were observed in 24 patients (18%). Escherichia coli represented most of Gram-negative isolates (18.9%), while coagulase-negative Staphylococci were the most frequent among Gram-positive (14.2%). The 30-day mortality of patients with SI was higher when compared to patients without SI (69% vs. 15%, p < 0.001). The occurrence of SI worsened COVID-19 outcome in HM patients. Timely diagnosis and adequate management should be considered to improve their prognosis.

Differential Immune Checkpoint and Ig-like V-Type Receptor Profiles in COVID-19: Associations with Severity and Treatment

Identifying patients' immune system status has become critical to managing SARS-CoV-2 infection and avoiding the appearance of secondary infections during a hospital stay. Despite the high volume of research, robust severity and outcome markers are still lacking in COVID-19. We recruited 87 COVID-19 patients and analyzed, by unbiased automated software, 356 parameters at baseline emergency department admission including: high depth immune phenotyping and immune checkpoint expression by spectral flow cytometry, cytokines and other soluble molecules in plasma as well as routine clinical variables. We identified 69 baseline alterations in the expression of immune checkpoints, Ig-like V type receptors and other immune population markers associated with severity (O₂ requirement). Thirty-four changes in these markers/populations were associated with secondary infection appearance. In addition, through a longitudinal sample collection, we described the changes which take place in the immune system of COVID-19 patients during secondary infections and in response to corticosteroid treatment. Our study provides information about immune checkpoint molecules and other less-studied receptors with Ig-like V-type domains such as CD108, CD226, HVEM (CD270), B7H3 (CD276), B7H5 (VISTA) and GITR (CD357), defining these as novel interesting molecules in severe and corticosteroids-treated acute infections.

A Retrospective, Monocentric Study Comparing Co and Secondary Infections in Critically Ill COVID-19 and Influenza Patients

Few data are available on infectious complications in critically ill patients with different viral infections. We performed a retrospective monocentric study including all of the patients admitted to the intensive care unit (ICU) with confirmed COVID-19 (as of 13 March 2020) or Influenza A and/or B infections (as of 1 January 2015) until 20 April 2020. Coinfection and secondary infections (occurring within and after 48 h from admission, respectively) were recorded. Fifty-seven COVID-19 and 55 Influenza patients were included. Co-infections were documented in 13/57 (23%) COVID-19 patients vs. 40/55 (73%) Influenza patients (p < 0.001), most of them being respiratory (9/13, 69% vs. 35/40, 88%; p = 0.13) and of bacterial origin (12/13, 92% vs. 29/40, 73%; p = 0.25). Invasive aspergillosis infections were observed only in Influenza patients (8/55, 15%). The COVID-19 and Influenza patients presented 1 (0−4) vs. 0 (0−4) secondary infections (p = 0.022), with comparable sites being affected (lungs: 35/61, 57% vs. 13/31, 42%; p = 0.16) and causative pathogens occurring (Gram-negative bacteria: 51/61, 84% vs. 23/31, 74%; p > 0.99). The COVID-19 patients had longer ICU lengths of stay (15 (−65) vs. 5 (1−89) days; p = 0.001), yet the two groups had comparable mortality rates (20/57, 35% vs. 23/55, 41%; p = 0.46). We report fewer co-infections but more secondary infections in the ICU COVID-19 patients compared to the Influenza patients. Most of the infectious complications were respiratory and of bacterial origin.

Opportunistic Infections in COVID-19: A Systematic Review and Meta-Analysis

The prevalence, incidence, and characteristics of bacterial infections in patients infected with severe acute respiratory syndrome coronavirus 2 are not well understood and have been raised as an important knowledge gap. Therefore, our study focused on the most common opportunistic infections/secondary infections/superinfections in coronavirus disease 2019 (COVID-19) patients.

This systematic review and meta-analysis was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Eligible studies were identified using PubMed/Medline since inception to June 25, 2021. Studies meeting the inclusion criteria were selected. Statistical analysis was conducted in Review Manager 5.4.1. A random-effect model was used when heterogeneity was seen to pool the studies, and the result was reported as inverse variance and the corresponding 95% confidence interval.

We screened 701 articles comprising 22 cohort studies which were included for analysis. The pooled prevalence of opportunistic infections/secondary infections/superinfections was 16% in COVID-19 patients. The highest prevalence of secondary infections was observed among viruses at 33%, followed by bacteria at 16%, fungi at 6%, and 25% among the miscellaneous group/wrong outcome.

Opportunistic infections are more prevalent in critically ill patients. The isolated pathogens included Epstein-Barr virus, Pseudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, Hemophilus influenza, and invasive pulmonary aspergillosis. Large-scale studies are required to better identify opportunistic/secondary/superinfections in COVID-19 patients.

Improving management and antimicrobial stewardship for bacterial and fungal infections in hospitalized patients with COVID-19

SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2) infection is being one of the most significant challenges of health care systems worldwide. Bacterial and fungal infections in hospitalized patients with coronavirus disease 2019 (COVID-19) are uncommon but consumption of antibiotics and antifungals has increased dramatically during the ongoing pandemic resulting in increased selective pressure for global antimicrobial resistance. Nosocomial bacterial superinfections appear to be more frequent than community-acquired coinfections, particularly among patients admitted to the intensive care unit (ICU) and those receiving immunosuppressive treatment. Fungal infections associated with COVID-19 might be missed or misdiagnosed. Existing and new antimicrobial stewardship (AMS) programmes can be utilized directly in COVID-19 pandemic and are urgently needed to contain the high rates of misdiagnosis and antimicrobial prescription. The aim of this review is to describe the role of bacterial and fungal infections and possible strategies of AMS to use in daily practice for optimal management of COVID-19.

Severe Adaptive Immune Suppression May Be Why Patients With Severe COVID-19 Cannot Be Discharged From the ICU Even After Negative Viral Tests

During the COVID-19 pandemic, a phenomenon emerged in which some patients with severe disease were critically ill and could not be discharged from the ICU even though they exhibited negative viral tests. To explore the underlying mechanism, we collected blood samples from these patients and analyzed the gene expression profiles of peripheral immune cells. We found that all enrolled patients, regardless of changes in genes related to different symptoms and inflammatory responses, showed universally and severely decreased expression of adaptive immunity-related genes, especially those related to T/B cell arms and HLA molecules, and that these patients exhibited long-term secondary infections. In addition, no significant change was found in the expression of classic immunosuppression molecules including PD-1, PD-L1, and CTLA-4, suggesting that the adaptive immune suppression may not be due to the change of these genes. According to the published literatures and our data, this adaptive immunosuppression is likely to be caused by the "dysregulated host response" to severe infection, similar to the immunosuppression that exists in other severely infected patients with sepsis.

Infections in secondary immunodeficiency patients treated with Privigen® or Hizentra®: a retrospective US administrative claims study in patients with hematological malignancies

B cell-derived lymphoproliferative disorders are associated with secondary immunodeficiency (SID); some patients require immunoglobulin replacement therapy (IgRT) to mitigate infections. Using IQVIA's PharMetrics^® Plus database, patients with SID who received IgPro10/IgPro20 in the 12 months post-diagnosis (IgRT users) were matched to patients with SID not receiving IgRT (non-IgRT users). The risk of severe infection was compared using within-patient change from baseline to follow-up as well as between cohorts. Overall, 277 IgRT users were matched to 1019 non-IgRT users. Before IgRT, more IgRT users experienced any bacterial infection (88.4% vs. 72.9%; p<.0001) or ≥1 severe bacterial infection (SBI) (42.2% vs. 31.8%; p=.0011) vs. non-IgRT users. During follow-up, risk of SBI among IgRT users (21.7%) reached parity with non-IgRT users (21.2%). IgRT was associated with a reduction in SBIs to levels comparable with the lower 'baseline infection risk' of non-IgRT users. These criteria help define SID patients who may benefit from IgRT.

High-Density Blood Transcriptomics Reveals Precision Immune Signatures of SARS-CoV-2 Infection in Hospitalized Individuals

The immune response to COVID-19 infection is variable. How COVID-19 influences clinical outcomes in hospitalized patients needs to be understood through readily obtainable biological materials, such as blood. We hypothesized that a high-density analysis of host (and pathogen) blood RNA in hospitalized patients with SARS-CoV-2 would provide mechanistic insights into the heterogeneity of response amongst COVID-19 patients when combined with advanced multidimensional bioinformatics for RNA. We enrolled 36 hospitalized COVID-19 patients (11 died) and 15 controls, collecting 74 blood PAXgene RNA tubes at multiple timepoints, one early and in 23 patients after treatment with various therapies. Total RNAseq was performed at high-density, with >160 million paired-end, 150 base pair reads per sample, representing the most sequenced bases per sample for any publicly deposited blood PAXgene tube study. There are 770 genes significantly altered in the blood of COVID-19 patients associated with antiviral defense, mitotic cell cycle, type I interferon signaling, and severe viral infections. Immune genes activated include those associated with neutrophil mechanisms, secretory granules, and neutrophil extracellular traps (NETs), along with decreased gene expression in lymphocytes and clonal expansion of the acquired immune response. Therapies such as convalescent serum and dexamethasone reduced many of the blood expression signatures of COVID-19. Severely ill or deceased patients are marked by various secondary infections, unique gene patterns, dysregulated innate response, and peripheral organ damage not otherwise found in the cohort. High-density transcriptomic data offers shared gene expression signatures, providing unique insights into the immune system and individualized signatures of patients that could be used to understand the patient’s clinical condition. Whole blood transcriptomics provides patient-level insights for immune activation, immune repertoire, and secondary infections that can further guide precision treatment.

Antifungal Drug Susceptibility and Genetic Characterization of Fungi Recovered from COVID-19 Patients

Fungal infections are common complications of respiratory viral infections and are associated with the increased need for intensive care and elevated mortality. Data regarding microbiological and molecular characteristics of such infections in COVID-19 patients are scarce. Here, we performed a comprehensive analysis, including species identification, antifungal susceptibility testing, molecular resistance determinants analysis, typing, and retrospective clinical data review, of fungal isolates recovered from 19 COVID-19 patients, who were hospitalized at the Hackensack University Medical Center (HUMC) in Hackensack, New Jersey, USA, in the initial phase of the pandemic from April–May 2020. In total, 17 Candida albicans, two C. parapsilosis, and two Aspergillus fumigatus were analyzed. All Candida spp. isolates were susceptible to micafungin and azole drugs (fluconazole, voriconazole, posaconazole, itraconazole, isavuconazole). A. fumigatus isolates were susceptible to micafungin and all triazole drugs except fluconazole (intrinsic resistance). Multilocus sequence typing (MLST) of C. albicans isolates revealed 15 different sequence types (STs), which clustered below the clade-defining limit of p-distance < 0.04. Pulsed-field gel electrophoresis (PFGE) karyotyping revealed no chromosomal rearrangements in these isolates. A. fumigatus isolates were of different, non-related genotypes. We speculate that virus- and drug-induced immunosuppression (94.7% of the patients received corticosteroids), together with prolonged hospital stay (median duration of 29 days) and mechanical ventilation (median duration of 24 days) likely increased the susceptibility to secondary respiratory and bloodstream infections in the studied patient population. The presence of fungi in blood or respiratory tract fluid was a prognosticator for poor clinical outcome, which presented as an 89.5% 30-day mortality in our patient cohort.

Fatal outcomes of imported dengue fever in adult travelers from non-endemic areas are associated with primary infections

BACKGROUND

The case-fatality rate of dengue in travelers is low. Secondary dengue virus (DENV) infections are considered a risk factor for fatal outcome in endemic populations; however, the impact of secondary infections on mortality in travelers has not been studied systematically. We performed a descriptive analysis of case reports of dengue fatalities in travelers.

METHODS

We searched Medline for clinical case reports, using the free terms and MeSH headings: 'Dengue' OR 'Severe Dengue' AND 'Travel-Related Illness' OR 'travel' AND 'Mortality' OR 'Fatal Outcome'. We analyzed case reports of fatal dengue in returning travelers published from 1995 to 2020, with the objective to detail risk factors for dengue mortality in this population. We verified the authors' classifications of primary or secondary dengue infections; infections were considered as primary by absence of anti-DENV immunoglobulin (Ig)G or by IgM-to-IgG ratios greater than or equal to 1.8 in the first 7 days post symptom onset.

RESULTS

We identified nine detailed reports of dengue with fatal outcome among travelers from non-endemic countries. Eight fatalities were female. The median age was 32 years (range 21-63). Out of nine fatal cases, seven travelers had a primary DENV infection, one had a secondary infection and, in one, these data were not reported. The infecting DENV serotypes were DENV-1 (n = 2), DENV-2 (n = 2) and DENV-3 (n = 3); DENV-1 or 2 (n = 1) and in one case, the serotype could not be determined.

CONCLUSIONS

Dengue-related deaths in travelers are rare. Most dengue cases in travelers are primary infections. Contrary to prevailing conceptions, we found that fatal outcomes of dengue in travelers from non-endemic countries were reported mainly with primary DENV infections. We alert health care providers that primary DENV infections are not always harmless and that in adult travelers from non-endemic countries, primary infections may contribute more to dengue-related mortality than secondary infections.

Pharmacotherapy in Coronavirus Disease 2019 and Risk of Secondary Infections: A Single-Center Case Series and Narrative Review

Since the onset of the coronavirus disease 2019 pandemic, immune modulators have been considered front-line candidates for the management of patients presenting with clinical symptoms secondary to severe acute respiratory syndrome coronavirus 2 infection. Although heavy emphasis has been placed on early clinical efficacy, we sought to evaluate the impact of pharmacologic approach to coronavirus disease 2019 within the ICU on secondary infections and clinical outcomes.

DATA SOURCES

PubMed (inception to March 2021) database search and manual selection of bibliographies from selected articles.

STUDY SELECTION AND DATA EXTRACTION

Articles relevant to coronavirus disease 2019, management of severe acute respiratory syndrome coronavirus 2-associated respiratory failure, and prevalence of secondary infections with pharmacotherapies were selected. The MeSH terms "COVID-19," "secondary infection," "SARS-CoV-2," "tocilizumab," and "corticosteroids" were used for article identification. Articles were narratively synthesized for this review.

DATA SYNTHESIS

Current data surrounding the use of tocilizumab and/or corticosteroids for coronavirus disease 2019 management are limited given the short follow-up period and conflicting results between studies. Further complicating the understanding of immune modulator role is the lack of definitive understanding of clinical impact of the immune response in coronavirus disease 2019.

CONCLUSIONS

Based on the current available literature, we suggest prolonged trials and follow-up intervals for those patients managed with immune modulating agents for the management of coronavirus disease 2019.

Risk Factors and Outcomes of Hospitalized Patients With Severe Coronavirus Disease 2019 (COVID-19) and Secondary Bloodstream Infections: A Multicenter Case-Control Study

Background

Coronavirus disease 2019 (COVID-19) has become a global pandemic. Clinical characteristics regarding secondary infections in patients with COVID-19 have been reported but detailed microbiology, risk factors and outcomes of secondary bloodstream infections (sBSI) in patients with severe COVID-19 have not been well described.

Methods

We performed a multicenter, case-control study including all hospitalized patients diagnosed with severe COVID-19 and blood cultures drawn from March 1, 2020 to May 7, 2020 at three academic medical centers in New Jersey, USA. Data collection included demographics, clinical and microbiologic variables, and patient outcomes. Risk factors and outcomes were compared between cases (sBSI) and controls (no sBSI).

Results

A total of 375 hospitalized patients were included. There were 128 sBSIs during the hospitalization. For the first set of positive blood cultures, 117 (91.4%) were bacterial and 7 (5.5%) were fungal. Those with sBSI were more likely to have altered mental status, lower mean percent oxygen saturation on room air, have septic shock and be admitted to the intensive care unit compared to the controls. In-hospital mortality was higher in those with a sBSI versus controls (53.1% vs 32.8%, p=0.0001).

Conclusions

We observed hospitalized adult patients with severe COVID-19 and sBSI had a more severe initial presentation, prolonged hospital course, and worse clinical outcomes. To maintain antimicrobial stewardship principles, further prospective studies are necessary to better characterize risk factors and prediction modeling to better understand when to suspect and empirically treat for sBSI in severe COVID-19.

Antimicrobial Use in COVID-19 Patients in the First Phase of the SARS-CoV-2 Pandemic: A Scoping Review

This scoping review provides new evidence on the prevalence and patterns of global antimicrobial use in the treatment of COVID-19 patients; identifies the most commonly used antibiotics and clinical scenarios associated with antibiotic prescribing in the first phase of the pandemic; and explores the impact of documented antibiotic prescribing on treatment outcomes in COVID-19 patients. The review complies with PRISMA guidelines for Scoping Reviews and the protocol is registered with the Open Science Framework. In the first six months of the pandemic, there was a similar mean antibiotic prescribing rate between patients with severe or critical illness (75.4%) and patients with mild or moderate illness (75.1%). The proportion of patients prescribed antibiotics without clinical justification was 51.5% vs. 41.9% for patients with mild or moderate illness and those with severe or critical illness. Comparison of patients who were provided antibiotics with a clinical justification with those who were given antibiotics without clinical justification showed lower mortality rates (9.5% vs. 13.1%), higher discharge rates (80.9% vs. 69.3%), and shorter length of hospital stay (9.3 days vs. 12.2 days). In the first 6 months of the pandemic, antibiotics were prescribed for COVID-19 patients regardless of severity of illness. A large proportion of antibiotic prescribing for mild and moderate COVID-19 patients did not have clinical evidence of a bacterial co-infection. Antibiotics may not be beneficial to COVID-19 patients without clinical evidence of a bacterial co-infection.

Secondary Infections in Hospitalized COVID-19 Patients: Indian Experience

Purpose

Critically ill coronavirus disease 2019 (COVID-19) patients need hospitalization which increases their risk of acquiring secondary bacterial and fungal infections. The practice of empiric antimicrobial prescription, due to limited diagnostic capabilities of many hospitals, has the potential to escalate an already worrisome antimicrobial resistance (AMR) situation in India. This study reports the prevalence and profiles of secondary infections (SIs) and clinical outcomes in hospitalized COVID-19 patients in India.

Patients and Methods

A retrospective study of secondary infections in patients admitted in intensive care units (ICUs) and wards of ten hospitals of the Indian Council of Medical Research (ICMR) AMR surveillance network, between June and August 2020, was undertaken. The demographic data, time of infection after admission, microbiological and antimicrobial resistance data of secondary infections, and clinical outcome data of the admitted COVID-19 patients were collated.

Results

Out of 17,534 admitted patients, 3.6% of patients developed secondary bacterial or fungal infections. The mortality among patients who developed secondary infections was 56.7% against an overall mortality of 10.6% in total admitted COVID-19 patients. Gram-negative bacteria were isolated from 78% of patients. Klebsiella pneumoniae (29%) was the predominant pathogen, followed by Acinetobacter baumannii (21%). Thirty-five percent of patients reported polymicrobial infections, including fungal infections. High levels of carbapenem resistance was seen in A. baumannii (92.6%) followed by K. pneumoniae (72.8%).

Conclusion

Predominance of Gram-negative pathogens in COVID-19 patients coupled with high rates of resistance to higher generation antimicrobials is an alarming finding. A high rate of mortality in patients with secondary infections warrants extra caution to improve the infection control practices and practice of antimicrobial stewardship interventions not only to save patient lives but also prevent selection of drug-resistant infections, to which the current situation is very conducive.

On the SARS-CoV-2 "Variolation Hypothesis": No Association Between Viral Load of Index Cases and COVID-19 Severity of Secondary Cases

Background: Emerging evidence supports the “variolation hypothesis” in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), but the derivative idea that the viral load of index cases may predict disease severity in secondary cases could be unsubstantiated. We assessed whether the prevalence of symptomatic infections, hospitalization, and deaths in household contacts of 2019 novel coronavirus disease (COVID-19) cases differed according to the SARS-CoV-2 PCR cycle threshold (Ct) from nasal-pharyngeal swab at diagnosis of linked index cases.

Methods: Cross-sectional study on household contacts of COVID-19 cases randomly sampled from all the infections diagnosed in March at our Microbiology Laboratory (Amedeo di Savoia, Turin). Data were retrospectively collected by phone interviews and from the Piedmont regional platform for COVID-19 emergency. Index cases were classified as high (HVl) and low viral load (LVl) according to two exploratory cut-offs of RdRp gene Ct value. Secondary cases were defined as swab confirmed or symptom based likely when not tested but presenting compatible clinical picture.

Results: One hundred thirty-two index cases of whom 87.9% symptomatic and 289 household contacts were included. The latter were male and Caucasian in 44.3 and 95.8% of cases, with a median age of 34 years (19–57). Seventy-four were swab confirmed and other 28 were symptom based likely secondary cases. Considering both, the contacts of HVl and LVl did not differ in the prevalence of symptomatic infections nor COVID-19-related hospitalization and death. No difference in median Ct of index cases between symptomatic and asymptomatic, hospitalized and not hospitalized, or deceased and survived secondary cases was found. Negative findings were confirmed after adjusting for differences in time between COVID-19 onset and swab collection of index cases (median 5 days) and after removing pediatric secondary cases.

Conclusions: The amount of SARS-CoV-2 of the source at diagnosis does not predict clinical outcomes of linked secondary cases. Considering the impelling release of assays for SARS-CoV-2 RNA exact quantification, these negative findings should inform clinical and public health strategies on how to interpret and use the data.

A Weather-Driven Model for Predicting Infections of Grapevines by Sporangia of Plasmopara viticola

A mechanistic model was developed to predict secondary infections of Plasmopara viticola and their severity as influenced by environmental conditions; the model incorporates the processes of sporangia production and survival on downy mildew (DM) lesions, dispersal and deposition, and infection. The model was evaluated against observed data (collected in a 3-year vineyard) for its accuracy to predict periods with no sporangia (i.e., for negative prognosis) or with peaks of sporangia, so that growers can identify periods with no/low risk or high risk. The model increased the probability to correctly predict no sporangia [P(P-O-) = 0.67] by two times compared to the prior probability, with fewer than 3% of the total sporangia found in the vineyard being sampled when not predicted by the model. The model also correctly predicted peaks of sporangia, with only 1 of 40 peaks unpredicted. When evaluated for the negative prognosis of infection periods, the model showed a posterior probability for infection not to occur when not predicted P(P-O-) = 0.87 with only 9 of 108 real infections not predicted; these unpredicted infections were mild, accounting for only 4.4% of the total DM lesions observed in the vineyard. In conclusion, the model was able to identify periods in which the DM risk was nil or very low. It may, therefore, help growers avoid fungicide sprays when not needed and lengthen the interval between two sprays, i.e., it will help growers move from calendar-based to risk-based fungicide schedules for the control of P. viticola in vineyards.

Current Evidence of Interleukin-6 Signaling Inhibitors in Patients With COVID-19: A Systematic Review and Meta-Analysis

Background: Interleukin-6 (IL-6) is known to be detrimental in coronavirus disease 2019 (COVID-19) because of its involvement in driving cytokine storm. This systematic review and meta-analysis aimed to assess the safety and efficacy of anti-IL-6 signaling (anti-IL6/IL-6R/JAK) agents on COVID-19 based on the current evidence. Methods: Studies were identified through systematic searches of PubMed, EMBASE, ISI Web of Science, Cochrane library, ongoing clinical trial registries (clinicaltrials.gov), and preprint servers (medRxiv, ChinaXiv) on August 10, 2020, as well as eligibility checks according to predefined selection criteria. Statistical analysis was performed using Review Manager (version 5.3) and STATA 12.0. Results: Thirty-one studies were included in the pooled analysis of mortality, and 12 studies were identified for the analysis of risk of secondary infections. For mortality analysis, 5630 COVID-19 cases including 2,132 treated patients and 3,498 controls were analyzed. Anti-IL-6 signaling agents plus standard of care (SOC) significantly decreased the mortality rate compared to SOC alone (pooled OR = 0.61, 95% CI 0.45-0.84, p = 0.002). For the analysis of secondary infection risk, 1,624 patients with COVID-19 including 639 treated patients and 985 controls were included, showing that anti-IL-6 signaling agents did not increase the rate of secondary infections (pooled OR = 1.21, 95% CI 0.70-2.08, p = 0.50). By contrast, for patients with critical COVID-19 disease, anti-IL-6 signaling agents failed to reduce mortality compared to SOC alone (pooled OR = 0.75, 95% CI 0.42-1.33, p = 0.33), but they tended to increase the risk of secondary infections (pooled OR = 1.85, 95% CI 0.95-3.61, p = 0.07). A blockade of IL-6 signaling failed to reduce the mechanical ventilation rate, ICU admission rate, or elevate the clinical improvement rate. Conclusion: IL-6 signaling inhibitors reduced the mortality rate without increasing secondary infections in patients with COVID-19 based on current studies. For patients with critical disease, IL-6 signaling inhibitors did not exhibit any benefit.

Development of secondary bacterial pneumonia in adults presenting with influenza versus noninfluenza viral respiratory infection

BACKGROUND

Respiratory viral infections, particularly influenza, are known to cause significant morbidity and mortality, often due to secondary infections. Our aim was to comparatively analyze the incidence, epidemiology, and outcomes of secondary pneumonia in adult patients hospitalized with influenza versus noninfluenza viral infections and determine whether influenza particularly predisposes to secondary infections.

METHODS

This was a retrospective analysis from a single tertiary medical center of adult patients admitted to the hospital between 2008 and 2010 with respiratory viral infections. Microbiological patterns and clinical outcomes were compared between those with influenza (VI, n = 57) and those with noninfluenza (NI, n = 77) respiratory viral infections.

RESULTS

The NI group was older (60.6 ± 14.0 versus 53.3 ± 19.7 years, p = 0.019) with higher rates of lung transplantation (29% versus 9%, p = 0.009) than VI. Overall, 35% developed secondary pneumonia, higher among NI (44%) than VI (23%, p = 0.017). Staphylococcus aureus was the most common cause of pneumonia in VI, whereas Gram-negative rods were most frequently identified in NI. The NI group had longer hospital [median 10 (interquartile range (IQR) 6-19) versus 6 (IQR 4-15) days, p = 0.019] and intensive care unit [median 4 (IQR 0-12) versus 0 (IQR 0-8) days, p = 0.029] stays compared with VI. Further, the NI group was more likely to be admitted to the intensive care unit compared with VI (62% versus 39%, p = 0.011). A trend towards increased mortality was observed in viral infections complicated by secondary pneumonia than primary viral infections (28% versus 15%, p = 0.122).

CONCLUSION

Secondary pneumonia is common among adults hospitalized with viral respiratory infections. Within our population, NI results in more frequent secondary pneumonia and longer hospital stays than those with VI. Given the high number of infections caused by Gram-negative rods, monitoring local epidemiology is critical for guiding initial antibiotic selection in empirical treatment of secondary infections.The reviews of this paper are available via the supplemental material section.

Can Spore Sampler Data Be Used to Predict Plasmopara viticola Infection in Vineyards?

Grapevine downy mildew (DM) is caused by the dimorphic oomycete Plasmopara viticola, which incites epidemics through primary and secondary infection cycles that occur throughout the season. The secondary infection cycles are caused by the sporangia produced on DM lesions. The current research examined the relationship between numbers of airborne sporangia and DM development on grape leaves to determine whether spore sampler data can be useful to predict the potential for secondary infections of P. viticola. Three years (2015-2017) of spore sampler data confirmed that sporangia are a common component of the airborne microflora in a DM-infested vineyard and that their numbers depend on weather conditions. For a total of 108 days, leaf samples were collected from the vineyard at 2- to 3-day intervals and incubated under optimal conditions for P. viticola infection. The numbers of airborne sporangia sampled on 1 to 7 days before leaf sampling were significantly correlated with the numbers of DM lesions on the leaves. The best correlation (r=0.59), however, was found for the numbers of viable airborne sporangia (SPV), which were assessed by using equations driven by the vapour pressure deficit. In Bayesian and ROC curve analyses, SPV was found to be a good predictor of P. viticola infection of grape leaves, with AUROC=0.821 and false positive predictions mainly occurring at low SPV. A binary logistic regression showed that a threshold of 2.52 viable sporangia m^-3 air day^-1 enables a prediction of no infection with a posterior probability of 0.870, which was higher than the prior probability of 0.574. Numbers of viable sporangia in the vineyard air is therefore a useful predictor of infection and especially of no infection. The predictor missed some observed infections, but these infections were not severe (they accounted for only 31 of 374 DM lesions).

Measles Virus Infects and Programs MAIT Cells for Apoptosis

Measles virus (MeV) binds, infects, and kills CD150+ memory T cells, leading to immune amnesia. Whether MeV targets innate, memory-like T cells is unknown. We demonstrate that human peripheral blood and hepatic mucosa-associated invariant T (MAIT) cells and invariant natural killer T cells express surprisingly high levels of CD150, more than other lymphocyte subsets. Furthermore, exposing MAIT cells to MeV results in their efficient infection and rapid apoptosis. This constitutes the first report of direct MAIT cell infection by a viral pathogen. Given MAIT cells' antimicrobial properties, their elimination by MeV may contribute to measles-induced immunosuppression and heightened vulnerability to unrelated infections.

The Application and Interpretation of IgG Avidity and IgA ELISA Tests to Characterize Zika Virus Infections

In the absence of viremia, the diagnostics of Zika virus (ZIKV) infections must rely on serological techniques. In order to improve the serological diagnosis of ZIKV, ZIKV-IgA and ZIKV-IgG avidity assays were evaluated. Forty patients returning from ZIKV endemic areas, with confirmed or suspected ZIKV infections were studied. Samples were classified as early acute, acute and late acute according to the number of days post illness onset. Low avidity IgG was only detected at acute and late acute stages and IgA mostly at the early acute and acute stages. The date of sampling provides useful information and can help to choose the best technique to use at a determined moment in time and to interpret low avidity IgG and IgA results, improving the serological diagnosis of ZIKV.

Respiratory Bordetella bronchiseptica Carriage is Associated with Broad Phenotypic Alterations of Peripheral CD4⁺CD25⁺ T Cells and Differentially Affects Immune Responses to Secondary Non-Infectious and Infectious Stimuli in Mice

The respiratory tract is constantly exposed to the environment and displays a favorable niche for colonizing microorganisms. However, the effects of respiratory bacterial carriage on the immune system and its implications for secondary responses remain largely unclear. We have employed respiratory carriage with Bordetella bronchiseptica as the underlying model to comprehensively address effects on subsequent immune responses. Carriage was associated with the stimulation of Bordetella-specific CD4⁺, CD8⁺, and CD4⁺CD25⁺Foxp3⁺ T cell responses, and broad transcriptional activation was observed in CD4⁺CD25⁺ T cells. Importantly, transfer of leukocytes from carriers to acutely B. bronchiseptica infected mice, resulted in a significantly increased bacterial burden in the recipient's upper respiratory tract. In contrast, we found that respiratory B. bronchiseptica carriage resulted in a significant benefit for the host in systemic infection with Listeria monocytogenes. Adaptive responses to vaccination and influenza A virus infection, were unaffected by B. bronchiseptica carriage. These data showed that there were significant immune modulatory processes triggered by B. bronchiseptica carriage, that differentially affect subsequent immune responses. Therefore, our results demonstrated the complexity of immune regulation induced by respiratory bacterial carriage, which can be beneficial or detrimental to the host, depending on the pathogen and the considered compartment.

Treatment with broadly neutralizing influenza antibodies reduces severity of secondary pneumococcal pneumonia in mice

Secondary bacterial pneumonia is a frequent complication of influenza, associated with high morbidity and mortality. We hypothesized that treatment with neutralizing influenza A antibody AT10_002 protects against severe secondary pneumococcal infection in a mouse model of influenza A infection. Influenza A (H3N2) virus–infected male C57Bl6 mice were treated intravenously with either AT10_002 or a control 2 days postinfection. Seven days later, both groups were infected with Streptococcus pneumoniae and killed 18 hours later. Mice receiving AT10_002 showed less loss of bodyweight compared with controls (+1% vs −12%, P < .001), lower viral loads in bronchoalveolar lavage fluids (BALFs) (7 vs 194 RNA copies per µL; P < .001), and reduced bacterial outgrowth in lung homogenates (3.3 × 10¹ vs 2.5 × 10⁵ colony‐forming units per mg; P < .001). The treatment group showed lower pulmonary wet weights, lower cell counts, and lower protein levels in BALF compared with controls. Treatment with AT10_002 was associated with lower levels of tumor necrosis factor‐α, interleukin (IL)‐6, cytokine‐induced neutrophil chemoattractant (KC), and interferon‐γ in BALF and lower IL‐6 and KC in lung homogenates. Treatment with anti‐influenza antibody AT10_002 is associated with reduced weight loss, viral load, bacterial outgrowth, and lung injury in a murine model of secondary pneumococcal pneumonia following influenza infection.

Secondary Infections with Ebola Virus in Rural Communities, Liberia and Guinea, 2014-2015

Persons who died of Ebola virus disease at home in rural communities in Liberia and Guinea resulted in more secondary infections than persons admitted to Ebola treatment units. Intensified monitoring of contacts of persons who died of this disease in the community is an evidence-based approach to reduce virus transmission in rural communities.

Secondary dengue virus infections during the 2009 outbreak in Buenos Aires

OBJECTIVES

To evaluate the occurrence of secondary dengue virus (DENV) infections during the 2009 outbreak in a non-endemic area. Viral loads were evaluated in serum from acute-phase patients, comparing primary and secondary infection.

METHODS

Serum samples from patients with clinical diagnosis of suspected dengue were referred to the Virology Laboratory at 'Ricardo Gutiérrez' Children's Hospital. Dengue-positive samples were classified as primary or secondary DENV infections through serological methods (anti-DENV IgM and IgG). Viral loads were measured by quantitative real-time PCR (qRT-PCR) in samples obtained in the first 5 days of infection. Statistical analyses were performed to evaluate factors that might correlate with differences in the viral load of primary or secondary infection.

RESULTS

A total of 229 DENV cases were confirmed; among them, 22.7% were secondary infections. No significant differences were found between the viral load of primary and secondary infections.

CONCLUSION

We detected a high percentage of secondary DENV infections in a non-endemic area; this finding might correspond to socio-demographic characteristics of the group under study or indicate a previous cryptic DENV circulation causing inapparent infections.