Community-acquired respiratory viral infections in lung transplant recipients:

Infectious Complications in Lung Transplant Recipients

Infection remains a common cause of death throughout the lifespan of a lung transplant recipient. The increased susceptibility of lung transplant recipients is multifactorial including exposure of the graft to the external environment, impaired mucociliary clearance, and high levels of immunosuppression. Long-term outcomes in lung transplant recipients remain poor compared with other solid organ transplants largely due to deaths from infections and chronic allograft dysfunction. Antibacterial, antifungal, and antiviral prophylaxis may be used after lung transplantation to target a number of different opportunistic infections for varying durations of time. The first-month posttransplant is most commonly characterized by nosocomial infections and donor-derived infections. Following the first month to the first 6 months after transplant-a period of intense immunosuppression-is associated with opportunistic infections. While immunosuppression is reduced after the first year posttransplant, infection remains a risk with community-acquired and rarer infectious agents. Clinicians should be vigilant for infection at all time points after transplant. The use of patient-tailored prophylaxis and treatments help ensure graft and patient survival.

Community-acquired respiratory viruses

PURPOSE OF REVIEW

Incidence of community-acquired respiratory viruses (CARVs) after lung transplantation (LTx) is 10-68 cases per 100 patient-years. Infected patients may develop graft failure and there seems to be an association between CARV infection and development of chronic lung allograft dysfunction (CLAD). This review summarizes the impact of CARV infection after LTx and potential treatment strategies.

RECENT FINDINGS

Detection rate of CARV depends on diagnostic methods. CARV infections after LTx are reported more frequently probably attributed to improved diagnostic methods, especially nucleic acid testing. Paramyxoviridae and picornaviridae are most frequent. For paramyxoviridae, the association with CLAD is reported in various single-center observational studies. Neuraminidase inhibitors are approved for influenza and can be safely used in flu-infected LTx patients. There is no approved treatment for paramyxoviruses, most centers use ribavirin in the infected LTx recipient.

SUMMARY

Antivirals against CARV in LTx recipients have not yet demonstrated reduced morbidity in randomized clinical trials. Agents against CARV under development are inhibiting viral attachment and use silencing mechanisms of viral replication. The cohort of lung transplant recipients is a focus of intense research because of the high morbidity of CARV infection and intense surveillance of LTx recipeints.

Cryptosporidium infections in terrestrial ungulates with focus on livestock: a systematic review and meta-analysis

Background

Cryptosporidium spp. are causative agents of gastrointestinal diseases in a wide variety of vertebrate hosts. Mortality resulting from the disease is low in livestock, although severe cryptosporidiosis has been associated with fatality in young animals.

Methods

The goal of this systematic review and meta-analysis was to review the prevalence and molecular data on Cryptosporidium infections in selected terrestrial domestic and wild ungulates of the families Bovidae (bison, buffalo, cattle, goat, impala, mouflon sheep, sheep, yak), Cervidae (red deer, roe deer, white-tailed deer), Camelidae (alpaca, camel), Suidae (boar, pig), Giraffidae (giraffes) and Equidae (horses). Data collection was carried out using PubMed, Scopus, Science Direct and Cochran databases, with 429 papers being included in this systematic analysis.

Results

The results show that overall 18.9% of ungulates from the investigated species were infected with Cryptosporidium spp. Considering livestock species (cattle, sheep, goats, pigs, horses and buffaloes), analysis revealed higher Cryptosporidium infection prevalence in ungulates of the Cetartiodactyla than in those of the Perissodactyla, with cattle (29%) being the most commonly infected farm animal.

Conclusions

Overall, the investigated domestic ungulates are considered potential sources of Cryptosporidium contamination in the environment. Control measures should be developed to reduce the occurrence of Cryptosporidium infection in these animals. Furthermore, literature on wild populations of the named ungulate species revealed a widespread presence and potential reservoir function of wildlife.

Prevalence and associated risk factors of Cystoisospora belli and Cyclospora cayetanensis infection among Iranian patients with colorectal cancer

From among intestinal parasites, coccidian intestinal parasites such as Cystoisospora belli (previously known as Isospora belli), and Cyclospora cayetanensis are well-known as opportunist parasites, particularly in patients with cancer. This study assessed the prevalence of C. belli and C. cayetanensis in patients with cancer in Lorestan Province, Southwest of Iran. This cross-sectional descriptive study was conducted on 87 patients with colorectal cancers, referred to the general hospitals of Lorestan from October 2017 to August 2018. A fresh stool specimen was collected from each subject in a sterile labeled container. The collected stool samples were concentrated through sucrose flotation method and then prepared for Ziehl-Neelsen staining for microscopic examination. Demographic and possible risk factors such as age, sex, education, residence, and unwashed vegetable/fruit consumption were collected by an applied questionnaire. Out of the 87 patients with colorectal cancer, eight (9.2%) were found positive for C. belli and C. cayetanensis infections, with five (5.74%) and three (3.44%) patients positive for C. belli and C. cayetanensis infections, respectively. Results also showed that sex and unwashed vegetable/fruit consumption were significantly associated with the prevalence of these parasites (p < 0.01). The findings revealed the considerable prevalence of C. belli and C. cayetanensis in patients with colorectal cancers. It is therefore essential for gastrointestinal specialists to pay special attention to the prevalence of coccidian parasites in patients with colorectal cancer.

Azithromycin reduces airway inflammation induced by human rhinovirus in lung allograft recipients

BACKGROUND AND OBJECTIVE

Human rhinovirus (RV) is a common upper and lower respiratory pathogen in lung allograft recipients causing respiratory tract exacerbation and contributing towards allograft dysfunction and long-term lung decline. In this study, we tested the hypothesis that RV could infect both the small and large airways, resulting in significant inflammation.

METHODS

Matched large and small airway epithelial cells (AEC) were obtained from five lung allograft recipients. Primary cultures were established, and monolayers were infected with RV1b over time with varying viral titre. Cell viability, receptor expression, viral copy number, apoptotic induction and inflammatory cytokine production were also assessed at each region. Finally, the effect of azithromycin on viral replication, induction of apoptosis and inflammation was investigated.

RESULTS

RV infection caused significant cytotoxicity in both large AEC (LAEC) and small AEC (SAEC), and induced a similar apoptotic response in both regions. There was a significant increase in receptor expression in the LAEC only post viral infection. Viral replication was elevated in both LAEC and SAEC, but was not significantly different. Prophylactic treatment of azithromycin reduced viral replication and dampened the production of inflammatory cytokines post-infection.

CONCLUSION

Our data illustrate that RV infection is capable of infecting upper and lower AEC, driving cell death and inflammation. Prophylactic treatment with azithromycin was found to mitigate some of the detrimental responses. Findings provide further support for the prophylactic prescription of azithromycin to minimize the impact of RV infection.

Evaluation of risk factors associated to detection of Blastocystis sp. in fecal samples in population from Barcelona, Spain: a case-control study

Blastocystis sp. is the most common intestinal parasite isolated in humans. The aim of the study was to describe the risk factors associated to Blastocystis sp. detection. A case-control retrospective study was carried out at Vall d'Hebron University Hospital (Barcelona, Spain), which receives all fecal samples collected in Barcelona at primary care level. Eligible patients were patients older than 18 years in whom three consecutive stool samples were examined for parasitic diagnosis from January to December 2017. Positive patients for Blastocystis sp. were assigned as cases whereas negative patients were assigned as controls. Overall, 4174 patients were eligible for the study, from whom 724 (17.3%) had Blastocystis sp. detection. From these, 170 cases (Blastocystis sp. positive) and 170 controls (Blastocystis sp. negative) were randomly selected for inclusion. One hundred and twenty-six (37.1%) of them were immigrants, and 171 (50.3%) patients had traveled out of Spain the year before. The majority of individuals had jobs with no direct contact with other people (health personnel, teachers, and caregivers) (85.6%), and 29.4% were in usual contact with animals. Regarding clinical information, 68.2% of patients presented digestive symptoms, 3.5% presented an immunosuppressant condition, and 6.5% were infected by other intestinal parasites. Variables associated to Blastocystis sp. detection were being born in Africa, having traveled abroad, and working in direct contact with other people. Having other intestinal parasitic infections had a protective value. Our study provides new insights into the epidemiology of Blastocystis sp. in industrialized countries.

A retrospective molecular study of Cryptosporidium species and genotypes in HIV-infected patients from Thailand

Background

Opportunistic infections represent a serious health problem for HIV-infected people. Among enteric infections, cryptosporidiosis, a severe and life-threatening diarrheal disease, is of particular importance in low economic settings where access to anti-retroviral therapy is limited. Understanding transmission routes is crucial in establishing preventive measures, and requires the use of informative genotyping methods. In this study, we performed a retrospective analysis of Cryptosporidium species in 166 stool samples collected from 155 HIV-infected patients during 1999–2004 at the Siriraj Hospital in Bangkok, Thailand.

Results

Microscopic examination of stools identified 104 of the 155 patients as positive for Cryptosporidium. Other common pathogens identified were microsporidia, Isospora, Giardia, Strongyloides and Opisthorchis. All samples were tested by amplification of a fragment of the 18S rDNA locus, and sequencing showed the presence of Cryptosporidium hominis (n = 42), C. meleagridis (n = 20), C. canis (n = 12), C. felis (n = 7), C. suis (n = 6) and C. parvum (n = 5). Genotyping at the glycoprotein 60 (gp60) locus revealed substantial variability in isolates of C. hominis and C. meleagridis. Among C. hominis isolates, subtype IeA11G3T3 was the most prevalent, but allelic family Id was the more diverse with four subtypes described, two of which were identified for the first time. Among C. meleagridis isolates, seven subtypes, two of which were new, were found in the allelic family IIIb, along with new subtypes in allelic families IIIe and IIIg. In the four C. parvum isolates, subtype IIoA16G1, a rare subtype previously reported in a Swedish patient who had traveled to Thailand, was identified.

Conclusions

This study confirms the high susceptibility of HIV-infected individuals to infection with different Cryptosporidium species and subtypes, and further stresses the importance of surveillance for opportunistic intestinal protozoans.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3348-4) contains supplementary material, which is available to authorized users.

Infections in Heart, Lung, and Heart-Lung Transplantation

Half a century has passed since the first orthotopic heart transplant took place. Surgical innovations allowed for heart, lung, and heart-lung transplantation to save lives of patients with incurable chronic cardiopulmonary conditions. The complexity of the surgical interventions, chronic host health conditions, and antirejection immunosuppressive medications makes infectious complications common. Infections have remained one of the main barriers for successful transplantation and a source of significant morbidity and mortality. Recognition of infections and its management in this setting require outstanding clinical skills since transplant recipients may not exhibit classic signs or symptoms of disease, and laboratory work has some pitfalls. The prevention, identification, and management of infectious diseases complications in this population are a priority to undertake to improve the medical outcomes of transplantation. Herein, we reviewed the historical aspects, epidemiology, and prophylaxis of infections in heart, lung, and heart-lung transplantation. We also discuss the most prevalent organisms affecting the host and the organ systems involved.

Infections after lung transplantation

The good clinical result of lung transplantation is constantly undermined by the high incidence of infection, which negatively impacts on function and survival. Moreover, infections may also have immunological interactions that play a role in the acute rejection and in the development of chronic lung allograft dysfunction. There is a temporal sequence in the types of infection that affects lung allograft: in the first postoperative month bacteria are the most frequent cause of infection; following this phase, cytomegalovirus and Pneumocystis carinii are common. Fungal infections are particularly feared due to their association with bronchial complication and high mortality. Scrupulous postoperative surveillance is mandatory for the successful management of lung transplantation patients with respect to early detection and treatment of infections. This paper is aimed to address clinicians in the management of the major infectious complications that affect the lung transplant population.

Community-Acquired Respiratory Viruses

The incidence of community-acquired respiratory viruses (CARVs) is ∼15 cases per 100 patient-years after lung transplantation (LTx). Paramyxoviruses account for almost 50% of the cases of CARV infection in LTx. Most patients will be symptomatic with a mean decline of 15 to 20% in forced expiratory volume in 1 second. The attributable death rate is low in recent years 15 to 25% CARV infected LTx patients will develop chronic lung allograft dysfunction within a year after CARV infection. This risk seems to be increased in comparison to the noninfected LTx recipient.

Detection rate of CARV dependent on clinical awareness, sampling, and diagnostic method with nucleic acid testing by polymerase chain reaction in bronchoalveolar lavage is the gold standard after LTx.

There is no approved treatment for paramyxoviruses, most centers use ribavirin by various routes. Toxicity of systemic ribavirin is of concern and some patients will have contraindication to this treatment modality. Treatment may reduce the risk to develop chronic lung allograft dysfunction and respiratory failure. Agents under development are inhibiting viral attachment and use silencing mechanisms of viral replication.

Prevalence of Cryptosporidium, microsporidia and Isospora infection in HIV-infected people: a global systematic review and meta-analysis

BACKGROUND

Diarrhea caused by opportunistic intestinal protozoa is a common problem in HIV infection. We aimed to establish the prevalence of Cryptosporidium, misrosporidia, and Isospora in HIV-infected people using a systematic review and meta-analysis, which is central to developing public policy and clinical services.

METHODS

We searched PubMed, ScienceDirect, Google Scholar, Embase, Chinese Web of Knowledge, Wanfang, and Chongqing VIP databases for studies reporting Cryptosporidium, microsporidia, or Isospora infection in HIV-infected people. We extracted the numbers of people with HIV and protozoa infection, and estimated the pooled prevalence of parasite infection by a random effects model.

RESULTS

Our research identified 131 studies that reported Cryptosporidium, microsporidia, and Isospora infection in HIV-infected people. We estimated the pooled prevalence to be 14.0% (3283/43,218; 95% CI: 13.0-15.0%) for Cryptosporidium, 11.8% (1090/18,006; 95% CI: 10.1-13.4%) for microsporidia, and 2.5% (788/105,922; 95% CI: 2.1-2.9%) for Isospora. A low prevalence of microsporidia and Isospora infection was found in high-income countries, and a high prevalence of Cryptosporidium and Isospora infection was found in sub-Saharan Africa. We also detected a high prevalence of Cryptosporidium, microsporidia, and Isospora infection in patients with diarrhea. Sensitivity analysis showed that three studies significantly affect the prevalence of Isospora, which was adjusted to 5.0% (469/8570; 95% CI: 4.1-5.9%) by excluding these studies.

CONCLUSIONS

Our findings suggest that HIV-infected people have a high prevalence of Cryptosporidium, microsporidia, and Isospora infection in low-income countries and patients with diarrhea, especially in sub-Saharan Africa, reinforcing the importance of routine surveillance for opportunistic intestinal protozoa in HIV-infected people.

An overview of parasitic infections of the gastro-intestinal tract in developed countries affecting immunocompromised individuals

In both developed and developing countries, parasitic infections continue to be a frequent cause of mortality and morbidity. Due to the globalization of the world, doctors must be fully prepared to deal with a plethora of parasitic infections. More commonly the gastrointestinal (GI) tract is infected and in developed countries protozoans are more likely to be the cause of infection compared to helminths. These GI protozoa are progressively becoming recognized as important pathogens in patients that are immunocompromised. The number of immunocompromised patients is increasing and therefore the likelihood of similar infections will also increase. This paper aims to highlight the key GI parasites affecting immunocompromised individuals in developed countries, discussing diagnosis, treatment options and also prevention. Cryptosporidium parvum may be the most common GI parasite found in the immunocompromised host closely followed by Cyclospora, however, Giardia duodenalis is the most common GI parasite found in developed countries. The pathogenesis of parasitic infection is not clear, poorly understood and diagnostic testing remains difficult with management continuing to be a challenge.

The role of the NxTAG® respiratory pathogen panel assay and other multiplex platforms in clinical practice

INTRODUCTION

The advent of nucleic acid amplification tests has significantly improved the aetiologic diagnosis of respiratory infections. However, multiplex real-time polymerase chain reaction (PCR) can be technologically challenging. Areas covered: This paper reports the results of the main published studies on the NxTAG Respiratory Pathogen Panel (RPP) and discusses the advantages and disadvantages of extensive use of multiplex assays in clinical practice. Expert commentary: Currently available data seem to indicate that routine use of multiplex assays, including NxTAG RPP Assay, should be recommended only when epidemiological data concerning circulation of viruses and bacteria have to be collected. Their use in clinical practice seems debatable. They have limited sensitivity and specificity at least in the identification of some infectious agents or, as in the case of NxTAG RPP, they have not been evaluated in a sufficient number of patients to allow definitive conclusions. In the future, the clinical relevance of multiplex assays, including NxTAG RPP, could significantly increase, mainly because a number of new antiviral agents effective against several respiratory viruses for which no drug is presently available will be marketed. In addition, it is highly likely that the efficiency of multiplex assays will be significantly improved.

Lung Transplantation

The therapeutic options for patients with advanced pulmonary parenchymal or vascular disorders are currently limited. Lung transplantation remains one of the few viable interventions, but on account of the insufficient donor pool only a minority of these patients actually undergo the procedure each year. Following transplantation there are a number of early and late allograft complications such as primary graft dysfunction, allograft rejection, infection, post-transplant lymphoproliferative disorder and late injury that is now classified as chronic lung allograft dysfunction. The pathologist plays an essential role in the diagnosis and classification of these myriad complications. Although the transplant procedures are performed in selected centers patients typically return to their local centers. When complications arise it is often the responsibility of the local pathologist to evaluate specimens. Therefore familiarity with the pathology of lung transplantation is important.

Detection of Virus-Specific CD8+ T Cells With Cross-Reactivity Against Alloantigens: Potency and Flaws of Present Experimental Methods

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Virus-specific T cells have the intrinsic capacity to cross-react against allogeneic HLA antigens, a phenomenon known as heterologous immunity. In transplantation, these cells may contribute to the alloimmune response and negatively impact graft outcome. This study describes the various techniques that can be used to detect heterologous immune responses of virus-specific CD8⁺ T cells against allogeneic HLA antigens. The strengths and weaknesses of the different approaches are discussed and illustrated by experimental data.

Prospective evaluation of rhinovirus infection in healthy young children

BACKGROUND

Although the incidence of human rhinovirus (HRV) infection is highest in young, no study has yet been published concerning the types of HRV circulating in this population, the incidence of symptomatic infections due to the different types, or duration of shedding

OBJECTIVES

This prospective study evaluated the circulation of HRV species and types, and established the incidence of asymptomatic and symptomatic infections in young children.

STUDY DESIGN

The study enrolled 93 healthy children aged <2 years, 88 of whom completed the follow-up of weekly household visits from November 2013 to February 2014. At each visit, a record was made of any signs and symptoms of acute infection, and a nasopharyngeal (NP) swab was taken in order to identify the HRVs by means of RT-polymerase chain reaction and to construct the phylogenetic tree of the HRV-positive cases.

RESULTS

A total of 1408 NP samples were obtained and 326 HRV infections were diagnosed (23.1%), leading to a mean number of 3.7 ± 2.3 infections per child: HRV-A in 72 cases (22.1%), HRV-B in 29 (8.9%), HRV-C in 122 (37.4%), and non-typeable HRV in 103 (31.6%). Shedding was significantly longer for HRV-A (14 days) and HRV-B (14 days) than HRV-C (7 days; p = 0.002 and p = 0.012). Most of the HRV infections (209/326, 64.1%) remained asymptomatic and, when symptomatic, were of marginal clinical relevance.

CONCLUSIONS

In healthy young children, HRV infection is extremely frequent, generally asymptomatic or with a mild clinical presentation, and viral shedding is limited in time.

The lung microbiome after lung transplantation

Lung transplantation survival remains significantly impacted by infections and the development of chronic rejection manifesting as bronchiolitis obliterans syndrome (BOS). Traditional microbiologic data has provided insight into the role of infections in BOS. Now, new non-culture-based techniques have been developed to characterize the entire population of microbes resident on the surfaces of the body, also known as the human microbiome. Early studies have identified that lung transplant patients have a different lung microbiome and have demonstrated the important finding that the transplant lung microbiome changes over time. Furthermore, both unique bacterial populations and longitudinal changes in the lung microbiome have now been suggested to play a role in the development of BOS. In the future, this technology will need to be combined with functional assays and assessment of the immune responses in the lung to help further explain the microbiome's role in the failing lung allograft.