Cryptosporidiosis and microsporidiosis as causes of diarrhea in kidney and/or pancreas transplant recipients.

INTRODUCTION: Gastrointestinal disorders in solid organ recipients may have various origins including cryptosporidiosis and microsporidiosis. The prevalence of these infections is poorly known in solid organ transplant (SOT) patients in industrialized countries. METHODS: We prospectively assessed the infectious causes of diarrhea in SOT patients. Secondary objectives were to gain further insight into the main characteristics of cryptosporidiosis, and to assess risk factors for this infection. All adult kidney and/or pancreas recipients presenting with diarrhea and admitted to our facility between May 1, 2014 and June 30, 2015 were enrolled. A stool sample was analyzed using a standardized protocol including bacteriological, virological, and parasitological investigations. Data related to clinical symptoms, immunosuppression, and environmental potential risk factors were collected through a self-administered questionnaire and computerized medical records. RESULTS: Out of 73 enrolled patients, 36 had infectious diarrhea (49.3%). Viruses ranked first (17/36), followed by parasites and fungi (11/17). Cryptosporidiosis was the most common parasitic disease (n=6 patients). We observed four microsporidiosis cases. The estimated prevalence of cryptosporidiosis and microsporidiosis in this cohort was 3.7 and 2.40/00, respectively. No significant risk factor for cryptosporidiosis or microsporidiosis, neither environmental nor immunological, could be evidenced. CONCLUSION: Both cryptosporidiosis and microsporidiosis represent a significant cause of diarrhea in kidney transplant recipients.

Detection of ganciclovir resistance after valacyclovir-prophylaxis in renal transplant recipients with active cytomegalovirus infection.

Whether valaciclovir (VCV) prophylaxis could be responsible for ganciclovir (GCV)-resistance of Human cytomegalovirus (HCMV) in transplantation has never been documented. A multicentric retrospective pilot study was undertaken to detect GCV-resistance through mutations within the UL97 gene in renal transplant recipients who experienced active HCMV infection and received valacyclovir prophylaxis. Twenty-three patients who experienced HCMV antigenaemia or DNAemia during or at the end of prophylaxis were included. UL97 genotyping was carried out on peripheral blood samples, using a nested in-house PCR, which amplified the full-length UL97 gene. One patient has a resistance-related mutation (M460I); the major risk factor for emergence of resistance in this patient was the presence of early and persistent antigenaemia. GCV-resistance during VCV-prophylaxis was rare after renal transplantation. However, special attention must be paid to patients developing early active HCMV infection under prophylaxis.

Longitudinal study of bacterial, viral, and fungal infections in adult recipients of bone marrow transplants.

The epidemiology of infections was studied in a retrospective cohort of 446 recipients of bone marrow transplants (BMTs; 92 of which were allogeneic and 354 of which were autologous) during 1993--1996. Infections that were microbiologically documented in 274 recipients included bacteremia, urinary tract infections, cytomegalovirus viremia, fungemia, invasive aspergillosis, and catheter-related infections. During the period of neutropenia, no differences were found between recipients of allogeneic BMTs and recipients of autologous BMTs with regard to the incidence and the nature of infection. After patients underwent engraftment, bacteremia, cytomegalovirus viremia, and invasive aspergillosis were significantly more common in recipients of allogeneic BMTs than in recipients of autologous BMTs. Deaths caused by infection were uncommon and were mainly the result of invasive aspergillosis. Therefore, empirical antimicrobial therapy should be the same for recipients of both allogeneic and autologous BMTs during the period of neutropenia; after engraftment, more attention should be paid to the risk of infection in allogeneic BMT recipients, particularly with regard to detection and prevention of invasive aspergillosis.

Interaction of anti-HLA antibodies with pig xenoantigens.

BACKGROUND: Many patients with renal failure are condemned to long-term dialysis with little prospect of transplantation because they are highly sensitized with immunoglobulin G (IgG) directed against class I human leukocyte antigens (HLA) of virtually all donors. Xenotransplantation could represent an attractive solution providing their alloantibodies (alloAb) do not recognize porcine motifs. Hitherto there has been no in vivo demonstration of any cross-reactivity and the objective of this work was to investigate this problem using a technique of extracorporeal pig kidney perfusion as a model of clinical xenografting. METHODS: Pig kidneys were perfused ex vivo with plasma from both a group of highly sensitized patients and healthy individuals. Sequential plasma samples were analyzed for the titer of anti-Galalpha1-3Gal antibody (Ab) (major natural xenoreactive Ab) by enzyme-linked immunosorbent assay and anti-HLA class I Ab against a cell panel. At the end of perfusion, kidneys were perfused with a citric acid buffer to elute bound Ab. RESULTS: Galalpha1-3Gal Ab were shown to decrease rapidly in the plasma (in less than 10 min) and then reached a plateau. A fractional decrease in anti-HLA Ab was also found in some of the perfused plasma samples. Anti-Gal Ab were readily detected in all citric acid perfusates and anti-HLA Ab in 8 of 10. The HLA specificities of eluted Ab were mainly concordant with the originally designated specificities for each patient. CONCLUSION: Anti-HLA class I Ab presumably cross-react with pig class I homologues. However, some plasma samples did not cross-react, suggesting that negatively cross-matched pig kidneys could be identified in the pig population for xenotransplantation in these patients. Further studies are required to precisely describe these cross-reactivities and to understand their functional significance in xenotransplantation.

Highly altered V beta repertoire of T cells infiltrating long-term rejected kidney allografts.

Chronic rejection represents a major cause of long-term kidney graft loss. T cells that are predominant in long-term rejected kidney allografts (35 +/- 10% of area infiltrate) may thus be instrumental in this phenomenon, which is likely to be dependent on the indirect pathway of allorecognition only. We have analyzed the variations in T cell repertoire usage of the V beta chain at the complementary determining region 3 (CDR3) level in 18 human kidney grafts lost due to chronic rejection. We observed a strongly biased intragraft TCR V beta usage for the majority of V beta families and also a very high percentage (55%) of V beta families exhibiting common and oligoclonal V beta-C beta rearrangements in the grafts of patients with chronic rejection associated with superimposed histologically acute lesions. Furthermore, V beta 8 and V beta 23 families exhibited common and oligoclonal V beta-J beta rearrangements in 4 of 18 patients (22%). Several CDR3 amino acid sequences were found for the common and oligoclonal V beta 8-J beta 1.4 rearrangement. Quantitative PCR showed that biased V beta transcripts were also overexpressed in chronically rejected kidneys with superimposed acute lesions. In contrast, T lymphocytes infiltrating rejected allografts with chronic rejection only showed an unaltered Gaussian-type CDR3 length distribution. This pattern suggests that late graft failure associated with histological lesions restricted to Banff-defined chronic rejection does not involve T cell-mediated injury. Thus, our observation suggests that a limited number of determinants stimulates the recipient immune system in long-term allograft failure. The possibility of a local response against viral or parenchymatous cell-derived determinants is discussed.

A polymorphism in the major immediate-early gene delineates groups among cytomegalovirus clinical isolates.

Major immediate-early gene exon 4 sequences were determined at codons 161-241 and 254-397 in 25 cytomegalovirus clinical strains and compared with those of reference strains AD169 and Towne. The nucleotide sequences at codon 161-241 segregated into three groups which could be determined by restriction mapping of a 247-nucleotide amplified target. AD169 and Towne belonged to the same group. Clustered variations and group-specific amino-acid motifs found in the deduced peptide sequence of the two immediate-early (IE) exon 4 regions raised a question is to the effects of polymorphism on IE1 function and/or immunogenicity. On the basis of restriction analysis of polymerase chain reaction (PCR) products, virus isolates were also classified into four glycoprotein B (gB) genotypes. Strain distribution in IE1 and gB genotypes showed a lack of concordance of the two grouping methods, and no preferential association was observed between the clinical context or kind of specimen and IE1 or gB groups. These data lead up to further prospective studies which could provide important information on the implication of the MIE gene region in virus pathogenesis and indicate whether linkage unbalance exists in particular clinical contexts between IE1 and gB loci.

Detection of human papillomavirus in squamous intraepithelial lesions by consensus and type-specific polymerase chain reaction.

Polymerase chain reaction (PCR) was used to identify human papillomavirus (HPV) in 216 cervical biopsy specimens from women referred to the gynecological out-patient unit for colposcopy because of an abnormal smear. HPV DNA was screened using type-specific primers for HPV6, 11, 16, 18, 31 and 33 (TS-PCR) as well as a consensus primer located in the E1 region of the HPV genome (C-PCR). TS-PCR specificity was validated by Southern blot analysis. Low-grade (SIL 1) and high-grade (SIL 2) squamous intraepithelial lesions were found in 165 biopsies. HPV16 detection was better with PCR than Southern blot, particularly for SIL 1 and SIL 2. The fact that 10% of HPV16 (all SIL 2) were not detected by C-PCR indicates that both PCR techniques should be performed. C-PCR also detects uncharacterized HPV types (8.6% prevalence in our results), mainly in SIL 1 and SIL 2. HPV16, the most frequently isolated type (prevalence 21%), was associated with SIL 2 in 83% of cases. A low HPV prevalence was found in specimens without dysplastic cells. These results suggest that PCR may be an important tool for identifying women at risk for developing dysplasia or cervical cancer.