Emergence of amphotericin B-resistant Cryptococcus laurentii meningoencephalitis shortly after treatment for Cryptococcus neoformans meningitis in a patient with AIDS

Catheter-related infection due to Papiliotrema laurentii in an oncologic patient: Case report and systematic review

Background

Papiliotrema laurentii is one of several non-neoformans cryptococci that have rarely been associated with human infection, since it was previously considered saprophyte and thought to be non-pathogenic to humans. Nevertheless, increasing number of reports of human infection have emerged in recent years, mostly in oncologic patients.

Aim

To report a case of a female patient with pyloric obstructive cancer with a catheter-related Papiliotrema laurentii blood stream infection and systematically review the available evidence on P. laurentii infection in humans.

Methods

Retrieval of studies was based on Medical Subject Headings and Health Sciences Descriptors, which were combined using Boolean operators. Searches were run on the electronic databases Scopus, Web of Science, MEDLINE (PubMed), BIREME (Biblioteca Regional de Medicina), LILACS (Latin American and Caribbean Health Sciences Literature), Cochrane Library for Systematic Reviews and Opengray.eu. There was no language or date of publication restrictions. The reference lists of the studies retrieved were searched manually.

Results

The search strategy retrieved 1703 references. In the final analysis, 31 references were included, with the description of 35 cases. Every patient but one had a previous co-morbidity - 48.4 % of patients had a neoplasm. Amphotericin B was the most used treatment and only a single case of resistance to it was reported. Most patients were cured of the infection.

Conclusion

P. laurentii infection in humans is usually associated to neoplasia and multiple co-morbidities, and amphotericin B seems to be a reliable agent for treatment.

The antiproliferative peptide Ctn[15-34] is active against multidrug-resistant yeasts Candida albicans and Cryptococcus neoformans

AIMS

Crotalicidin (Ctn), a cathelicidin-related antimicrobial peptide from the South American rattlesnake venom gland, and its C-terminal Ctn[15-34] fragment, have exhibited important activities against micro-organisms, trypanosomatid protozoa and certain lines of tumour cells. Herein, the activity against clinical strains of fluconazole-resistant Candida albicans and of amphotericin B and fluconazole-resistant Cryptococcus neoformans was investigated.

METHODS AND RESULTS

Microdilution and luminescent cell viability tests were used to evaluate and compare the susceptibility of pathogenic yeasts to these peptides. The time-kill curves of the most active Ctn[15-34] alone or in combination with fluconazole against drug-resistant yeasts were determined. Concomitantly, the fungicidal and/or fungistatic effects of Ctn[15-34] were visualized by the spotting test. The peptides were active against all strains, including those resistant to antifungal agents. The association of fluconazole with both Ctn and Ctn[15-34], although not synergic, was additive. In contrast, such pattern was not observed for C. neoformans.

CONCLUSIONS

Overall, Ctn and Ctn[15-34] are potential antifungal leads displaying anti-yeast activities against clinical isolates endowed with drug resistance mechanisms.

SIGNIFICANCE AND IMPACT OF THE STUDY

The effective peptide activity against resistant strains of pathogenic yeasts demonstrates that crotalicidin-derived peptides are promising templates to develop new antifungal pharmaceuticals.

Cryptococcus laurentii meningitis in a non-HIV patient

Cryptococcus species (other than Cryptococcus neoformans) have been labeled as saprophytic and nonpathogenic in immunocompetent individuals in the past. In recent years, infections caused by non-neoformans Cryptococcus species have been recognized. Cryptococcus laurentii is known to be a rare human pathogen. In this case report, we present a 59-year-old man who did not have HIV infection with meningoencephalitis caused by Cryptococcus laurentii. No significant underlying immunosuppressive disorder was found. The only identifiable risk factors were that the patient was a farmer with previous exposure to pigeon droppings. Here, we describe what we believe to be the fifth reported case of meningitis caused by Cryptococcus laurentii.

Treatment of cryptococcosis in non-HIV immunocompromised patients

PURPOSE OF REVIEW

Cryptococcosis has become a common opportunistic infection among non-HIV immunocompromised hosts. Recent reports have shown the incidence of Cryptococcosis among HIV-negative immunocompromised patients reaches close to half of the overall cases reported in the USA. Management of this infection in this population carries unique challenges. We aim to review relevant and recent research findings to develop treatment recommendations for this type of population.

RECENT FINDINGS

Most of the recommendations for the management of non-HIV immunocompromised host are extrapolated from HIV studies. Cryptococcosis among non-HIV patients is common but often overlooked. Some clinical factors, when present, may increase the risk of Cryptococcosis among HIV-negative patients and appropriate screening and assessment for the disease is necessary. Treating clinicians should consider a longer duration of induction with Amphotericin B depending on the type of host, immunocompromised state, antifungal response and presence of neurological complications. Baseline fluconazole resistance can reach up to 12%, which is an important consideration for cryptococcal meningitis relapses or suboptimal responses to therapy.

SUMMARY

Cryptococcus spp. conveys a high disease burden among immunocompromised hosts. Clinicians must consider numerous variables and factors in a dynamic way to offer the best possible treatment and to monitor their response to therapy. Due to the high cost and associated toxicities, we still need new affordable therapies and studies among non-HIV immunocompromised patients.

Scalp microbiota alterations in children with pediculosis

Pediculosis is a disease caused by the insect Pediculus humanus capitis that mainly occurs in childhood. A comparative study was carried out evaluating groups of schoolchildren with (group A) and without pediculosis (group B) to analyse the characteristics of the scalp microbiota. Samples were collected by swab using Stuart transport medium and incubate in Sabouraud dextrose agar with tetracycline to analyse the fungal microbiota and in blood agar to assess the bacterial microbiota. The isolates identity was confirmed by sequencing of the 16S and 18S regions of the ribosomal DNA gene for bacteria and fungi, respectively. The analysis of the 186 isolates led to the identification of 35 bacteria and 40 fungi in group A and 47 bacteria and 64 fungi in group B. The results indicate differences in bacterial and fungal species in the groups analysed. In the observed bacterial microbiota, Staphylococcus capitis occurred more frequently than Staphylococcus epidermidis in group A vs B. Among fungal isolates, Debaryomyces sp. was more frequent in group B vs A. Our findings showed scalp microbiota alterations in children with pediculosis, meriting future studies to analyse the relationship between these agents and their impact on human health.

Yeasts

Yeasts are unicellular organisms that reproduce mostly by budding and less often by fission. Most medically important yeasts originate from Ascomycota or Basidiomycota. Here, we review taxonomy, epidemiology, disease spectrum, antifungal drug susceptibility patterns of medically important yeast, laboratory diagnosis, and diagnostic strategies.

Pd@Ag Nanosheets in Combination with Amphotericin B Exert a Potent Anti-Cryptococcal Fungicidal Effect

Silver nanoparticles have received considerable interest as new "nanoantibiotics" with the potential to kill drug-resistant microorganisms. Recently, a class of new core-shell nanostructures, Pd@Ag nanosheets (Pd@Ag NSs), were created using deposition techniques and demonstrated excellent inhibitory effects on various bacteria in vitro. In this study, we evaluated the antifungal activity of Pd@Ag NSs against common invasive fungal pathogens. Among these organisms, Cryptococcus neoformans complex species was most susceptible to Pd@Ag NSs, which exhibited potent antifungal activity against various molecular types or sources of cryptococcal strains including fluconazole-resistant isolates. The anticryptococcal activity of Pd@Ag NSs was significantly greater than fluconazole and similar to that of amphotericin B (AmB). At relatively high concentrations, Pd@Ag NSs exhibited fungicidal activity against Cryptococcus spp., which can likely be attributed to the disruption of cell integrity, intracellular protein synthesis, and energy metabolism. Intriguingly, Pd@Ag NSs also exhibited strong synergistic anti-cryptococcal fungicidal effects at low concentrations in combination with AmB but exhibited much better safety in erythrocytes than AmB, even at the minimal fungicidal concentration. Therefore, Pd@Ag NSs may be a promising adjunctive agent for treating cryptococcosis, and further investigation for clinical applications is required.

David and Goliath: chemical perturbation of eukaryotes by bacteria

Environmental microbes produce biologically active small molecules that have been mined extensively as antibiotics and a smaller number of drugs that act on eukaryotic cells. It is known that there are additional bioactives to be discovered from this source. While the discovery of new antibiotics is challenged by the frequent discovery of known compounds, we contend that the eukaryote-active compounds may be less saturated. Indeed, despite there being far fewer eukaryotic-active natural products these molecules interact with a far richer diversity of molecular and cellular targets.

Phylogenetic analysis of phenotypically characterized Cryptococcus laurentii isolates reveals high frequency of cryptic species

BACKGROUND

Although Cryptococcus laurentii has been considered saprophytic and its taxonomy is still being described, several cases of human infections have already reported. This study aimed to evaluate molecular aspects of C. laurentii isolates from Brazil, Botswana, Canada, and the United States.

METHODS

In this study, 100 phenotypically identified C. laurentii isolates were evaluated by sequencing the 18S nuclear ribosomal small subunit rRNA gene (18S-SSU), D1/D2 region of 28S nuclear ribosomal large subunit rRNA gene (28S-LSU), and the internal transcribed spacer (ITS) of the ribosomal region.

RESULTS

BLAST searches using 550-bp, 650-bp, and 550-bp sequenced amplicons obtained from the 18S-SSU, 28S-LSU, and the ITS region led to the identification of 75 C. laurentii strains that shared 99-100% identity with C. laurentii CBS 139. A total of nine isolates shared 99% identity with both Bullera sp. VY-68 and C. laurentii RY1. One isolate shared 99% identity with Cryptococcus rajasthanensis CBS 10406, and eight isolates shared 100% identity with Cryptococcus sp. APSS 862 according to the 28S-LSU and ITS regions and designated as Cryptococcus aspenensis sp. nov. (CBS 13867). While 16 isolates shared 99% identity with Cryptococcus flavescens CBS 942 according to the 18S-SSU sequence, only six were confirmed using the 28S-LSU and ITS region sequences. The remaining 10 shared 99% identity with Cryptococcus terrestris CBS 10810, which was recently described in Brazil. Through concatenated sequence analyses, seven sequence types in C. laurentii, three in C. flavescens, one in C. terrestris, and one in the C. aspenensis sp. nov. were identified.

CONCLUSIONS

Sequencing permitted the characterization of 75% of the environmental C. laurentii isolates from different geographical areas and the identification of seven haplotypes of this species. Among sequenced regions, the increased variability of the ITS region in comparison to the 18S-SSU and 28S-LSU regions reinforces its applicability as a DNA barcode.

Cryptococcus laurentii biofilms: structure, development and antifungal drug resistance

A great number of fungal infections are related to biofilm formation on inert or biological surfaces, which are recalcitrant to most treatments and cause human mortality. Cryptococcus laurentii has been diagnosed as the aetiological pathogen able to cause human infections mainly in immunosuppressed patients and the spectrum of clinical manifestations ranges from skin lesions to fungaemia. The effect of temperature, pH and surface preconditioning on C. laurentii biofilm formation was determined by 2, 3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide (XTT) reduction assay. Scanning electron microscopic (SEM) analysis of C. laurentii biofilms demonstrated surface topographies of profuse growth and dense colonization with extensive polymeric substances around the cells. In this study, we determined the activity of amphotericin B, itraconazole and fluconazole against C. laurentii free-living cells and biofilms. The activity of antifungals tested was greater against free-living cells, but sessile cells fell into the resistant range for these antifungal agents. Extracellular polymeric substances (EPS), comprising the matrix of C. laurentii biofilms, were isolated by ultrasonication. Fourier transform infrared spectroscopy (FT-IR) was performed with ethanol-precipitated and dried samples. Also, the multielement analysis of the EPS was performed by inductively coupled plasma optical emission spectroscopy (ICP-OES).

Long-term stabilized immunological-virological parameters of HIV infection in an AIDS presenter followed for 20 years, with irregular or no antiretroviral therapy

We report the case of an HIV-infected patient who has been followed for 20 years, and despite presenting with AIDS (due to three episodes of cryptococcosis plus one of Pneumocystis jirovecii pneumonia) who during subsequent years missed, refused or took with limited compliance all recommended medications, including combination antiretroviral therapy, and primary and secondary antimicrobial chemoprophylaxis against opportunistic infections. The unexpected clinical and laboratory stabilization of our patient paralleled a progressive increase in his peripheral CD4+ T-lymphocyte count (range 410-825 cells/mL) and a relatively controlled HIV viraemia (5970-44,000 HIV-RNA copies/mL). Such a recovery of sufficient immune competency after experiencing four episodes of severe AIDS-associated opportunistic infections, without reliable antiretroviral and antimicrobial support raises several questions.

Antifungal susceptibility, enzymatic activity, PCR-fingerprinting and ITS sequencing of environmental Cryptococcus laurentii isolates from Uberaba, Minas Gerais, Brazil

Cryptococcus laurentii has been classically considered a saprophytic species, although several cases of human infection have been already reported. This study aimed to evaluate the phospholipase, proteinase and hemolysins activity, the antifungal susceptibility profile, the genetic variability by M13 and (GACA)(4) fingerprinting and the internal transcribe spacer (ITS) sequencing of 38 C. laurentii isolates recovered from captive bird droppings and surrounding hospital areas. All of them exhibited phospholipase activity, while the hemolytic activity was evidenced in 34 (89.4%) isolates. None of them exhibited proteinase activity. Twenty-seven isolates (71.1%) presented susceptibility dose dependent to fluconazole. Most isolates (94.7%) were susceptible to voriconazole, while one (2.65%) was resistant to this drug. Twenty-one (55.3%) isolates showed reduced susceptibility to itraconazole while nine (23.7%) were resistant. Three (7.9%) and five (13.1%) isolates exhibited resistance to ketoconazole and amphotericin B, respectively. Most C. laurentii fingerprinting obtained with M13 and (GACA)(4) showed high heterogeneity. By using the two primers, seven (18.4%) isolates grouped as A (CL2, CL7, and CL8), B (CL35, CL38) and C (CL29, CL30) with 100% similarity. Different from most variable surrounding hospital isolates, all but one of the pet shops strains clustered with the two primers, although they had been recovered from different neighborhoods. All isolates were identified as C. laurentii phylogenetic group I by ITS sequencing. Thus, the presence of virulence factors, a decreased antifungal susceptibility and a heterogeneous molecular pattern of the C. laurentii isolates here described suggests this species can be a potential pathogen in the context of the immunocompromised population.

Meningitis caused by Filobasidium uniguttulatum: case report and overview of the literature

Cryptococcal meningitis is mainly caused by Cryptococcus neoformans and Cryptococcus gattii, but occasionally other Cryptococcus species and phylogenetically related species are involved. Herein, we present a case of cryptococcal meningitis from China, which was caused by an azole and flucytosine resistant Filobasidium uniguttulatum. In addition, we present an overview of the literature of meningitis caused by Cryptococcus species other than C. neoformans and C. gattii. Eight cases were related to infections of the central nervous system. Leukaemia and cancer were important risk factors in HIV-negative patients. Molecular identification and susceptibility testing are important for proper management of patients because the species involved may differ in susceptibility to antifungal drugs.

Genotyping of Cryptococcus neoformans isolated from captive birds in Uberaba, Minas Gerais, Brazil

To evaluate Cryptococcus spp. molecular types isolated from captive birds' droppings, an epidemiological survey was carried out in Uberaba, Minas Gerais, Brazil, from December 2006 to September 2008. A total of 253 samples of bird excreta (120 fresh and 133 dry) were collected from pet shop cages and houses in different neighbourhoods. Cryptococcus neoformans was isolated in 19 (14.28%) dry samples and one fresh sample (0.84%). Cryptococcus laurentii was recovered from seven (5.26%) dry samples, but not in the fresh samples. The canavanine-glycine-bromothymol blue test was positive in all but one of the C. laurentii isolates. Cryptococcus neoformans molecular typing was performed using URA5-RFLP and the mating type locus using mating type specific PCR. Nineteen (95.0%) presented genotype VNI and one VNII (5.0%). In addition, all isolates presented mating type α. Thus, the genotype of the environmental C. neoformans isolates observed in this study is in accordance with others already reported around the world and adds information about its distribution in Brazil. Cryptococcus laurentii strains were typed using URA5-RFLP and M13 fingerprinting, which showed similar profiles among them. Thus, despite the low number of C. laurentii isolates analysed, their molecular profile is different from another already reported.

The efficacy of self-assembled cationic antimicrobial peptide nanoparticles against Cryptococcus neoformans for the treatment of meningitis

Cationic antimicrobial peptides have received considerable interest as new therapeutics with the potential for treatment of multiple-drug resistant infections. We recently reported that cholesterol-conjugated G(3)R(6)TAT (CG(3)R(6)TAT) formed cationic nanoparticles via self-assembly, which demonstrated strong antimicrobial activities against various types of microbes in vitro. In this study, the possibility of using these nanoparticles for treatment of Cryptococcus neoformans (yeast)-induced brain infections was studied. The antimicrobial activity of the nanoparticles was tested against 12 clinical isolates of C. neoformans in comparison with conventional antifungal agents amphotericin B and fluconazole. Minimum inhibitory concentrations (MICs) of the nanoparticles were determined to be much lower than those of fluconazole in all the isolates, but slightly higher than those of amphotericin B in some isolates. At a concentration three times higher than the MIC, the nanoparticles completely sterilized C. neoformans after 3.5 h. Cell wall disruption and release of cytoplasmic content were observed under TEM. The biodistribution studies of FITC-loaded nanoparticles in rabbits revealed that the nanoparticles were able to cross the blood-brain barrier (BBB). The efficacy of nanoparticles was further evaluated in a C. neoformans meningitis rabbit model. The nanoparticles crossed the BBB and suppressed the yeast growth in the brain tissues with similar efficiency as amphotericin B did. In addition, unlike amphotericin B, they neither caused significant damage to the liver and kidney functions nor interfered with the balance of electrolytes in the blood. CG(3)R(6)TAT nanoparticles can be a promising antimicrobial agent for treatment of brain infections caused by C. neoformans.

Cryptococcosis of the upper genital tract

Upper genital tract infection by Cryptococcus neoformans has not previously been reported. We describe such a case, in order to alert clinicians to the existence of this rare infection. A 34-year-old woman with AIDS presented with chronic menorrhagia, fever, anemia, and thrombocytopenia. Despite blood transfusions and hormonal therapy, her vaginal bleeding could not be controlled and she became hemodynamically unstable. Total abdominal hysterectomy and bilateral salpingo-oophorectomy were performed, at which time granulomatous peritonitis and prominent myometrial blood vessels were found. Histologic examination revealed cryptococcal infection of all upper genital organs. This case demonstrates that disseminated cryptococcosis may involve the upper genital tract in women, and may be associated with profuse vaginal bleeding.

Cryptococcal meningitis manifesting as a large abdominal cyst in a HIV-infected patient with a CD4 count greater than 400 cells/mm(3)

Cryptococcal meningitis usually occurs among HIV-positive patients with CD4 counts less than 100 cells/mm(3) and manifests as headaches, fevers, and mental status changes. We present an unusual case of cryptococcal meningitis in a 34-year-old HIV-positive man presenting as a large abdominal cyst at the ventriculoperitoneal shunt site despite receiving highly active antiretroviral therapy (HAART) for more than 5 years and having a CD4 count more than 400 cells/mm(3).

Synthesis of cell envelope glycoproteins of Cryptococcus laurentii

Fungi of the genus Cryptococcus are encapsulated basidiomycetes that are ubiquitously found in the environment. These organisms infect both lower and higher animals. Human infections that are common in immune-compromised individuals have proven difficult to cure or even control with currently available antimycotics that are quite often toxic to the host. The virulence of Cryptococcus has been linked primarily to its polysaccharide capsule, but also to cell-bound glycoproteins. In this review, we show that Cryptococcus laurentii is an excellent model for studies of polysaccharide and glycoprotein synthesis in the more pathogenic relative C. neoformans. In particular, we will discuss the structure and biosynthesis of O-linked carbohydrates on cell envelope glycoproteins of C. laurentii. These O-linked structures are synthesized by at least four mannosyltransferases, two galactosyltransferases, and at least one xylosyltransferase that have been characterized. These glycosyltransferases have no known homologues in human tissues. Therefore, enzymes involved in the synthesis of cryptococcal glycoproteins, as well as related enzymes involved in capsule synthesis, are potential targets for the development of specific inhibitors for treatment of cryptococcal disease.