Urinary tract infections and Candida albicans

Epidemiology of candiduria and Candida urinary tract infections in inpatients and outpatients: results from a 10-year retrospective survey

Introduction

The presence of Candida species in urine (candiduria) is a common clinical finding, which may frequently represent colonization or contamination of specimens, however, they may be etiological agents in urinary tract infections (UTIs) or be indicators of underlying pathology in the genitourinary system or disseminated candidaemia. C. albicans is the most frequently isolated species of the genus, however, an increase in the occurrence of non-albicans Candida species (NACS) has been reported, which may be attributable to frequent exposure to fluconazole.

Material and methods

The aim of this study was to retrospectively assess and compare the prevalence of candiduria and UTIs caused by Candida spp. among inpatients and outpatients at a major clinical center in Hungary, during a 10-year period (2008-2017).

Results

Candiduria was detected in 0.11-0.75% of positive samples from outpatients, while this number was significantly higher for inpatients, ranging between 3.49-10.63% (p <0.001). Overall, C. albicans was the most frequently isolated species (65.22% in outpatients and 59.64% in inpatients), however, the presence of C. glabrata as a relevant etiologic agent (~20-30%) is also noteworthy, because there are corresponding therapeutic consequences.

Conclusions

A pronounced female dominance (1.7-2.15-fold), advanced age (~70 years) and hospitalization of affected patients during candiduria is in line with the findings in literature.

Network analysis of hyphae forming proteins in Candida albicans identifies important proteins responsible for pathovirulence in the organism

Candida albicans causes two types of major infections in humans: superficial infections, such as skin and mucosal infection, and life-threatening systemic infections, like airway and catheter-related blood stream infections. It is a polymorphic fungus with two distinct forms (yeast and hyphal) and the morphological plasticity is strongly associated with many disease causing proteins. In this study, 137 hyphae associated proteins from Candida albicans (C. albicans) were collected from different sources to create a Protein-Protein Interaction (PPI) network. Out of these, we identified 18 hub proteins (Hog1, Hsp90, Cyr1, Cdc28, Pkc1, Cla4, Cdc42, Tpk1, Act1, Pbs2, Bem1, Tpk2, Ras1, Cdc24, Rim101, Cdc11, Cdc10 and Cln3) that were the most important ones in hyphae development. Ontology and functional enrichment analysis of these proteins could categorize these hyphae associated proteins into groups like signal transduction, kinase activity, biofilm formation, filamentous growth, MAPK signaling etc. Functional annotation analysis of these proteins showed that the protein kinase activity to be essential for hyphae formation in Candida. Additionally, most of the proteins from the network were predicted to be localized on cell surface or periphery, suggesting them as the main protagonists in inducing infections within the host. The complex hyphae formation phenomenon of C. albicans is an attractive target for exploitation to develop new antifungals and anti-virulence strategies to combat C. albicans infections. We further tried to characterize few of the most crucial proteins, especially the kinases by their sequence and structural prospects. Therefore, through this article an attempt to understand the hyphae forming protein network analysis has been made to unravel and elucidate the complex pathogenesis processes with the principal aim of systems biological research involving novel Bioinformatics strategies to combat fungal infections.

Isolation, characterization, and molecular identification of Candida species from urinary tract infections

BACKGROUND AND PURPOSE

Candida species are reportedly the most common human fungal pathogens. The incidence of urinary tract infections (UTIs) caused by Candida pathogens has increased in recent decades. However, such infections rarely occur in the absence of any predisposing factors. Regarding this, the aim of the present study was to identify the Candida species causing UTIs and determine the predisposing factors for candiduria.

MATERIALS AND METHODS

The current study was conducted on 1,450 urine samples obtained from patients suspected of UTI. Out of this number, 19 cases were candidiasis, and 2 cases were mixed infections caused by bacteria and fungi. Candida species were diagnosed differentially using the germ tube test, colony staining on CHROMagar medium, intracellular beta-glucosidase enzyme activity, and glucose absorption pattern. Then, the colonies with the same morphology were confirmed by the DNA sequencing of internal transcribed spacer regions.

RESULTS

According to the results, 38%, 28.6%, 14.3%, and 9.5% of the isolates were identified as C. albicans, C. glabrata, C. tropicalis, and C. kefir/C. krusei, respectively. The presence of one or more predisposing factors was proved in all patients in whom diabetes was the most prevalent predisposing factor (21.1%).

CONCLUSION

Based on the obtained results, C. albicans species was the most prevalent fungal species. In addition, urinary fungal infections were less prevalent than bacterial urinary infections.

Exploring anti-quorum sensing and anti-virulence based strategies to fight Candida albicans infections: an in silico approach

The complex virulence attributes of Candida albicans are an attractive target to exploit in the development of new antifungals and anti-virulence strategies to combat C. albicans infections. Particularly, quorum sensing (QS) has been reported as critical for virulence regulation in C. albicans. This work presents two knowledge networks with up-to-date information about QS regulation and experimentally tested anti-QS and anti-virulence agents for C. albicans. A semi-automatic bioinformatics workflow that combines literature mining and expert curation was used to retrieve otherwise scattered information from the scientific literature. The network representation offers an innovative and continuously updatable means for the Candida research community to query QS and virulence data systematically and in a user-friendly way. Notably, the reconstructed networks show the complexity of QS regulation and the impact that some molecules have on the inhibition of virulence mechanisms responsible for infection establishment (e.g. hyphal development) and perseverance (e.g. biofilm formation). In the future, the compiled knowledge may be used to build decision-making models that help infer new knowledge of practical significance. The knowledge networks are publicly available at http://pcquorum.org/. This Web platform enables the exploration of fungal virulence cues as well as reported inhibitors in a user-friendly fashion.

Urinary tract infections (UTIs) or genital tract infections (GTIs)? It's the diagnostics that count

Urinary tract infections (UTIs) and genital tract infections (GTIs) are both very common infectious diseases. Thus, accuracy and rapidity in recognition and treatment of sexually transmitted urogenital tract infections (ST-UGTIs) is a major concern in global public health systems. The application of reliable, accurate diagnostic tools is the key to definite detection, identification and treatment. This literature review focused on different characteristics of UGTIs in patients and the importance of diagnostic methodologies.

The articles published and indexed from 1980 through October 2018 in the databases of PubMed and MEDLINE, as well as the Google Scholar web search engine, were collected and studied. MeSH keywords of “Sexual intercourse”, “Urinary Tract Infections”, “Genital Tract Infections” and “Toll-Like Receptors” were used for searching articles. Then, the proper articles (original and review articles) were subjected to a very rigorous selection process.

The clinical symptoms and signs or asymptomatic properties of UTIs and GTIs are similar and often overlap. In many cases, the lack of suitable diagnostic techniques leads to misdiagnosed/undignosed GTIs and overdiagnosed UTIs. The outcome of poor diagnostics is failure of definite identification and treatment.

The application of advanced techniques comprising PCR, microarray and next-generation sequencing promises to be more effective, together with the use of the microbial pattern of the individual’s UGT to provide reliable detection, identification and definite treatment. This will be an option in the near future.

Identification of medically important Candida species by polymerase chain reaction-restriction fragment length polymorphism analysis of the rDNA ITS1 and ITS2 regions

AIM

We aimed to identify the distribution of species in candidal strains isolated from clinical samples and restriction fragment length polymorphism (RFLP) method based on Msp I and Bln I restrictive enzyme cuts of polymerase chain reaction (PCR) products after the amplification of ITS1 and ITS2 regions of rDNA genotypically.

MATERIALS AND METHODS

One hundred and fifty candidal strains isolated from various clinical samples were studies/ included. Phenotypic species assessment was performed using automated VITEK-2 system and kit used with the biochemical tests. Common genomic region amplification peculiar to candidal strains was carried out using ITS1 and ITS2 primer pairs. After the amplification, PCR products were cut with Msp I and Bln I restriction enzymes for species identification.

RESULTS

The majority of Candida isolates were isolated from urine (78.6%) while other isolates were composed of strains isolated from swab, wound, blood and other samples by 11.3%, 3.3%, 2% and 4.7%, respectively. The result of RFLP analysis carried out with Msp I and Bln I restriction enzymes showed that candidal strains were Candida albicans by 45.3%, Candida glabrata by 19.3%, Candida tropicalis by 14.6%, Candida parapsilosis by 5.3%, Candida krusei by 5.3%, Candida lusitaniae by 0.6% and other candidal strains by 9.3%.

CONCLUSION

When the ability to identify Candida to species level of phenotypic and PCR-RFLP methods was assessed, a great difference was found between these two methods. It may be argued that Msp I and Bln I restriction enzyme fragments can be used in the identification of medically important Candida species. Further studies are needed to develop this kind of restriction profile to be used in the identification of candidal strains.

Voltammetric analysis for fast and inexpensive diagnosis of urinary tract infection: a diagnostic study

BACKGROUND

Dipstick test is widely used to support the diagnosis of urinary tract infections (UTI). It is effective in ruling out UTI, but urine culture is needed for diagnosis confirmation. In this study we compared the accuracy of voltammetric analysis (VA) with that of DT to detect UTI (diagnosed using urine culture), and its usefulness as a second-stage test in people with positive DT.

METHODS

142 patients were enrolled with no exclusion criteria. VA was performed using the BIONOTE device. Partial Least Square Discrimination Analysis was used to predict UTI based on VA data; diagnostic performance was evaluated using sensitivity, specificity, positive and negative predictive values (PPV and NPV, respectively), positive and negative likelihood ratios (LR), accuracy, diagnostic odds ratio (DOR).

RESULTS

Mean age was 76.6 years (SD 12.6), 57% were male. VA had a better overall performance respect to DT in detecting UTI with accuracy 81.7% vs 75.9%, specificity 90.8% vs 82.5%, PPV 75% vs 61.4%, positive LR 6.68 vs 3.5, DOR 17.7 vs 7.47; sensibility, NPV and negative LR of the two tests were similar. VA had an accuracy of 82.4% in discriminating bacterial from fungal infections. When added as a second-stage test, VA identified 9 of the 17 false positive patients, with a net specificity of 91.7%, sensitivity 54%, PPV 75% and NPV 81%.

CONCLUSIONS

VA is a quick and easy method that may be used as a second stage after DT to reduce the number of urine culture and of inappropriate antibiotic prescriptions.

Species distribution and antifungal susceptibility patterns of Candida isolates from a public tertiary teaching hospital in the Eastern Cape Province, South Africa

Candida species are the leading cause of invasive fungal infections, and over the past decade there has been an increased isolation of drug resistant Candida species. This study aimed to identify the species distribution of Candida isolates and to determine their unique antifungal susceptibility and resistance patterns. During a cross-sectional study, 209 Candida isolates (recovered from 206 clinical samples) were collected and their species distribution was determined using ChromAgar Candida. The Vitek-2 system (Biomerieux, South Africa) was used to determine minimum inhibitory concentrations (MICs) to azoles (fluconazole, voriconazole), echinocandins (caspofungin, micafungin), polyenes (amphotericin B) and flucytosine. Four species of Candida were isolated, of which C. albicans was the most frequent, isolated in 45.4% (95/209) of the isolates, followed by C. glabrata: 31.1% (65/209). The MICs of the different antifungal drugs varied amongst the species of Candida. From the 130 isolates tested for MICs, 90.77% (112/130) were susceptible to all antifungal drugs and 6.9% (9/130) of the isolates were multi-drug resistant. C. dubliniensis (n=2) isolates were susceptible to all the above mentioned antifungal drugs. There was no significant difference in species distribution amongst clinical specimens and between patients' genders (P>0.05). An increase in MIC values for fluconazole and flucytosine towards the resistance range was observed. To our knowledge, this is the first report on surveillance of Candida species distribution and antifungal susceptibility at a public tertiary teaching hospital in Eastern Cape, South Africa.

The prevalence of quinolone resistance genes of A, B, S in Escherichia coli strains isolated from three major hospitals in Tehran, Iran

Introduction

Escherichia coli (E.coli) as an opportunistic pathogen is a major cause of the hospital infections. The main goal of this research was to determine the frequency of quinolone resistance genes (qnr) among E.coli pathotypes isolated from patients with urinary tract infections (UTIs).

Material and methods

Urine samples were obtained from patients with UTIs in three major hospitals of Mofid, Bu Ali, and Vali-Asr during the year of 2015 in Tehran, Iran. The antibiogram was done for isolated bacterial isolates using nalidixic acid, norfloxacin, gentamicin, streptomycin, and chloramphenicol. Then the plasmids of the bacterial samples were extracted. PCR was used to detect qnr genes. Finally, the PCR products were run on a 1% agarose gel electrophoresis and the results were analyzed by the program SPSS version 22.

Results

Overall, 100 E.coli strains were isolated from patients with UTIs. The highest resistance rate was against Streptomycin. The frequency of the genes of qnrA, qnrB and qnrS were 0%, 25% and 36%, respectively. Moreover, the presence of the both genes of qnrB and qnrS was recognized in 10% of isolated bacterial strains.

Conclusions

Our results indicated increasing rates of quinolone resistant E.coli strains circulating in hospitals under the study. Dissemination of these strains harboring qnr determinants is of particular concern.

The role of toll-like receptors (TLRs) in urinary tract infections (UTIs)

Introduction

Urinary Tract Infections (UTIs) are caused by different types of microbial agents such as uropathogenic Escherichia coli (UPEC) and Candida albicans. The presence of strong physical barriers may prevent the breach of pathogens into the urinary tract. However, sometimes the pathogenic microorganisms may pass through the barriers and stimulate the innate and adaptive responses. Among a variety of innate immune responses, Toll-Like Receptors (TLRs) are one of the most unique and interesting molecules regarding UTIs. Thus, the authors have focused their attention on the role of TLRs in urinary tract defense against pathogenic microbial agents such as UPEC and C.albicans through this literature review.

Material and methods

Several papers regarding UTIs and TLRs including original and review articles were searched by PubMed and Google Scholar. They were studied and the most important aspects in association with the role of TLRs in UTIs were extracted. Additionally, this paper was prepared using the experience of the authors.

Results

The TLRs 2, 4 and 5 are the most functional molecules that contribute to urinary tract defense system and UTIs. It is incredible that TLRs are able to detect and recognize different parts of microbial components relating to the same pathogen. Besides, the flexibility of the TLR molecules may lead to identification of different types of microorganisms with different signaling pathways.

Conclusions

Our knowledge associated with TLRs and their activities against microbial causative agents of UTIs may help us to prevent, control and treat UTIs at a higher quality level.

Microarray long oligo probe designing for Escherichia coli: an in-silico DNA marker extraction

INTRODUCTION

Urinary tract infections are predominant diseases which may be caused by different pathogenic microorganisms, particularly Escherichia coli (E.coli). DNA microarray technology is an accurate, rapid, sensitive, and specific diagnostic tool which may lead to definite diagnosis and treatment of several infectious diseases. DNA microarray is a multi-process method in which probe designing plays an important. Therefore, the authors of the present study have tried to design a range of effective and proper long oligo microarray probes for detection and identification of different strains of pathogenic E.coli and in particular, uropathogenic E.coli (UPEC).

MATERIAL AND METHODS

E.coli O26 H11 11368 uid41021 was selected as the standard strain for probe designing. This strain encompasses the largest nucleotide sequence and the most number of genes among other pathogenic strains of E.coli. For performing this in silico survey, NCBI database, GReview Server, PanSeq Server, Oligoanalyzer tool, and AlleleID 7.7 were used to design accurate, appropriate, effective, and flexible long oligo microarray probes. Moreover, the genome of E.coli and its closely related microorganisms were compared.

RESULTS

In this study, 15 long oligo microarray probes were designed for detecting and identifying different strains of E.coli such as UPEC. These probes possessed the best physico-chemical characteristics. The functional and structural properties of the designed probes were recognized by practical tools and softwares.

CONCLUSIONS

The use of reliable advanced technologies and methodologies for probe designing guarentees the high quality of microarray probes and makes DNA microarray technology more flexible and an effective diagnostic technique.

Pushing the Limits of MALDI-TOF Mass Spectrometry: Beyond Fungal Species Identification

Matrix assisted laser desorption ionization time of flight (MALDI-TOF) is a powerful analytical tool that has revolutionized microbial identification. Routinely used for bacterial identification, MALDI-TOF has recently been applied to both yeast and filamentous fungi, confirming its pivotal role in the rapid and reliable diagnosis of infections. Subspecies-level identification holds an important role in epidemiological investigations aimed at tracing virulent or drug resistant clones. This review focuses on present and future applications of this versatile tool in the clinical mycology laboratory.