Role of candida in pathogenesis of antibiotic-associated diarrhoea in elderly inpatients

Metagenomics Analysis Reveals an Extraordinary Inner Bacterial Diversity in Anisakids (Nematoda: Anisakidae) L3 Larvae

L3 larvae of anisakid nematodes are an important problem for the fisheries industry and pose a potential risk for human health by acting as infectious agents causing allergies and as potential vectors of pathogens and microrganisms. In spite of the close bacteria-nematode relationship very little is known of the anisakids microbiota. Fresh fish could be contaminated by bacteria vectored in the cuticle or in the intestine of anisakids when the L3 larvae migrate through the muscles. As a consequence, the bacterial inoculum will be spread, with potential effects on the quality of the fish, and possible clinical effects cannot be discarded. A total of 2,689,113 16S rRNA gene sequences from a total of 113 L3 individuals obtained from fish captured along the FAO 27 fishing area were studied. Bacteria were taxonomically characterized through 1803 representative operational taxonomic units (OTUs) sequences. Fourteen phyla, 31 classes, 52 orders, 129 families and 187 genera were unambiguously identified. We have found as part of microbiome an average of 123 OTUs per L3 individual. Diversity indices (Shannon and Simpson) indicate an extraordinary diversity of bacteria at an OTU level. There are clusters of anisakids individuals (samples) defined by the associated bacteria which, however, are not significantly related to fish hosts or anisakid taxa. This suggests that association or relationship among bacteria in anisakids, exists without the influence of fishes or nematodes. The lack of relationships with hosts of anisakids taxa has to be expressed by the association among bacterial OTUs or other taxonomical levels which range from OTUs to the phylum level. There are significant biological structural associations of microbiota in anisakid nematodes which manifest in clusters of bacteria ranging from phylum to genus level, which could also be an indicator of fish contamination or the geographic zone of fish capture. Actinobacteria, Aquificae, Firmicutes, and Proteobacteria are the phyla whose abundance value discriminate for defining such structures.

Antimicrobial effectors in the nematode Caenorhabditis elegans: an outgroup to the Arthropoda

Nematodes and arthropods likely form the taxon Ecdysozoa. Information on antimicrobial effectors from the model nematode Caenorhabditis elegans may thus shed light on the evolutionary origin of these defences in arthropods. This nematode species possesses an extensive armory of putative antimicrobial effector proteins, such as lysozymes, caenopores (or saposin-like proteins), defensin-like peptides, caenacins and neuropeptide-like proteins, in addition to the production of reactive oxygen species and autophagy. As C. elegans is a bacterivore that lives in microbe-rich environments, some of its effector peptides and proteins likely function in both digestion of bacterial food and pathogen elimination. In this review, we provide an overview of C. elegans immune effector proteins and mechanisms. We summarize the experimental evidence of their antimicrobial function and involvement in the response to pathogen infection. We further evaluate the microbe-induced expression of effector genes using WormExp, a recently established database for C. elegans gene expression analysis. We emphasize the need for further analysis at the protein level to demonstrate an antimicrobial activity of these molecules both in vitro and in vivoThis article is part of the themed issue 'Evolutionary ecology of arthropod antimicrobial peptides'.

The native microbiome of the nematode Caenorhabditis elegans: gateway to a new host-microbiome model

BACKGROUND

Host-microbe associations underlie many key processes of host development, immunity, and life history. Yet, none of the current research on the central model species Caenorhabditis elegans considers the worm's natural microbiome. Instead, almost all laboratories exclusively use the canonical strain N2 and derived mutants, maintained through routine bleach sterilization in monoxenic cultures with an E. coli strain as food. Here, we characterize for the first time the native microbiome of C. elegans and assess its influence on nematode life history characteristics.

RESULTS

Nematodes sampled directly from their native habitats carry a species-rich bacterial community, dominated by Proteobacteria such as Enterobacteriaceae and members of the genera Pseudomonas, Stenotrophomonas, Ochrobactrum, and Sphingomonas. The C. elegans microbiome is distinct from that of the worm's natural environment and the congeneric species C. remanei. Exposure to a derived experimental microbiome revealed that bacterial composition is influenced by host developmental stage and genotype. These experiments also showed that the microbes enhance host fitness under standard and also stressful conditions (e.g., high temperature and either low or high osmolarity). Taking advantage of the nematode's transparency, we further demonstrate that several Proteobacteria are able to enter the C. elegans gut and that an Ochrobactrum isolate even seems to be able to persist in the intestines under stressful conditions. Moreover, three Pseudomonas isolates produce an anti-fungal effect in vitro which we show can contribute to the worm's defense against fungal pathogens in vivo.

CONCLUSION

This first systematic analysis of the nematode's native microbiome reveals a species-rich bacterial community to be associated with C. elegans, which is likely of central importance for our understanding of the worm's biology. The information acquired and the microbial isolates now available for experimental work establishes C. elegans as a tractable model for the in-depth dissection of host-microbiome interactions.

Antibiotic-associated diarrhea: a refresher on causes and possible prevention with probiotics--continuing education article

Antibiotic-associated diarrhea (AAD) describes any unexplained diarrhea associated with the use of an antibiotic. AAD also includes infection caused by Clostridium difficile, however this organism only accounts for a small percentage of diarrhea caused by antibiotics. AAD can be caused by multiple other organisms including C perfringens, S aureus, and Candida. Some antibiotics are more likely to cause non-C difficile AAD, such as erythromycin and the penicillin class. AAD develops through the loss of normal flora and reduced colonic bacterial carbohydrate metabolism during antibiotic administration. There is an increasing interest in the use of probiotics for the prevention of AAD. There are several meta-analyses that report a relative risk reduction of AAD with the use of probiotics during antibiotic administration. Interpretation of these studies has been challenging due to the heterogeneity and size of the patient populations, unclear probiotic regimen, and unclear safety profile. Since AAD can be a reason for a patient to become non-compliant or receive incomplete treatment, clinicians should monitor for this potential adverse effect caused by antibiotics.

Characterization of Antimicrobial Peptides toward the Development of Novel Antibiotics

Antimicrobial agents have eradicated many infectious diseases and significantly improved our living environment. However, abuse of antimicrobial agents has accelerated the emergence of multidrug-resistant microorganisms, and there is an urgent need for novel antibiotics. Antimicrobial peptides (AMPs) have attracted attention as a novel class of antimicrobial agents because AMPs efficiently kill a wide range of species, including bacteria, fungi, and viruses, via a novel mechanism of action. In addition, they are effective against pathogens that are resistant to almost all conventional antibiotics. AMPs have promising properties; they directly disrupt the functions of cellular membranes and nucleic acids, and the rate of appearance of AMP-resistant strains is very low. However, as pharmaceuticals, AMPs exhibit unfavorable properties, such as instability, hemolytic activity, high cost of production, salt sensitivity, and a broad spectrum of activity. Therefore, it is vital to improve these properties to develop novel AMP treatments. Here, we have reviewed the basic biochemical properties of AMPs and the recent strategies used to modulate these properties of AMPs to enhance their safety.

Study of fungal isolates in patients with chronic diarrhea at a tertiary care hospital in north India

OBJECTIVE

The aim of this study was to evaluate the rate of isolation and antifungal susceptibility profile of various opportunistic yeasts in faeces of patients with chronic diarrhea.

PATIENTS

The study included 120 patients who received the consultation and treatment for the complaints of chronic diarrhea for a period of more than 15 days.

MATERIALS AND METHODS

The microscopy of samples of stool was followed by the culture on Sabourauds-dextrose agar. Isolate were tried for their sensitivity to fluconazole, flucytosine, amphotericin B and voriconazole.

RESULTS

The significant growth of fungal organism was seen in 32 (26.7%) stool specimen. These fungal isolates include five (15.6%) of C. albicans, 14 (43.8%) of C. tropicalis, five (15.6%) of C. krusei, two (6.3%) of C. famata, two (6.3%) of C. parapsilosis isolates and one isolate each of C. lusitaniae, C. guilliermondii, Stephanoascus ciferri and Trichosporon asahii (3.1% each). Most of the yeast isolates (65.6%) were found to be sensitive to all four antifungal agents i.e., fluconazole, flucytosine, amphotericin B and voriconazole. The highest resistance was seen against fluconazole in 10 (31.3%) isolates followed by flucytosine in eight (25%) isolates. No resistance to voriconazole was observed in any of the isolates. The resistance to the antifungal agents was higher among the other species of Candida compared to C. albicans.

CONCLUSION

The study could establish the relation between the opportunistic yeasts and chronic diarrhea and gives information on the antifungal sensitivity profile of the isolated yeasts.

Clostridium difficile and the disease it causes

Clostridium difficile is a spore-forming, toxin-producing, anaerobic bacterium abundant in soils and water. Frequent and early colonization of the human intestinal flora is common and often asymptomatic. Antimicrobials given commonly disrupt the intestinal microflora and through proliferation in colon and production of toxin A and B it precipitates C. difficile infection (CDI). The enterocytic detachment and bowel inflammation provoke C. difficile-associated diarrhoea (CDAD) sometimes developing into severe pseudomembranous colitis (PMC) and paralytic ileus. Infection is acquired from an endogenous source or from spores in the environment, most easily facilitated during hospital stay. In the elderly, comorbidity, hospitalization and antimicrobial treatment present as major risk factors and the slow recolonization of the normal flora likely responsible for single or multiple recurrences of CDI (25-50%) post therapy. The key procedure for diagnosis is toxin detection from stool specimens and sometimes in combination with culture to increase sensitivity. In mild cases stopping the offending antimicrobial will lead to resolution (25%) but standard therapy still consist of either oral metronidazole or vancomycin. Alternative agents are presently being developed and fidaxomicin, as well as nitrothiazolide are promising. Furthermore, host factors like low antitoxin A levels in serum relates to increased risk of recurrence and small numbers of patients have received immunoglobulin with good results. An immunogenic toxoid vaccine has been developed and human colostrum rich in specific secretory Ig A also support the future use of immunotherapy. Today we experience a tenfold increase of CDI incidence in the western world and both epidemics and therapeutic failure of metronidazole is contributing to morbidity and mortality. The current epidemic of the C. difficile strain NAP1/027 emerging in 2002 in Canada and the USA has now spread to most parts of Europe and virulence factors like high toxin production and sporulation challenge the therapeutic situation and cause great concern among infection control workers. Excessive use of modern fluoroquinolones is thought to play an important role in facilitating this epidemic since NAP1/027 was shown to have acquired moxifloxacin resistance compared to historical strains of the same genotype. Both the current epidemic like this and other local outbreaks from resistant or virulent strains warrant culture to be routinely performed enabling susceptibility testing and typing of the pathogen. Genotyping is most commonly done today by pulse-field gel electrophoresis (PFGE) or PCR ribotyping but multilocus variable-number tandem-repeat analysis (MLVA) seems promising. Epidemiological surveillance using all these tools will help us to better understand the global spread of C. difficile.

Yeasts in the gut: from commensals to infectious agents

BACKGROUND

Controversy still surrounds the question whether yeasts found in the gut are causally related to disease, constitute a health hazard, or require treatment.

METHODS

The authors present the state of knowledge in this area on the basis of a selective review of articles retrieved by a PubMed search from 2005 onward. The therapeutic recommendations follow the current national and international guidelines.

RESULTS

Yeasts, mainly Candida species, are present in the gut of about 70% of healthy adults. Mucocutaneous Candida infections are due either to impaired host defenses or to altered gene expression in formerly commensal strains. The expression of virulence factors enables yeasts to form biofilms, destroy tissues, and escape the immunological attacks of the host. Yeast infections of the intestinal mucosa are of uncertain clinical significance, and their possible connection to irritable bowel syndrome, while plausible, remains unproved. Yeast colonization can trigger allergic reactions. Mucosal yeast infections are treated with topically active polyene antimycotic drugs. The adjuvant administration of probiotics is justified on the basis of positive results from controlled clinical trials.

CONCLUSION

The eradication of intestinal yeasts is advised only for certain clearly defined indications.

Antibiotic-associated diarrhea and pseudomembranous colitis: are they less common with poorly absorbed antimicrobials?

Diarrhea is a well-known complication of antibiotic therapy. Rates of antibiotic-associated diarrhea (AAD) vary from 5 to 25%. Some antibiotics are more likely to cause diarrhea than others, specifically, those that are broad spectrum and those that target anaerobic flora. This paper reviews the effects of antibiotics on the fecal flora as well as host factors which contribute to AAD. Clinical features and treatment of AAD are also described. Prevention of AAD rests on wise antibiotic policies, the use of probiotics and prevention of acquisition in the hospital setting. Data from clinical trials suggest that poorly absorbed antimicrobials might have a decreased risk of causing AAD and Clostridium difficile-associated disease, as concluded from studies of antibiotics used for preoperative bowel decontamination and poorly absorbed antibiotics used for traveler's diarrhea. Controlled trials would prove this but are not yet available. Probiotics may be a good adjunct to poorly absorbed antibiotics to minimize the risk of diarrhea associated with antibiotics.

A Pseudomonas aeruginosa quorum-sensing molecule influences Candida albicans morphology

Candida albicans is an opportunistic pathogen that is commonly found as a member of the human microflora. The ability of C. albicans to alter its cellular morphology has been associated with its virulence; yeast cells are more prevalent in commensal interactions whereas filamentous cells appear important in opportunistic infections. C. albicans encounters a multitude of other microbial species in the host environment and it is likely that they impact the C. albicans transition between virulent and non-virulent states. Here, we report that C. albicans morphology is significantly affected by the presence of Pseudomonas aeruginosa, another opportunistic pathogen. In a screen using a C. albicans HWP1-lacZ strain to indicate regions of filamentous growth, we identified P. aeruginosa mutants incapable of inhibiting C. albicans filamentation. Through these studies, we found that 3-oxo-C12 homoserine lactone, a cell-cell signalling molecule produced by P. aeruginosa, was sufficient to inhibit C. albicans filamentation without affecting fungal growth rates. Both microscopic analysis and real-time reverse transcription polymerase chain reaction analysis of morphology-specific markers confirmed that filamentation was suppressed by 200 microM 3-oxo-C12 homoserine lactone. Structurally related compounds with a 12-carbon chain length, e.g. C12-acyl homoserine lactone and dodecanol also affected C. albicans filamentation at similar concentrations. In contrast, other acylated homoserine lactones of different chain lengths did not affect fungal morphology. The activity of 3OC12HSL is compared with that of farnesol, a C. albicans-produced molecule also with a C12-backbone. The effects that bacteria have on the morphology of C. albicans represents one of the ways by which bacteria can influence the behaviour of fungal cells.

Candida and antibiotic-associated diarrhoea

The role of Candida in antibiotic-associated diarrhoea (AAD) has been controversial for many years. Since Candida exists physiologically in the gastrointestinal tract, the presence of small numbers of Candida organisms in stool has therefore been considered normal, and thus non-pathogenic. Increased Candida counts have been linked to the development of diarrhoea in antibiotic-treated patients. However, recent findings have not confirmed this. To date, there is no convincing evidence that Candida may cause AAD in adults.

Microbial-gut interactions in health and disease. Antibiotic-associated diarrhoea

Most cases of antibiotic-associated diarrhoea (AAD) are directly or indirectly due to the alteration of gut microflora by antibiotics. 'Functional' diarrhoea, usually limited to a mild and brief change in stool frequency, is considered as the most frequent pattern of AAD. Reduced carbohydrate fermentation and impaired metabolism of bile acids have been claimed as the potential causes of this transient digestive discomfort but a critical analysis of the data supporting these theories is necessary. Alternatively, changes in the gut flora ecosystem allow pathogens to proliferate. Clostridium difficile is responsible for approximately 10% of cases of AAD and almost all cases of antibiotic-associated pseudomembranous colitis. The level of evidence which supports the potential responsibility of other candidate pathogens (Klebsiella oxytoca, enterotoxin-producing Clostridium perfringens and Staphylococcus aureus, Candida) needs to be appreciated according to the updated postulates of causality relationships between a bacterium and a disease.

Diarrhées associées aux antibiotiques chez le sujet âgé

PURPOSE

Most of the antibiotic-associated diarrhea (AAD) cases result from a transient disturbance in the function of the normal intestinal flora and are spontaneously solved when discontinuing the antibacterial therapy. However, a mild diarrhea lasting several days may induce a dehydration or worsen a denutrition in frail elderly people.

CURRENT KNOWLEDGE AND KEY POINTS

The incidence of AAD varies between 5 and 25% depending on the concerned antibiotic. Only 10-20% of all AAD cases are caused by infection, especially with Clostridium difficile, for which advanced age is a major risk factor. The first biological exam to perform when severe AAD or in frail people is the detection of C. difficile toxins, especially in elderly patient treated with beta-lactam antibiotics. Nevertheless, other infectious organisms causing AAD may be considered, as Staphylococcus aureus when predominant in stool cultures from patients treated with fluoroquinolones or as Klebsiella oxytoca when isolated in bloody diarrhea from patients treated with ampicillin. Elevated fecal counts of Candida spp. found in patients treated with antibiotics is rather the consequence of therapy than the cause of AAD. The prevention of AAD is based on a rational antibiotic use to avoid endogenous selection of C. difficile and on the improvement of the hygiene measures to limit the exogenous transmission of the bacteria or related spores by spoiled hands.

FUTURE PROSPECTS

Simultaneous prescription of non-pathogenic living organisms, capable of re-establishing the equilibrium of the intestinal flora, should be better described, especially in elderly people, because of its important economic impact.

Antibiotic-associated diarrhoea and Clostridium difficile in the community

BACKGROUND

Clostridium difficile is the main cause of nosocomial infectious diarrhoea and the causative agent of antibiotic-associated colitis. The involvement of C. difficile infection in antibiotic-associated diarrhoea in the community is poorly documented.

METHODS

We studied prospectively 266 adult out-patients in the Paris (France) area who were prescribed a 5-10-day course of antimicrobial chemotherapy. Stools were screened for C. difficile before and 14 days after the start of treatment by standard culture, toxigenic culture and testing for the cytopathic effect of toxin B. Patients were requested to note daily stool frequency and consistency. Diarrhoea was defined as the passage of at least three loose stools per day.

RESULTS

Forty-six (17.5%) of the 262 assessable patients had diarrhoea during the study period. Diarrhoea was mild and self-limited in all patients, and lasted for only 1 day in 65.6% of cases. C. difficile was isolated before and after treatment from one patient, who did not develop diarrhoea. C. difficile was detected only on day 14 in 10 patients (3.8%). The isolate was toxin producing in seven patients. Four of these seven patients had mild self-limited diarrhoea. Toxin-producing C. difficile was isolated significantly more frequently from patients who had diarrhoea than from those who were diarrhoea free (8.7% vs. 1.4%, P = 0.02).

CONCLUSION

The acquisition of toxin-producing C. difficile appears to be frequent during antimicrobial chemotherapy in the community [estimated rate of 2700 (1150-5400) cases per 100 000 exposures to antibiotics]. However, C. difficile is not the main agent of mild antibiotic-associated diarrhoea in out-patients.

Elevated fecal Candida counts in patients with antibiotic-associated diarrhea: role of soluble fecal substances

To assess the role of soluble fecal substances in the elevation of fecal Candida counts in patients with antibiotic-associated diarrhea (AAD), we investigated the growth of Candida albicans in vitro in serially diluted stool fluids from patients with AAD and healthy subjects. There were significantly higher Candida albicans counts in stool fluids diluted 1:10 from AAD patients than in healthy subjects and the phosphate-buffered saline growth control, which may be due to reduced soluble Candida inhibitors and increased availability of growth factors and nutrients.

The pathogenetic significance of intestinal Candida colonization--a systematic review from an interdisciplinary and environmental medical point of view

The etiological significance of intestinal Candida colonization continues to be controversial. This is a systematic review to determine the pathogenetic significance of intestinal Candida colonization. The search was essentially performed from 1990 to 12/7/2000 in Medline and the Cochrane-Library. The data source was restricted to articles in English and German. Selection criteria covered the topics "Epidemiology", "Infectious Diseases", "Candida-Syndrome" and "Therapy" and were essentially confined to in-vivo examination of immunocompetent adults. Two reviewers extracted independently data using predefined criteria. In total, 96 citations that proved suitable for use in the systematic review were found. Depending on the localization in the gastrointestinal tract, the recovery technique employed, and transport times, Candida colonization is frequently detected in healthy, immunocompetent adults (prevalence: 4-88%). None of the studies available so far furnish any evidence that nutritional factors, food additives, pollutants, anti-ovulants, other types of medication or diabetes mellitus might be predisposing factors for intestinal Candida colonization. However, therapeutic studies point to the possibility of Candida playing a role in antibiotic-associated diarrhea. On the other hand, antibiotics seem to favor bacterial dysbiosis, and this, like the direct side effects of drugs, offers a more plausible explanation for diarrhea or gastrointestinal symptoms. The role of intestinal colonization by Candida in Candida-associated vulvovaginitis and IgE-mediated disorders remains contradictory. Nevertheless, neither epidemiological nor therapeutic studies provide evidence for the existence of the so-called "Candida-syndrome" or "Candida-hypersensitivity-syndrome". At present, there are no proven treatment indications for antifungal "bowel decontamination".

Faecal candida and diarrhoea

BACKGROUND

Candida species are frequently isolated from stools of children with diarrhoea but are not proven enteropathogens. It is hypothesised that faecal candida causes diarrhoea.

AIMS

To determine the prevalence of faecal candida in childhood diarrhoea and the relation between faecal yeasts and diarrhoea.

METHODS

Comparison of clinical and laboratory data, including quantitative stool culture for yeasts from 107 children hospitalised with diarrhoea and 67 age matched controls without diarrhoea.

RESULTS

Yeast species, predominantly candida, were identified in the stools of 43 children (39%) with diarrhoea and 26 (36%) without diarrhoea. The concentration of candida was positively associated with recent antibiotic use (p = 0.03) and with the presence of another enteric pathogen (p < 0.005), but not with patient age, nutritional status, or duration of diarrhoea.

CONCLUSION

Candida species do not cause childhood diarrhoea in well nourished children.

Genetically distinct strains of Candida albicans with elevated secretory proteinase production are associated with diarrhoea in hospitalized children

BACKGROUND

Candida albicans has been implicated as the aetiological agent in a significant percentage of children with diarrhoea. The virulence properties of C. albicans strains associated with acute and chronic diarrhoea in hospitalized children were investigated.

METHODS

The genotypic relationships between the isolates were determined using restriction enzyme analysis and hybridization with a C. albicans-specific DNA probe, 27A.

RESULTS AND CONCLUSION

In patients with acute and chronic diarrhoea, there is evidence for selection of specific, genetically distinct strains of C. albicans. Higher levels of secretory Candida acid proteinase produced by isolates from patients with acute diarrhoea may account for the more severe symptoms. However, the lower adherence of these isolates may predispose to the rapid (within 2 to 4 days) resolution of the condition. In patients with chronic diarrhoea the lower levels of proteinase produced correlate with the less severe symptoms, while the increased adherence may account for the persistence of the infection.

Drug-induced diarrhoea

Diarrhoea is a relatively frequent adverse event, accounting for about 7% of all drug adverse effects. More than 700 drugs have been implicated in causing diarrhoea; those most frequently involved are antimicrobials, laxatives, magnesium-containing antacids, lactose- or sorbitol-containing products, nonsteroidal anti-inflammatory drugs, prostaglandins, colchicine, antineoplastics, antiarrhythmic drugs and cholinergic agents. Certain new drugs are likely to induce diarrhoea because of their pharmacodynamic properties; examples include anthraquinone-related agents, alpha-glucosidase inhibitors, lipase inhibitors and cholinesterase inhibitors. Antimicrobials are responsible for 25% of drug-induced diarrhoea. The disease spectrum of antimicrobial-associated diarrhoea ranges from benign diarrhoea to pseudomembranous colitis. Several pathophysiological mechanisms are involved in drug-induced diarrhoea: osmotic diarrhoea, secretory diarrhoea, shortened transit time, exudative diarrhoea and protein-losing enteropathy, and malabsorption or maldigestion of fat and carbohydrates. Often 2 or more mechanisms are present simultaneously. In clinical practice, 2 major types of diarrhoea are seen: acute diarrhoea, which usually appears during the first few days of treatment, and chronic diarrhoea, lasting more than 3 or 4 weeks and which can appear a long time after the start of drug therapy. Both can be severe and poorly tolerated. In a patient presenting with diarrhoea, the medical history is very important, especially the drug history, as it can suggest a diagnosis of drug-induced diarrhoea and thereby avoid multiple diagnostic tests. The clinical examination should cover severity criteria such as fever, rectal emission of blood and mucus, dehydration and bodyweight loss. Establishing a relationship between drug consumption and diarrhoea or colitis can be difficult when the time elapsed between the start of the drug and the onset of symptoms is long, sometimes up to several months or years.

Limited effect of refined carbohydrate dietary supplementation on colonization of the gastrointestinal tract of healthy subjects by Candida albicans

BACKGROUND

Infections due to Candida albicans occur readily in situations in which ample glucose is available. In mice, dietary refined carbohydrate supplementation leads to higher rates of Candida growth in the gastrointestinal tract and favors mucosal invasion.

OBJECTIVE

The modulating properties of dietary carbohydrate supplementation on colonization of the human gastrointestinal tract by C. albicans were evaluated.

DESIGN

A 2-step study was conducted in 28 healthy volunteers. First, we determined the subjects' habitual uptake of refined carbohydrates and correlated these data with the C. albicans blastoconidia concentration in the mouth washes and feces of subjects with no intervention. Second, we compared C. albicans counts in the specimens before, during, and after a high-sugar diet.

RESULTS

No correlation between C. albicans counts in the specimens and the habitual uptake of refined carbohydrates was observed. A high-sugar diet did not increase the frequency of C. albicans-positive samples, the number of subjects positive for C. albicans in the mouth washes, or the concentration of candidal blastoconidia in the samples of the 28 subjects. However, in selected subjects with elevated counts of oral C. albicans, we observed an increase in fecal C. albicans counts in response to the diet.

CONCLUSIONS

The effect of adding a high amount of refined carbohydrates to the diet of healthy human subjects has a limited influence on Candida colonization. Follow-up studies should define whether selected patient groups might benefit from dietary restriction of refined carbohydrates.

Nosocomial Candida. Epidemiology, transmission, and prevention

The NNIS and the newly established SCOPE data indicate that the relative proportion of organisms causing nosocomial bloodstream infections has changed over the last decade, with Candida species now being firmly established as one of the most frequent agents. The epidemiology of nosocomial candidemia is continually being refined, but established predisposing factors including immunosuppression and malignancies, use of broad spectrum antibiotics, and use of indwelling central catheters remain as significant risk factors. The high cost of health care and greater attention to continuous quality improvement will stimulate better and more effective ways of diagnosing and treating candida infections using combined clinical and microbiologic acumen. There is room for optimism as newer antifungal agents with reduced toxicities have impact on therapy of candidal infections. Aggressive development of still more agents and reformulations of older agents continue in earnest. Even greater consolation comes from the increased awareness of lay and medical personnel alike regarding the appropriate and judicious use of antimicrobial agents.

Diarrheal diseases associated with HIV infection

Diarrhea is a major complication of HIV infection and adversely impacts health care costs, quality of life, and even survival of patients. There is a wide variety of potential causes of diarrhea in HIV-infected patients, and the number of pathogens found continues to increase with time. In addition, there is some controversy concerning the role of some organisms in the pathogenesis of diarrhea and the appropriate diagnostic evaluation of affected patients. This article reviews our current understanding of these pathogens and some of the diagnostic and therapeutic approaches for diarrhea associated with HIV infection.

Results of culture form colonoscopically obtained specimens for bacteria and fungi in HIV-infected patients with diarrhea

BACKGROUND

The aim of our study was to determine the diagnostic yield of culture for bacteria and fungi from colonic biopsy specimens in 290 consecutive HIV-infected patients with diarrhea.

METHODS

During each colonoscopy, three biopsy specimens were homogenized and cultured on media for Salmonella and Shigella and for Campylobacter and Yersinia, on Loewenstein medium and on Sabouraud medium.

RESULTS

Cultures were found positive for one (n = 32) or two (n = 5) infectious agents in 37 cases, i.e., in 12.8% of the patients. Bacteria were isolated in 24 cases, and identified as Campylobacter jejunl-coli (n = 14), Salmonella (n = 2), Shigella (n = 1), or Pseudomonas aeruginosa (n = 7). Among the 14 patients with C. jejuni-coli intestinal infection, 11 had normal-appearing mucosa at colonoscopy, and 3 had a concomitant stool culture negative for Campylobacter. Mycobacterial cultures were positive for Mycobacterium avium intracellulare in 6 patients, who were already known as having a disseminated M. avium intracellulare infection from positive blood cultures. Fungal cultures were positive for Candida in 10 cases, without clear clinical significance.

CONCLUSIONS

The overall yield of culture for bacterial pathogens from colonic tissue in HIV-infected patients with diarrhea is low, but some individual cases of C. jejuni-coli infections may be detected from colonic tissue culture and not diagnosed by concomitant stool culture.

Epidemiology of nosocomial fungal infections

This paper briefly reviews the current knowledge of the epidemiology and modes of transmission of nosocomial fungal infections and some of the therapeutic options for treating these diseases. In the mid-1980s, many institutions reported that fungi were common pathogens in nosocomial infections. Most, if not all, hospitals care for patients at risk for nosocomial fungal infections. The proportion in all nosocomial infections reportedly caused by Candida spp. increased from 2% in 1980 to 5% in 1986 to 1989. Numerous studies have identified common risk factors for acquiring these infections, most of which are very common among hospitalized patients; some factors act primarily by inducing immunosuppression (e.g., corticosteroids, chemotherapy, malnutrition, malignancy, and neutropenia), while others primarily provide a route of infection (e.g., extensive burns, indwelling catheter), and some act in combination. Non-albicans Candida spp., including fluconazole-resistant C. krusei and Torulopsis (C.) glabrata, have become more common pathogens. Newer molecular typing techniques can assist in the determination of a common source of infection caused by several fungal pathogens. Continued epidemiologic and laboratory research is needed to better characterize these pathogens and allow for improved diagnostic and therapeutic strategies.

Role of Candida in indirect pathogenesis of antibiotic associated diarrhoea in infants

One hundred and thirty seven isolates of Candida species were isolated from antibiotic associated diarrhoea cases and were examined to study the role of Candida in the pathogenesis of diarrhoea in infants. The quantitative estimation of yeast population by simple gram stain smear revealed more than 70% of the cases had 3+ score. The isolates further screened for detection of beta-lactamases. Among the isolated Candida sp, beta-lactamases was secreted by C. albicans, C. tropicalis, C. krusei and C. parapsilosis. Further, 46% of the Candida isolates were found to be produced 741-1110 mU/ml of beta-lactamases, suggesting that these enzyme would inactivate penicillin group of drugs and cause failure in the therapy directed against other diarrhoegenic bacteria.

Methods for detection of an intestinal secretory immunoglobulin A response to Candida spp. and their preliminary application in human immunodeficiency virus-infected patients with chronic diarrhea

Six of 11 human immunodeficiency virus (HIV)-infected patients with chronic diarrhea, shedding only Candida spp. in their stools, elicited a Candida-specific secretory immunoglobulin A response. Similar responses were identified in only 1 of 10 HIV-positive patients with chronic diarrhea but without Candida spp. and in none of 10 HIV-negative subjects without diarrhea. Candida spp. may play a role in the etiology of chronic diarrhea associated with HIV infection.

Etiology and outcome of diarrhea after marrow transplantation: a prospective study

BACKGROUND/AIMS

Acute diarrhea after marrow transplant is usually ascribed to acute graft-vs.-host disease (GVHD) or infection, with a reported 40%-50% incidence of infection. The aim of this study was to determine the incidence of acute diarrhea after transplantation, its causes, and its outcome.

METHODS

Two hundred ninety-six patients were followed up; patients with diarrhea were studied using standard evaluation of stool plus immunoelectron microscopy; assays for astrovirus, picobirnavirus, and Norwalk virus; and gene-probe methods for toxin-producing Escherichia coli. In 38 patients with diarrhea, intestinal biopsy specimens and duodenal fluid were also analyzed.

RESULTS

One hundred fifty acute diarrheal episodes developed in 126 patients (an incidence of 43%). Intestinal infection was found in 20 of 150 episodes: viruses (astrovirus, adenovirus, cytomegalovirus, and rotavirus) in 12 patients, nosocomially acquired bacteria (Clostridium difficile and Aeromonas) in 7 patients, and mixed infection in 1 patient. Acute GVHD was responsible for 72 of 150 episodes (48%). Clinical signs and symptoms of infection and GVHD were similar. In 58 of 150 episodes (39%), no clear etiology could be found for self-limited diarrhea.

CONCLUSIONS

Intestinal infection accounted for 13% and acute GVHD for 48% of diarrheal episodes. The most common infecting organisms were astrovirus, C. difficile, and adenovirus. Most cases of diarrhea after marrow transplant are not caused by infection.

[Unexplained chronic diarrhea, apropos of 4 new cases under Cyclo 3 fort and review of the literature]

We report 4 cases of chronic diarrhoea in patients treated with Cylclo 3 fort. This side-effect was not mentioned in the French list of therapeutic drugs until 1992. The diarrhoea was without faeces and without glairy mucus or blood. Symptomatic treatments were totally ineffective. The diarrhoea itself was well tolerated, but 3 patients lost weight, with hypokalaemia in 2 of them, and 1 had regressive acute renal failure. The time elapsed between the first dose of Cyclo 3 fort and the diarrhoea ranged from 1 to 3 months, and it took 5 months to make the aetiological diagnosis. Two patients were hospitalized. Withdrawal of the drug always resulted in cure. One patient taking enemas developed a regressive subocclusion of the bowel. The physiopathological mechanism of this diarrhoea is unknown. These cases are similar to the 5 other cases reported in the literature.

The role of faecal Candida albicans in the pathogenesis of food-intolerant irritable bowel syndrome

Candida albicans was sought in stool samples from 38 patients with irritable bowel syndrome and 20 healthy controls. In only three patients with irritable bowel syndrome was C. albicans discovered and these patients had either recently received antibiotics or the stool sample had been delayed more than 24 hours in transit. C. albicans was isolated from none of the control stool samples. We conclude that C. albicans is not involved in the aetiology of the irritable bowel syndrome.