Repellency of the Components of the Essential Oil, Citronella, to Triatoma rubida, Triatoma protracta, and Triatoma recurva (Hemiptera: Reduviidae: Triatominae)

The kissing bugs--Triatoma rubida (Uhler), Triatoma protracta (Uhler), and Triatoma recurva (Stal)--are common hematophagous bugs in southeastern Arizona and responsible for severe allergic reactions in some individuals who are bitten. They also possess the potential to transmit the blood parasite, Trypanosoma cruzi. We previously found the essential oil, citronella, to be an excellent deterrent of feeding of T. rubida on a restrained mouse. In this work, we tested major components--alcohols, aldehydes, and monoterpenes--of citronella oil for repellency against the three common triatome species endemic in southern Arizona. The following citronella oil components--geraniol, citronellol, limonene, and citronellal--in different concentrations and combinations were tested. All components of citronella oil demonstrated some inhibition of feeding, ranging from very weak inhibition (limonene) to significant inhibition (geraniol and citronellol). A mixture of geraniol and citronellol was found to be repellant at concentrations of .165 and .165 vol%, respectively, for all three triatome species. Citronellal and limonene had no significant repellent activity. The repellent activity of citronella oil appears to be acting through direct contact with the bugs rather than diffusion of vapors.

Repellency of DEET, picaridin, and three essential oils to Triatoma rubida (Hemiptera: Reduviidae: Triatominae)

The kissing bug, Triatoma rubida (Uhler) is a common hematophagous bug in Tucson, AZ, and is responsible for causing severe allergic reactions in some bitten individuals. DEET, picaridin, tea tree oil, peppermint oil, and citronella oil were tested for repellency to T. rubida and its ability to probe and feed on a small restrained rat. No long range repellency was observed with any of the test materials. The lowest repellent concentrations observed were: 10% DEET, 7% picaridin; 30% tea tree oil, 3.3% peppermint oil, and 0.165% citronella oil. Only citronella oil was able to stop all probing and feeding by T. rubida. Citronella oil appears to be a promising potential repellent to prevent sleeping people from being bitten by kissing bugs.

Antibodies to alpha5beta1 and alpha(v)beta3 integrins react with Candida albicans alcohol dehydrogenase

It has been hypothesized that Candida albicans possesses integrin-like receptors on its cell surface. This is because C. albicans binds numerous fluid-phase extracellular matrix (ECM) proteins on its cell surface and adheres to the same ECM proteins when immobilized. In addition, numerous antibodies to human integrins (receptors for ECM proteins) bind to the fungal cell surface and in so doing inhibit the binding of the respective proteins. To demonstrate the presence of such a cell surface integrin, a cDNA library of C. albicans yeast cells was screened with polyclonal antiserum to the human fibronectin receptor (alpha5beta1 integrin). Clones isolated by this screening technique also reacted specifically to antiserum against the human vitronectin receptor (alpha(v)beta3 integrin). DNA sequence analysis of the cloned insert predicted a 350 aa protein (37 kDa). This predicted protein showed 75% homology at the nucleotide sequence level to alcohol dehydrogenase (ADH) of Saccharomyces cerevisiae. In vitro transcription/translation of the cloned inserts yielded a 37 kDa protein that was immunoprecipitated with antibodies to the alpha5beta1 and alpha(v)beta3 integrins and an antibody to a C. albicans fibronectin receptor. These antibodies and an mAb to the human vitronectin receptor demonstrated an antigen of -37 kDa present in the cell-wall preparations of C. albicans and in spent growth medium. All four antibodies reacted with authentic ADH. The possible significance of these results in relation to C. albicans adherence is discussed.

Fungal and parasitic infections of the eye

The unique structure of the human eye as well as exposure of the eye directly to the environment renders it vulnerable to a number of uncommon infectious diseases caused by fungi and parasites. Host defenses directed against these microorganisms, once anatomical barriers are breached, are often insufficient to prevent loss of vision. Therefore, the timely identification and treatment of the involved microorganisms are paramount. The anatomy of the eye and its surrounding structures is presented with an emphasis upon the association of the anatomy with specific infection of fungi and parasites. For example, filamentous fungal infections of the eye are usually due to penetrating trauma by objects contaminated by vegetable matter of the cornea or globe or, by extension, of infection from adjacent paranasal sinuses. Fungal endophthalmitis and chorioretinitis, on the other hand, are usually the result of antecedent fungemia seeding the ocular tissue. Candida spp. are the most common cause of endogenous endophthalmitis, although initial infection with the dimorphic fungi may lead to infection and scarring of the chorioretina. Contact lens wear is associated with keratitis caused by yeasts, filamentous fungi, and Acanthamoebae spp. Most parasitic infections of the eye, however, arise following bloodborne carriage of the microorganism to the eye or adjacent structures.

Two unusual presentations of urogenital histoplasmosis and a review of the literature

Two unusual clinical presentations of urogenital histoplasmosis are described. A review of the literature on urogenital histoplasmosis is provided.

Overexpression of the Candida albicans ALA1 gene in Saccharomyces cerevisiae results in aggregation following attachment of yeast cells to extracellular matrix proteins, adherence properties similar to those of Candida albicans

Candida albicans maintains a commensal relationship with human hosts, probably by adhering to mucosal tissue in a variety of physiological conditions. We show that adherence due to the C. albicans gene ALA1 when transformed into Saccharomyces cerevisiae, is comprised of two sequential steps. Initially, C. albicans rapidly attaches to extracellular matrix (ECM) protein-coated magnetic beads in small numbers (the attachment phase). This is followed by a relatively slower step in which cell-to-cell interactions predominate (the aggregation phase). Neither of these phases is observed in S. cerevisiae. However, expression of the C. albicans ALA1 gene from a low-copy vector causes S. cerevisiae transformants to attach to ECM-coated magnetic beads without appreciable aggregation. Expression of ALA1 from a high-copy vector results in both attachment and aggregation. Moreover, transcriptional fusion of ALA1 with the galactose-inducible promoters GALS, GALL, and GAL1, allowing for low, moderate, and high levels of inducible transcription, respectively, causes attachment and aggregation that correlates with the strength of the GAL promoter. The adherence of C. albicans and S. cerevisiae overexpressing ALA1 to a number of protein ligands occurs over a broad pH range, is resistant to shear forces generated by vortexing, and is unaffected by the presence of sugars, high salt levels, free ligands, or detergents. Adherence is, however, inhibited by agents that disrupt hydrogen bonds. The similarities in the adherence and aggregation properties of C. albicans and S. cerevisiae overexpressing ALA1 suggest a role in adherence and aggregation for ALA1 and ALA1-like genes in C. albicans.

Expression, cloning, and characterization of a Candida albicans gene, ALA1, that confers adherence properties upon Saccharomyces cerevisiae for extracellular matrix proteins

Adherence of Candida albicans to host tissues is a necessary step for maintenance of its commensal status and is likely a necessary step in the pathogenesis of candidiasis. The extracellular matrix (ECM) proteins are some of the host tissue and plasma proteins to which C. albicans adheres through adhesins located on the fungal cell surface. To isolate genes encoding ECM adhesins, an assay was developed based on the ability of yeast cells to adhere to magnetic beads coated with the ECM protein fibronectin, type IV collagen, or laminin. A C. albicans genomic library was constructed by cloning XbaI-partially-digested and size-selected fragments into pAUR112, an Escherichia coli-yeast low-copy-number shuttle vector. The C. albicans library was transformed into Saccharomyces cerevisiae YPH 499, and clones capable of adherence were selected by using ECM protein-coated magnetic beads. A plasmid containing an approximately 8-kb insert was isolated from 29 adherent clones. These clones exhibited adherence to all ECM protein-coated magnetic beads and to human buccal epithelial cells. The ALA1 gene (for agglutinin-like adhesin) was localized by subcloning it into a 5-kb XbaI fragment which retained the adherence phenotype in both orientations. The complete DNA sequence of the 5-kb insert was determined, and an open reading frame (ORF) encoding 1,419 amino acid residues was identified. Deletions from the 5' and 3' ends extending into the DNA sequence encoding the 1,419-amino-acid ORF product inactivated the adherence phenotype, suggesting that it is the coding region of the ALA1 gene. A database search identified ALA1 to be similar to the C. albicans ALS1 (for agglutinin-like sequence 1) protein and the S. cerevisiae agglutinin protein (AG alpha1), although the homology at the primary amino acid sequence level is limited to the first half of each of these proteins. ALA1 contains a central domain of six tandem repeats of 36 amino acids. We discuss the significance of various predicted ALA1 structural motifs and their relationships to function in the adherence process.

Infection due to Paecilomyces lilacinus: a challenging clinical identification

We describe a case of noninvasive sinusitis caused by Paecilomyces lilacinus in a patient with diabetes mellitus. Cure was achieved by endoscopic drainage and aspiration of the fungal mass. We discuss the difficulty in and clinical importance of distinguishing Paecilomyces from Aspergillus.

Anthrax pneumonia

Inhalation anthrax is a rare and almost uniformly fatal form of human anthrax caused by the inhalation of spores of Bacillus anthracis. A clue to the diagnosis is provided by taking a work history which will disclose patient exposure to contaminated animal products, most often animal hair and wool used in the textile industry. It is an illness with a biphasic course marked by the presence of a widened mediastinum on chest radiograph and often accompanied by hemorrhagic meningitis. The pathogenesis of this disease as well as the differential diagnosis of inhalation anthrax in the context of other zoonotic pneumonias is discussed. Therapy has been ineffectual probably because it has begun too late, but includes intravenous high dose penicillin G and perhaps vaccination to prevent relapse.

A pseudoepidemic of Rhodotorula rubra: a marker for microbial contamination of the bronchoscope

Rhodotorula rubra was isolated from bronchoscopy specimens from 11 patients. An investigation of the bronchoscopy equipment and the bronchoscopy suite revealed contamination of the suction channel with R rubra, as well as potentially pathogenic bacteria. Disinfection control methods included gas sterilization of the bronchoscope and the institution of an alcohol and air flush through the suction channel to allow complete drying of the scope between each patient use. We have had no further isolates of R rubra from bronchoscopy specimens since these measures were instituted, and repeat cultures from the suction channel have been negative.

Gelatin fragments block adherence of Candida albicans to extracellular matrix proteins

The adherence of Candida albicans to extracellular matrix proteins may be a critical step in the pathogenesis of candidiasis. Yeast cell adherence to type I and IV collagen, fibronectin and laminin was blocked by peptide fragments from denatured type I collagen (gelatin). Gelatin fragments were obtained by digestion of the reduced protein with trypsin or CNBr. The fragments did not have antifungal properties, presumably inhibiting adherence by blocking receptors (adhesins) on the surface of the fungus. A 10-mer (GQRGVVGLPG) fashioned from the alpha-1 chain of type I collagen reduced adherence by 68%. However, a gelatin peptide possessing 47 amino acids reduced fungal adherence to type I collagen by 100%. Peptides derived from the biocompatible protein gelatin, therefore, may have a potential role in reducing the adherence of the fungus to host proteins.

Adherence of Candida albicans to host cells

Research devoted to uncovering the mechanisms of adherence of Candida albicans to human tissue is reviewed. The physical aspects of adherence of the fungus to host cells and the biochemical and molecular features, as far as they are known, are discussed. Relevant pre- and post-adherence events in the pathogenesis of disease caused by this fungus are also noted. Putative adhesins and surface receptors of C. albicans for host proteins are discussed in detail.

Binding of plasma fibronectin to Candida albicans occurs through the cell binding domain

Candida albicans yeast cells bind soluble human plasma fibronectin (Fn) through a glycoprotein receptor (adhesin) located on the cell surface. This work demonstrates that a 120 kDa proteolytic fragment of Fn encompassing the cell binding domain binds more avidly to the yeast cell adhesin than does the parent Fn molecule. The presence of binding of Fn fragments containing heparin- and gelatin-binding domains of Fn could not be detected. The binding of the 120 kDa fragment is inhibited by a monoclonal antibody to the cell binding domain containing the amino acid sequence, Arginine-Glycine-Aspartic acid (RGD) as well as by an RGD-containing approximately 23-mer Fn peptide, but not with heparin or GRGDSPL. The fact that the cell binding domain of soluble Fn binds more avidly than does the parent molecule may explain the difference in the interaction of soluble Fn and immobilized Fn with Candida. It is possible that, upon immobilization, Fn may expose domains of the molecule previously unexposed when the molecule is in the soluble state.

The fibronectin adhesin of Candida albicans

Candida albicans possesses on its cell surface an adhesin which binds the whole viable fungus to subendothelial extracellular matrix and matrix proteins. The adhesin is composed of 75 to 80% carbohydrate and approximately 20 to 25% protein by weight. High-performance liquid chromatography of material eluted from a fibronectin-agarose affinity column demonstrates the presence of three peaks, all of which on sodium dodecyl sulfate-polyacrylamide gel electrophoresis show the presence of one protein of approximately 60 kDa. Molecular weight sizing column chromatography, however, demonstrates that the adhesin elutes with an apparent molecular mass of 42 kDa. The N terminus of the 60-kDa glycoprotein is blocked to Edman degradation. The fibronectin adhesin of C. albicans is a glycoprotein that may be present and functional as an aggregate or multimer of a 60-kDa protein.

The contribution of electrostatic forces to the process of adherence of Candida albicans yeast cells to substrates

The contribution of electrostatic interactions to the adherence process of Candida albicans and other Candida species was investigated by mixing cationic or anionic exchange resins possessing free -COO- or -NH+4 groups, respectively, on their surface. The adherence process of yeast cells to the anionic exchange resin is a saturable event that is essentially complete by 60 min. There is no measurable interaction of yeast cells with the cationic exchange resin. All clinical isolates of C. albicans, C. pseudotropicalis, one isolate each of C. tropicalis and Torulopsis glabrata possessed electrostatic charge as defined by this method, whereas two clinical isolates of C. parapsilosis, C. krusei and one isolate of C. tropicalis did not have measurable electrostatic surface charge. The adherence process to the exchange resin with the free -NH+4 group was dependent upon the pH of the suspending medium and varied from one isolate to another. Fixing yeast cells, or alternatively, endothelial cells, in such a manner as to change the surface charge of both and then measuring adherence of yeast cells to the target cells was an event that was not controlled by electrostatic interactions as they are defined herein. It appears that whatever contribution electrostatic charges make to the adherence process, that at best, it is a minor contribution.

Mycobacterium chelonae (M. chelonae subspecies chelonae): report of a patient with a sporotrichoid presentation who was successfully treated with clarithromycin and ciprofloxacin

We describe a sporotrichoid presentation of infection with Mycobacterium chelonae (M. chelonae subspecies chelonae). The disease occurred in a patient receiving corticosteroid therapy and was cured by the use of clarithromycin and ciprofloxacin.

Plasma and extracellular matrix proteins mediate in the fate of Candida albicans in the human host

The fungus, Candida albicans, causes trivial to life-threatening diseases in man when normal host defenses are compromised. The fungus appears to have evolved receptors (hereinafter referred to as adhesins) for human fluid phase glycoproteins such as fibronectin and immobilized basement membrane glycoproteins in order to establish and maintain a niche in the mucus-lined cavities of man. The hypothesis advanced is that the fate of the fungus may be determined by interactions with these same glycoproteins. For example, Candida may adhere to fibronectin on the surface of epithelial cells in order to maintain its residency in mucus-lined cavities, whereas when the fungus has escaped its normal niche and become bloodborne, yeast cells may be opsonized by fluid phase fibronectin and hence phagocytosed and killed more rapidly than uncoated fungi. On the other hand, bloodborne yeast cells may preferentially adhere to immobilized fibronectin exposed in the interstitial space or contained within fibrin-platelet aggregates. Adherence to immobilized proteins would enhance the ability of the fungus to establish a foothold in the human host outside its normal niche, avoid destruction by host phagocytic cells and hence establish a metastatic site of infection. This sequence of events, viz., adherence followed by growth may be similar to that which occurs in the metastasis of cancer cells. Many cancer cells employ receptors for basement membrane glycoproteins in order to effect movement from one area of the body to another. The adhesins of Candida may be analogous or perhaps homologous to the human integrin receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Medical treatment of recurrent candidemia in a patient with probable Candida parapsilosis prosthetic valve endocarditis

Fungal endocarditis is considered an absolute indication for valve replacement surgery. We describe the successful medical treatment of recurrent Candida parapsilosis candidemia with sequential treatment with amphotericin B and fluconazole in a patient with probable prosthetic valve endocarditis. Because of the presumed effectiveness of amphotericin B and fluconazole in the treatment of this patient, medical therapy should be considered as potentially useful in the treatment of recurrent C parapsilosis fungemia or endocarditis or both.

Adherence of Candida albicans to endothelial cells is inhibited by prostaglandin I2

The adherence of Candida species yeast cells to bovine and human endothelium was measured. The adherence phenomenon is a saturable event which can be altered by the release of prostaglandin I2 (PGI2 or prostacyclin) by endothelial cells. Release of PGI2 by endothelium has a protective effect, reducing Candida albicans yeast cell adherence to endothelial cells in a dose-dependent manner. Conversely, C. albicans appears to inhibit the release of PGI2 by endothelial cells and thus perhaps is capable of increasing the number of yeast cells which adhere to endothelium. Furthermore, a long-acting analog of PGI2, carbacyclin, reduced the number of yeast cells adhering to human platelet aggregates. Thus, it is possible that the release of PGI2 by endothelium has a protective effect against the hematogenous dissemination of C. albicans and its ability to adhere to vascular endothelium and fibrin-platelet matrices.

Adherence of Candida albicans to immobilized extracellular matrix proteins is mediated by calcium-dependent surface glycoproteins

The adherence of Candida albicans to the extracellular matrix proteins type I collagen and fibronectin (Fn) is dependent upon the presence of extracellular calcium. In the absence of calcium, 14 +/- 3% of yeast cells added to type I collagen adhered, whereas 62 +/- 3% of yeast cells adhered in the presence of 2 mM calcium. EDTA and EGTA reduced C. albicans adherence in a dose-dependent manner. Calcium, and to a lesser extent, cesium and magnesium, enhanced yeast cell adherence. The fluorescent probe, terbium (Tb+3), bound to the surface of yeast cells in a dose-dependent manner demonstrating the presence of cationic metal-binding sites on the yeast cell surface. When extracts of C. albicans yeast cells were applied to columns of Fn or gelatin coupled to agarose, two surface proteins of C. albicans were specifically eluted with 10 mM EDTA, 2% alpha-methylmannopyranoside or an Arg-Gly-Asp-containing peptide. The fungal proteins had relative molecular masses of 60,000 and 105,000 in the unreduced state. The proteins were present in the cell membrane as well as the cell wall and were demonstrated to be glycoproteins by their ability to bind concanavalin A. Immunoblot analysis of yeast extracts demonstrated that anti-integrin antibodies to the human fibronectin, vitronectin and complement receptor cross-reacted with the Candida 60 kDa glycoprotein. Thus, calcium-dependent fungal cell wall glycoproteins likely related to integrins may be receptors responsible for yeast cell adherence to host tissue such as the extracellular matrix.

Glycosaminoglycans inhibit Candida albicans adherence to extracellular matrix proteins

The ability of Candida albicans to adhere to subendothelial extracellular matrix (ECM) may be important in the pathogenesis of disseminated candidiasis. ECM proteins, such as fibronectin, laminin, and types I and IV collagen bind C. albicans avidly. These proteins all possess heparin-binding domains. The influence of the glycosaminoglycans (GAGS) including heparin, heparan sulfate and dextran sulfate on C. albicans adherence to subendothelial ECM and ECM proteins was studied. It was demonstrated that the GAGS inhibited C. albicans adherence to ECM and ECM proteins. This possibly occurred by the GAGS binding to the ECM proteins and, in so doing, masking a preferred ligand for C. albicans adherence.

"Through a drinking glass and what was found there": pseudocontamination of a hospital's drinking water

OBJECTIVE

Examination of suspended macroscopic debris that was noted in hospital cafeteria drinking water over a prolonged period of time.

SETTING

A tertiary care hospital.

DESIGN

A retrospective description of events.

METHODS

Conventional medical microbiology techniques were employed to determine if contamination of drinking water had occurred.

RESULTS

Microscopic examinations of the debris showed live nematodes similar to Strongyloides stercoralis rhabditiform larvae and amoebic trophozoites. A culture of an ice container in the cafeteria yielded coliform bacteria. Hospital employees lost work because of a diarrheal illness thought to be contracted from drinking cafeteria water. Further investigation revealed that the debris contained numerous ciliated organisms, nematodes, fresh water amoebae, bacterial mats, flagellated fungi, and unidentified cysts suggesting that the debris was of a freshwater origin rather than fecal contamination. Another hospital served by a collateral city water line experienced a similar problem. The debris was observed in November when lake water in the reservoir undergoes inversion.

CONCLUSIONS

Nonpathogenic freshwater microbiota probably originating from the city reservoir were the cause of pseudocontamination of hospital drinking water.

Peritoneal coccidioidomycosis associated with human immunodeficiency virus infection

Peritoneal coccidioidomycosis is extremely rare. This report describes a patient infected with the human immunodeficiency virus who presented with unexplained ascites and was found to have peritoneal coccidioidomycosis. The ascites had a low serum-ascites albumin gradient, and laparoscopy showed peritoneal implants that grew Coccidioides immitis. This case is unique in several ways; this is the first case in which a patient's acquired immunodeficiency syndrome-defining illness was peritoneal coccidioidomycosis, and the serum-ascites albumin gradient determination as well as laparoscopy provided information critical to the diagnosis. This patient's dramatic response to systemic antifungal therapy, as evidenced by resolution of ascites and constitutional symptoms, underscores the importance of timely diagnosis and prompt therapy. In summary, this report reviews the previous cases of coccidioidal peritonitis and reports the first case in which localized peritoneal coccidioidomycosis was the acquired immunodeficiency syndrome-defining illness in a human immunodeficiency virus-infected patient.

Effect of an arginine-glycine-aspartic acid-containing peptide on hematogenous candidal infections in rabbits

The adherence of Candida albicans yeast cells to the subendothelial extracellular matrix, fibronectin, laminin, and type I and IV collagen was tested. Fibronectin (10(-7) M) and a peptide, PepTite-2000 (Telios Pharmaceuticals Inc., San Diego, Calif.), containing the sequence arginine-glycine-aspartic acid (RGD) inhibited Candida adherence to these targets by greater than 90%. When C. albicans was perfused over ex vivo rabbit aortic endothelium, there was no significant difference in the amount of adherence in the presence or absence of the RGD-containing peptide. However, the RGD-containing peptide reduced the number of Candida organisms present in liver, brain, heart, and kidneys (P less than 0.05) of rabbits 4 h after intravenous inoculation of 5 x 10(7) C. albicans yeast cells. The peptide also reduced the number of macroscopic Candida abscesses in the kidneys of rabbits 72 h after intravenous inoculation of 10(7) C. albicans yeast cells (P less than 0.05). Inhibition of Candida adherence in vitro and in vivo may occur because the peptide blocks a fungal receptor that is necessary for adherence.

Fungal adherence to the vascular compartment: a critical step in the pathogenesis of disseminated candidiasis

The importance of adherence of Candida albicans to the vascular structures in the pathogenesis of disseminated candidiasis is discussed. The evidence for adherence of this fungus to endothelial cells and to the subendothelial basement membrane in vivo is reviewed, as are the data documenting these events in vitro. Information on the subcellular interactions of the host's vascular structures with this pathogen is presented. For example, the C. albicans surface receptors for iC3b, laminin, and fibronectin are discussed in light of their possible ability to mediate the adherence of the fungus to vascular structures. The review is concluded with a potentially unifying concept of integrin-like receptors on Candida that bind arginine-glycine-aspartic acid-containing peptides that may account for the binding of numerous human proteins to C. albicans.

Preventing transmission of infectious diseases including the human immunodeficiency virus in the practice of optometry

The risks of acquisition of infectious diseases including the human immunodeficiency virus--1 (HIV) to practitioners and patients in the practice of optometry is discussed. Measures that reduce the risk of contracting or transmitting HIV and other infectious diseases in optometry are presented. Effective disinfection including that for HIV are discussed.

A fibronectin receptor on Candida albicans mediates adherence of the fungus to extracellular matrix

Binding of fibronectin, an extracellular matrix (ECM) protein, to Candida albicans was measured, and adherence of the fungus to immobilized ECM proteins, fibronectin, laminin, types I and IV collagen, and subendothelial ECM was studied. 125I-labeled fibronectin was inhibited from binding to the fungus by unlabeled human plasma fibronectin and by Arg-Gly-Asp (RGD), Gly-Arg-Gly-Glu-Ser-Pro (GRGESP), and Gly-Arg-Gly-Asp-Thr-Pro (GRGDTP), but binding was not inhibited by Gly-Arg-Gly-Asp-Ser-Pro. Soluble fibronectin, RGD, GRGESP, and GRGDTP also inhibited fungal adherence to the individual immobilized ECM proteins in a complex pattern, but only soluble fibronectin (10(-7) M) inhibited fungal adherence to subendothelial ECM. Thus, C. albicans possesses at least one type of cell surface receptor for binding soluble fibronectin that can be inhibited with peptides. This receptor apparently is used to bind the fungus to immobilized ECM proteins and to subendothelial ECM and may play a role in the initiation of disseminated disease by bloodborne fungi by providing for adherence of the microorganisms to ECM proteins.

Contact lens surface deposits increase the adhesion of Pseudomonas aeruginosa

Soft contact lenses are bathed with tear components during wear and surface deposits accumulate. This report shows that Pseudomonas aeruginosa adheres to the surface of worn extended wear contact lenses in direct proportion to the amount of lens surface deposits as determined by the Rudko method (P less than .05). More hydrophobic bacteria adhered 10 times greater than bacteria which were relatively hydrophilic (P less than .005). The effect upon bacterial adhesion of enzyme and surfactant cleaning of worn extended wear contact lenses was investigated by two independent methods: one involving a high inoculum and the other a low inoculum of Pseudomonas. Treatment of worn lenses with commercially available enzymes such as papain and pork pancreatin as well as treatment with neuraminidase, mannosidase, glucosidase and alkylcarboxylic acid for as long as 48 hours failed to reduce subsequent bacterial adhesion in both the high and low inoculum experiments. We conclude that soft contact lens surface deposits are a major determinant in the adhesion of Pseudomonas aeruginosa to the worn lens surface and that enzyme cleaning of worn lenses does not significantly reduce bacterial adhesion.

Contact lens wear enhances adherence of Pseudomonas aeruginosa and binding of lectins to the cornea

Extended wear soft contact lenses are associated with an increased incidence of Pseudomonas aeruginosa keratitis. Because the first step in the pathogenesis of this disease is adherence of the microorganism to the corneal surface, we studied the effect of soft contact lens wear on the adherence of P. aeruginosa to the cornea. Rabbits were fitted for extended wear soft contact lenses in the left eye, and the right eye served as a control. Both eyes were then closed with a partial tarsorrhaphy. After 1-5 days of wear, the lenses were removed and the corneas of the left and right eye were removed. Differences in the number of adherent Pseudomonas and in lectin binding to lens-wearing corneas and non-lens-wearing corneas were determined. After 1, 3, and 5 days of soft contact lens wear, there was a significant increase in the number of P. aeruginosa adherent to the lens-wearing cornea. Three to eight times as many bacteria adhered to the lens-wearing eye as compared with the control eye (p less than 0.05). In addition, a soft contact lens placed in the eye followed by the immediate application of P. aeruginosa resulted in an eightfold increase in adherence of bacteria to the lens-wearing cornea (p less than 0.05). Lens wear also led to an increase in binding of concanavalin A (Con A), wheat germ agglutinin (WGA), and Maclura pomifera agglutinin (MPA) to surface epithelium covered by the lens. These corneal epithelial changes induced by extended wear soft contact lenses may provide some insight as to why soft contact lens wearers are predisposed to Pseudomonas keratitis.

Adherence of Candida albicans to components of the subendothelial extracellular matrix

Candida albicans yeasts adhered avidly to extracellular matrix (ECM) proteins, type IV collagen, laminin, and fibronectin immobilized on plastic. Type IV collagen showed an increase of adherence of 400% above control values; laminin, 300%; and fibronectin, 150%. In addition, all three (in quantities of 0.02-200 micrograms/well of a culture tray) bound yeasts in a dose-response fashion. Adherence was inhibited when the proteins were preincubated with specific antibody, except with type IV collagen. Soluble laminin or fibronectin inhibited yeast adherence to the same proteins by 36 and 94%, respectively. Soluble fibronectin bound to the yeast surface and in so doing inhibited subsequent yeast adherence to fibronectin by 66%. By comparison, Candida albicans yeasts adhered in smaller numbers to glycosaminoglycans (GAGs). Keratan sulfate, hyaluronic acid, chondroitin sulfate, Type B, and heparin actually decreased yeast adherence compared to control from 10% to 25%.

Aggregated platelets enhance adherence of Candida yeasts to endothelium

The adherence of Candida albicans yeasts to human umbilical vein endothelium to subendothelial extracellular matrix (ECM) was investigated. Yeasts added to confluent endothelium in citrated platelet-poor plasma adhered on the average of 1 colony forming unit (cfu) per culture well. When platelets were added as platelet-rich plasma, a significant increase of yeast adherence was not seen. However, when endothelium was contracted by treatment with 2 mM EDTA, resulting in exposure of ECM, yeast adherence was increased to 10 cfu/well. When platelets were added with these yeasts, the number of adhering yeasts was further increased to 23 cfu/well (P less than .01). This represented an increase in adherence of yeasts of 230%. When the endothelial cells were completely removed and ECM exposed, platelets were found to likewise augment yeast adherence. Platelets, when added to the ECM, formed aggregates to which the yeasts firmly adhered. Likewise, when platelets were aggregated by adenosine diphosphate and mixed with yeasts, yeasts were shown to bind avidly to aggregated platelets, whereas yeasts did not adhere to unactivated, discoid platelets. Thus, exposed subendothelial ECM induces the aggregation of platelets and yeasts bind avidly to these platelet aggregates.

Surface-active properties of Candida albicans

Cell surface hydrophobicity may be an important factor contributing to the virulence of Candida yeast cells. Surface hydrophobic and surface polar groups would be required for a yeast cell to act as a surface-active agent. In this report, the surface activities of whole yeast cells were measured. Yeast cells added at 10(8)/ml reduced the surface tension (gamma s) of saline by 20% as determined by the du Nouy method. A 1% suspension of yeast cell wall fragments reduced gamma s of saline by 36%. Whole yeast cells caused a reduction in interfacial tension (gamma I) between hexadecane and saline. The reduction of gamma I was proportional to the surface hydrophobicity of the yeasts. Yeast cells grown in glucose as the sole carbon source (thus possessing a relatively more hydrophilic cell surface) reduced gamma I by 30%, whereas yeast cells grown in hexadecane (thus possessing a more hydrophobic cell surface) reduced gamma I by 41%. The reduction of gamma I was reversed upon the addition of a strong surfactant. It was also demonstrated that yeast cells blended with nonionic surfactants during growth in a glucose broth in order to change their cell surface hydrophobicity adhered to solid surfaces in direct proportion to their cell surface hydrophobicity. Thus, the surface-active properties of Candida yeast cells may significantly contribute to the accumulation of yeast cells at various biological interfaces such as liquid-solid, liquid-liquid, and liquid-air, leading to their eventual adhesion to solid or tissue surfaces.

A partial-thickness epithelial defect increases the adherence of Pseudomonas aeruginosa to the cornea

Some patients with infectious keratitis have no clinically demonstrable corneal abrasion predisposing them to infection. Subtle, undetectable corneal injuries may facilitate bacterial adherence to the cornea, eventually leading to keratitis. To study this concept, we have developed a rabbit model in which a partial-thickness corneal epithelial defect was induced by filter paper impression on the cornea that removed one to two layers of corneal epithelium. Following this injury, the corneas were incubated with Pseudomonas aeruginosa, washed, and the number of bacteria adhering to the injured corneas as well as to control corneas was quantitated. Corneas treated with filter paper, either ex vivo or in vivo, allowed 20 times more bacteria to adhere than did the untreated control corneas (P less than 0.01). This superficial epithelial defect increased Pseudomonas adherence to the cornea for up to 72 hr after injury. When corneal injury was extended to the stroma, the adherence of Pseudomonas was further augmented as compared to adherence to the superficially injured cornea. Thus, we conclude that a clinically subtle, partial-thickness corneal epithelial injury can markedly facilitate the adherence of Pseudomonas aeruginosa, which may be an important predisposing factor for infectious keratitis.

Malassezia furfur

Malassezia furfur is a saprophytic fungus that is part of the normal cutaneous microflora of adults. It frequently causes tinea versicolor and less often, a distinctive folliculitis. In infants and occasionally in adults the fungus is associated with a sepsis syndrome that heralds a deep-seated infection. These entities, their diagnosis, and their treatment are discussed.

The contribution of bacterial surface hydrophobicity to the process of adherence of Pseudomonas aeruginosa to hydrophilic contact lenses

Ten isolates of Pseudomonas aeruginosa obtained from the corneas of patients with Pseudomonas keratitis adhered to soft contact lenses in significantly greater numbers than did six isolates from other body sites (P less than .05). However, there was no predominant serotype among the 10 corneal isolates tested. Isolates grown statically in broth at 37 degrees C formed a pellicle and adhered two times as much to contact lenses as did isolates grown in broth while shaking which did not form a pellicle (P less than .01). The more adherent isolates (grown at 37 degrees C) were shown to be more hydrophobic than the less adherent bacteria (grown at 26 degrees C) by their propensity to accumulate at the interface between hexadecane and saline and their movement into polyethylene glycol from dextran. These corneal isolates agglutinated erythrocytes, a process that was inhibited by dilute solutions (as low as 0.01%) of three commonly used surfactants. These same surfactants inhibited the adherence of Pseudomonas aeruginosa to soft contact lens surfaces by as much as 52%. It is concluded that hydrophobic interactions may significantly contribute to the ability of Pseudomonas aeruginosa to adhere to contact lenses.

Factitious meningitis: a recurring problem

Although gram-negative meningitis is rare in our hospital, between July, 1982 and July, 1983 clusters of cerebrospinal fluid (CSF) smears were reported positive for gram-negative bacilli. Fourteen specimens were obtained by diagnostic lumbar punctures, and one was obtained during a myelogram. No CSF cultures were positive, and a diagnosis of factitious meningitis was eventually established for each patient. Nonviable gram-negative bacilli were found in 6.7% of manometers, and 23.3% to 90% of the specimen tubes tested from the same lots of commercial lumbar puncture trays. It was estimated that there were between 44 and 333 organisms per specimen tube. Two lots of the commercial myelogram trays yielded nonviable gram-negative bacilli from 50% of the specimen tubes and 33.3% of the manometers tested. Retrospective review of laboratory records for 1982 and 1983 revealed 23 total CSF smears positive for gram-negative bacilli. No CSF grew gram-negative bacilli, and chart reviews confirmed a diagnosis of factitious meningitis in each case. In addition to the clusters of false-positive smears, this had occurred sporadically in both years. The problem did not recur after separate sterile tubes were provided for CSF collection. Physicians and laboratories should be aware that nonviable contaminants in commercial products may be a source of false-positive CSF gram-stained smears.

Enhancing recovery of Francisella tularensis from blood

Francisella tularensis may be isolated with the BACTEC 460 blood culture system even though bottles may not meet the established criteria for recognizing positive blood cultures. We describe three proven bacteremic cases in which growth indices were not positive, gram stain of broth showed no microorganisms but F. tularensis grew on chocolate agar culture.

Endothelial cell contraction increases Candida adherence to exposed extracellular matrix

Bovine vascular endothelial cells treated with EDTA, urea, or thrombin underwent a marked, reversible contraction resulting in exposure of the subendothelial extracellular matrix (ECM). Candida yeasts adhered more to contracted monolayers than to confluent monolayers (P less than 0.01) by preferentially adhering to the ECM. Two strains of Candida albicans and one strain of Candida tropicalis bound avidly to exposed ECM, but Pseudomonas aeruginosa did not. However, treatment of endothelium with forskolin, which induces cell shape changes without exposure of the ECM, did not cause an increase in adherence.

Clinical differentiation of abscess from neoplasm in newly diagnosed space-occupying lesions of the liver

The clinical presentations of liver abscess, hepatoma, and metastatic tumor to the liver may be quite similar, and procedures such as computerized tomography, radionuclide scanning, and ultrasonography of the liver cannot make a specific diagnosis. Therefore, we compared the clinical presentations of 38 patients seen during the last five years with liver abscess (13 patients), hepatoma (eight patients), and undifferentiated carcinoma metastatic to the liver (17 patients). Patients with liver abscess were distinguished from the other two groups by a significantly shorter prodrome, a history of known risk factors for liver abscess, fever, leukocytosis, and a normal-sized liver (P values all less than .1). A finding of three or more of these criteria correctly identified all cases of liver abscess. Only one of the 25 patients with neoplasms had three of the criteria. The presence of multiple or single lesions, abdominal pain, weight loss, or liver function abnormalities did not differ significantly among the three groups. Thus patients with liver abscess can be reliably differentiated from patients with hepatic neoplasms by clinical criteria alone, and appropriate empiric antibiotic therapy can be started while the diagnosis is being confirmed.

Acid-fast staining of urine and gastric contents is an excellent indicator of mycobacterial disease

It is a commonly held opinion that acid-fast staining of urine or gastric aspirates is not a reliable indicator of mycobacterial disease because of the presence of saprophytic mycobacteria. In order to determine the clinical usefulness of acid-fast staining of these body fluids, we reviewed our 10-yr experience with acid-fast stains. Forty-seven of 5,829 urine specimens (0.8%) and 39 of 309 gastric aspirates (12.6%) yielded mycobacteria on culture. Twenty-three urine specimens and 12 gastric aspirates had positive acid-fast stains. Of these, only one possible false positive acid-fast stain of urine (less than 1%) was found and none was found in gastric aspirates. Thus, acid-fast stains of urine and gastric aspirates are, when positive, reliable indicators of true mycobacterial disease.

The adherence of Pseudomonas aeruginosa to soft contact lenses

The adherence of Pseudomonas aeruginosa to extended-wear soft contact lenses (EWSCLs) may be an important initial step in the pathogenesis of EWSCL-associated infectious keratitis. P. aeruginosa tend to adhere more to worn EWSCLs than unworn EWSCLs (P less than 0.05). Normal tear components such as aqueous solutions of albumin, lysozyme, and lactoferrin all significantly enhance adherence of P. aeruginosa to unworn EWSCLs often by as much as 300%. The presence of a 1% solution of sialic acid in the bathing medium significantly reduces the adherence of P. aeruginosa to both unworn and worn lenses. Inhibition of bacterial adherence could also be achieved with the addition of mucin (which contains terminal sialic acid residues in its major sugar chains). Therefore, selective adherence by P. aeruginosa to a specific sugar (sialic acid) may be important in the initial attachment of the bacterium to soft contact lenses.

Carbohydrate deposits on the surfaces of worn extended-wear soft contact lenses

Three different commercial extended-wear soft contact lenses worn continuously by patients for at least 28 days were stained with fluorescein isothiocyanate-labeled lectins. These lectins detected the presence of alpha-linked or beta-linked D-mannose, D-glucose, D-galactose, L-fucose, N-acetyl-D-glucosamine, N-acetyl-D-galactosamine, and N-acetyl neuraminic acid (sialic acid) on the surfaces of the contact lenses. These saccharides are bound to other sugars that likely account for an integral part of glycoprotein and/or glycolipid deposits on lens surfaces. These tear deposits may contribute to the chemical spoilage of the lens and, furthermore, may serve as specific receptors for pathogenic microorganisms commonly implicated in extended-wear soft contact lens-associated infectious keratitis.