Performance of the NG OligoGen kit for the diagnosis of Neisseria gonorrhoeae: comparison with cobas 4800 assay

PCR assays are nowadays between the most sensitive and reliable methods for screening and diagnosing sexually transmitted infections (STIs). The aim of this study was to analyze the reliability, accuracy, and usefulness of the new NG OligoGen kit in comparison with the cobas 4800 assay for the detection of Neisseria gonorrhoeae in clinical samples. A prospective study was designed for detection of N. gonorrhoeae including urine samples (n=152), rectal (n=80), endocervical (n=67), pharyngeal (n=41), and urethral swabs (n=5) that were sent from a regional STI clinic in Seville, Spain. Samples were collected from 255 (73.9%) men and 90 women. Sensitivity, specificity, positive and negative predicative values, and kappa value for N. gonorrhoeae detection using the NG OligoGen kit were 99.6%, 100%, 100%, 99.1%, and 0.99, respectively. Statistical data obtained in this study confirm the usefulness and reliable results of this new assay.

Evaluation of the Etest method for susceptibility testing of Aspergillus spp. and Fusarium spp. to three echinocandins

We performed Etest and broth microdilution (BMD) susceptibility testing of caspofungin, micafungin and anidulafungin against 67 clinical isolates of Aspergillus spp. and 10 Fusarium spp. Minimal effective concentrations (MECs) by BMD were read after 24 h of incubation at 35 degrees C and Etest MICs were read at 24 and 48 h. MECs < or =0.25 mg/l were obtained with caspofungin for all Aspergillus spp. tested but Etest MICs were < or =1 mg/l at 24 h. The agreement between caspofungin Etest and broth microdilution was good for all Aspergillus species tested (range 82.4-100%) except for A. niger and A. glaucus at 24 h of incubation. Micafungin and anidulafungin MEC and MIC results were lower than those of caspofungin (< or =0.015 mg/l) at 24 and 48 h for all Aspergillus tested. The agreement between the methods was excellent (100%) for micafungin and anidulafungin for all Aspergillus species tested. The three echinocandins were inactive against all isolates of Fusarium spp. showing MECs and MICs >8 mg/l. The Etest method could be a suitable procedure to test the susceptibility of most Aspergillus species to caspofungin, micafungin and anidulafungin; the best agreement was at 24 h.

Comparative study of disc diffusion and microdilution methods in susceptibility testing of micafungin against Candida species

OBJECTIVES

To compare the Clinical Laboratory Standards Institute CLSI M44-A disc diffusion (DD) and M27-A2 broth microdilution (MD) methods for determining the susceptibility of Candida spp. to micafungin (FK463).

PATIENTS AND METHODS

A total of 355 clinical yeast isolates including 270 Candida albicans, 45 Candida glabrata, 24 Candida krusei, 11 Candida tropicalis and 5 Candida parapsilosis were studied. The MIC of micafungin was determined by following the CLSI M27-A2 guidelines (MD). Endpoints were defined as the lowest concentration of micafungin resulting in partial inhibition (IC(50)) of visual growth after 24/48 h of incubation at 35 degrees C. Final concentrations were 0.008-4 mg/L of micafungin. DD testing was performed using a CLSI M44-A document with 2.5 mug micafungin discs. Zone diameter endpoints were read after 24/48 h of incubation at 35 degrees C. Arbitrary breakpoints were 4 mg/L for MD and 15 mm for DD.

RESULTS

The best correlation was observed when we read MD 48 h/DD 24 and 48 h (97%). When the reading was MD 24 h/DD 24 and 48 h the percentage of correlation was 95.2%.

CONCLUSIONS

The DD method performs well for testing the susceptibility of Candida spp. to micafungin. More studies involving more Candida strains with elevated MIC values are needed.

Evaluation of disk diffusion method for determining posaconazole susceptibility of filamentous fungi: comparison with CLSI broth microdilution method

The disk diffusion method was evaluated for determining posaconazole susceptibility against 78 strains of molds using two culture media in comparison with the CLSI (Clinical Laboratory Standards Institute) broth microdilution method (M38-A). A significant correlation between disk diffusion and microdilution methods was observed with both culture media.

A comparative study of the disc diffusion method with the broth microdilution and Etest methods for voriconazole susceptibility testing of Aspergillus spp

OBJECTIVE

The activity of voriconazole against Aspergillus spp. (n = 77) was tested by the Etest, disc diffusion and the NCCLS M38-A methods.

METHODS

Four Rhizomucor spp. isolates were included to study the suitability of the three susceptibility testing methods to detect isolates resistant to voriconazole. The disc diffusion method performed on Mueller-Hinton agar (Difco) supplemented with 2% glucose and Methylene Blue (0.5 mg/L) gave zone diameters with very clear border edges.

RESULTS

The disc diffusion method showed excellent correlation with the Etest and the NCCLS methods.

CONCLUSION

On the basis of our results, it appears that the disc diffusion test is a useful method for testing the activity of voriconazole against Aspergillus spp.

Determinación del genotipo del virus de la hepatitis B y detección de mutaciones de resistencia al tratamiento con lamivudina

OBJECTIVES

To determine hepatitis B virus (HBV) genotypes in southern Seville (Spain) and investigate the development of lamivudine-resistance mutations by using a hybridization technique with specific probes and by comparing the results with those of the direct sequencing technique. To evaluate the temporal relationship between variations in the level of HBV-DNA and detection of mutant variants. To analyze the influence of several genotypes on the pattern of mutations developed and on values of viral load and alanine aminotransferase (ALT) after their development.

PATIENTS AND METHOD

In 37 patients with chronic HBV infection, HBV genotype was determined using the LiPA technique. In 10 of these patients undergoing lamivudine treatment for a mean of 19.2 months, the development of lamivudine-resistant mutations was investigated. In these 10 patients, the LiPA technique was compared with direct sequencing. During lamivudine treatment, we determined HBV-DNA by polymerase chain reaction (PCR) and ALT every 3-6 months.

RESULTS

The most frequent genotypes were D (45.9%) and A (18.9%); 2 patients were genotype B while 18.9% had mixed genotypes. Sequencing showed identical results except in one mixed genotype. Mutations were found in 60% of the cases. The results of sequencing were in agreement, except in the detection of mixed populations composed of mutants and wild-type (WT). Patients with genotype A showed the pattern M204I+WT in the first 12 months and those with genotype D showed the pattern L180M+M204V with or without WT at 18 months. In 5/6 cases, an increase of > 1 log10 in HBV-DNA was observed 3-8 months before the mutation was detected by LiPA. In patients with genotype B, levels of HBV-DNA and ALT after the development of mutations was lower than basal levels and was also lower than those in patients with genotypes A and D.

CONCLUSIONS

The LiPA technique for determination of HBV genotype and detection of lamivudine-resistance mutations shows excellent correlation with the most complex sequencing technique. Genotype D predominates in southern Seville. During lamivudine treatment, an increase in the level of HBV-DNA detected by PCR predicts the development of mutations before these are demonstrated by LiPA.

[Epidemiological study of cryptococcosis in Spain: first results]

The study constitutes an approach to the knowledge of the epidemiology of cryptococosis in Spain. For detection of cases 167 Spanish hospitals were contacted. All cases included were accompanied by the correspondent isolate of Cryptococcus neoformans, together with clinical, demographic and mycological data. Results obtained from January 1998 to end of December 1999 are analysed and presented here. Fifty-six Spanish hospitals reported 58 cases of cryptococcosis; only 43 of them were adequately documented and accompanied by the clinical isolate. The results showed a higher incidence in males (88.4%) than in females (11.6%); being most frequently affected those between 30 and 40 years old (48.8%). The 84.6% (33) corresponded to new cases and 15.4% (6) to relapses of the disease. The HIV infection was the most frequent risk factor reported (86%) and, for 29.7% (11) of them, cryptococcosis was the AIDS defining disease. For the diagnosis, CSF analysis showed the best results (India ink; culture and antigen detection). All strains collected (100%) corresponded to C. neoformans variety neoformans. Serotypes distribution was 45.5% for serotype A and 22.7% for each of serotypes D and AD.

[Evaluation of a new chromogenic medium (Candida ID) for the isolation and presumptive identification of Candida albicans and other medically important yeasts]

Candidiasis is a frequent human infection caused mainly by Candida albicans. However, other species are emerging as important pathogens, as Candida glabrata, Candida parapsilosis, Candida tropicalis, Candida krusei or Candida guilliermondii. Rapid identification of clinical isolates could facilitate diagnosis and treatment. Candida ID (bioMerieux, Spain) is a new medium for the isolation and presumptive identification of yeasts: C. albicans grows as blue colonies, and C. tropicalis, C. guilliermondii, Candida kefyr and Candida lusitaniae as pink ones. The utility of Candida ID was evaluated with more than 700 clinical isolates and type culture collection strains from different genera including Candida, Cryptococcus, Saccharomyces, and Rhodotorula. Presumptive identification was confirmed by germ tube test, microscopic morphology and chlamydoconidia production on corn meal agar and carbohydrate assimilation on API-ATB ID 32C or Vitek (bioMerieux). Growth on Candida ID was rapid (18-24 h) for most of the yeast strains tested. Sensitivity and specificity of identification of C. albicans was significantly high (>98%), since a very low number of isolates were found to be false negative or false positive. A better result was obtained for species growing as pink colonies (>99.5%). Detection of different species of medical important yeasts was easy with Candida ID, as perfectly distinct colors and textures of colonies were observed on this medium. Candida ID allowed the discrimination between C. glabrata (creamy and smooth) and C. krusei (rough and white) colonies. Other species showed different colony textures and colours, white being the predominant colour. Candida ID was very useful for the presumptive identification C. albicans isolates.

Comparison of the Etest and microdilution method for antifungal susceptibility testing of Cryptococcus neoformans to four antifungal agents

We performed a prospective study to compare the Etest and the microdilution method (NCCLS guidelines) for determining the MICs of fluconazole, itraconazole, flucytosine and amphotericin B for 35 strains of Cryptococcus neoformans. For the microdilution method (MDM) RPMI 1640 medium with 2% glucose was used for fluconazole, itraconazole and flucytosine, and Antibiotic Medium 3 for amphotericin B. For the Etest, RPMI 1640 medium with 2% glucose and solidified with 1.5% agar was used for the four antifungal agents. Amphotericin B was also tested on Antibiotic Medium 3 solidified with 1.5% agar. Fluconazole and flucytosine MICs by the Etest showed good correlation with the broth MDM (81.1 and 89.2% agreement within two dilutions, respectively). With the tested population of itraconazole- and amphotericin B-susceptible isolates, the MIC agreement for itraconazole was 54%; amphotericin B showed the lowest agreement (8.1% on Antibiotic Medium 3 and 13.5% on RPMI).

In vitro susceptibility of Candida dubliniensis to current and new antifungal agents

BACKGROUND

Candida dubliniensis is a recently described Candida species closely related to Candida albicans, which has been associated with oral candidiasis in HIV-infected patients. Fluconazole-resistant strains of C. dubliniensis are easily obtained in vitro and this fact could be a complication if this resistance develops during treatment with this drug.

METHODS

In the present study, the in vitro antifungal susceptibilities of 36 C. dubliniensis clinical isolates and culture strains to current and new antifungal agents, such as amphotericin B (AMB), amphotericin B lipid complex (ABLC), amphotericin B colloidal dispersion (ABCD), 5-fluorocytosine (5FC), fluconazole (FLC), itraconazole (ITC), ketoconazole (KTC), liposomal amphoteri- cin B (LAMB), liposomal nystatin (LNYT), LY303366 (LY), SCH56592 (SCH), and voriconazole (VRC), were determined according to the National Committee for Clinical Laboratory Standards M27-A broth microdilution method for yeasts.

RESULTS

Most isolates of C. dubliniensis were susceptible to both new and current antifungal drugs, with 75.9% isolates susceptible to KTC, 86.2% to FLC and to ITC, and approximately 100% to the other antifungal agents tested. The cross-resistance phenotypes are detailed. Four isolates were resistant (MIC > or =64 microg/ml) to FLC. These 4 isolates were also resistant to KTC, and 3 of them were also resistant to ITC (MIC > or =1 microg/ml for both agents). However, these isolates were highly susceptible to 5FC and all polyene formulations (AMB, ABLC, ABCD, LAMB, and LNYT), triazole (SCH and VRC) and echinocandin (LY) antifungal agents.

CONCLUSION

The new liposomal and lipidic formulations of AMB, LNYT, and the new triazoles and echinocandins may provide new alternatives to FLC for the treatment of infections by C. dubliniensis.

[Incidence of genitourinary infection caused by Chlamydia trachomatis in a STD center calculated by direct antigen detection]

OBJECTIVE

Chlamydia trachomatis is one of the most common sexually transmitted agents which causes a wide spectrum of diseases including urethritis in men and endocervicitis in women. We analyzed patients with genitourinary C. trachomatis infections evaluating risk factors and the association with other sexually transmitted infections.

MATERIAL AND METHODS

We processed 1,180 specimens from 913 patients (772 women and 141 men), attended at a Sexually Transmitted Diseases (STD) Center. The diagnostic of C. trachomatis infection was made by an enzyme-linked fluorescent immunoassay, Vidas Chlamydia test (bioMérieux).

RESULTS

The incidence of C. trachomatis infection was 4.8% (57 cases) and was higher in women (70.1%) than in men (29.8%). The risk groups observed were: 26 prostitute, 7 contact with prostitute or risk partner, 5 homosexual, 5 promiscuous heterosexual and 14 without risk groups. Associated with this infection we observed other: 10 bacterial vaginosis, 8 Papillomavirus infection, 3 Trichomonas vaginalis infections, 2 Neisseria gonorrhoeae infections and 2 Candidiasis. The 53.4% of these patients didn't have any symptomatology at the consult moment.

CONCLUSIONS

The control of patients with risk factors is important for the diagnostic of C. trachomatis and other sexually transmitted infections, because most of them were prostitutes and asymptomatic. Within men, homosexuality, contact with prostitute or risk partner were the practices with higher risk.

[In vitro activity of a liposomal nystatin formulation (Nyotran) against Cryptococcus neoformans]

The in vitro antifungal activity of a new liposomal nystatin formulation (NISTL, Nyotran, Aronex Ltd., EE.UU.) was evaluated by a microdilution method with RPMI based on the M27A document of the National Committee for Clinical Laboratory Standards (NCCLS) against 22 isolates of Cryptococcus neoformans. This antifungal activity was compared with those of other seven antifungal agents, such as nystatin (NIST), amphotericin B deoxycholate, liposomal amphotericin B, amphotericin B lipid complex, amphotericin B colloidal dispersion, fluconazole, and itraconazole. NISTL was more active in vitrothan NIST, showing MIC values 2-3 fold smaller in 90% of the isolates. The results obtained suggest that this new formulation would be very helpful for the treatment of cryptococcosis.

Multicenter evaluation of Neo-Sensitabs, a standardized diffusion method for yeast susceptibility testing

The agar diffusion method Neo-Sensitabs for sensitivity testing, was evaluated with 33 reference strains by fourteen laboratories. Tablets with 5-fluorocytosine, amphotericin B, nystatin, fluconazole, itraconazole, ketoconazole and tioconazole were used on Shadomy modified medium. These tests classify each strain as susceptible, intermediate or resistant to all tested antifungals by measuring the inhibition zone diameters. Intra and interlaboratory reproducibility was studied. Neo-Sensitabs sensitivity for fungi was easy to perform and reliable method with a reproducibility of 97.1% and superior to other commercialized methods, being specially interesting for antifungal susceptibility in vitro testing of triazole derivatives fluconazole and itraconazole.

Multicenter survey of in vitro antifungal resistance in yeasts of medical importance isolated from Spanish patients

Twelve Spanish laboratories collected 325 yeast clinical isolates during a 30 day's period, among them 224 Candida albicans, 30 Candida glabrata, and 27 Candida parapsilosis. In vitro antifungal susceptibility to amphotericin B, ketoconazole, fluconazole and itraconazole was determined by an agar diffusion test (Neo-Sensitabs, Rosco, Denmark). All the isolates tested were susceptible in vitroto amphotericin B and nearly all (97.2%) to itraconazole. In vitrosusceptibility to fluconazole and ketoconazole was high (90.2% and 91.4% of isolates, respectively) but showed variations depending on the species tested. Resistance to fluconazole and ketoconazole was low in C. albicans (4% and 3%, respectively), but 30% of Candida guilliermondii and 36% of C. glabrata isolates were resistant to fluconazole. Ketoconazole resistance was observed in 40% of C. glabrata, and 17% of Candida tropicalis. Resistance to antifungal drugs is very low in Spain and it is related to non-C. albicans isolates.

A comparative evaluation of Etest and broth microdilution methods for fluconazole and itraconazole susceptibility testing of Candida spp

The Etest strip is a promising tool of broad application in clinical microbiology. The method provides MIC readings and is easier to perform than broth microdilution. We carried out a study to compare the MICs of fluconazole and itraconazole obtained by the Etest with those obtained by broth microdilution, performed according to the guidelines of the NCCLS document M27-A, with 402 clinical isolates (360 Candida albicans, 17 Candida tropicalis, nine Candida krusei, nine Candida glabrata and seven Candida parapsilosis) and seven control isolates. The agreement between MICs by the two methods (at +/- 2 dilutions) was 74.5% for fluconazole and 61.4% for itraconazole. These results suggest that further development is necessary to standardize the medium and incubation conditions before introduction of the Etest as a routine method in the clinical microbiology laboratory for fluconazole and itraconazole susceptibility testing.

[Seroepidemiologic study of human herpesvirus-6 in intravenous drug addicts, with and without infection caused by human immunodeficiency virus type 1]

BACKGROUND

The human herpesvirus-6 (HHV-6) may be a cofactor of infection by the human immunodeficiency virus type 1 (HIV-1). However, there are discrepancies with respect to the possible epidemiological relation between both viruses. The aim of the present study was to study the prevalence of infection by the HHV-6 in intravenous drug addicts (IVDA) with and without HIV-1 infection.

METHODS

IgG antibodies vs HHV-6 (anti-HHV-6-IgG) were determined by indirect immunofluorescence in 100 IVDA (29 seronegative and 71 seropositive for HIV-1 of which 45 were in stage II and 26 in IV-C1 of CDC) as well as in 100 healthy subjects of a similar age (control group).

RESULTS

The prevalence of anti-HHV-6-IgG was much higher in the whole group of IVDA than in the control group and was equal in the IVDA with HIV-1 infection and in those patients without infection. There was no significant difference between the latter and the control group with the same being seen between the IVDA in different stages of HIV-1 infection.

CONCLUSIONS

The results of this study suggest the existence of an epidemiological relation between human herpes virus-6 (HHV-6) infection and human immunodeficiency virus -1 (HIV-1). However, infection by the HHV-6 has no relation with the evolutive degree of the HIV-1 infection nor with intravenous drug addiction.