Biomedical subjects

T Peláez

Publications and source records attributed to T Peláez.

At least 19 recordsLinked to original sources

PubMed2006

Fluconazole resistance mechanisms in Candida krusei: the contribution of efflux-pumps.

The main resistance mechanism for fluconazole in Candida krusei is the diminished sensitivity of the target enzyme cytochrome P450 sterol 14 alpha-demethylase (CYP51) to inhibition by azole agents. An alternative mechanism of resistance, efflux-pump activity, has been proposed. The aim of our study was to find out the possible contribution of efflux-pumps in conferring resistance to fluconazole in 33 C. krusei isolates from different clinical sources. The activity of efflux-pumps was checked using the inhibitor CCCP (carbonyl cyanide 3-chloro-phenylhydrazone), which decreases the minimum inhibitory concentration (MIC) when resistance is attributed. We established a concentration of 0.5 microg/ml of CCCP. The susceptibility patterns of our isolates for five antifungal drugs (amphotericin B, fluconazole, itraconazole, flucytosine and voriconazole) were determined according to an NCCLS M27-A2 protocol modification (Sensititre Yeast One). We tested all the strains before and after adding CCCP to the RPMI medium. The MIC90s and ranges of the drugs were identical before and after addition of CCCP. The MIC for fluconazole was higher than for the other antifungals. The new triazoles were active and the MICs were lower, although this should be interpreted carefully as the drugs showed different cut-offs. Only one isolate showed a two-fold decrease in MIC to fluconazole when CCCP was added. We did not find any multi-resistant strains. According to our study with C. krusei, CCCP-inhibited efflux-pumps do not play a significant role in resistance to fluconazole.

ATP-Binding Cassette Transporters↗

PubMed2005

An improved protocol for pulsed-field gel electrophoresis typing of Clostridium difficile.

Pulsed-field gel electrophoresis (PFGE) is the 'gold standard' technique for bacterial typing and has proved to be discriminatory and reproducible for typing Clostridium difficile. Nevertheless, a high proportion of strains are non-typable by this technique due to the degradation of the DNA during the process. The introduction of several modifications in the PFGE standard procedure increased typability from 40% (90 isolates) to 100% (220 isolates) while maintaining the high degree of discrimination and reproducibility of the technique.

Bacterial Typing Techniques↗

PubMed2005

Toxigenic status of Clostridium difficile in a large Spanish teaching hospital.

The aim of this study was to evaluate the toxigenic status of circulating strains of Clostridium difficile in a large teaching hospital. Overall 220 isolates were studied of which 199 (90.5 %) produced both large clostridial toxins detected by conventional methods. Ten more strains (4.5 %) had toxin A and B genes detectable by PCR. Eleven (5.0 %) variant strains (A- B+) were detected among the isolates studied and 10 strains (4.5 %) had the binary toxin genes (cdtA and cdtB).

Bacterial Proteins↗

PubMed2005

In vitro activity of ramoplanin against Clostridium difficile, including strains with reduced susceptibility to vancomycin or with resistance to metronidazole.

We evaluated the in vitro activity of ramoplanin, an antimicrobial compound that inhibits cell wall synthesis by acting at the level of lipid intermediate formation, against Clostridium difficile. We included strains with reduced susceptibilities to vancomycin (vancomycin-intermediate [Van(i)] strains) or with resistance to metronidazole (Mtz(r)), in order to assess the potential utility of ramoplanin for the treatment of C. difficile-associated diarrhea. We tested the activity of ramoplanin against a total of 105 nonduplicate clinical isolates of toxigenic C. difficile, including 8 Van(i) isolates and 6 Mtz(r) isolates, obtained from our laboratory. Ramoplanin was active against all strains tested at concentrations ranging from 0.03 to 0.5 microg/ml (MICs at which 50 and 90% of isolates were inhibited, 0.25 microg/ml; geometric mean MIC, 0.22 microg/ml). All isolates, independently of their levels of susceptibility to vancomycin or metronidazole, were considered susceptible to ramoplanin (MICs, < or =0.5 microg/ml).

Clostridioides difficile↗

PubMed2005

Antifungal susceptibility of 596 Aspergillus fumigatus strains isolated from outdoor air, hospital air, and clinical samples: analysis by site of isolation.

We analyzed the activities of six antifungal drugs (amphotericin B, itraconazole, voriconazole, posaconazole, caspofungin, and micafungin) against 596 Aspergillus fumigatus strains isolated from outdoor air, hospital air, and clinical samples. We did not find differences among the susceptibilities by site of isolation.

Air Microbiology↗

PubMed2005

Workload due to Aspergillus fumigatus and significance of the organism in the microbiology laboratory of a general hospital.

The increase in the immunocompromised population and the incidence of invasive aspergillosis (IA) are leading to an overinterpretation of the potential clinical significance of many isolates of Aspergillus fumigatus. Our work prospectively assesses the workload of the isolation of A. fumigatus and its clinical significance in the microbiology laboratory of a large teaching hospital. During a 3-year period, all patients from whom A. fumigatus was isolated were prospectively monitored and classified as having IA or "nonsignificant" disease. A point score based on the prediction of five easily obtained laboratory and clinical parameters was applied. We found 404 A. fumigatus isolates in 260 patients (1/1,000 microbiology laboratory samples; 2.1 patients/10,000 admissions). A total of 90 isolates (22.3%) were from patients with IA. Of the 260 patients, 31 (12%) had invasive disease (IA), and the remaining 229 had "nonsignificant" disease. A score based on points for five parameters was applied to our population. It was constructed as follows: "sample obtained by invasive procedures" (1 point), "presence of two or more positive samples from the same patient" (1 point), "leukemia" (2 points), "neutropenia" (5 points), and "corticosteroid treatment" (2 points). Patients with a score of 0 had only a 2.5% probability of IA. Those with a score of 1 or 2 had an increased probability of 10.3%. The probabilities rose to 40% and 70%, respectively, for patients with a score of 3 or 4 or a score of > or = 5. A simple score based on five easily available parameters may be of help to microbiologists and clinicians to predict the risk of IA.

Analysis of Variance↗

PubMed2004

Nosocomial invasive aspergillosis in a heart transplant patient acquired during a break in the HEPA air filtration system.

We report a case of nosocomially acquired invasive aspergillosis (IA) in a low-risk heart transplant recipient due to a break in the air conditioning system. A high overload of Aspergillus spores in the intensive care unit room led this patient to acquire IA. Identical environmental and patient isolates allowed our hypothesis to be confirmed and a very precise incubation time to be estimated.

Air Conditioning↗

PubMed2002

Demolition of a hospital building by controlled explosion: the impact on filamentous fungal load in internal and external air.

The demolition of a maternity building at our institution provided us with the opportunity to study the load of filamentous fungi in the air. External (nearby streets) and internal (within the hospital buildings) air was sampled with an automatic volumetric machine (MAS-100 Air Samplair) at least daily during the week before the demolition, at 10, 30, 60, 90,120, 180, 240, 420, 540 and 660 min post-demolition, daily during the week after the demolition and weekly during weeks 2, 3 and 4 after demolition. Samples were duplicated to analyse reproducibility. Three hundred and forty samples were obtained: 115 external air, 69 'non-protected' internal air and 156 protected internal air [high efficiency particulate air (HEPA) filtered air under positive pressure]. A significant increase in the colony count of filamentous fungi occurred after the demolition. Median colony counts of external air on demolition day were significantly higher than from internal air (70.2 cfu/m(3) vs 35.8 cfu/m(3)) (P < 0.001). Mechanical demolition on day +4 also produced a significant difference between external and internal air (74.5 cfu/m(3) vs 41.7 cfu/m(3)). The counts returned to baseline levels on day +11. Most areas with a protected air supply yielded no colonies before demolition day and remained negative on demolition day. The reproducibility of the count method was good (intra-assay variance: 2.4 cfu/m(3)). No episodes of invasive filamentous mycosis were detected during the three months following the demolition. Demolition work was associated with a significant increase in the fungal colony counts of hospital external and non-protected internal air. Effective protective measures may be taken to avoid the emergence of clinical infections.

Air Conditioning↗

PubMed2002

In vitro activity of linezolid against Clostridium difficile.

We examined the in vitro activity of linezolid against Clostridium difficile, including isolates with reduced susceptibility to metronidazole or vancomycin. The MIC at which 50% of the isolates were inhibited (MIC50) and MIC90 were 0.5 and 2 microg/ml, respectively (range, 0.03 to 4 microg/ml). MICs were always <or= 4 microg/ml, and thus, all isolates were considered susceptible.

Acetamides↗

PubMed2002

Reassessment of Clostridium difficile susceptibility to metronidazole and vancomycin.

Clostridium difficile is the most frequently identified enteric pathogen in patients with nosocomially acquired, antibiotic-associated diarrhea. The drugs most commonly used to treat diseases associated with C. difficile are metronidazole and vancomycin. Most clinical laboratories assume that all C. difficile isolates are susceptible to metronidazole and vancomycin. We report on the antimicrobial susceptibilities of 415 C. difficile isolates to metronidazole and vancomycin over an 8-year period (1993 to 2000). The overall rate of resistance to metronidazole at the critical breakpoint (16 microg/ml) was 6.3%. Although full resistance to vancomycin was not observed, the overall rate of intermediate resistance was 3.1%. One isolate had a combination of resistance to metronidazole and intermediate resistance to vancomycin. Rates of resistance to metronidazole and vancomycin were higher among isolates from human immunodeficiency virus-infected patients. Molecular typing methods proved the absence of clonality among the isolates with decreased susceptibilities to the antimicrobials tested.

Adult↗

PubMed2001

Extra-intestinal infections caused by Clostridium difficile.

The objective of this paper was to investigate the incidence of extra-intestinal infections caused by Clostridium difficile. During a 10-year period, the microbiology laboratory of our institution isolated 2034 isolates of C. difficile. Of the 2034 isolates, 21 (1.08%) were obtained from extra-intestinal sources. This represents an incidence of extra-intestinal isolation of four cases per 100 000 admissions. We were able to review the records of 17 patients for our study. The isolates in 12 patients were obtained from structures or fluids anatomically close to the colon and included the following infections: peritonitis in five cases (three primary and two secondary), intra-abdominal abscesses in three patients and abdominal wound infections in four cases. The infections in the other five patients were not in the anatomic vicinity of the colon. They included one case with a brain abscess, two episodes of bacteremia and two cases of foot infections (one chronic osteomyelitis). In all but one case, C. difficile isolation was obtained as part of a polymicrobial flora. The isolates were frequently non-toxigenic and the extra-intestinal infections occurred without concomitant diarrhea or prior anti-microbial therapy. Out of the 17 patients, eight died and nine survived. Death could not be directly attributed to C. difficile in any of the cases. The isolation of C. difficile outside the intestinal tract is very uncommon. Its clinical significance should be interpreted with caution.

Abdominal Abscess↗

PubMed2001

Molecular analysis of relapse vs re-infection in HIV-positive patients suffering from recurrent Clostridium difficile associated diarrhoea.

Recurrence is a major complication of Clostridium difficile associated diarrhoea, especially in human immunodeficiency virus (HIV) positive patients, and it is important to distinguish between relapse and re-infection in recurrent episodes. The aim of our study was to analyse C. difficile isolates obtained from HIV-positive patients with recurrent diarrhoea in order to distinguish between relapse and re-infection. This analysis was based on the study of DNA similarities among isolates obtained from different episodes within each patient. Relapses occurred in 64% of patients, 32% suffered re-infections and a combination of relapse plus re-infection was seen in 4%. DNA typing methods can be useful tools to characterize recurrent episodes of C. difficile associated disease.

AIDS-Related Opportunistic Infections↗

PubMed2001

"Second-look" cytotoxicity: an evaluation of culture plus cytotoxin assay of Clostridium difficile isolates in the laboratory diagnosis of CDAD.

Clostridium difficile is one of the most frequent causes of hospital-acquired diarrhoea. Our objective was to prove that some stool samples with a direct negative cytotoxicity assay may indeed harbour toxigenic C. difficile and that this can be demonstrated by performing a "second-look" cytotoxicity assay using the isolated C. difficile strains. Over an eight-year period (1992-1999), the 8241 stool samples submitted for direct cell culture from patients with suspected C. difficile-associated diarrhoea (CDAD) were simultaneously plated on cycloserine cefoxitin fructose agar. C. difficile strains isolated from samples with a negative direct cell culture assay were re-tested for toxin production "second-look" cell culture assay). Using both methods 6423 samples (78%) were negative. Of the remaining 1818 samples, 127 (7%) yielded C. difficile isolates which were confirmed as non-producers of toxin by both methods, 1437 (85%) were positive in direct cell culture assay, and 254 were positive only after the "second-look" cell culture assay. Thus, our approach allowed us to detect an extra 15% of toxin-producing strains that could have gone undetected otherwise.The combination of direct-cell culture assay, culture for toxigenic C. difficile and "second-look" cell culture assay enhances the potential for diagnosis of CDAD and enables us to be more efficient with our patient care resources.

Bacterial Toxins↗

PubMed2001

In vitro activity of new quinolones against Clostridium difficile.

We evaluated the in vitro activities of ofloxacin, levofloxacin, grepafloxacin, trovafloxacin and ciprofloxacin against Clostridium difficile. The MIC(90) was 128 mg/L for ofloxacin and levofloxacin, 64 mg/L for ciprofloxacin, 16 mg/L for grepafloxacin and 8 mg/L for trovafloxacin. Thirty per cent of isolates were resistant to trovafloxacin, and rates of resistance to ofloxacin, levofloxacin, grepafloxacin and ciprofloxacin were considerably higher. None of the antimicrobials studied would be a reliable therapeutic option against C. difficile. Whether some of the new fluoroquinolones can induce C. difficile-associated diarrhoea remains to be answered.

4-Quinolones↗

PubMed1999

Rapid detection of toxigenic Clostridium difficile from stool samples by a nested PCR of toxin B gene.

Toxigenic Clostridium difficile is the aetiologic agent of most cases of antibiotic-associated diarrhoea and pseudomembranous colitis. The present standard method for C. difficile diagnosis is a cytotoxicity assay, performed on human fibroblast cultures. It is time consuming and requires special facilities. A nested-PCR assay detecting toxin B gene within a few hours was designed. One hundred and two stool samples were collected during four months. All samples were processed for toxin B-PCR, cultured for C. difficile and tested for cytotoxicity. This approach achieved 99% concordance with the cytotoxic assay. The sensitivity and specificity for the new PCR assay were 96.3% and 100% respectively. The procedure described is easy to perform, does not require special equipment and has produced excellent results. It deserves serious consideration for routine clinical microbiology laboratory use.

Bacterial Toxins↗

PubMed1998

Comparison of broth microdilution method using Haemophilus test medium and agar dilution method for susceptibility testing of Eikenella corrodens.

Susceptibility testing of Eikenella corrodens is usually performed by a Mueller-Hinton sheep blood agar dilution (AD) method. However, this method is impractical for testing only a few strains. We compared AD with the broth microdilution method using Haemophilus test medium (HTM) in order to determine the susceptibility of 36 clinical isolates of E. corrodens to eight antimicrobial agents. MICs obtained by the HTM method yielded 95.5 and 84% agreement (within 2 and 1 log2 dilutions, respectively) with those obtained by AD. The HTM method with incubation in CO2 for 48 h was highly reproducible and constitutes an easy alternative for antimicrobial susceptibility testing of E. corrodens.

Agar↗

PubMed1997

Haemophilus species bacteremia in adults. The importance of the human immunodeficiency virus epidemic.

BACKGROUND: Until the late 1970s, invasive infections caused by Haemophilus species were thought to occur mainly in children and only infrequently in adults. OBJECTIVE: To report the largest series to date of Haemophilus species bacteremia (HB) from a single center. DESIGN: Retrospective. SETTING: Large, tertiary care, general teaching hospital. METHODS: We reviewed the charts of adult patients with HB detected from January 1, 1986, to December 31, 1994. Haemophilus strains were serotyped, and the antimicrobial resistance pattern was analyzed. RESULTS: One hundred sixteen patients had HB (0.26 cases per 1000 admissions). Thirty-eight children and 16 adults were excluded. Human immunodeficiency virus (HIV) infection was the most common underlying condition (n = 18 [29%]), followed by malignant neoplasms (n = 12 [19%]) and chronic obstructive pulmonary disease (n = 12 [19%]). Prevalence in HIV-positive patients was 5 cases per 1000 admissions vs 0.2 cases per 1000 admissions in HIV-negative patients. Infection was nosocomial in 16 patients (26%). Focal diseases were pneumonia in 41 patients (66%), cholangitis in 5 patients (8%), endocarditis in 3 patients (5%), meningitis and septic arthritis each in 1 patient (2%), and primary bacteremia in 9 patients (14%). The HIV-positive patients were significantly younger and presented more frequently with pneumonia (P < .05). Overall, 14 patients died (22%). Bacteremia was polymicrobial in 11 patients (18%). Haemophilus influenzae was isolated in 53 patients (85%). Rates of antimicrobial resistance were 11% to chloramphenicol sodium succinate, 48% to ampicillin sodium, 78% to erythromycin stearate, 76% to combined sulfamethoxazole and trimethoprim, 15% to rifampin, and 57% to clarithromycin. CONCLUSIONS: Infection with HIV has become the most common underlying disease in adults with HB in our hospital. Therapeutic approaches must take into account the high rate of antimicrobial resistance.

AIDS-Related Opportunistic Infections↗

PubMed1997

Group B streptococcus bacteremia in nonpregnant adults.

BACKGROUND: We report the largest series of group B streptococcal (GBS) bacteremia cases reported at a single institution. METHODS: During a 10-year period (1985-1994), 90 GBS bacteremia cases (0.95% of significant bacteremic episodes) were detected. We describe the 51 episodes that occurred in nonpregnant adults for which enough clinical and microbiological information is available. RESULTS: Incidence of GBS has significantly increased during the study period (from 0.08 per 1000 admissions in 1985 to 0.3 per 1000 in 1994). Mean age of patients was 63.3 years (range, 21-88 years) and 53% were men. The most common underlying conditions were liver diseases (35.3%), malignancies (33.3%), and diabetes mellitus (27.5%). Only 2 patients did not have any underlying condition and no patient with the human immunodeficiency virus had GBS bacteremia in our series. The origins of the episodes of bacteremia were as follows: primary bacteremia (39.2%), skin and soft tissue infections (15.7%), urinary tract infections (11.8%), pneumonia (9.8%), peritonitis (9.8%), catheter infection (5.9%), postendoscopic bacteremia (5.9%), and endocarditis (2%). All isolates were susceptible to penicillin G potassium, ampicillin sodium, cephalothin sodium, cefotaxime sodium, and vancomycin hydrochloride. One ciprofloxacin hydrochloride-resistant strain was discovered and resistance to erythromycin stearate increased from 8% in 1992 to 18% in 1994. The overall mortality rate was 33.3% and deaths were considered related to the GBS bacteremia in 25.5% of the cases. Factors for poor prognosis were central nervous system diseases, alcoholism, shock, renal failure, and consciousness impairment. CONCLUSIONS: Group B streptococcus is a rising cause of bacteremia in elderly patients with severe underlying conditions. It conveys high morbidity and mortality rates. Macrolides should not be used empirically for treatment of patients with penicillin allergies.

Adult↗