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Biomedical subjects

F Baquero

Publications and source records attributed to F Baquero.

At least 19 recordsLinked to original sources
PubMed2003

Antimicrobial resistance in recent fecal enterococci from healthy volunteers and food handlers in Spain: genes and phenotypes.

Susceptibility patterns to 15 different antibiotics and the presence of resistance genes were evaluated in recent fecal Enterococcus isolates recovered from 42 healthy volunteers (HV) and 43 food-handlers (FH). A total of 142 Enterococcus faecalis, 74 Enterococcus faecium, and 23 Enterococcus spp. with different antibiotic susceptibility patterns were studied. A higher percentage of resistance for moxifloxacin, erythromycin, glycopeptides and high-level resistance (HLR) to gentamicin were observed in the FH group. Ampicillin- or linezolid-resistant isolates were not recovered in any of the groups. The tet(M) gene was found in 96% and in 85% of tetracycline-resistant isolates from HV and FH, respectively. HLR-kanamycin was mediated by aph(3')-IIIa, or aac(6')-aph(2"), or both genes in all isolates from HV group and in 86% from FH group. The aac(6')-aph(2") gene was found in all HLR-gentamicin isolates. Ninety-one percent of HV and 71% of FH erythromycin-resistant isolates harbored the erm(B) gene (erythromycin MIC range of 8-128 microg/ml), whereas erm(A), erm(C), or mef(A) genes were not detected. Coexistence of erm(B), aph(3')-IIIa, and tet(M) genes was observed in 17% of the isolates of both groups. The HLR-gentamicin isolates presented unrelated PFGE patterns while 2 out of 3 vanA E. faecium isolates showed an indistinguishable SmaI-pulsed-field gel electrophoresis (PFGE) pattern. This study shows that despite 4 years of official banning of antibiotic growth promoters in animals, enterococci isolated from FH are more resistant than those from HV. This suggests the permanence of resistant clones or transferable resistance elements in farms and a possible exchange between food products and humans, or eventually the long-term permanence of certain clones in the FH intestinal tract.

Anti-Bacterial Agents↗
PubMed2002

Antibiotic therapy of community respiratory tract infections: strategies for optimal outcomes and minimized resistance emergence.

Widespread, increasing antibiotic resistance amongst the major respiratory pathogens has compromised traditional therapy of the major infective respiratory syndromes, including bacterial pneumonia and acute exacerbations of chronic bronchitis. Guidelines for antibiotic prescribing dating from the 1980s to 1990s, which attempted to address such problems, were commonly too prescriptive and difficult to apply, and took little account of end-user practice or locally prevalent resistance levels. Further confusion was caused by conflicting recommendations emanating from differing specialty groups. The evidence that such guidelines benefited either clinical outcomes or treatment costs has been disputed. They have probably had little effect on resistance emergence. We report the recommendations of an independent, multi-national, inter-disciplinary group, which met to identify principles underlying prescribing and guideline formulation in an age of increasing bacterial resistance. Unnecessary prescribing was recognized as the major factor in influencing resistance and costs. Antibiotic therapy must be limited to syndromes in which bacterial infection is the predominant cause and should attempt maximal reduction in bacterial load, with the ultimate aim of bacterial eradication. It should be appropriate in type and context of local resistance prevalence, and optimal in dosage for the pathogen(s) involved. Prescribing should be based on pharmacodynamic principles that predict efficacy, bacterial eradication and prevention of resistance emergence. Pharmacoeconomic analyses confirm that bacteriologically more effective antibiotics can reduce overall management costs, particularly with respect to consequential morbidity and hospital admission. Application of these principles should positively benefit therapeutic outcomes, resistance avoidance and management costs and will more accurately guide antibiotic choices by both individuals and formulary/guideline committees.

Community-Acquired Infections↗
PubMed2002

Multicentre evaluation of the VITEK 2 Advanced Expert System for interpretive reading of antimicrobial resistance tests.

Interpretive reading analyses the complete resistance profiles of bacteria to multiple antibiotics and infers the resistance mechanisms present; it aids therapeutic choice and enhances surveillance data. We evaluated the Advanced Expert System (AES), which interprets MICs generated by the VITEK 2. Ten European laboratories tested 42 reference strains and 76-106 of their own strains, representing important resistance genotypes. Interpretive reading by the VITEK 2 AES achieved full agreement with genotype data for 88-89% of strains, with the correct mechanism identified as one of two possibilities for a further 5-6%. Mechanisms inferred with 90% agreement with reference data included methicillin resistance in staphylococci, glycopeptide resistance in enterococci, quinolone resistance in staphylococci and Enterobacteriaceae, AAC(6')-APH(2")-mediated aminoglycoside resistance in Gram-positive cocci, erm-mediated macrolide resistance in pneumococci, extended-spectrum beta-lactamases (ESBLs) in Enterobacteriaceae and Pseudomonas aeruginosa, and acquired penicillinases in Enterobacteriaceae. VanA, VanB and VanC phenotypes of enterococci were distinguished reliably, and ESBL production was accurately inferred in AmpC-inducible species as well as Escherichia coli and Klebsiella spp. Mechanisms identified, but only as possibilities among several, included IRT-type beta-lactamases and individual aminoglycoside-modifying enzymes in Enterobacteriaceae. Most disagreements with reference data concerned pneumococci found to have high-level penicillin resistance by the VITEK 2 AES but previously determined, phenotypically, to have intermediate resistance. When ESBL production was inferred in E. coli and klebsiellae, the VITEK 2 AES edited susceptible results for cephalosporins (except cefoxitin) to resistant; when an acquired penicillinase was inferred in Enterobacteriaceae, piperacillin results were edited to resistant; and when staphylococci were found methicillin resistant, resistance was reported for all beta-lactams. Further editing may be desirable (e.g. of cephalosporin results for salmonellas inferred to have ESBLs).

Data Interpretation, Statistical↗
PubMed2002

Antibiotic resistance in 1962 invasive isolates of Escherichia coli in 27 Spanish hospitals participating in the European Antimicrobial Resistance Surveillance System (2001).

In Europe, antimicrobial resistance of invasive pathogens has been monitored since 1998 by the European Antimicrobial Resistance Surveillance System (EARSS). The goal of this study is to analyse the susceptibility data of invasive Escherichia coli collected by 27 Spanish laboratories in 2001. Each laboratory identified strains and tested their susceptibility using its own methods. To assess the comparability of susceptibility test results, a quality assurance exercise was performed. We report data from 1962 invasive isolates of E. coli: 1959 from blood and three from cerebrospinal fluid, corresponding to the same number of patients. Resistance to ampicillin, co-trimoxazole, ciprofloxacin and gentamicin was found in 58.46%, 32.91%, 17.19% and 6.39% of isolates, respectively. Extended-spectrum beta-lactamase (ESBL) production was detected in 30 strains (1.55%). Ciprofloxacin resistance was higher in isolates from men and in-patients than in those from women and out-patients (P < 0.001). Resistance to ampicillin and co-trimoxazole was more widespread in children than in adults: 70.37% versus 57.87% (P = 0.01) and 41.84% versus 32.53% (P = 0.05). Non-significant differences in resistance to fluoroquinolones were observed between isolates from children (11.1%) and adults (17.54%), despite the fact that fluoroquinolones are not administered to children. Significantly, resistance to non-beta-lactam antibiotics (co-trimoxazole, ciprofloxacin and gentamicin) was more prevalent in ampicillin-resistant strains and ESBL-producing strains than in ampicillin-susceptible strains and non-ESBL-producing strains. Multidrug resistance was present in 13.92% of isolates; the most prevalent phenotype was resistance to ampicillin, co-trimoxazole and ciprofloxacin, which was detected in 59.36% of multiresistant strains and in 8.22% of strains overall.

Adult↗
PubMed2002

Antibiotic consumption and resistance selection in Streptococcus pneumoniae.

Selection of antibiotic-resistant Streptococcus pneumoniae is an inescapable consequence of antibiotic use. The correlation between antibiotic consumption and selection of resistant organisms can be shown at every ecological level: patient, community, region or country. In the case of multiple resistance, the intensity of antibiotic selection is increased. However, different antibiotics may exert different selective powers. Because of this, co-selection of macrolide and beta-lactam resistance is an asymmetrical phenomenon: macrolides select more efficiently strains resistant to both macrolides and beta-lactams than aminopenicillins. The difference in rates of antibiotic resistance is also influenced by the local spread of susceptible or resistant clones; it is suggested that under mild antibiotic selection, the susceptible organisms that are more fit for host-to-host transmission could be favoured. Subsequent acquisition of resistance in these clones may rapidly increase the prevalence of resistance, and that may lead to an increase in the use of antibiotics. The reasons for antibiotic resistance are mainly the reasons explaining antibiotic consumption. A number of possible sociobiological determinants of antibiotic consumption can be identified: genetic factors in the human populations (for instance, involving different symptomatic types of infection), cultural factors and attitudes of patients towards antibiotics, sociological factors or public health factors, including incidence of other infectious diseases in the human population. Only 'excess' in the use of antibiotics should be controlled; for such a purpose, the concept, 'appropriate demand for antibiotics' (ADA) is proposed.

Animals↗
PubMed2002

Pharmacoepidemiological analysis of provincial differences between consumption of macrolides and rates of erythromycin resistance among Streptococcus pyogenes isolates in Spain.

The M phenotype is by far the most common mechanism of erythromycin resistance among Streptococcus pyogenes isolates in Spain. A geographic analysis of the relationship between within-country differences in the prevalence of M-type resistance to erythromycin in S. pyogenes and the level of consumption of 14- and 15-membered macrolides within different provinces was carried out. From 1998 to 1999, a nationwide multicenter surveillance study yielded 2,039 consecutive pharyngeal isolates of S. pyogenes. Data on antibiotic consumption for the same period were gathered from IMS Health, and the corresponding daily defined doses per 1,000 inhabitants per day were calculated according to the Anatomic Therapeutic Classification index. Macrolide use was subdivided into dosages given three times a day (TID), twice a day (BID), or once a day (OD). Spearman nonparametric correlation coefficients (R) were calculated, and variables proving to be significantly associated (P < 0.1) were introduced into a linear regression model. The total consumption of macrolides presented a significant correlation with the prevalence of resistance (R = 0.527; P = 0.032). Neither TID nor BID macrolide consumption showed significant correlations. Only OD consumption had a significance below 0.1. These data are consistent with the hypothesis that only the total consumption of macrolides influences the local rates of M-type erythromycin resistance in S. pyogenes, and subgroups of macrolides seem to have an additive rather than a selective effect by contributing to increasing the final amount of macrolides used. Local variations in total consumption were associated only with BID consumption (R = 0.849; P = 0.004). The simple linear regression with total macrolide consumption showed a considerable determination coefficient (R(2) = 0.678; P = 0.006). The model explains up to 68% of the measured variation and is clearly better as a predictor of the prevalence of resistance than the mere mean is. By solving the regression equation, the resultant value of 2.2 defined doses per 1,000 inhabitants per day fits with the existence of a critical threshold of selective pressure.

Anti-Bacterial Agents↗
PubMed2001

Comparative genomics of Listeria species.

Listeria monocytogenes is a food-borne pathogen with a high mortality rate that has also emerged as a paradigm for intracellular parasitism. We present and compare the genome sequences of L. monocytogenes (2,944,528 base pairs) and a nonpathogenic species, L. innocua (3,011,209 base pairs). We found a large number of predicted genes encoding surface and secreted proteins, transporters, and transcriptional regulators, consistent with the ability of both species to adapt to diverse environments. The presence of 270 L. monocytogenes and 149 L. innocua strain-specific genes (clustered in 100 and 63 islets, respectively) suggests that virulence in Listeria results from multiple gene acquisition and deletion events.

Adaptation, Physiological↗
PubMed2001

Nontuberculous mycobacteria in patients with cystic fibrosis.

The prevalence and clinical implications of colonization with nontuberculous mycobacteria were prospectively studied in 37 patients who had cystic fibrosis. Sputum samples were cultured on Coletsos and Löwenstein-Jensen selective media after decontamination with sodium hydroxide and oxalic acid. Oxalic acid-decontaminated fractions were also cultured in selective liquid medium. Nontuberculous mycobacteria were isolated from 6 patients (16.1%). Mycobacterium chelonae and Mycobacterium avium-intracellulare complex were the most common species. Three patients with positive results of culture had at least 1 positive result by acid-fast smear. Oxalic acid decontamination and culture in liquid medium had the lowest contamination rate (6.7%). Colonization with nontuberculous mycobacteria was associated with humoral response to mycobacteria (immunoglobulin G titers against antigen A60) in patients with samples that tested positive by acid-fast smear. An improvement in pulmonary function was observed in 2 patients after they received a course of antimycobacterial therapy. Screening for nontuberculous mycobacteria in patients with cystic fibrosis will contribute to understanding the relevance of these pathogens with regard to deterioration of pulmonary function in patients with cystic fibrosis.

Adolescent↗
PubMed2001

Performance of the VITEK2 system for identification and susceptibility testing of routine Enterobacteriaceae clinical isolates.

The VITEK2 system was evaluated with 138 fresh consecutive routine clinical Enterobacteriaceae isolates. Susceptibility results to 10 beta-lactams, three aminoglycosides and a quinolone were compared with those obtained following the NCCLS standard microdilution. API20E was used as reference method for identification. All but three isolates were correctly identified in 3 h at species level (97.8%), two isolates (1.4%) at genus level and only one isolate was misidentified. Overall essential agreement for susceptibility testing was 97.1%. Discrepancies were mainly observed with piperacillin (1.1%), cefuroxime (0.6%) and amoxycillin/clavulanate (0.3%). Discrepancies for aminoglycosides and ciprofloxacin were low (<0.1%). Minor, major and very major errors (NCCLS categories) were 4.1%, 0.2% and 6.1%, respectively. Very major errors were due to piperacillin (4.5%), ampicillin (0.8%) and amoxycillin/clavulanate (0.8%). The VITEK2 system gave accurate identification and susceptibility testing results of routine Enterobacteriaceae clinical isolates.

4-Quinolones↗
PubMed2001

Evaluation of the OSIRIS video reader system for disk diffusion susceptibility test reading.

OBJECTIVE: The objective of this study was to compare the performance of the OSIRIS video-assisted reading system for disk diffusion susceptibility testing with conventional manual reading. METHODS: Prospectively collected clinical isolates (n = 119) and isolates with well-characterised resistant mechanisms, including extended-spectrum (ESBL) or inhibitor-resistant TEM (IRT) beta-lactamases producing Enterobacteriaceae (80), methicillin-resistant Staphylococcus aureus (MRSA) (16) and vancomycin-resistant enterococci (14) were studied using the National Committee for Clinical Laboratory Standards disk-diffusion technique. The OSIRIS reading (inhibition zone in mm) was compared with manual reading (reference value). RESULTS: Essential agreement (< or =3 mm discrepancy with manual reading) was 91.6% in routine isolates and 94.8% in those with well-characterised resistant mechanisms, respectively. Overall agreement for susceptibility testing interpretation was slightly higher in the former (95.5%) than in the latter (93.2%) group. The presence of ESBL enzymes enhanced variations of measurements due to synergy among amoxicillin-clavulanate and cephalosporins, as a consequence of closer disk placement. The poor growth characteristic of enterococci affected the video reading; on the other hand, there was a high performance with MRSA isolates. Combining all interpretative results, 4.1% minor, 1.0% major and 2.8% very major errors were observed. CONCLUSION: The OSIRIS system is a useful tool for the reading and interpretation of inhibition zone sizes in disk diffusion susceptibility testing.

Anti-Bacterial Agents↗
PubMed2001

Low-level antibacterial resistance: a gateway to clinical resistance.

The huge amount of antibiotic substances released in the human environment has probably resulted in an acceleration in the rate of bacterial evolution. It is to note that most interactions between chemotherapeutic agents and microbial populations occur at very low antibiotic concentrations. Thus, natural selection is expected to act on very small increases in the bacterial ability to resist to antibiotic inhibitory effects. On the other hand, there is a wealth of mechanisms to resist to these low antibiotic concentrations. The progressive enrichment in low-level resistant populations favours secondary selections for more specific and effective mechanisms of resistance, particularly in treated patients. These adaptations may have a biological cost in the absence of antibiotics, but frequently compensatory mutations occur, minimizing such genetic burden. In this way, a phenomenon of directional selection takes place, with low possibilities of return to susceptibility. Moreover, low antibiotic concentrations are not only able to select low-level antibiotic resistant variants, but may produce a substantial stress in bacterial populations, that eventually influences the rate of genetic variation and the diversity of adaptive responses. More attention should be devoted to the mechanisms of low-level resistance in microorganisms, as they can serve as stepping stones to develop high level, clinically relevant resistance. These mechanisms should be identified early in the development of drugs in order to adapt the therapeutic strategies (for instance dosage) to minimize the selection of low-level resistant variants, as frequently they emerge by means of concentration-specific selection. At the same time, conventional susceptibility testing should probably be able to detect low-level resistance, and not only clinically-relevant resistance. We should be vigilant of the evolutionary trends of microorganisms; for that a purpose, knowledge of the biology and epidemiology of low-level resistance is becoming a real need.

Animals↗
PubMed2001

Evidence to support the rationale that bacterial eradication in respiratory tract infection is an important aim of antimicrobial therapy.

Clinical outcome is dependent upon antibiotic-mediated bacterial eradication in a number of infections. However, in respiratory tract infections, the need for bacterial eradication has been controversial. Clinical data are now available that support the need for active bacterial eradication in otitis media. This may also be the case for other respiratory tract infections. An increase in antimicrobial resistance reduces the probability of achieving eradication. Conversely, failure to eradicate bacteria may promote the emergence and dissemination of antimicrobial-resistant clones. Pharmacokinetic/pharmacodynamic parameters can be used to predict the bacteriological efficacy of antimicrobial therapy. In conclusion, the aim of antimicrobial therapy in respiratory tract infections should be the eradication of the infecting organism.

Anti-Bacterial Agents↗
PubMed2001

Antimicrobial susceptibilities of 1,684 Streptococcus pneumoniae and 2,039 Streptococcus pyogenes isolates and their ecological relationships: results of a 1-year (1998-1999) multicenter surveillance study in Spain.

A nationwide multicenter susceptibility surveillance study which included 1,684 Streptococcus pneumoniae and 2,039 S. pyogenes isolates was carried out over 1 year in order to assess the current resistance patterns for the two most important gram-positive microorganisms responsible for community-acquired infections in Spain. Susceptibility testing was done by a broth microdilution method according to National Committee for Clinical Laboratory Standards M100-S10 interpretative criteria. For S. pneumoniae, the prevalences of highly resistant strains were 5% for amoxicillin and amoxicillin-clavulanic acid; 7% for cefotaxime; 22% for penicillin; 31% for cefuroxime; 35% for erythromycin, clarithromycin, and azithromycin; and 42% for cefaclor. For S. pyogenes, the prevalence of erythromycin resistance was 20%. Efflux was encountered in 90% of S. pyogenes and 5% of S. pneumoniae isolates that exhibited erythromycin resistance. Erythromycin resistance was associated with clarithromycin and azithromycin in both species, regardless of phenotype. Despite the different nature of the mechanisms of resistance, a positive correlation (r = 0.612) between the two species in the prevalence of erythromycin resistance was found in site-by-site comparisons, suggesting some kind of link with antibiotic consumption. Regarding ciprofloxacin, the MIC was >or=4 microg/ml for 7% of S. pneumoniae and 3.5% of S. pyogenes isolates. Ciprofloxacin resistance (MIC, >or=4 microg/ml) was significantly (P < 0.05) associated with macrolide resistance in both S. pyogenes and S. pneumoniae and with penicillin nonsusceptibility in S. pneumoniae.

Drug Prescriptions↗
PubMed2001

Nucleotide sequence and characterization of a novel cefotaxime-hydrolyzing beta-lactamase (CTX-M-10) isolated in Spain.

A cefotaxime-resistant, ceftazidime-susceptible Escherichia coli isolate was obtained from a patient with sepsis in 1997, from which a beta-lactamase with a pI of 8.1 was cloned. Cephaloridine and cefotaxime relative hydrolysis rates were 167 and 81, respectively (penicillin G rate = 100), whereas ceftazidime hydrolysis was not detected. The nucleotide sequence revealed a bla gene related to that coding for CTX-M-3. Despite 21 nucleotide substitutions, only 2 determined amino acid changes (Ala27Val and Arg38Gln). The amino acid sequence identity between this enzyme, designated CTX-M-10, and the chromosomal beta-lactamase of Kluyvera ascorbata was 81%.

Cefotaxime↗