Rev Esp Quimioter 2011:24(4):175-183

Antimycobacterial natural products – an opportunity for the Colombian biodiversity       


J. BUENO, E. D. COY, E. STASHENKO            

It is estimated that one-third part of the world population is infected with the tubercle bacillus. While only a small percentage of infected individuals will develop clinical tuberculosis, each year there are approximately eight million new cases and two million deaths. Mycobacterium tuberculosis is thus responsible for more human mortality than any other single microbial species. The goals of tuberculosis control are focused to cure active disease, prevent relapse, reduce transmission and avert the emergence of drug-resistance. For over 50 years, natural products have served us well on combating infectious bacteria and fungi. During the 20th century, microbial and plant secondary metabolites have helped to double our life span, reduced pain and suffering, and revolutionized medicine. Colombia is a megadiverse country with enormous potential to offer leads for new antimycobacterial drugs. The principal aim of this article is to show a state of the art on antimycobacterial natural products research in Colombia compared to the rest of the world, in order to develop programs for bioprospecting with a view to determining the biological activity for pharmaceutical and industrial application of natural products in our country. 

 
Rev Esp Quimioter 2011:24(4):175-183 [pdf]

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Rev Esp Quimioter 2012:25(1):37-41

Antimicrobial resistance in clinical patterns of Pseudomonas aeruginosa                

M. M. CASAL, M. CAUSSE, F. RODRÍGUEZ-LÓPEZ, M. CASAL                              

 

Pseudomonas aeruginosa is an opportunistic microorganism that is frequently the cause of nosocomial infections. Multiple mechanisms are involved in its natural and acquired resistance to many of the antimicrobial agents commonly used in clinical practice. We performed an antibiotic resistance study on P. aeruginosa isolated from intrahospitalary and extrahospitalary samples between 2005 and 2010 years. We included in the study a global amount of 3,029 P. aeruginosa isolates from clinical samples received at University Hospital Reina Sofia. Microbiology Service in Córdoba (Spain). Semiautomatic system WIDER I for strains identification and sensibility testing was employed. We considered susceptibility and resistance criteria recommended by MENSURA group. Results of the analysis showed that P. aeruginosa maintanied similar levels of antimicrobial susceptibility during the period 2005-2010, with increased susceptibility to amikacin, gentamicin and cefalosporins. Therewere also important differences in the degree of susceptibility between intrahospital and extrahospital strains during 2010 year, except for tobramicin and fosfomycin. The intrahospital difference in susceptibility was also evaluated, emphasizing the importance of periodically surveillance of susceptibility and resistance patterns of P. aeruginosa, in each setting in order to evaluate different therapeutic guidelines, because it is not always advisable to extrapolate data from different
regions. 

 
Rev Esp Quimioter 2012:25(1):37-41 [pdf]

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Rev Esp Quimioter 2012:25(3):183-188

Antimicrobial resistance of the most frequently isolated microorganisms in the Hospital General La Mancha Centro between June 2009 and May 2010                 

M. A. ASENCIO, R. CARRANZA, M. HUERTAS                                                                           

 
Introduction: During the last two decades an increased incidence of infections caused by multiresistant bacteria has been observed. The spread of these microorganisms in the hospital is a major therapeutic and epidemiological problem. The aim of this study was to determine local resistance patterns of microorganisms causative of multirresistant infections in patients admitted to our hospital.
Methods: A retrospective study was designed, including Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii strains isolated from clinical and surveillance samples of patients admitted to the Hospital General La Mancha Centro, between June 2009 and May 2010.
Results: The rate of S. aureus isolates resistant to oxacillin was 50%, with 0% resistance to vancomycin. The percentage of resistance to 3rd generation cephalosporins in E. coli and K. pneumoniae was 17 and 19%, respectively; the ESBL-production in enterobacterial strains was 15 and 19%, respectively, and the quinolone resistance was 41 and 28%, respectively. The resistance of P. aeruginosa to ceftazidime and imipenem was 30 and 40%, respectively. Most strains of A. baumannii studied came from a single multidrug-resistant clone, endemic in the ICU of our hospital.
Conclusions: Of particular concern is the high rate of MRSA, E. coli and K. pneumoniae ESBL producers and resistant to fluoroquinolones as well as P. aeruginosa multiresistant. A. baumannii isolates belong mainly to endemic multidrug-resistant clone from the ICU.

 

Rev Esp Quimioter 2012:25(3):183-188 [pdf]

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Rev Esp Quimioter 2010:23(1):36-42

Changes in the antimicrobial susceptibility of Escherichia coli isolates from community diagnosed urinary tract infections during the period 2003-2007. Multicentre study in Castilla la Mancha (Spain)

D. TENA, A. GONZÁLEZ-PRAETORIUS, J. C. GONZÁLEZ, E. HEREDERO, S. ILLESCAS, C. SAINZ DE BARANDA, G. SESEÑA

 

Objective: To know the evolution of susceptibility patterns of Escherichia coli in patients with communitydiagnosed urinary tract infections (UTIs) during last years in Castilla la Mancha (Spain).
Methods: Descriptive and retrospective study performed between january 2003 and december 2007. We studied data about frequency and susceptibility of 33.651 E. coli isolates from urine cultures that were remited from primary care centres depending of 6 hospitals in Castilla la Mancha (Spain).
Results: Susceptibility rates of E. coli for most antibiotics decreased significantly during the 5-year period, especially for amoxicillin-clavulanic acid, cefuroxime and quinolones. Average rates of susceptibility for amoxicillin- clavulanic acid, ciprofloxacin, cefuroxime, fosfomycin and nitrofurantoin were: 86,7, 75,4, 87,3, 97,6 and 96,2%, respectively. We observed a significantly increase of E. coli isolates producing extended-spectrum betalactamases (ESBLs), from 1,9% in 2003 to 4,9% in 2007 (χ2 TL = 143,6, p<0,001).
Conclusions: We observed a significantly reduction of E. coli susceptibility for most antibiotics and an increase of E. coli isolates producing ESBLs. Fosfomycin and nitrofurantoin are the best choices for empiric treatment. Prospective studies should be performed in the future to confirm the results of our study.

 
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Rev Esp Quimioter 2010:23(4):158-168

Nosocomial candidemia: new challenges of an emergent problem 

J. GÓMEZ, E. GARCÍA-VAZQUEZ, A. HERNÁNDEZ, C. ESPINOSA, J. RUIZ GÓMEZ   

 

Candida spp. are currently one of the most common causes of bloodstream infections in hospitals. Over the last two decades there has been a shift towards a greater involvement of non-Candida albicans as the cause of candidemia. Several of these non-albicans spp. (e.g., C. glabrata and C.krusei) exhibit resistance to traditional triazole antifungals (fluconazole), and cross-resistance with newer triazoles (voriconazole), focusing attention on the first-line use of antifungals such as the echinocandins, which possess improved activity against fluconazole-resistant strains. Early and adequate empirical treatment as well as early removing of the central catheters are the main factors related to mortality; thus it is necessary to implement guidelines of empirical treatment (including these aspects) in patients with risk factors and possible candidemia. Recent treatment guidelines from the Infectious Diseases Society of America (IDSA) recommend an echinocandin as primary therapy for non neutropenic or neutropenic patients with moderately severe to severe candidiasis and for patients at risk for infection with a triazole-resistant strain; the increasing MIC of echinocandins in case of C. parapsilosisis also an emerging concern. Clinicians should remain vigilant to prescribe early empiric treatment of patients at risk of having candidemia.   

 
Rev Esp Quimioter 2010:23(4):158-168 [pdf]

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Rev Esp Quimioter 2011:24(2):74-78

Activity of vancomycin, ciprofloxacin, daptomycin, and linezolid against coagulase-negative staphylococci bacteremia   

M. FAJARDO, R. HIDALGO, S. RODRÍGUEZ, F. F. RODRÍGUEZ-VIDIGAL, A. VERA, M. ROBLES       

 

Objective. Multiresistant coagulase-negative staphylococci (CNS) infections are mainly increased in hospitalized patients. We have studied the activity of vancomycin, ciprofloxacin, daptomycin and linezolid in methicillin-resistant CNS strains, isolated from true blood cultures.
Methods. We collected 87 strains of different CNS species from positive blood cultures. Staphylococci were identified by MicroScan Walkaway (Dade Behring, Siemens) and with the Api ID 32 Staph (BioMerieux, France). The susceptibility to oxacillin, vancomycin and ciprofloxacin was performed by automatic microdilution plate as cited above. The susceptibility to daptomycin and linezolid was performed by Etest (AB BioMerieux, Solna, Sweden). Interpretative criteria were done following the CLSI guidelines.
Results. Eighty-seven CNS strains were studied: 55 (63%) were S. epidermidis, 15 (17%) S. haemolyticus, 10 (12%) S. hominis, and 7 (8%) other species. Fifty-three (61%) strains showed loss of susceptibility to vancomycin, MIC = 2 mg/L. Ciprofloxacin resistance, MIC > 2 mg/L, was observed in 56 (64%) strains. Daptomycin resistance was not observed, with a susceptibility range between 0.032-1 mg/L and modal value of 0.25 mg/L. Ten strains (11.5%) resistant to linezolid were observed. Nine patients were in ICU, where the average length of stay was 38 days (range 16-58 days) and one belonged to Hepato-Pancreatic Surgery, where he stayed for 64 days.
Conclusions. Low susceptibility to vancomycin is frecuent in the CNS strains studied in our hospital. Daptomycin shows a high efficacy against CNS, and it could be useful for the treatment of primary bacteremia or catheter associated bacteremia. The massive and continuous use of linezolid has led to the appearance of resistance. 

 
Rev Esp Quimioter 2011:24(2):74-78 [pdf]

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Rev Esp Quimioter 2011:24(4):184-190

Bacteroides mobilizable and conjugative genetic elements: antibiotic resistance among clinical isolates          


C. QUESADA-GÓMEZ              

The conjugation is one of the most important mechanisms of horizontal gene transfer in prokaryotes, leading to genetic variation within a species and the acquisition of new traits, such as antibiotic resistance. Bacteroides is an obligate anaerobe of the colon and a significant opportunistic pathogen. Antibiotic resistance among Bacteroides spp. is rapidly increasing, largely due to the dissemination of DNA transfer factors (plasmids and transposons) harbored by members of this genus. Transfer factors can be divided into two classes, conjugative and mobilizable. Species of the intestinal Bacteroides have yielded different resistance plasmids, all of which have been intensely studied, the plasmids encode high-level MLS resistance conferred by a conserved erm gene. It has been reported an interesting observation associated with the transfer of several of these types of elements, all of which conferred Tcr and displayed greatly increased transfer efficiency following exposure to tetracycline. Many of the conjugative transposons (CTns) in Bacteroides are related to various genetic elements (such as CTnDOT, CTnERL, NBU and others). CTnDOT carries a tetracycline resistance gene, tetQ, and an erythromycin resistance gene, ermF. Resistance to drugs used to treat Bacteroides infections, such as clindamycin, has also been increasing. These conjugal elements have been found in Bacteroides clinical isolates. Thus, horizontal gene transfer could conceivably have played a role in the rising incidence of resistance in this bacterial group. 

 
Rev Esp Quimioter 2011:24(4):184-190 [pdf]

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Rev Esp Quimioter 2012:25(1):42-46

Phenotypes and mechanisms of resistance to macrolides and lincosamides in Streptococcus agalactiae isolates with clinical significance in an eight-year period (2002-2010)                

F. ARTILES, A. CAÑAS, I. ÁLAMO, B. LAFARGA                               

 

Introduction. Streptococcus agalactiae is the most prevalent agent of invasive disease in the newborn (sepsis, pneumonia, and meningitis), as well as an important cause of puerperal fever, urinary tract infection and surgical site infection. The aim of our study was to know the evolution of macrolide and lincosamide resistance in this microorganism.
Methods. Resistance phenotypes were established according to the erythromycin-clindamycin induction test: M (efflux pump) or MLSB (methylase). Genetic mechanisms were detected by PCR for the following genes: ermB, ermA, ermTR, and mefA/E. Molecular typing was based on chromosomal DNA macrorestriction and detection of fragments using pulsed-field gel electrophoresis.
Results. During 8 years, 300 isolates of S. agalactiae were recovered. Seventy-eight (26%) were resistant to macrolides, and seventy (23%) were resistant to lincosamides. Constitutive MLSB was observed in 21% of the isolates (all but one carrying the ermB gene), with a erythromycin MIC90 ≥ 256 mg/L. Inducible MLSB was observed in 2.3% of the isolates (all carrying the ermTR gene), with a MIC90 of 6 mg/L. M phenotype was observed in 2.7% of the isolates (all carrying the mefA/E gene), with a MIC90 of 6 mg/L. Molecular typing revealed the presence of two major clones (A and B) comprising 56.6% of the isolates. Most of the isolates (90.5%) belonging to clon A carried the ermB gene.
Conclusions. Macrolide resistance in our area is similar to that observed in the rest of Spain, but there has been no increase in the incidence rate along the study period. 

 
Rev Esp Quimioter 2012:25(1):42-46 [pdf]

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Rev Esp Quimioter 2012:25(3):189-193


Evaluation of the variability in the susceptibility of Acinetobacter baumannii to tigecycline in the same medium with two methods of quantitative diffusion different commercial                 

R. TEJERO, M. CAUSSE, M. A. MORENO, F. SOLÍS, F. RODRÍGUEZ-LÓPEZ, M. CASAL                                                                           

 
Introduction: Tigecycline may be a therapeutic alternative for the control of multidrug-resistant Acinetobacter baumannii, although there is no consensus on the cutoffs or susceptibility to the variability of the minimum inhibitory concentration (MIC) according to the culture medium and strips for the antibiogram against this microorganism by quantitative diffusion method. Therefore, the objective was to verify this variability and propose epsilometer test strip that more closely resemble to the standard method.
Material and methods: 38 strains of A. baumannii were selected and evaluated their susceptibility to tigecycline with two different commercial strips (E-TEST and Liofilchem). MICs were compared with those obtained by the standard technique of microdilution broth.
Results: MICs obtained by the Liofilchem strip were more similar to standard method than those obtained by E-TEST strips.
Conclusion: In the two studied strips, higher MICs to those obtained by the standard method were observed leading to false-positive tigecicline resistance in many cases. However, the Liofilchem strip showed the results more closely resemble to the standard method.

 

Rev Esp Quimioter 2012:25(3):189-193 [pdf]

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Rev Esp Quimioter 2013:26(1):12-20

Physicians with access to point-of-care tests significantly reduce the antibiotic prescription for common cold                                 
 

C. LLOR, S. HERNÁNDEZ, J. M. COTS, L. BJERRUM, B. GONZÁLEZ, G. GARCÍA, J. D. ALCÁNTARA, G.  GUERRA, M. CID, M. GÓMEZ, J. ORTEGA, C. PÉREZ, J. ARRANZ, M. J. MONEDERO, J. PAREDES, V. PINEDA, GRUPO DE TRABAJO HAPPY AUDIT ESPAÑA               

Objective. This study was aimed at evaluating the effect of two levels of intervention on the antibiotic prescribing in patients with common cold.
Methods. Before and after audit-based study carried out in primary healthcare centres in Spain. General practitioners registered all the episodes of common cold during 15 working days in January and February in 2008 (preintervention). Two types of intervention were considered: full intervention, consisting in individual feedback based on results from the first registry, courses in rational antibiotic prescribing, guidelines, patient information leaflets, workshops on rapid tests –rapid antigen detection and C-reactive protein tests– and provision of these tests in the surgeries; and partial intervention, consisting of all the above intervention except for the workshop and they did not have access to rapid tests. The same registry was repeated in 2009 (postintervention). In addition, new physicians filled out only the registry in 2009 (control group).
Results. 210 physicians underwent the full intervention, 71 the partial intervention and 59 were assigned to the control group. The 340 doctors prescribed antibiotics in 274 episodes of a total of 12,373 cases registered (2.2%).The greatest percentage of antibiotic prescription was found in the control group (4.6%). The partial intervention increased the antibiotic prescription percentage from 1.1% to 2.7% while only doctors who underwent the complete intervention lead to a significant reduction of antibiotics prescribed, from 2.9% before to 0.7% after the intervention (p<0.001).
Conclusion. Only physicians with access to rapid tests significantly reduced antibiotic prescription in patients with common cold.

Rev Esp Quimioter 2013:26(1):12-20 [pdf]

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