Rev Esp Quimioter 2008;21(3):184-188

Comparison between Phoenix system and agar-based methods for antimicrobial susceptibility testing of Streptococcus spp

L. Martínez-Lamas ,  M. Treviño Castellano ,  P. A. Romero-Jung ,  B. J. Regueiro García 

  

Introduction. Antibiotic resistance is an emerging problem among streptococcal species, especially for severe infections. Automated diagnostic systems for antimicrobial susceptibility testing, such as BD Phoenix, is a recently available instruments that makes it possible to obtain results within 12 h.

Methods. Antimicrobial susceptibility testing results of the BD Phoenix system were compared to those obtained from Clinical Laboratory Standards Institute (CLSI) disk-diffusion method. Two-hundred different clinical isolates of streptococci were assayed: beta-hemolytic (n=65), viridans (n=87), S. penumoniae (n=48).

Results. Overall, there was categorical agreement greater than 96.7% (94.8% for beta-hemolytic and 97.9% for viridans group) in relationship to the disk-diffusion method. The minor error rates were less than 10% for all the antibiotics. The greatest percentage of serious errors corresponded to erythromycin and clindamycin within the beta-hemolytic group (14.7%). Overall percentage of very serious errors was less 0.5%. The results for penicillin in viridans streptococci and S. pneumoniae results showed 89.7% and 91.7% of categorical agreement, respectively, using the Etest as reference.

Conclusions. The automated BD Phoenix system is a very useful and effective diagnostic tool for quantitative testing of sensitivity to antibiotics in the streptococci group.

  

Key words: Streptococcus. Antimicrobial susceptibility testing. Phoenix. Disk-diffusion. ETest

Rev Esp Quimioter 2008;21(3):184-188 [pdf]      

/por

Rev Esp Quimioter 2008;21(3):180-183

In vitro generation of mutants of Klebsiella pneumoniae following exposure to fluorquinolones. Relationship with the presence of extended spectrum betalactamases

O. Noguera ,  J. C. Rodríguez ,  R. Cremades ,  M. Ruiz ,  G. Royo 

  

In order to provide data that may help to explain the relationship between production of extended spectrum betalactamases and fluorquinolone resistance in Klebsiella pneumoniae, we have developed an in vitro model of exposure to sub-inhibitory concentrations of various fluorquinolones (ciprofloxacin, levofloxacin and moxifloxacin) in two strains, one of which is a producer of extended spectrum betalactamases (ESBL). Our data show that mutants with reduced fluorquinolone susceptibility appear in both cases, but that they appear earlier in ESBL-producing strains (13.3 days versus 14.4 days), especially following exposure to ciprofloxacin (12.5 days versus 14.9 days for levofloxacin and 14.2 days for moxifloxacin). Therefore, our data help explain the greater fluorquinolone resistance in ESBL-producing strains and confirm the need to administer the correct doses of fluoroquinolones, especially in the case of ciprofloxacin, in order to prevent the emergence of resistant mutants. This is particularly important if the strain is an ESBL-producer.

  

Key words:  Klebsiella pneumoniae. Fluorquinolones. ESBL. Ciprofloxacin. Levofloxacin.

Rev Esp Quimioter 2008;21(3):180-183 [pdf]    

/por

Rev Esp Quimioter 2008;21(3):174-179

Evaluation of marine sponge extracts as new sources of antimicrobial substances

J. A. Mora Cristancho ,  F. Newmark Umbreit ,  M. Santos-Acevedo ,  J. Sánchez Nieves 

  

As part of the search for new natural sources of antibiotic compounds, in this study, carried out in the northeastern coast of Colombia, 15 sponge species were collected. A crude organic extract was obtained from each in vitro against microorganisms with clinical importance for humans (one strain for each specie of Streptococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans). Sponge extracts from Halichondria spp., Petromica ciocalyptoides and Xestospongia proxima exhibited antibacterial activity against gram-positive bacteria and antifungal activity against the fungi, while the sponge Dragmacidon reticulata showed activity only for the same yeast specie. Bioactivity of the extracts was compared with that of both a antibiotic (cefoperazone) and an antimicotic (nistatine). It was found that inhibition values of X. proxima extracts in vitro are, in some cases, higher than those observed for cefoperazone and nistatine. Crude extracts from the sponges Myrmekioderma gyroderma, Myrmekioderma rea, Biemna cribaria, Cinachyrella kuekenthali, Iotrochota imminuta, Oceanapia peltata, Polymastia tenax, Desmapsamma anchorata, Spirastrella coccinea, Cribrochalina infundibulum and Oceanapia bartschi did not show any antimicrobial activity whatsoever.

 

Key words: Porifera. Antimicrobial. Crude extracts. Marine bioprospecting. Colombian Caribbean.

 

Rev Esp Quimioter 2008;21(3):174-179 [pdf] 

/por

Rev Esp Quimioter 2008;21(3):166-173

Evolution of antimicrobial susceptibility patterns of aerobic and facultative gram-negative bacilli causing intra-abdominal infections: results from the SMART studies 2003-2007

 

M. Guembe ,  E. Cercenado ,  L. Alcalá ,  M. Marín ,  R. Insa ,  E. Bouza 

  

Study for Monitoring Antimicrobial Resistance Trends (SMART) is an ongoing global antimicrobial surveillance program focused on clinical isolates from intra-abdominal infections (IAI). The objective of this subanalysis was to assess the evolution of the antimicrobial susceptibility patterns among aerobic and facultative gram-negative bacilli (GNB) recovered over a 5-year period at our institution. We tested the in vitro activity of the antimicrobials, commonly used to treat IAI, against consecutive unique isolates from IAI using microdilution techniques according to the CLSI guidelines for MIC testing. All isolates were screened phenotypically for extended-spectrum beta-lactamase (ESBL) production. Isolates recovered within 48 h of hospitalization were considered community-acquired (CA). Over the study period a total of 572 aerobic and facultative gram-negative bacilli were recovered from 510 patients, of which 258 (45%) were CA. Enterobacteriaceae composed 91% of the total isolates. Escherichia coli was the most common isolated species (52%). Susceptibility rates of Enterobacteriaceae ranged from 96.5 %-100 % to ertapenem, 96.5 %-100 % to imipenem, 87.7%-94.3% to piperacillin-tazobactam, 85.1%-94.3% to cefotaxime, 89.5%-100% to cefepime, 76.3%-84.8% to ciprofloxacin, and 93.8%-100% to amikacin. ESBL were detected in 6.3% of E. coli, 5.7% of Klebsiella spp. and 2.7% of Enterobacter spp. ESBL producers generally had a more antibiotic- resistant profile than non-ESBL producers and 16% of them were CA. Susceptibility rates to ertapenem, imipenem, piperacillin-tazobactam, ceftazidime, cefepime, ciprofloxacin and amikacin were, respectively, for P. aeruginosa: 28.2 %, 58.9%, 82%, 84.6 %, 76.9 %, 71.8% and 82%; for Acinetobacter baumannii: 33.3 %, 100 %, 66.6 %, 66.6 %, 66.6%, 66.6% y 66.6%, and for Stenotrophomonas maltophilia: 0%, 0%, 0%, 28.6%, 0%, 42.9% and 14.3%. Over the 5 year-study period we have not observed significant increases in resistance of aerobic and facultative GNB causing IAI to commonly used beta-lactam antimicrobial drugs. A minority of ESBL-producing Enterobacteriaceae were CA. Carbapenems, including group I agents like ertapenem, were the most reliably active drugs in vitro against isolates producing IAI.

  

Key words: Intra-abdominal infections. Extended-spectrum beta-lactamases (ESBL). Carbapenems. Antimicrobial resistance.

Rev Esp Quimioter 2008;21(3):166-173   [pdf] 

/por

Rev Esp Quimioter 2008;21(3):157-165

Distribution of patterns of sensitivity and associated phenotypes of resistance in nosocomial and community acquired Escherichia coli during 2005

M. V. García López ,  M. M. Gallardo García ,  R. Rodríguez-Ortega ,  F. Ropero Pinto ,  E. Granados Martín ,  M. I. Viciana Ramos ,  A. Gutiérrez-Cobos ,  A. Pinedo Sánchez

  

Introduction. The increase of resistances to Escherichia coli over recent years has made it necessary to know the patterns of sensitivity in a certain area in order to be able to orient adequate empirical treatment with this knowledge.

Method. Prospective longitudinal study using E. coli isolations obtained during year 2005 in the University Hospital Virgen de la Victoria was performed. Sensitivity identification and study were made according to standardized laboratory protocols.

Results. A total of 2,612 strains of E. coli were isolated from 2,098 patients with an average age of 52 years who had urinary infection as the most frequent sign. E. coli sensitivity was: ampicillin (AMP) (35.4%), ciprofloxacin (QUIN) (67.3 %), trimethoprim-sulfametoxazole (SXT) (63.4 %), phosphomycin (97.2 %) and amoxicillin-clavulanic acid (89%). The percentage of E. coli extended-spectrum β-lactamase (ESBL) producers was 8.2%. In general, nosocomial isolations were more resistant, this difference being significant for third generation cephalosporins, gentamicin and piperacillin/tazobactam (p < 0.005). Resistance in men was greater than in women and also in adults compared to children, with significant differences to ciprofloxacin and gentamicin (p < 0.005). A total of 27.5% of the strains were multiresistant, the most frequent phenotype being the one to AMP/SXT (11.9%), followed by AMP/QUIN/SXT (10.9%).

Conclusions. Resistances to E. coli are very elevated in out setting, above all, in quinolones, that even appear in children, so that up to half of the multiresistant phenotypes present resistance to this family. Furthermore, during the last year, an increase in the isolations of E. coli ESBL producers has been observed.

Key words: Escherichia coli. Phenotype of resistance. Antibiotic sensitivity. ESBL.

Rev Esp Quimioter 2008;21(3):157-165 [pdf] 

/por

Rev Esp Quimioter 2008;21(3):153-156

Bacteremia after periodontal procedures

J. R. Maestre Vera ,  M. Mateo Mestre ,  P. Sánchez Santana 

  

Introduction. Bacteremia frequently occurs after oral surgery and odontology procedures. Periodontitis may affect the incidence and bacterial spectrum of bacteremia. Periodontal disease may be a significant risk factor for the development of certain systemic diseases. This study has aimed to evaluate the frequency of aerobic and anaerobic bacteria in the bloodstream following scaling and root planing.

Material and methods. Thirteen patients with generalized chronic periodontitis were included in the study. Two samples of peripheral blood were drawn for culture at different times: pre-treatment and immediately after odontology treatment (full-mouth scaling).

Results. None of the 13 patients had bacteremia before the procedures. Bacteremia after scaling occurred in 10/13 (76.9 %) of periodontitis patients. The anaerobic bacteria (Prevotella spp., Micromonas micros and Fusobacterium nucleatum) were the most predominant microorganism. Conclusions. Our findings suggest that periodontal procedures induce bacteremia and may represent risk of developing systemic complications. The use of antibiotic prophylaxis is crucial for its prevention.

 

Key words:Bacteremia. Periodontal procedures. Anaerobic bacteria. Antibiotic prophylaxis.

Rev Esp Quimioter 2008;21(3):153-156  [pdf]

/por

Rev Esp Quimioter 2008;21(3):149-152

β-lactam susceptibility of Escherichia coli isolates from urinary tract infections exhibiting different resistance phenotypes

 

M. Lerma ,  L. Cebrián ,  M. J. Giménez ,  P. Coronel ,  M. Gimeno ,  L. Aguilar ,  J. García de Lomas 

Susceptibility to β-lactams was determined in 203 recent Spanish E. coli isolates from urinary tract infections exhibiting different resistance phenotypes: a) susceptible (n = 60); b) quinolone-resistant (n = 45); c) penicillinase (n=64); d) hyperproduction of penicillinase (n=8); e) inhibitor resistant TEM (IRT) (n=18), and f) extended spectrum betalactamase (ESBL) (n=8). Minimum inhibitory concentration (MIC) determination by agar dilution and susceptibility tests for ESBL detection by macrodilution were performed following CLSI recommendations. All the β-lactams tested showed high activity against susceptible and penicillinase phenotypes, with close to 100 % susceptibility. Hyperproduction of penicillinase increased MIC90 values for all antibiotics except for meropenem, with 100% resistance to cefuroxime and amoxicillin/clavulanic acid, and 100% susceptibility to cefotaxime, piperacillin/tazobactam and meropenem. All the antibiotics, except for amoxicillin/clavulanic acid, exhibited high activity against IRT. Meropenem, cefminox and piperacillin/tazobactam exhibited the highest activity against ESBL, followed by amoxicillin/clavulanic acid. The most active compound among the parenteral antibiotics was meropenem, regardless of the resistance phenotype. Among the oral antibiotics, the most active compound was cefditoren with the exception of ESBL where amoxicillin/clavulanic acid where the MIC90 value was one dilution lower.  

Key words: E. coli. β-lactamase. Cefditoren.

Rev Esp Quimioter 2008;21(3):149-152  [pdf] 

/por

Rev Esp Quimioter 2008;21(3):143-148

Obtain best usage of meropenem dose in severe infections. Results of an observational multicenter study

B. Álvarez-Sánchez ,  F. Álvarez-Lerma ,  J. L. Romero ,  L. Fernández Quero ,  F. Ruiz Ferrón ,  H. Sancho Ruiz   

Objective. To describe the effectiveness and tolerability of the dose adjustment of meropenem in empirical treatment of nosocomial infections in critically-ill patients admitted to intensive care medicine services.

Methods. Prospective, observational and multicenter study in patients admitted to 17 intensive care medicine services with nosocomial infection, who were initially treated with meropenem, 1 g every 8 h, were eligible. The initial dose was adjusted to 0.5 g every 8 h if there were: a) a favorable clinical course, and b) microbiological isolation of meropenem-susceptible pathogens or absence of pathogens in cultures.

Results. Ninety-two patients in whom meropenem doses were adjusted to 0.5 g every 8 h were included. Ventilator-associated pneumonia followed by bacteremia was the most frequently treated infections. Microbiological studies were positive in 53 patients, with a predominance of gram-positive bacteria (53.7%), especially methicillin-susceptible Staphylococcus aureus, followed by gram-negative bacteria (42.7 %). A total of 18 patients were not evaluable at the end of treatment. Sixty-seven (90.5 %) of the 74 evaluable patients had a favorable clinical course (54 patients cured and 13 improved). In 50 out of 53 microbiologically evaluable cases, eradication or apparent eradication of initial microorganisms was achieved. In 3 cases, the initial pathogen persisted: Acinetobacter baumannii (2 cases) and Pseudomonas aeruginosa (1 case). On three occasions, new pathogens developed during treatment: A. baumannii (2 cases) and methicillin-resistant S. aureus (1 case). Adverse events occurred in 3 patients (4%), none of which was considered severe, and withdrawal of meropenem was not necessary. A total of 25 (27.2 %) patients died, three of them in relation to the infectious process.

Conclusions. Dose adjustment of meropenem to 0.5 g every 8 h is a useful tool in the treatment of severe nosocomial infections in patients admitted to services of intensive care medicine except in cases in which causative pathogens are non-fermenting Gram-negative bacteria.  Key words:Meropenem. Severe infections. Therapeutic strategy. Acinetobacter baumannii. Pseudomonas aeruginosa.  

Rev Esp Quimioter 2008;21(3):143-148 [pdf]

/por

Rev Esp Quimioter 2008;21(2):127-142

Recommendations of antifungal treatment in patients with low grade inmunosuppression

 

J. Barberán ,  J. Mensa ,  C. Fariñas ,  P. Llinares ,  R. Serrano ,  R. Menéndez ,  C. Agustí ,  M. Gobernado ,  J. R. Azanza ,  J. A. García Rodríguez 

Because of the relevance that the systemic mycoses has acquired in non-highly immunocompromised patients, thetreatment difficulties they have due to the increase of the non-albicans Candida species and the need to have a better and more rational use of the new antifungal agents (voriconazole, posaconazole, caspofungin, anidulafungin and micafungin), an experts’ panel on infectious diseases in representation of the Spanish Society of Chemotherapy, Spanish Society of Internal Medicine, and Spanish Society of Pneumology and Thoracic Surgery has met in order to make a few recommendations based on the scientific evidence in an effort to improve their efficiency.

  

Key words:Systemic mycoses. Low grade immunosuppression. New antifungal agents.

Rev Esp Quimioter 2008;21(2):127-142 [pdf]

/por

Rev Esp Quimioter 2008;21(2):123-126

Isolation of the first metallo-β-lactamase producing Klebsiella pneumoniae in Lebanon

 

Z. Daoud ,  E. Hobeika ,  A. Choucair ,  R. Rohban 

  

Introduction. A 58 year-old man was admitted to the Saint Joseph Hospital-Raymond and Aida Najjar polyclinic in Beirut on July 17, 2007 to undergo surgery for a moderately differentiated colonic adenocarcinoma (T3N0). Following several discharges and re-admissions, an extended spectrum beta-lactamase (ESBL) producing Escherichia coli susceptible to imipenem was isolated. The patient was put on imipenem and metronidazole. Three weeks later, imipenem (IMP) resistant Klebsiella pneumoniae was isolated.

Methods and results. The antimicrobial susceptibility profile of the imipenem-resistant Klebsiella pneumoniae strain and related minimum inhibitory concentrations of antibiotics were determined. Hydrolysis of IMP was evaluated and production of metallo-β-lactamase (MBL) was detected by a double disk-synergy test, ethylene diamine tetraacetic

acid (EDTA) inhibited the imipenemase activity, whereas clavulanate and tazobactam did not, this suggesting the production of a metallo-β-lactamase. Isoelectric focusing analysis was performed and indicated the presence of a cefotaximase (blaCTX-M-15). Polymerase chain reaction (PCR) was used and detected the presence of blaIMP-1 and blaCTX-M genes.

Conclusions. During the last decade, many hospital outbreaks caused by ESBL-producing Enterobacteriaceae spp. have been reported in Lebanon. To our knowledge, this is the first report of a clinical isolate of K. pneumoniae producingan MBL in Lebanon.   

 

Key words: Metallo-β-lactamase. Klebsiella pneumoniae. Extended spectrum beta-lactamase (ESBL). Resistance. Carbapenemases. BlaIMP-1. BlaCTX-M-15. Lebanon.

Rev Esp Quimioter 2008;21(2):123-126 [pdf]

/por