Rev Esp Quimioter 2008;21(4):217-223

Staphylococcus aureus bacteremia in Castellón General Hospital (2001-2005)

S. Sabater Vidal ,  R. Moreno Muñoz 

  

Objective. The aim of this study was to know the frequency of bacteremias produced by Staphylococcus aureus and the sensibility that strains showed, as well as the clinical characteristics of the patients.

Method. We retrospectively studied cases of S. aureus bacteremia detected in our hospital from 2001 to 2005 and also reviewed medical histories from patients during 2005.

Results. A total of 295 cases of S. aureus bacteremia were detected in this study. Annual distributions of the cases were as follows: 35, 54, 62, 64 and 80. By gender, 62.7 % related to males and 37.3 % to females. A total of 58.6 % of the patients were admitted to medical services and 49 % were older than 65 years. Regarding resistance, 34 % of the strains showed resistance to oxacillin, 33 % to ciprofloxacin, 41 % to erythromycin and 4.4 % to gentamicin. In one-third of the patients, S. aureus was isolated in other samples, the catheter being the most common. A total of the 73.5 % of the patients had some baseline disease and the most frequent predisposing factor was the intravascular catheter. The bacteremias were nosocomial-acquired in 73.5 % of the cases.

Conclusions. In our hospital, S. aureus bacteremia and oxacillin resistance has been increasing over the years of this study.    

 

Key words: Staphylococcus aureus. Bacteremia. Oxacillin resistance. Catheter. Nosocomial.   

 

Rev Esp Quimioter 2008;21(4):217-223 [pdf]

/por

Rev Esp Quimioter 2008;21(4):213-216

Evaluation of the cefoxitin 30 μg disk diffusion method for detection of methicillin-resistance in selected Staphylococcus aureus isolates

N. Batista Díaz ,  I. Gutiérrez González ,  M. Lara Pérez ,  F. Laich ,  S. Méndez Álvarez 

  

Oxacillin tests may fail to detect some methicillinresistant S. aureus populations. The objective of this study is to evaluate the discriminative capacity of the Clinical and Laboratory Standards Institute (CLSI) disk diffusion method with a cefoxitin 30 μg disk on S. aureus isolates with unusual phenotypic characteristics of antimicrobial resistance. We studied 53 clinical S. aureus isolates. The antimicrobial susceptibility of all isolates was routinely studied by the VITEK 2 System (bioMérieux). Methicillin resistance was also studied by CLSI oxacillin method and confirmed by a previously described multiplex polymerase chain reaction (PCR) method which permits S. aureus identification and simultaneous detection of methicillin resistance. MecA positive isolates presenting a diffuse growth within the zone of inhibition when exposed to oxacillin were considered heteroresistant; mecA negative, oxacillin intermediate or resistant isolates were considered borderline. All the isolates were tested with a cefoxitin 30 μg disk, according to the CLSI guidelines (susceptibility: > 22 mm; resistance: < 21 mm). Control strains for all assays included MRSA ATCC 43300 and MSSA ATCC 25923. The isolates formed four groups. Group I: 20 multiresistant, oxacillin susceptible and mecA negative isolates; group II: 16 resistant or with intermediate oxacillin susceptibility and mecA negative isolates; group III: 11 heteroresistant and mecA positive isolates; group IV: six mecA positive isolates with atypical resistance profiles (penicillin and oxacillin, or ciprofloxacin and erythromycin resistance). Thirty-five mecA negative isolates included in groups I and II showed inhibition zones > 22 mm; one isolate from group II showed 20 mm. The 17 mecA positive isolates from groups III and IV showed resistance to cefoxitin disk. The 30 μg cefoxitin disk diffusion method is proposed as an efficient method for the detection of methicillin resistance and permits a clear determination set S. aureus isolates, even those with atypical antimicrobial characteristics.

  

Key words: Staphylococcus aureus. Cefoxitin. Methicillin-resistance

 

Rev Esp Quimioter 2008;21(4):213-216 [pdf]

/por

Rev Esp Quimioter 2008;21(4):206-212

A day in Spanish microbiology. Descriptive study of the activity of the clinical microbiology departments

J. Prieto ,  J. Á. García Rodríguez ,  J. Barberán ,  J. J. Granizo ,  M. P. Rodicio ,  J. González     

Introduction. The laboratory is an essential part of the work in the Clinical Microbiology Department. This study has aimed to measure the activity of these laboratories.

Material and methods. A survey was self-administered on the activity occurring during one work day by each hospital in October 2007.

Results. Thirty six hospitals reported 14,076 tests. Serology was the most frequently reported test (30.3%) followed by urine culture (27.8 %), blood tests (13.2 %), respiratory tract samples (8%), feces (7.1%), urethral (5.8%), skin (5.3%) and cerebrospinal fluid (2.6%). According to species, 73.2% of the isolates were bacteria (22.9 % were positive), 8.9% were virus (17% positive), fungi 8.1% (25.2% positive), and 5.5% mycobacterias (5.9% were positive) and parasite 4.5% (12.5% positive). Susceptibility test were performed by automatic methods (62.3%) followed by diffusion test (27.1%) and E-test (9.1%). A total of 5.6% of the susceptibility tests showed in vitro resistance to antibiotics. Fungi were identified in 108 isolates. Candida and Aspergillus were the most frequent genus (85.1% and 8.3%, respectively). Origins of the samples were: lower respiratory tract (32.4 %), genital tract (24.1 %), urine (10.2 %), blood (10.2 %) and skin (10.2 %). Twelve identification techniques were used, the most frequent being the morphological test (54.8%) and biochemical test (39.7%). Broken down by departments, 20.4% were sent from the ICU, 16.7% from surgery, 29.6% from medicine and 18.5% from primary care.

Discussion. Although the workload of the laboratories has been measured in this work, aspects such as specimen manipulation, clinical advice and research were not considered.

  

Key words: Laboratory. Fungi. Activity. Assistance. Organization.

Rev Esp Quimioter 2008;21(4):206-212 [pdf]  

/por

Rev Esp Quimioter 2008;21(3):198-202

Why not revisiting tinidazole as potential treatment of odontogenic infections?

F. Manso ,  M. S. Gamboa ,  M. J. Giménez ,  A. Bascones ,  M. L. Gómez-Lus ,  L. Aguilar 

  

Tinidazole is a 5-nitroimidazole initially introduced into clinical medicine in 1969 for the treatment of unicellular parasites. Tinidazole offers selective bactericidal activity, not influenced by the inoculum size, against anaerobic bacteria, that make it of theoretical interest against periodontopathogen infections. This article reviews the required characteristics of an antibiotic directed to odontogenic anaerobic infections, as well as the pharmacodynamic pitfalls of common antibiotic treatments. In addition the in vitro, pharmacokinetic and pharmacodynamic properties of tinidazole are reviewed, assessing the degree of its adhesion to the required characteristics, as well as identifying the gaps to be fulfilled prior to its use in this medical field. Tinidazole offers interesting characteristics making worthy investigations as a candidate for the treatment of anaerobic odontogenic infections.

 

Key words: Tinidazole. Odontogenic infections. Odontopathogens. Pharmacodynamia.

Rev Esp Quimioter 2008;21(3):198-202  [pdf] 

/por

Rev Esp Quimioter 2008;21(3):194-197

Antimicrobial drugs errors: the silent epidemic in patient safety

M. D. Menéndez Fraga ,  J. J. Corte García ,  M. Alonso Álvarez ,  M. Espín Fernández ,  J. Solano Jaurrieta. ,  F. Vázquez Valdés 

  

Introduction. Prescribed drugs and the mistakes in the administration to patient is the first cause of adverse events in the hospitals. The aim of this study has been to evaluate antimicrobial drug mistakes in one of our hospital wards in a two year period 2005 and 2006.

Methods. All the errors were reported through the National Health Service IR2 form (England) on a voluntary basis and classified by means of process, type of errors, their causes and contributory factors, as well as the severity. We analyzed the economic costs.    

Results. A 1.3% of the inpatients had an antimicrobial error in the administration to the patient (0.84 by 1,000 prescribing orders). Classified by processes, the administration (32.4%) and dispensation (44.1%) were the most frequent errors. By type of error: the erroneous medication (32.4%), the main root cause the human factors (58.8 %) and the contribution factor due to design of tasks (55.9 %). The 5.9% of errors were severe events, mainly in the group of the betalactamic drugs, and mainly by parenteral administration (50%).

Conclusions. Antimicrobial drug errors, frequent and sometimes severe, suppose a silent epidemic not being detected without the patient safety methodology. They represent a high cost for a hospital.

  

Key words: Medication errors. Antimicrobial drugs. Patient safety.

Rev Esp Quimioter 2008;21(3):194-197 [pdf]   

/por

Rev Esp Quimioter 2008;21(3):189-193

In vitro activities of colistin combinations against Pseudomonas aeruginosa isolated from the intensive care unit

F. López-Fabal ,  E. Culebras ,  I. Bonilla ,  M. Gómez ,  J. J. Picazo 

  

Introduction. As the number of multidrug-resistant strains of Pseudomonas aeruginosa has risen in the intensive care unit (ICU) of the San Carlos Clinic Hospital, 12 consecutive isolates from different patients were collected to determine the possibility of an epidemic outbreak caused by the spread of a single strain. We determined the antimicrobial susceptibility to the most common agents used in the treatment of infections caused by this bacteria. The results of susceptibility studies suggest that different strains of P. aeruginosa are responsible for the respiratory tract infections in ICU.

Methods. The clonal relationship between the isolates using was determined using BOX and ERIC primers by means of repetitive sequence-based polymerase chain reaction (rep-PCR). The in vitro activity of these strains against colistin, rifampicin, doxicycline and azythromycin was studied to determine in which cases the combination of colistin with any of the other three antibiotics was synergistic.

Results. Sensitivity studies point out the presence of several strains of P. aeruginosa as the causal agents of respiratory infections produced by this microorganism in the ICU. Combinations of colistin with doxycicline and colistin with azithromycin were synergistic for some isolates in the synergy studies. 

Discussion. Clonal studies reveal the presence of five different clones among our isolates. Therefore we can conclude that there was no outbreak of P. aeruginosa in the ICU. Synergistic activity of combinations of colistin plus azithromycin, colistin plus doxicycline and colistin plus rifampicin was less than expected and a high percentage of indifferent results was observed.    

Key words: P. aeruginosa. Synergistic activity. Colistin. Rep-PCR.

 

Rev Esp Quimioter 2008;21(3):189-193 [pdf]  

/por

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