Rev Esp Quimioter 2013:26(3):221-225

Protection of Enterococcus faecalis in mixed cultures with carbapenemase-producing Escherichia coli and Bacteroides fragilis: effect of the bacterial load                                 
 

DAVID SEVILLANO, LORENZO AGUILAR, LUIS ALOU, MARÍA-JOSÉ GIMÉNEZ, FABIO CAFINI, NATALIA GONZÁLEZ, JOSÉ PRIETO             

Introduction. This study explores effects of pH and inoculum size on imipenem versus tigecycline activity against E. coli, B. fragilis and E. faecalis, both in individual and mixed cultures.
Methods. MIC/MBCs (mg/L) of tigecycline and imipenem were 0.12/≥16 and 4/4 for E. coli, 0.12/0.5 and ≥16/≥16 for B. fragilis, and 0.12/≥16 and 2/≥16 for E. faecalis, respectively. Killing curves in supplemented Brucella broth were performed at pH 7 or 5.8, with two final inocula (≈105 or ≈107 cfu/ml) of each isolate (individual cultures) and with 1:1:1 mixed inocula. Tubes were 48h incubated at 37ºC in anaerobiosis. Final concentrations (estimated concentrations in colon) were 1.50 mg/L for tigecycline and 26.40 mg/L for imipenem, with antibiotic-free curves as controls. Experiments were performed in triplicate.
Results. Imipenem showed inoculum effect against E.coli and B. fragilis, with reductions in initial inocula in experiments with standard inocula contrasting with increases in experiments with high inocula (both individual and mixed cultures). Against E. faecalis no inoculum effect for imipenem was observed in individual cultures, with marked reductions in initial inocula regardless inoculum size. However in mixed experiments the indirect protection of E. faecalis by the two gramnegatives resulted in bacterial regrowth. This protection was inoculum-dependant since it occurred with high but not with standard inocula. Tigecycline reduced initial inocula of the three isolates regardless culture type (individual/mixed) or experimental conditions (pH/inocula size), with lower reductions for the tolerant E. faecalis.
Conclusion. Carbapenemase activity was inoculum-dependant for self-protection and indirect protection of E. faecalis.

Rev Esp Quimioter 2013:26(3):221-225 [pdf]

/por

Rev Esp Quimioter 2014:27(1):43-45

Evaluation of galactomannan antigen and Aspergillus real time PCR for diagnosis of invasive aspergillosis                                
 

MERCEDES CHANZÁ, Mª TERESA FRAILE, CONCEPCIÓN GIMENO, Mª DOLORES OCETE               

Introduction. The aim of the study was to compare the galactomannan antigen (GA) and  molecular biology(PCRrt) tests with the culture in the diagnosis of invasive aspergillosis (IA). 
Material and methods. Four hundred and seventy two samples were analyzed: 388 respiratory and 84 serum samples from 271 patients. Culture and GA were evaluated in the respiratory samples and GA in the serum samples. PCR was used when discrepancies were observed among culture and GA tests.
Results. The detection of GA in serum was positive in 22 (of 84), 21 had the test positive respiratory sample. Of the 62 sera with negative GA, 45 were also negative respiratory specimens. The culture was positive in 37 of which were positive for GA. Comparing culture with AG, it showed PPV=23%, NPV=100%, S=100% and E=52%. The PCR showed respect to culture: PPV=69%, NPV=89%, S=64% and E=82%. In sera were found in 60% discrepancies between PCRrt and GA.
Conclusions. We consider useful the GA detection in serum combined with culture and GA in respiratory samples, for diagnosis of AI. PCR requires further studies for standardization and set breakpoints.

Rev Esp Quimioter 2014:27(1):43-45 [pdf]

/por

Rev Esp Quimioter 2014:27(3):180-189

State of infection caused by methicillin-resistant Staphylococcus aureus (MRSA) in Extremadura: susceptibility, clonality and role of community-associated MRSA                                 
 


VICENTE AGUADERO, CARMEN GONZÁLEZ-VELASCO, ANA VINDEL, MIGUEL GONZÁLEZ-VELASCO, JUAN JOSÉ MORENO               

The correct surveillance and control of infection caused by methicillin-resistant Staphylococcus aureus (MRSA) needs of update knowledge of its specific properties in each place. Our study aims to describe the current characteristics of infection due to MRSA in Extremadura. During 2010, 309 MRSA were collected from clinical samples in our region. A susceptibility test that included 17 antibiotics tested by AST -588 card Vitek 2 ® and E -test method was performed on all isolates. A sample of 100 strains, selected by stratified random sampling, were genotyped by pulsed field electrophoresis (PFGE). The prevalence of MRSA in Extremadura was 20.2%. Don Benito-Villanueva area showed the most prevalence and a higher incidence. Merida reported the most favourable situation, with a relatively low ratios of prevalence and incidence. The community acquired reached 44 % in the region, showing predominantly in less populated areas (Navalmoral and Coria). The most common multiresistant pattern was tobramycin-levofloxacin-erythromycin (44%), followed tobramycin-erythromycin-clindamycin (20%). No linezolid, daptomycin and tigecycline resistant strains were observed, but 42 % of the MRSA strains showed decreased susceptibility vancomycin (DSV). PFGE analysis reported 27 genotypes, with 3 major genotypes: E8a (25%), E7b (17%) and E7a (12%). The post-hoc statistical analysis did not reveal significant differences in the distribution of genotypes between different areas. However it revealed some trends that should be considered.

Rev Esp Quimioter 2014:27(3):180-189 [pdf]

/por

Rev Esp Quimioter 2013:26(2):92-96

Incidence and susceptibility of Campylobacter jejuni in pediatric patients: involvement in bacteremia                                
 

MARÍA JOSÉ GONZÁLEZ-ABAD, MERCEDES ALONSO-SANZ               

Introduction. Invasive disease as a result Campylobacter spp. is rarely reported. Bloodstream infections have been reported in patients with immune deficiency or other serious underlying conditions. We conducted a prospective study to know the incidence of Campylobacter jejuni bacteremia in pediatric patients and its susceptibility to erythromycin and ciprofloxacin.
Methods. The identification of Campylobacter isolates was based on routine culture methods. Antimicrobial susceptibility was performed using a disk diffusion method.
Results. During April 2010-June 2012, at Hospital Niño Jesús of Madrid, Campylobacter spp. was isolated from 171 stool specimens in 154 patients. The median age was 2 years (3 months-21 year). One hundred and one (66%) isolates were identified as C. jejuni. Nine patients with enteritis due C. jejuni (9%) were immunocompromised. Erythromycin resistance was observed in 5% of the isolates. The resistance to ciprofloxacin was 88%. Blood cultures were obtained of 19 patients infected with C. jejuni (19%). Of these, one had C. jejuni bacteremia. During the study period, other episode of C. jejuni bacteremia was detected in one patient different without positive stool culture for C. jejuni (0.34% of all bloodstreams infections). Both patients were immunocompromised.
Conclusions. Campylobacter spp. is an uncommon cause of bloodstream infection in our serie occurring in pediatric patients with immune deficiency as predisposing factor. In our institution, empirical use of fluoroquinolones for Campylobacter infections should not be recommended by the high rate of resistance. Moreover in our study the resistance to erythromycin is low, however is advisable its surveillance.

Rev Esp Quimioter 2013:26(2):92-96 [pdf]

/por

Rev Esp Quimioter 2013:26(3):253-260

Control of Chagas disease in pregnant Latin-American women and her children  

 

FRANCISCO J MERINO, ROCÍO MARTÍNEZ-RUIZ, ICIAR OLABARRIETA, PALOMA MERINO, SILVIA GARCÍA-BUJALANCE, TERESA GASTAÑAGA, MARÍA FLORES-CHAVEZ, GRUPO DE ESTUDIO DE LA ENFERMEDAD DE CHAGAS DE LA COMUNIDAD DE MADRID             

Chagas disease is a chronic and systemic infection caused by Trypanosoma cruzi. According to estimates from WHO, 10 million people are affected by this parasite. In the last years, birthrate among the immigrant women from Latin America settled in the Comunidad Autónoma de Madrid has been increasing, and as T. cruzi can be transmitted from mother to child, in fact 11 cases of congenital Chagas disease have been confirmed. Therefore, the aim of this paper is encouraging improvements in the coverage of the anti-T. cruzi antibodies detection in pregnant women from endemic areas. By this strategy, an active search for infected pregnant women and early detection of her infected newborns could be conducted, and then an early specific treatment could be administrated. Thus, there could be an important contribution to the control of Chagas disease in non-endemic area.

Rev Esp Quimioter 2013:26(3):253-260 [pdf]

/por

Rev Esp Quimioter 2014:27(1):46-50

Antimicrobial stewardship in patients recently transferred to a ward from the ICU                                
 

ANTONIO RAMOS, LAURA BENÍTEZ-GUTIERREZ, ANGEL ASENSIO, BELÉN RUIZ-ANTORÁN, CARLOS FOLGUERA, ISABEL SÁNCHEZ-ROMERO, ELENA MUÑEZ               

Purpose. Inappropriate use of antibiotics is an important health problem that is related to increasing bacterial resistance. Despite its relevance, many health institutions assign very limited resources to improving prescribing practices. An antimicrobial stewardship programme (APS) centred on patients discharged from the ICU could efficiently undertake this task.
Methods. During this six month study the main activity was performing a programmed review of antimicrobial prescriptions in patients transferred to the ward from the ICU. In the case of inadequate antimicrobial treatment, a recommendation was included in the medical record.
Results. A total of 437 antimicrobial prescriptions for 286 patients were revised during a six month period. In all, 271 prescriptions (62%) were considered inappropriate in 183 patients. The most common reasons for inappropriateness were treating unconfirmed infection (43%), inadequate antimicrobial coverage (34%) and intravenous administration when the oral route was feasible (11%). Proposed recommendations were addressed in 212 cases (78%). There was no significant difference in adherence with respect to the type of recommendation (p=0.417). There was a 5% lower use of antibiotics during the year the study was conducted compared to the previous one.
Conclusions. ASPs centred on patients discharged from the ICU may be an efficient strategy to ameliorate antimicrobial use in hospitals.

Rev Esp Quimioter 2014:27(1):46-50 [pdf]

/por

Rev Esp Quimioter 2014:27(3):190-195

Prevalence and risk factors for meticillin-resistant Staphylococcus aureus in an acute care hospital and long-term care facilities located in the same geographic area                                 
 


M. PILAR BARRUFET, ESTER VENDRELL, LLUIS FORCE, GORETTI SAUCA, SANDRA RODRIGUEZ, ENCARNA MARTINEZ, ELISABET PALOMERA, MATEU SERRA-PRAT,  JOSEP ANTON CAPDEVILA, JORDI CORNUDELLA, ANABEL LLOPIS, M. ASUNCIÓN ROBLEDO, CRISÓSTOMO VAZQUEZ               

To determine the prevalence and risk factors (RF) for methicillin-resistant Staphylococcus aureus (MRSA) during stay in 1 acute care hospital (ACH) and 4 long-term care facilities (LTCF). After obtaining the informed consent, nasal and skin ulcer swabs were taken and a survey was conducted to determine RF for MRSA. Six hundred and ninety nine patients were included, 413 LTCF and 286 ACH patients and MRSA prevalence were 22.5% and 7.3% respectively. MRSA was located in the nares, skin ulcers, and in both in 61.4%, 21.1%, and 17.5%. Among MRSA carriers, 81% of the ACH and 66.7% of the LTCF patients were only colonized. The multivariate analysis for the ACH revealed the following factors to be associated with MRSA: referral from an LTCF (OR 4.84), pressure ulcers (OR 4.32), a Barthel score < 60 (OR 2.60), and being male (OR 5.21). For the LTCF: urinary catheterisation (OR 3.53), pressure ulcers (OR 2.44), other skin lesions (OR 2.64), antibiotic treatment in ≤ 6 months, (OR 2.23), previous MRSA colonization (OR 2.15), and a Barthel score <20 (OR 1.28). Molecular typing identified 2 predominant clones Q, P, present in all centres. No relationship was found between clones and antibiotic susceptibility.
In conclusion: MRSA prevalence is high in all centres but is 3 times greater in LTCF. The risk factors most strongly associated with MRSA were pressure ulcers and a stay in an LTCF. We propose preventive isolation in these cases.

Rev Esp Quimioter 2014:27(3):190-195 [pdf]

/por

Rev Esp Quimioter 2013:26(2):97-102

Biofilm score: is it a differential element within gram negative bacilli?                                
 

JAVIER GÓMEZ, MARÍA LUISA GÓMEZ-LUS, PEDRO BAS, CARMEN RAMOS, FABIO CAFINI, JUAN RAMÓN MAESTRE, JOSÉ PRIETO             

The aim of the study was to investigate biofilm formation in Gram negative bacteria and to quantify biofilm production applying a new developed technique that made possible to compare results about biofilm formation within the different Gram negative bacteria species. A total of 153 Gram negative strains corresponding to 12 different bacterium species were studied applying a variation of the optic density measurement technique reported by Stepanovic et al. Data obtained with optic density analysis allow to classify microorganisms in strong biofilm developers, moderate biofilm developers, weak biofilm developers and no biofilm developers. The results were expressed in two ways, using in both cases the same statistical method: without standardization, where controls were different depending on the day optic density measurements were performed, and standardized using a correction factor, using the same control for every strain of all our bacterium species in our study, which allows result homogenization. The obtained results in our study after data analysis and standardization show that over the 153 Gram negative strains in our study, 105 of them were no biofilm developers, representing 63.75% of all the studied bacterium genera. We consider that standardization and quantification of biofilm development in Gram negative bacteria can be useful in clinical practice, because biofilm development ability can lead or focus the gold treatment of pathologies produced by these microorganisms.

Rev Esp Quimioter 2013:26(2):97-102 [pdf]

/por

Rev Esp Quimioter 2013:26(4):287-297

Immunization practices for workers. Update recommendations

MARÍA CARMEN SÁENZ-GONZÁLEZ, IGNACIO HERNÁNDEZ-GARCÍA             

Introduction. Infectious diseases are a major cause of morbidity and mortality in the workplace. Worker vaccination against a number of infectious diseases is considered the most effective strategy of primary prevention to control them.
Sources. A literature review was performed in Medline and websites of Spanish scientific societies were consulted to detect workers vaccination recommendations. The inclusion criteria was that the recommendation had been made from January 2007 to October 2012.
Development. Seventeen papers were selected and websites of the Ministry of Health, Spanish Society of Chemotherapy, Spanish Society of Preventive Medicine, Public Health and Hygiene, and Vaccinology Spanish Association provided relevant information to our review. Groups of workers at increased risk of acquiring infectious diseases during their professional activity were determined, and vaccination recommendations were established (vaccination against tetanus, diphtheria, pertussis, hepatitis A, hepatitis B, pneumococcus, meningococcus, measles, rubella, mumps, chickenpox, influenza, Haemophilus influenzae b, typhoid, polio, tuberculosis and rabies).
Conclusions. Epidemiological changes in recent years, with the re-emergence of some diseases such as whooping cough, measles or mumps, force the exposed workers (especially the health care workers) to check their immune status.

Rev Esp Quimioter 2013:26(4):287-297 [pdf]

/por

Rev Esp Quimioter 2014:27(1):51-55

In vitro emergence of ertapenem resistance in Escherichia coli producing extended-spectrum β-lactamase                                
 

HUGO E. VILLAR, MÓNICA B JUGO, MATÍAS VISSER, MARIANA HIDALGO, GABRIEL HIDALGO, GUSTAVO CESAR MACCALLINI               

Introduction. The occurrence of community-associated infections due to extended-spectrum β-lactamase (ESBL)-producing Escherichia coli is increasing worldwide. These organisms are frequently resistant to many of the antimicrobial agents but remain susceptible to carbapenems. We investigated the in vitro emergence of carbapenem resistance in a collection of clinical isolates of ESBL -producing E. coli.
Material and methods. First and second-step resistant mutants were obtained from E. coli with ESBL. Aliquots of 50μl containing > 109 CFU were applied to Mueller-Hinton plates containing meropenem, imipenem or ertapenem. MICs for native strains and mutants were determined using the epsilometric test (E-test).
Results. Resistant mutants were not selected with imipenem or meropenem. E. coli growth was observed on ertapenem (0.5 mg/L)-containing plates in 13 of 57 clinical isolates (22.8 %).The ertapenem MIC for these first-step mutants were ≥ 1 mg/L, remaining susceptible to imipenem and meropenem. The first-step mutants were used as native strains. Six second-step resistant mutants were selected with ertapenem. All were fully resistant (CMI ≥ 8 mg/L) to ertapenem, three were resistant to meropenem and one to imipenem. Four second-step resistant mutants were selected with meropenem. All were resistant to ertapenem, meropenem, and two of them were resistant to imipenem.
Conclusions. Stable resistant mutants were easy to select with ertapenem among ESBL-producing E. coli. Two steps were necessary to select resistant mutants to meropenem or imipenem.The use of ertapenem in high-inoculum infections or in undrained focus of infection should be monitored to reduce the risk on selection of resistance.

Rev Esp Quimioter 2014:27(1):51-55 [pdf]

/por