Rev Esp Quimioter 2013:26(2):81-91

Mathematical modelling of the propagation of infectious diseases: Where we came from, and where we are going                                 
 

MARIA JOSÉ FRESNADILLO-MARTÍNEZ, ENRIQUE GARCÍA-SÁNCHEZ, ENRIQUE GARCÍA-MERINO, ÁNGEL MARTÍN DEL REY, JOSÉ ELÍAS GARCÍA-SÁNCHEZ               

This work deals with the study of the use of mathematical models to simulate the spreading of infectious diseases. There is no doubt about the importance of the use of computational tools that allow the health staff to model and predict the spreading of an infectious disease. Using such tools one can establish and simulate disease control strategies. The development of such technologies is a multidisciplinary issue; in this sense, the mathematical algorithms –that must be computationally implemented- play a central role. The main goal of this work is to highlight among health community the increasing importance of the use of mathematical models for epidemic disease spreading. Consequently, the main features of such models are introduced and their classification is stated taking into account the behavior, the basic population unit or the mathematical objects used. An exhaustive search of related papers through the most important databases (Medline and Web of Science) are performed. The main conclusion obtained from this work is the central role that mathematical models can play in the simulation of epidemic spreading; moreover, some ideas about the future research are stated.

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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]

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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.

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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.

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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.

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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.

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Rev Esp Quimioter 2013:26(2):103-107

Reasons for the introduction of darunavir in the antirretroviral treatment in HIV-infected patients                                
 

ENRIC PEDROL, JUAN CARLOS LÓPEZ-BERNALDO DE QUIRÓS, SHEILA RUIZ, HENAR HEVIA, FRANCISCO LEDESMA             

Introduction. In 2009 a deep change in ARV treatment took place in Spain with the introduction of new ARV drugs.The principal objective of the study was to determine the clinical situation of the patients in which DRV/r was introduced in the ARV therapy.
Methods. Observational, cross sectional and multicentre study in which 91 reference hospitals participated. Patient’s enrolment was carried out between 2008 and 2009. Data were collected retrospectively considering standard clinical practice.
Results. 719 medical records were reviewed. Patients had a different clinical situation compared to nowadays with predominance of multiresistant virus which leaded to virologic failure. The principal reason for introducing DRV/r in the ARV regimen was the virologic failure (54.2%).
Conclusions. Considering this situation, DRV/r became a therapeutic option which represented a change in the ARV paradigm in that period.

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Rev Esp Quimioter 2013:26(4):298-311

Prevention and control of nosocomial and health-care facilities associated infections caused by species of Candida and other yeasts

JAVIER PEMÁN, RAFAEL ZARAGOZA, MIGUEL SALAVERT             

Knowledge of the epidemiology of invasive fungal diseases caused by yeasts (Candida spp., especially) in health care settings allows the establishment of the levels necessary for its prevention. A first step is to identify groups of patients at high risk of nosocomial invasive fungal infections, establish accurate risk factors, observing the periods of greatest risk, and analyze the epidemiological profile in genera and species as well as the patterns of antifungal resistance. Secondly, mechanisms to avoid persistent exposure to potential fungal pathogens must be programed, protecting areas and recommending measures such as the control of the quality of the air and water, inside and outside the hospital, and other products or substances able to cause outbreaks. Finally, apart from the correct implementation of these measures, in selected patients at very high risk, the use of antifungal prophylaxis should be considered following the guidelines published.

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Rev Esp Quimioter 2013:26(1):1-5

Use of peripheral catheters: too much to learn                                 
 

J. A. CAPDEVILA               

Frequently incident complications due to the use of peripheral catheters are considered not relevant. However, recently multiple observational studies have demonstrated its role causing nosocomial bacteraemia. Guidelines about prevention of catheter-related infection are focused in central lines instead of peripheral ones. This approach causes an important lack of knowledge about the best manner to manipulate peripheral lines.
Risk factors related to the development of a peripheral phlebitis, its clinical relevance and doubts related to prevention are presented and discussed in this article. The main objective is to alert about the importance of peripheral catheters in the prevention of nosocomial infection.

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Rev Esp Quimioter 2013:26(2):108-111

Serological markers of Spanish and immigrant pregnant women in the south of Madrid during the period 2007-2010                                
 

FÁTIMA LÓPEZ-FABAL, JOSÉ LUÍS GÓMEZ-GARCÉS             

Objective. The prevalence and evolution of the markers including in the serologic profile of pregnant woman was studied in our hospital during a period of 4 years.
Material and methods. A retrospective study of the prevalence of antibodies against Treponema pallidum, human immunodeficiency virus (HIV), Toxoplasma gondii, rubeola virus and hepatitis B virus (HBV), was performed in our hospital among Spanish and immigrant pregnant women, from January 2007 to December 2010.
Results. A total of 8,012 pregnant were studied, 2,752 (34.2%) of them were foreign. The non-treponemal tests (RPR) were positive in 40 (0.49%) women, being the prevalence slightly superior in foreigners than in natives (0.8 as opposed to 0.3%). The IgG anti-T. gondii global prevalence was 23,35% (1,874 patients). In Spanish pregnant this prevalence was 18%, and 33.8% in the immigrant women. Almost the total of Spanish pregnant (99.5%) displayed IgG antibodies against rubeola virus whereas in the foreigners this rate was 61.6%. The presence of HBsAg for HBV was tested in 86.6% of pregnant women (6,939/8,012), being positive the 0.75% (59 patients), with a prevalence in foreigners greater than in Spanish (1.65 as opposed to 0.4%). Antibodies anti-HVI were detected in 22 patients (0.22%), being the prevalence 0.15% among the Spanish and 0.51% among the foreigners.

Rev Esp Quimioter 2013:26(2):108-111 [pdf]

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