Resistencia bacteriana a antibióticos en ambientes acuáticos: origen e implicaciones para la salud pública

El alarmante incremento de la resistencia bacteriana a los antibióticos a nivel global ha dilucidado otras fuentes diferentes al hospital y la comunidad, donde el agua ha cobrado gran importancia. El ambiente acuático constituye la fuente y el hábitat natural de un gran número de microorganismos, incluyendo bacterias resistentes a antibióticos; así mismo, se considera uno de los principales receptores de antimicrobianos, bacterias resistentes y genes de resistencia a antibióticos provenientes de las actividades humanas. La contaminación del agua con estos contaminantes emergentes tiene implicaciones serias para la salud humana, relacionadas con la diseminación de la resistencia bacteriana y la emergencia de nuevos mecanismos de resistencia. En esta revisión se brinda una descripción global del papel de los ambientes acuáticos en el problema de la resistencia bacteriana, las principales fuentes de contaminación, además del impacto para la salud pública. Ante este panorama, se establece la necesidad de abordar la problemática de la resistencia bacteriana desde la perspectiva de "una salud", donde a la vigilancia tradicional, enfocada a nivel humano y veterinario, se articule la vigilancia epidemiológica ambiental, principalmente basada en aguas residuales.

The alarming increase in bacterial resistance to antibiotics globally has diluted sources other than the hospital and community, where water has taken on great importance. The aquatic environment is the source and natural habitat of a large number of microorganisms, including antibiotic-resistant bacteria, as well as being considered one of the main receptors for antimicrobials, resistant bacteria and antibiotic resistance genes from human activities. Contamination of water with these emerging contaminants has serious implications for human health related to the spread of bacterial resistance and the emergence of new resistance mechanisms. This review provides a global description of the role of aquatic environments in the problem of bacterial resistance, the main sources of contamination, as well as the impact on Public Health. In this context, the need arises to address the problem of bacterial resistance from the perspective of "one health", where traditional surveillance, focused at the human and veterinary level, is articulated with environmental epidemiological surveillance, mainly in wastewater.

O incremento alarmante da resistência bacteriana aos antibióticos no nível global tem revelado outras fontes diferentes do hospital e da comunidade, em que a água tem ganho grande importância. O ambiente aquático constitui a fonte e o hábitat natural de um grande número de microrganismos, incluindo bactérias resistentes a antibióticos; é considerado, também, um dos principais receptores de antimicrobianos, bactérias resistentes e genes de resistência a antibióticos provindos das atividades humanas. A poluição da água com esses poluentes emergentes tem sérias implicações para a saúde humana, relacionadas com a disseminação da resistência bacteriana e a emergência de novos mecanismos de resistência. Nesta revisão oferece-se uma descrição global do papel dos ambientes aquáticos na situação problemática da resistência bacteriana, as principais fontes de poluição, além do impacto para a saúde pública. Diante desse panorama, determina-se a necessidade de abordar a problemática da resistência bacteriana desde a perspectiva de "uma saúde" em que a vigilância tradicional, focada nos níveis humano e veterinário, esteja articulada com a vigilância epidemiológica ambiental, principalmente baseada em águas residuais.

Acinetobacter baumannii resistente a carbapenémicos causante de osteomielitis e infecciones de la piel y los tejidos blandos en hospitales de Medellín, Colombia / Carbapenem-resistant Acinetobacter baumannii causing osteomyelitis and infections of skin and soft tissues in hospitals of Medellín, Colombia

Introducción. Acinetobacter baumannii es una bacteria oportunista que infecta a pacientes gravemente enfermos, principalmente con neumonía asociada al uso del respirador y bacteriemia. La aparición de resistencia a los carbapenémicos limita las opciones terapéuticas para el manejo de las infecciones ocasionadas por esta bacteria. Objetivo. Describir las características clínicas y moleculares de las infecciones ocasionadas por A. baumannii resistente a carbapenémicos en hospitales de Medellín. Materiales y métodos. Durante dos años se llevó a cabo un estudio descriptivo de corte transversal en cinco hospitales de Medellín. La información clínica provenía de las historias clínicas. La presencia de carbapenemasas se evaluó mediante el test tridimensional y la técnica de reacción en cadena de la polimerasa. La tipificación molecular se hizo con electroforesis en gel de campo pulsado y tipificación de secuencias de múltiples locus. Resultados. Se incluyeron 32 pacientes, 13 de los cuales presentaban infecciones de la piel y los tejidos blandos (n=7, 21,9 %), y osteomielitis (n=6, 18,7 %). Los porcentajes de resistencia fueron superiores a 80 % para todos los antibióticos evaluados, excepto para la colistina y la tigecilina. Las carbapenemasas OXA-23 y OXA-51, así como la secuencia de inserción IS Aba1 , se detectaron en todos los aislamientos. La electroforesis en gel de campo pulsado reveló una gran diversidad genética en los aislamientos, y la tipificación de secuencias de múltiples locus evidenció la circulación de los clones ST229 y ST758 en la ciudad. Conclusión. Contrario a lo reportado previamente, los resultados del estudio revelaron que la osteomielitis y las infecciones de la piel y los tejidos blandos eran los principales cuadros clínicos causados por A. baumannii resistente a carbapenémicos en instituciones de Medellín, y resaltan su importancia como agente etiológico de este tipo de infecciones.

Introduction: Acinetobacter baumannii is an opportunistic bacterium which infects seriously ill patients, particularly those with ventilator-associated pneumonia and bacteremia. The emergence of resistance to carbapenem limits the options for the treatment of infections caused by this bacterium. Objective: To describe the clinical and molecular characteristics of infections caused by carbapenem-resistant A. baumannii in Medellín hospitals. Materials and methods: A cross-sectional descriptive study was carried out in five Medellín hospitals over a 2-year period. Clinical information was obtained from medical histories of patients. The presence of carbapenemases was evaluated by three-dimensional test and PCR. Molecular typing was performed using PFGE and MLST. Results: The study included 32 patients, 13 of whom presented skin and soft tissue infections (n=7, 21.9%) or osteomyelitis (n=6, 18.7%). Resistance rates of the isolates exceeded 80% for all the antibiotics evaluated except colistin and tigecycline. Carbapenemases OXA-23 and OXA-51, as well as the insertion sequence IS Aba1 , were detected in all the isolates. PFGE revealed high genetic diversity in the isolates and MLST showed clones ST229 and ST758 are circulating in the city. Conclusion: In contrast to previous reports, the results of the present study showed osteomyelitis and infections of skin and soft tissues to be the main infections caused by carbapenem-resistant A. baumannii in Medellín hospitals and revealed its importance as an etiological agent for this type of infections.

Characterisation of virulence genes in methicillin susceptible and resistant Staphylococcus aureus isolates from a paediatric population in a university hospital of Medellín, Colombia

Virulence and antibiotic resistance are significant determinants of the types of infections caused by Staphylococcus aureus and paediatric groups remain among the most commonly affected populations. The goal of this study was to characterise virulence genes of methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains isolated from a paediatric population of a Colombian University Hospital during 2009. Sixty MSSA and MRSA isolates were obtained from paediatric patients between zero-14 years. We identified the genes encoding virulence factors, which included Panton-Valentine leucocidine (PVL), staphylococcal enterotoxins A-E, exfoliative toxins A and B and toxic shock syndrome toxin 1. Typing of the staphylococcal chromosome cassette mec (SCCmec) was performed in MRSA strains. The virulence genes were more diverse and frequent in MSSA than in MRSA isolates (83 percent vs. 73 percent). MRSA strains harboured SCCmec types IVc (60 percent), I (30 percent), IVa (7 percent) and V (3 percent). SCCmec type IVc isolates frequently carried the PVL encoding genes and harboured virulence determinants resembling susceptible strains while SCCmec type I isolates were often negative. PVL was not exclusive to skin and soft tissue infections. As previously suggested, these differences in the distribution of virulence factor genes may be due to the fitness cost associated with methicillin resistance.