Caracterización de staphylococcus aureus resistentes a meticilina en personas institucionalizadas en centros geriátricos

Abstract

The epidemiology of S. aureus depends on conditions on conditions in specific populations. Institutionalized older people are a particularly vulnerable population to be able to suffer from severe infections due to multiresistant microorganisms, since in addition to their own physiological characteristics, they receive a significant amount of antibiotic therapy. In addition, the residences share elements of the hospital, where it has been studied in more depth to multiresistant bacteria, such as S. aures. Few studies of S.aureus colonization in the elderly population have been performed in Spain. The main objective of the study was to describe the characteristics of colonization by S. aureus in the institutionalized population in institutionalized population in community nursing homes in the Bay of Cádiz. Methods: A Cross-sectional study in nursing homes from September 2016 to May 2017. Samples from the anterior nares and axillary areas were tested to all institutionalized residents (N = 359) in three socio-health centers with the highest number of places, with 66 losses. The main variable was being colonized by S. aureus sensitive and resistant to methicillin (SASM and MRSA). SCCmec typing, multilocus sequence typing (MLST) and Pulsed-field Gel Electrophoresis (PFGE) of MRSA strains were carried out. The presence of Panton-Valentine leukocidin (PVL) genes was determined by PCR in all S.aureus strains. The microbiological variables were to give or not positive for Panton-Valentine, to determine the SCCmecA, and to know the antimicrobial resistance. The independent epidemiological variables were: age, sex, comorbidity (Charlson scale), functional status (Barthel scale), antibiotic therapy and hospitalization in the last three months. Analysis was performed through logistic regression. Results: A total of 293 residents were included. Fifty-one residents (17.4%) were colonized with methicillin-sensitive S.aureus (MSSA) and eleven (3.8%) with MRSA. Resistance to at least two aminoglycosides was observed in 25.4% and 90.9% of MSSA and MRSA isolates, respectively, and resistance to levofloxacin in 80.3% and 100% of MSSA and MRSA isolates, respectively. SCCmecIV was detected in all MRSA isolates. ST-8 was the main genotype and was detected in the most of isolates. None of the 62 S.aureus isolates were positive for PVL. The independent epidemiological variables associated with colonization in the bivariate analyses were antibiotic intake in the three months prior to sample collection, a Charlson index ≥ 3 and hospital admission in the previous three months. Use of beta-lactams was significantly related to a MSSA and MRSA carrier status using multivariate logistic regression OR = 2.8 and OR = 3.6, respectively. Conclusions: A low rate of S. aureus carriage was detected, and the prevalence of MRSA was very low. the dominant clone, and only one strain belonged to ST125-MRSA-IVc. Intra-nursing home transmission of MRSA was demonstrated in our study. A very high rate of quinolone resistance was observed in MSSA and MRSA isolates. The profile of the institutionalized patient is that of a woman close to 84 years of age, with high comorbidity. As the use of beta-lactams in three months prior to the study was significantly associated with carrier status. It was related to be a carrier of MRSA and MSSA with having a high comorbidity and being admitted to the hospital for the previous three months, and a significant relationship with the intake of beta-lactams in the last three months of the sample collection