| Abstract |
Introduction
With the advance of science as well as living conditions, life expectancy has increased worldwide, resulting in a constantly increasing number of elderly people. Infections in the elderly are presented with atypical signs and symptoms, so there is difficulty in their appropriate and immediate treatment. Older patients usually have chronic diseases and frequent hospitalizations, while at a hospital the elderly are prone to being colonized by nosocomial pathogens. The elderly who live in nursing homes, after their return from the hospital, transmit nosocomial pathogens to other residents, consequently spreading these pathogens in nursing homes resulting in the colonization of other residents.
The present study aims to investigate the epidemiology of infections in the elderly who live in the community and compare the results with the respective ones of those who live in a long-term care facility. Furthermore, purpose of this study is to investigate the epidemiology of colonization by multidrug bacteria, in residents of nursing homes in a country of such a high rate of microbial resistance to antibiotics like Greece. Materials and Methods
This Thesis carries out a prospective epidemiological study of both infections and colonization by multidrug-resistant pathogens in elderly patients. This study was conducted during September 2012 and August 2017. It took place in the Department of Internal Medicine of the University Hospital and six long-term care facilities (LTCF) in Heraklion, Greece. Blood and urine cultures were taken from patients aged ≥ 65 years with a possible infection. For the study of colonization swabs from the anterior nares and rectal area were obtained from residents in LTCF and some samples were collected from elderly who live in the community.
The following data were prospectively collected from all participants: age, gender, residence (house / LTCF), duration of living in LTCF, number of residents, previous hospitalization, comorbidities (Charlson index), functional status (Katz index of independence in activities of Daily living), previous antibiotic treatment in the last month, presence of decubitus ulcers.
Staphylococcus aureus isolated from the nares of residents of 4 LTCF was characterized by standard microbiological methods and molecular analysis. MRSA isolates were further classified as hospital-acquired (HA-MRSA) and community-acquired (CA-MRSA) based on established clinical criteria and molecular methods.
The present study was according to the guidelines and approved by the Ethics Committee of the University Hospital of Heraklion, Greece. Moreover, informed consent was obtained from each participant following a thorough briefing about the research goals before every sampling. Results
During the five-year period of the study, 670 individuals over 65 years old participated, 309 of them were admitted to hospital with infection and 361 were studied for colonization of which 333 (92%) lived in LTCF.
Totally 469 cultures were collected, 228 blood cultures and 241 urine cultures from 309 patients. Consequently, 293 pathogens were isolated, 207 Gram-negative, 59 Gram-positive and 27 fungi.
From 228 patients‟ blood cultures, 102 (45%) were found positive from which 105 pathogens were isolated. The most common pathogen was Escherichia Coli in 41 patients. Fifty-seven (54%) were sensitive and 44 (42%) were multidrug resistant (MDR).
Positive blood cultures were collected from 87 out of 168 patients (52%) who lived in the community and from 15 out of 60 residents (25%) in LTCF. Eighty-nine pathogens were isolated from individuals who lived in the community and 16 from LTCF. The most common was Escherichia Coli in both groups.
Younger participants seem to be more prone in having positive blood cultures (p = 0.015), while from older participants multidrug resistant pathogens were more commonly isolated (p = 0.044). Residents in LTCF seem to have less positive blood cultures when compared with the participants who lived in the community (p = 0.003).
Positive urine cultures resulted from 169 (70%) out of the 241 participants from which the samples were taken. A number of 188 pathogens was isolated, of which 23 (12%) were fungi. The most common pathogen to be isolated was E.Coli out of 87 patients (51%). Positive urine cultures were found in 128 samples (72%) from patients who lived in the community and in 41 samples (65%) from residents of LTCF. The most common pathogen was E.Coli in both groups, in 68 (53%) samples from the community and in 19 samples (46%) from LTCF.
Significant difference was found between the residents of LTCF and the patients who live in the community (p = 0.001) concerning the sensibility of the pathogens from urine cultures. The residents of LTCF tended to have more multidrug bacteria isolated, than the ones isolated from the urine cultures of the community residents.
The use of antimicrobial treatment and a patient‟s reduced functionality proved to be related with the resistance of pathogens, both in urine and in blood cultures.
For the study of colonization 361 people participated, of which 318 (88%) resided in LTCF.
A total of 470 samples were collected, 333 samples from the anterior nares and 137 from the rectal area. Staphylococcus aureus was isolated from the anterior nares of 94 individuals (28%), 34 stains (36%) of which were sensitive. Concerning the rectal area a total of 254 pathogens were collected. The most common was E.Coli in 163 samples (64%).
Molecular characterization of isolates performed by PFGE resulted in six different types. Staphylococcus aureus was isolated from the anterior nares of 62 out of 218 participants (28%). Thirty three (53.2%) of these strains were CA- MRSA.
Discussion
The present study examines the infections and the colonization in the elderly, residing both in the community and in LTCF. Regarding the infections, the present study finds that the residents of LTCF have less positive blood cultures, when compared with the cultures from participants residing in the community (p = 0.003). Although there is no significant difference when comparing the two groups‟ urine cultures with each other.
Nevertheless, significant difference was observed in the strains of the pathogens that infect the elderly, while residents of LTCF are found more prone in developing an antibiotic-resistant infection.
Regarding colonization, this study resulted that 29% of LTCF residents from the Heraklion area are colonized in their nares (65% MRSA), a percentage higher than the respective one of other European countries. Moreover 17% of the pathogens which were isolated from the rectal area of LTCF residents were ESBL, while 2% of the pathogens were XDR, a result being in good agreement with the ones of other European countries.
The above findings dictate the necessity of applying an infection control protocol in LTCF, since the later are proved to be crucial reservoirs of CA-MRSA and „hotspots‟ for the prevention and the transmission of infectious diseases, concerning their frail residents.
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