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. 2022 Nov 1;11(11):1526.
doi: 10.3390/antibiotics11111526.

Molecular Epidemiology of Staphylococcus aureus and MRSA in Bedridden Patients and Residents of Long-Term Care Facilities

Lucas Porangaba Silva  1 , Carlos Magno Castelo Branco Fortaleza  2 , Nathalia Bibiana Teixeira  1 , Luís Thadeo Poianas Silva  1 , Carolina Destro de Angelis  1 , Maria de Lourdes Ribeiro de Souza da Cunha  1
Affiliations

Molecular Epidemiology of Staphylococcus aureus and MRSA in Bedridden Patients and Residents of Long-Term Care Facilities

Lucas Porangaba Silva et al. Antibiotics (Basel). .

Abstract

At present, multidrug-resistant microorganisms are already responsible for community-acquired infections. Methicillin-resistant Staphylococcus aureus (MRSA) poses a serious public health risk worldwide because of the rapid spread and diversification of pandemic clones that are characterized by increasing virulence and antimicrobial resistance. The aim of this study was to identify the prevalence and factors associated with nasal, oral and rectal carriage of S. aureus and MRSA in bedridden patients and residents of long-term care facilities for the elderly (LTCFs) in Botucatu, SP, Brazil. Nasal, oral and rectal swab isolates obtained from 226 LTCF residents or home-bedridden patients between 2017 and 2018 were submitted to susceptibility testing, detection of the mecA gene, SCCmec characterization, and molecular typing by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Logistic regression analysis was used to identify risk factors associated with the presence of S. aureus and MRSA. The prevalence of S. aureus and MRSA was 33.6% (n = 76) and 8% (n = 18), respectively. At the nine LTCFs studied, the prevalence of S. aureus ranged from 16.6% to 85.7% and that of MRSA from 13.3% to 25%. Living in an LTCF, male gender, a history of surgeries, and a high Charlson Comorbidity Index score were risk factors associated with S. aureus carriage, while MRSA carriage was positively associated with male gender. This study showed a high prevalence of S. aureus among elderly residents of small (<15 residents) and medium-sized (15−49 residents) LTCFs and a higher prevalence of MRSA in the oropharynx.

Keywords: MRSA; Staphylococcus aureus; bedridden patients; elderly population; long-term care facility; molecular epidemiology.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Flow chart of the total number of individuals colonized with S. aureus and number of individuals colonized with methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) according to the sampling site. Note: Total number of individuals included in the study (226), number of individuals colonized with S. aureus (76), and number of colonized individuals according to the sampling site. * Overall prevalence of S. aureus. ** Overall prevalence of MRSA.
Figure 2
Figure 2
Dendrogram of PFGE-SmaI profiles of MRSA isolated from bedridden patients at home or long-term care facility residents generated by Dice analysis/UPGMA (BioNumerics, Applied Maths). Note: N: nasal mucosa. O: oropharyngeal mucosa. NT: not typed. Oxa: oxacillin. Cfx: cefoxitin. S: susceptible. R: resistant. LTCF: long-term care facility. ABCD letters represent clusters, lineages that showed 80% or more similarity.
Figure 3
Figure 3
Dendrogram of PFGE-ApaI profiles of MRSA isolated from bedridden patients at home or long-term care facility residents generated by Dice analysis/UPGMA (BioNumerics, Applied Maths). Note: N: nasal mucosa. O: oropharyngeal mucosa. NT: not typed. Oxa: oxacillin. Cfx: cefoxitin. S: susceptible. R: resistant. LTCF: long-term care facility. E and F letter represent clusters, lineages that showed 80% or more similarity.
Figure 4
Figure 4
Dendrogram of PFGE-SmaI and PFGE-ApaI profiles of MRSA isolated from bedridden patients or institutionalized individuals generated by Dice analysis/UPGMA (BioNumerics, Applied Maths) and sequence types (ST) obtained by MLST. Note: Resistant isolates forming clusters >80% similarity after digestion with SmaI (clusters A, B, C, D) and ApaI (clusters E and F). N: nasal mucosa. O: oropharyngeal mucosa. LTCF: long-term care facility. arcC: carbamate kinase. aroE: shikimate dehydrogenase. glpF: glycerol kinase. gmk: guanylate kinase. pta: phosphate acetyltransferase. tpi: triosephosphate isomerase. yqiL: acetyl coenzyme A acetyltransferase. ST: sequence type. CC: clonal complex.
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