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Papers by Kátia Regina dos Santos

SSRN Electronic Journal, 2022

Antimicrobial Resistance & Infection Control

Background Staphylococcus aureus is one of the leading causes of bloodstream infections (BSI) wor... more Background Staphylococcus aureus is one of the leading causes of bloodstream infections (BSI) worldwide. In Brazil, the hospital-acquired methicillin-resistant S. aureus USA100/SCCmecII lineage replaced the previously well-established clones. However, the emergence of community-associated (CA) MRSA lineages among hospitalized patients is an increasing issue. Methods Consecutive S. aureus isolates recovered from BSI episodes of patients admitted between January 2016 and December 2018 in a Brazilian teaching hospital were tested for antimicrobial resistance, their genotypic features were characterized, and the clinical characteristics of the patients were evaluated. Results A total of 123 S. aureus isolates were recovered from 113 patients. All isolates were susceptible to linezolid, teicoplanin and vancomycin and 13.8% were not susceptible to daptomycin. Vancomycin MIC50 and MIC90 of 2 mg/L were found for both MRSA and MSSA isolates. The MRSA isolation rate was 30.1% (37/123), and 51...

Infection Prevention in Practice, 2020

Summary Background Staphylococcus aureus is a human pathogen of clinical importance related to a ... more Summary Background Staphylococcus aureus is a human pathogen of clinical importance related to a variety of infections. Aim The objective of this study was to analyze the molecular and epidemiological characteristics of S. aureus obtained from healthcare professionals (HCP) of a hospital in southwestern Bahia, Brazil. Methods Samples were collected from hands, nasal cavity, and laboratory coats of 80 HCP. The bacterial isolates recovered from 240 samples were identified as S. aureus, and then analyzed for their antimicrobial resistance profile, genotypic characterization, and pathogenicity. Findings 178 isolates were identified as S. aureus, being mostly isolated from the nasal cavity. Thirty isolates (16.8%) were characterized as MRSA. The virulence gene frequency varied according to isolate source. All virulence genes were identified in at least one hand isolate. Isolates from laboratory coats did not show seb and pvl. Isolates from the nasal cavity did not exhibit pvl. The SCCmec type I was identified in 56.7% of MRSA isolates. Among MRSA isolates, 14 PFGE pulsotypes were characterized, with profile A being predominant (nine isolates). Clonal complexes CC5, CC45, and CC398 were found. MRSA isolates induced cytokine gene expression in macrophages, with IL-10 and IL-17 being expressed more often. Conclusion We found a high colonization rate for S. aureus among HCP. Moreover, we observed that MRSA strains presented different virulence factors and could induce cytokine gene expression, indicating an urgent need to control colonization rates of HCP by MRSA isolates in order to protect hospital patients and the general public.

Atopic dermatitis (AD) is a chronic inflammatory skin disease and colonization by Staphy... more Atopic dermatitis (AD) is a chronic inflammatory skin disease and colonization by Staphylococcus aureus may affect up to 100% of these patients. Virulent and resistant isolates can worsen AD patient clinical condition and jeopardize the treatment. We aimed to detect virulence genes and to evaluate the biofilm production of S. aureus isolates from infected skin lesions of children with AD. Methicillin resistance was detected by phenotypic and molecular tests and the virulence genes were detected by PCR. Biofilm formation was assessed by bacterial growing on microtiter plates and later stained with safranin. Genotyping was performed by Pulsed-Field Gel Electrophoresis and Multilocus Sequence Typing. Among 106 AD patients, 55 (51.8%) had developed S. aureus cutaneous infections and 23 (41.6%) were methicillin-resistant (MRSA). All 55 isolates carried the fnbA, hla, icaA, sasG, and seu genes, ...

INTRODUCTION: Methicillin-resistant Staphylococcus aureus (MRSA) can be difficult to detect at th... more INTRODUCTION: Methicillin-resistant Staphylococcus aureus (MRSA) can be difficult to detect at the clinical practice. METHODS: We analyzed 140 MRSA isolates from inpatients to correlate the antimicrobial susceptibility with the SCCmec types. RESULTS: Type III (n = 63) isolates were more resistant to ciprofloxacin, clindamycin, cloramphenicol, erythromycin, gentamicin, and rifampin than type IV (n = 65) ones (p < 0.05). Moreover, type IV isolates were susceptible to tetracycline (100%) and trimethoprim/sulfamethoxazole (98%), while type III isolates presented resistance to them. CONCLUSIONS: In regions where these SCCmec types are prevalent, the detection of specific resistant phenotypes could help to predict them, mainly when there are no technical conditions to SCCmec typing.

Journal of Medical Microbiology, 2021

Introduction. Biofilm formation is a major virulence factor associated with Staphylococcus aureus... more Introduction. Biofilm formation is a major virulence factor associated with Staphylococcus aureus infections. However, the influence of plasma proteins on biofilm formation of clinical isolates in vitro remains unclear. Hypotheses. We hypothesized that coating surfaces with plasma proteins might induce biofilm formation by S. aureus of different clonal lineages. Aim. To evaluate biofilm production by clinical S. aureus isolates of different clonal lineages isolated in Rio de Janeiro hospitals and investigated the presence of biofilm-associated genes. Methodology. This study assessed biofilm production of 60 S. aureus isolates in polystyrene microtitre plates with and without fibrinogen or fibronectin. The biochemical composition of the biofilm matrices was determined and the biofilm formation on fibrinogen-coated surfaces was also evaluated by confocal laser scanning microscopy. The presence of biofilm-related genes was detected by PCR, and the typing and functionality of agr operon...

Applied and Environmental Microbiology, 2020

Brazilian Journal of Microbiology, 2020

Human milk is the best nutrient for infants. The donor human milk is stored in a milk bank before... more Human milk is the best nutrient for infants. The donor human milk is stored in a milk bank before pasteurization. However, the human milk is not sterile and could be colonized with different types of bacteria. Many studies have shown S. aureus to be the most prevalent potential pathogen detected in human milk. This study characterized 22 methicillin-resistant and methicillinsensitive Staphylococcus aureus isolates from raw human milk for the presence of virulence genes and agr type. Moreover, the genotypic as identified characterization was realized. The presence of virulence genes sei, seg, sec, seh, and etb was identified in resistant and sensitive strains. We observed the predominance of agr type II. The presence of SCCmec IV (67%, 4/6) and V (33%, 2/6) characterized resistant strains as CA-MRSA. Endemic lineages detected (ST1635/CC5-t002, ST5/CC5-t002, ST72/CC5-t126, ST1/CC1-t127, ST45/CC45-t065, and ST398/t1451) could be related to epidemic clones, such as USA800/ ST5, USA700/ST72, USA400/ST1, USA600/ST45, and ST398. This study made it possible to understand the characteristics of virulence and clonality of some strains that circulate in breast milk in our region. The discovery of human milk colonization by MSSA and MRSA strains with molecular characteristics similar to infectious clones spread globally demonstrates the importance of monitoring strains that can spread and cause serious infections.

Current Genomics, 2020

Background: Staphylococcus aureus isolates expressing the Panton-Valentine Leukocidin (PVL) have ... more Background: Staphylococcus aureus isolates expressing the Panton-Valentine Leukocidin (PVL) have been related to a wide range of diseases. Recently, pvl-positive community-associated methicillin-resistant S. aureus belonging to USA1100 (ST30/CC30/SCCmec IV) lineage has emerged in Brazilian hospitals. Objective: the aim of this work was to sequence the genome of a pvl-positive USA1100 Vancomycin-Intermediate-Resistant S. aureus (VISA) isolate from Rio de Janeiro, Brazil. Methods: The 13420 genome was sequenced using the HiSeq 2500 platform. The draft genome, plasmids annotation and genome analysis were performed using RAST. Comparison of the relative pvl gene expression of six S. aureus isolates was performed by qRT-PCR. Results: The isolate presented the ϕPVL phage codifying for the H2b PVL protein isoform, and another prophage carrying a PVL variant named lukF and lukS-PV.2. The 13420 genome presented a high number of virulence determinants, such as genes codifying for serine-prote...

Background: Staphylococcus aureus is one of the major causes of bloodstream infections (BSI) worl... more Background: Staphylococcus aureus is one of the major causes of bloodstream infections (BSI) worldwide, representing a major challenge for public health due to its resistance profile. Higher vancomycin minimum inhibitory concentrations (MIC) in S. aureus are associated with treatment failure and defining optimal empiric options for BSIs in settings where these isolates are prevalent is rather challenging. I n silico pharmacodynamic models based on stochastic simulations (Monte Carlo) are important tools to estimate best antimicrobial regimens in different scenarios. We aimed to compare the pharmacodynamic profiles of different antimicrobials regimens for the treatment of S. aureus BSI in an environment with high vancomycin MIC . Methods: Steady-state drug area under the curve ratio to MIC (AUC⁄MIC) or the percent time above MIC ( f T>MIC) were modeled using a 5000-patient Monte Carlo simulation to achieve pharmacodynamic exposures against 110 consecutive S. aureus isolates associ...

The Journal of Infection in Developing Countries, 2019

Introduction: Staphylococcal colonization is a risk factor for healthcare-associated infections, ... more Introduction: Staphylococcal colonization is a risk factor for healthcare-associated infections, which are frequent in Neonatal Intensive Care Units (NICU). This study analyzed microbiology, epidemiology and clinical aspects of Staphylococcus spp. colonizing neonates. Methodology: Nasal or periumbilical swabs were evaluated from 175 newborns admitted to a NICU of a Rio de Janeiro hospital from March to September 2009. Clinical data were obtained from the medical records. SCCmec typing and the mecA and Panton-Valentine Leukocidin (PVL) genes were detected by PCR. Clonal diversity was evaluated by pulsed-field gel electrophoresis. Results: Staphylococcus spp. isolates were detected in 98 (56%) neonates, 66.3% of them had birth weight ≤ 2500 g, 62.2% were preterm (˂ 37 weeks) and the mean length of hospitalization was 14.9 days. Among the 133 isolates identified, 48.1% were S. epidermidis, 23.3% S. haemolyticus and 13.5% S. aureus. Methicillin-resistant Staphylococcus isolate was detec...

Journal of Global Antimicrobial Resistance, 2019

OBJECTIVES Methicillin-resistant Staphylococcus aureus (MRSA) is an important agent of nosocomial... more OBJECTIVES Methicillin-resistant Staphylococcus aureus (MRSA) is an important agent of nosocomial infections, and mutations at the Quinolone Resistance-Determining Region (QRDR) of gyr and par genes have been described among them. This study aimed to characterize phenotypic and genotypic resistance for fluoroquinolones in 69 MRSA isolates of different clonal lineages from hospitals in Rio de Janeiro, Brazil. METHODS QRDR mutations of gyrA, gyrB, parC and parE genes were detected by DNA sequencing. MICs for ciprofloxacin and moxifloxacin were determined by the microdilution broth method. We then verified the occurrence of associations between mutations and MICs among the different clonal lineages of MRSA isolates. RESULTS Most isolates from the USA400/ST1/SCCmec IV lineage, but mainly USA100/ST5/SCCmec II isolates, which have been more recently found in Rio de Janeiro hospitals, showed different patterns of mutations, including double mutation at the QRDR of parC (80:ser→tyr and 84:glu→lys/gly) and/or gyrA (84:ser → leu and/or 88:glu → lys) genes associated with higher moxifloxacin and ciprofloxacin MIC (MIC90 ≥ 8 mg/L and = 256 mg/L, respectively). On the other hand, all USA800/ST5/SCCmec IV and the BEC/ST239/SCCmec III isolates, which have disappeared from hospitals, showed single mutations at parC (80:ser→phe) and gyrA (84:ser→ leu or 88:glu → gly) genes, and lower fluoroquinolones MIC (MIC90≥2 mg/L and ≥ 16 mg/L). CONCLUSIONS This study highlighted an increase in number and types of mutations at QRDR of gyrA and parC genes associated with high fluoroquinolones MIC that may be related to changes in the epidemiological profile of MRSA isolates from hospitals in Rio de Janeiro.

Acta odontologica Scandinavica, Jan 6, 2017

To compare the risk for caries in children as determined by Cariogram(®) software (CS; Stockholm,... more To compare the risk for caries in children as determined by Cariogram(®) software (CS; Stockholm, Sweden) with and without its microbiological component and by a form based on Cariogram(®) (FBC). Children (n = 28) aged 3-9 years were included. Data were collected clinically and from anamnesis. The salivary levels of Streptococcus mutans (SM) were evaluated. A linear regression model was used to determine which variables were predictive for each type of risk analysis. Caries risk was the dependent variable and the independent variables were caries experience, related disease, plaque amount, diet frequency, salivary levels of SM, fluoride sources and clinical judgment. A paired Student t-test was used for the following comparisons: (a) CS with and without SM; (b) CS without SM and FBC; (c) CS with SM and FBC. The mean dmft/DMFT was 5.56 ± 2.51. There was no difference between the methods (p < .05). Regardless of caries risk, the children presented the same levels of SM (p = .889). ...

Acta odontologica Scandinavica, Jan 5, 2017

This study investigated the presence of Enterococcus faecalis in primary teeth with primary root ... more This study investigated the presence of Enterococcus faecalis in primary teeth with primary root canal infections and related to the possible failure of pulpectomy outcome after 36 months. Root canal samples were obtained from 25 out of 244 patients using the sterile paper cone method. The identification of E. faecalis was done with culture and molecular tests using species-specific 16S rRNA gene-based polymerase chain reaction (PCR). After 36 months, the pulpectomy outcome was evaluated. Enterococcus faecalis was found in five (20%) samples, and dental caries were the cause of primary infection in all of them. Pulpectomy outcome was evaluated only in teeth that completed the entire clinical protocol and were followed up to 36 months (n = 8). From these, 75% (n = 6) were successful and 25% (n = 2) failed. E. faecalis was present in 50% of both successful and failed cases. Enterococcus faecalis was not related to the failure of endodontic treatment of primary teeth.

The Brazilian Journal of Infectious Diseases, 2017

Staphylococcus aureus is an important cause of bloodstream infections. Therefore, the main purpos... more Staphylococcus aureus is an important cause of bloodstream infections. Therefore, the main purpose of this work was to characterize a collection of 139 S. aureus isolates from bloodstream infections in two public hospitals in relation to their antimicrobial susceptibility profile, staphylococcal cassette chromosome mec types, and clonal relationship. Methicillin resistance and resistance to other 12 agents were accessed by the disk diffusion test. Minimum inhibitory concentration to mupirocin was also determined. The SCCmec types were accessed by multiplex PCR, and the clonal relationship was determined by pulsed field gel electrophoresis method and restriction modification system characterization. Besides, multilocus sequence typing was performed for representative methicillin-resistant S. aureus isolates. The military hospital showed a dissemination of the New York/Japan (USA100/ST5/CC5/SCCmecII) lineage associated to multidrug resistance, including mupirocin resistance, and the teaching hospital presented polyclonal and non-multidrug resistant MRSA isolates. Complete substitution of the Brazilian endemic clone by other lineages was found in both hospitals. These findings can highlight differences in policy control and prevention of infections used in the hospitals and a change in the epidemiological profile of MRSA in Brazilian hospitals, with the replacement of BEC, a previously well-established clone, by other lineages.

African Journal of Microbiology Research, Apr 30, 2013

This study investigated the microbial species present in necrotic pulps of permanent teeth needin... more This study investigated the microbial species present in necrotic pulps of permanent teeth needing endodontic treatment. The search for articles was conducted on the Health Science Database and considered all articles published until October 2011, with selected human clinical studies examined, through molecular biology the microorganisms that are present in root canals of permanent teeth requiring root canal treatment with necrosis pulps (exposition). The selected articles were categorized according to the methodological quality and evidence in levels A (high), B (moderate), and C (low). The search strategy was based on PubMed, Bireme, Cochrane and OVID databases. The data extracted from the studies were also tabulated. Eighty-four titles and abstracts were assessed and eight articles met the inclusion criteria, showing that there is a high diversity of microorganisms involved in necrotic permanent teeth. The microorganisms found in these articles were: Porphyromonas gingivalis (27.8%), Porphyromonas endodontalis (42.6%), Prevotella intermedia (5.6%), Prevotella nigrescens (7.4%), Bacteroides forsythus (21%) and Enterococcus faecalis (>50%). This systematic review found high evidence of the polymicrobial nature of primary endodontic infections in necrotic permanent teeth, and also showed that there is a dominance of anaerobic bacteria.

Journal of Endodontics, 2006

Enterococcus faecalis is the most commonly found species in root-filled teeth evincing recalcitra... more Enterococcus faecalis is the most commonly found species in root-filled teeth evincing recalcitrant periradicular lesions and as a consequence, a role in causation of endodontic treatment failure has been suggested. The purpose of this study was to evaluate the prevalence of this bacterial species in root-filled teeth with or without periradicular lesions. Identification of E. faecalis was carried out by polymerase chain reaction (PCR) or conventional culture procedures. Overall, E. faecalis was detected by species-specific 16S rRNA gene-based PCR in 40/50 teeth (80%), while culture revealed the occurrence of this species in 8/50 teeth (16%). PCR was significantly more effective than culture in detecting this bacterial species (p Ͻ 0.001). Of 27 root-filled teeth with no periradicular lesions, E. faecalis was found in 22 cases (81.5%) by PCR and in five cases (18.5%) by culture. Of 23 root-filled teeth with periradicular lesions, E. faecalis was identified in 18 cases (78%) by PCR and in three cases (13%) by culture. Regardless of the identification technique used, no significant difference was observed when comparing the occurrence of E. faecalis in root-filled teeth with and without periradicular lesions (p Ͼ 0.05). Although these findings apparently put into question the status of E. faecalis as the main species causing endodontic treatment failure, other related factors still need to be clarified before this assumption turns into certainty.

Annals of Agricultural and Environmental Medicine, 2015

AS, van Elsas JD, dos Santos KR N. Peanut allergy as a trigger for the deterioration of atopic de... more AS, van Elsas JD, dos Santos KR N. Peanut allergy as a trigger for the deterioration of atopic dermatitis and precursor of staphylococcal and herpetic associated infections-case report.

The Brazilian Journal of Infectious Diseases, 2011

Staphylococcus lugdunensis is a rare cause of severe infections and clinical manifestations are s... more Staphylococcus lugdunensis is a rare cause of severe infections and clinical manifestations are similar to those related to S. aureus infection. We describe a hospital-acquired bacteremia due to methicillin-resistant Staphylococcus lugdunensis, misidentified as methicillin-resistant S. aureus. The oxacillin MIC was 16 µg/mL and the mecA gene and SCCmec type V were determined by PCR. Although treatment had been appropriated, the patient died after rapid progressive respiratory failure and another nosocomial sepsis. It is important not only to identify S. lugdunensis in view of its clinical course, but also to determine its susceptibility to oxacillin by detecting the mecA gene or its product.

Advances in Microbiology, 2014

This study aimed to evaluate the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal ... more This study aimed to evaluate the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of Coffea canephora aqueous extract (Cc), trigonelline (Tg) and 5-caffeoylquinic acid (5-CQA) against cariogenic microorganisms: Streptococcus parasanguinis ATCC 903 (SP), Lactobacillus rhamnosus ATCC 9595 (LR); and pathogens related to periodontal disease: Porphyromonas gingivalis ATCC 33277 (PG), Fusobacterium nucleatum ATCC 25586 (FN), Prevotella intermedia ATCC 49046 (PI) and Prevotella nigrescens ATCC 33563 (PN). Different concentrations of Cc (0.15625 to 10 mg/mL), Tg and 5-CQA (0.005 to 10.24 mg/mL) were tested. Chlorhexidine (0.05%) was used as positive control and the substances without the inoculum comprised the blank control. The Cc showed bacteriostatic action against SP (MIC = 5 mg/mL) and LR (MIC = 10 mg/mL). Tg showed bacteriostatic action against SP (MIC = 2.56 to 1.28 mg/mL), LR (MIC = 2.56 mg/mL), PG (MIC = 2.56 to 1.28 mg/mL), FN (MIC = 5.12 mg/mL), PN (MIC = 2.56 mg/mL), and PI * Corresponding author. F. M. da Silva et al. 979 (MIC = 2.56 to 1.28 mg/mL). Also, Tg showed bactericide properties against SP (MBC = 2.56 mg/mL), PG (MBC = 2.56 mg/mL), FN (MBC = 10.24 mg/mL), PN (MBC = 5.12 mg/mL), and PI (MBC = 2.56 mg/mL). Although 5-CQA has previously shown activity against Streptococcus mutans, in the present study, it showed no activity against all tested microorganisms. C. canephora extract only showed antibacterial activity against cariogenic microorganisms, not presenting action against periodontal pathogens. It was concluded that trigonelline presented the best effect against all pathogens tested, therefore coffee extracts with higher trigonelline content should be tested against these specific pathogens.