Methicillin-resistant S. Aureus Carriage Research Articles

Nasal MRSA carriage is a risk factor for development of antibiotic resistance in diabetic foot ulcers and is significantly higher than diabetic and non-diabetic individuals without foot ulcer

BackgroundDiabetic foot ulcer (DFU) is a major complication of diabetes often impacted by polymicrobial infection in the wound site. Diabetic patients are immunocompromised in nature and hence vulnerable to infection once the skin barrier is breached. Microbiological culture-based methods show that Staphylococcus aureus (SA) is the most frequently isolated bacteria from the DFU wounds. SA and its most clinically important antibiotic resistant variant methicillin-resistant S. aureus (MRSA) are commonly found in the nasal vestibule and colonization of SA as well as MRSA in any wound site can aggravate the condition. We hypothesize that the presence of nasal MRSA carriage can serve as a potential risk factor contributing to the emergence of antibiotic resistance in diabetic foot ulcer wounds.MethodsIn the present study, we have compared the carriage of SA and MRSA in nasal cavity and foot skin among DFU patients (D+F+, n = 50), diabetic patients without any ulcer (D+F-, n = 50), and healthy controls (D-F-, n = 40) by using bacterial culture and PCR based methods. The D+F+, D+F- and D-F-individuals were further categorized based on the presence or absence of MRSA and clinical parameters were compared between MRSA+ ve and MRSA-ve individuals in each of the three groups mentioned above.ResultsOur results show that, (a) nasal MRSA carriage is significantly higher (p < 0.05) in D+F+ group than the D+F- and D-F- and significantly associated with wound MRSA carriage in D+ F+ individuals (O.R. = 4.09; 95% C.I. = 1.12–15.05) and (b) the HbA1C level is significantly higher (p < 0.02) in wound MRSA positive, compared to MRSA negative D+F+ patients. Interestingly more than half of the MRSA (64%) isolated from DFU wound were identified to be multidrug resistant.ConclusionThese findings strongly suggest that nasal MRSA carriage can act as a risk factor for development of antibiotic resistance in diabetic foot ulcers and it is therefore important to screen nasal and wound sites of these patients regularly. We have also developed a rapid multiplex PCR assay to detect MRSA from clinical isolates or microbial DNA isolated from clinical samples in the hospital settings.

Harnessing diversity and antagonism within the pig skin microbiota to identify novel mediators of colonization resistance to methicillin-resistant Staphylococcus aureus.

The microbiota mediate multiple aspects of skin barrier function, including colonization resistance to pathogens such as Staphylococcus aureus. The endogenous skin microbiota limits S. aureus colonization via competition and direct inhibition. Novel mechanisms of colonization resistance are promising therapeutic targets for drug-resistant infections, such as those caused by methicillin-resistant S. aureus (MRSA). Here, we developed and characterized a swine model of topical microbiome perturbation and MRSA colonization. As in other model systems, topical antimicrobial treatment had a little discernable effect on community diversity though the overall microbial load was sensitive to multiple types of intervention, including swabbing. In parallel, we established a porcine skin culture collection and screened 7,700 isolates for MRSA inhibition. Using genomic and phenotypic criteria, we curated three isolates to investigate whether prophylactic colonization would inhibit MRSA colonization in vivo. The three-member consortium together, but not individually, provided protection against MRSA colonization, suggesting cooperation and/or synergy among the strains. Inhibitory isolates were represented across all major phyla of the pig skin microbiota and did not have a strong preference for inhibiting closely related species, suggesting that relatedness is not a condition of antagonism. These findings reveal the porcine skin as an underexplored reservoir of skin commensal species with the potential to prevent MRSA colonization and infection. IMPORTANCE The skin microbiota is protective against pathogens or opportunists such as S. aureus, the most common cause of skin and soft tissue infections. S. aureus can colonize normal skin and nasal passages, and colonization is a risk factor for infection, especially on breach of the skin barrier. Here, we established a pig model to study the competitive mechanisms of the skin microbiota and their role in preventing colonization by MRSA. This drug-resistant strain is also a livestock pathogen, and swine herds can be reservoirs of MRSA carriage. From 7,700 cultured skin isolates, we identified 37 unique species across three phyla that inhibited MRSA. A synthetic community of three inhibitory isolates provided protection together, but not individually, in vivo in a murine model of MRSA colonization. These findings suggest that antagonism is widespread in the pig skin microbiota, and these competitive interactions may be exploited to prevent MRSA colonization.

Co-carriage of Staphylococcus aureus and Streptococcus pneumoniae among children younger than 2 years of age in a rural population in Pakistan

ObjectivesStaphylococcus aureus and Streptococcus pneumoniae are common colonizers of the human nasopharynx. In this study, we describe S. aureus nasopharyngeal carriage and evaluate its association with S. pneumoniae carriage post-10-valent pneumococcal conjugate vaccine (PCV10) introduction in Pakistan. MethodsA serial cross-sectional study was undertaken from 2014 to 2018, children <2 years were randomly selected, and nasopharyngeal swabs were collected using standard WHO guidelines. S. aureus and S. pneumoniae isolates were identified using standard methods and tested for antimicrobial susceptibility by the standard Kirby-Bauer disk-diffusion method as per Clinical & Laboratory Standards Institute (CLSI) recommendations. Regression analysis was used to determine predictors associated with S. aureus carriage. ResultsWe enrolled 3140 children. S. aureus carriage prevalence was 5.6% (176/3140), and 50.1% (81/176) of the isolates were methicillin-resistant S. aureus (MRSA). S. aureus carriage was higher in the absence of pneumococcus compared to isolates in which pneumococcus was present (7.5% vs 5.0%). S. aureus carriage was negatively associated with pneumococcal carriage, being in 3rd and 4th year of enrollment, and vaccination with two and three PCV10 doses, in addition, fast breathing, ≥2 outpatients visits, and rainy season were positively associated. The following resistance rates were observed: 98.9% for penicillin, 74.4% for fusidic acid, and 23.3% for gentamicin, 10.2% for erythromycin, and 8.5% for cotrimoxazole. All isolates were susceptible to amikacin. ConclusionsOverall S. aureus carriage prevalence was low, PCV10 vaccine was protective against the carriage. The proportion of MRSA carriage and antimicrobial resistance was high in this community warranting continuous monitoring for invasive infections.

Investigation of nasal Staphylococcus aureus carriage by real-time PCR in patients receiving hemodialysis treatment

Objectives: Staphylococcus aureus, coagulase-negative staphylococci (CoNS), and methicillin-resistant S. aureus (MRSA), which are significant nosocomial pathogens, have become a growing global problem because their carriage and diseases have become resistant to many antibiotics. This study aimed to investigate and determine the rate of MRSA carriage among patients receiving hemodialysis treatment using molecular methods. Methods: In the 254 hemodialysis patients, the nasal carriage rates, susceptibility and resistance to S. aureus, CoNS and MRSA were examined using culture and real-time PCR methods. Nasal samples from hemodialysis patients were examined using real-time PCR. Microscopic examination was performed using the Gram staining method, and S. aureus was identified using catalase and coagulase. The strains were then tested for antibiotic susceptibility. Staphylococci was isolated from 231 of the 254 patients. Results: S. aureus carriage was detected in 50 patients, MRSA in 16, methicillin-susceptible S. aureus (MSSA) in 33, CoNS in 66, methicillin-resistant CoNS (MR-CoNS) in 38, and methicillin-susceptible CoNS (MS-CoNS) in 28. S. aureus and MRSA strains exhibited 100% susceptibility to nitrofurantoin, and vancomycin. MSSA strains showed the highest susceptibility to chloramphenicol, clindamycin (84.8%), and co-trimoxazole (36.4%). CoNS showed 100% susceptibility to vancomycin, and 16.7% susceptibility to ampicillin. Vancomycin was found to be the most effective antibiotic against S. aureus, CoNS, and MRSA pathogens identified in patients undergoing hemodialysis, whereas penicillin resistance was found. Conclusions: It can be concluded that one of the most effective ways to prevent the formation of antibiotic resistant strains is the hygiene of the hospital and hospital staff. Real-time PCR is very important for analyzing with high sensitivity.

Multi-Drug Resistant Staphylococcus aureus Carriage in Abattoir Workers in Busia, Kenya.

Abattoir workers have been identified as high-risk for livestock-associated Staphylococcus aureus carriage. This study investigated S. aureus carriage in abattoir workers in Western Kenya. Nasal swabs were collected once from participants between February-November 2012. S. aureus was isolated using bacterial culture and antibiotic susceptibility testing performed using the VITEK 2 instrument and disc diffusion methods. Isolates underwent whole genome sequencing and Multi Locus Sequence Types were derived from these data. S. aureus (n = 126) was isolated from 118/737 (16.0%) participants. Carriage was higher in HIV-positive (24/89, 27.0%) than HIV−negative participants (94/648, 14.5%; p = 0.003). There were 23 sequence types (STs) identified, and half of the isolates were ST152 (34.1%) or ST8 (15.1%). Many isolates carried the Panton-Valentine leucocidin toxin gene (42.9%). Only three isolates were methicillin resistant S. aureus (MRSA) (3/126, 2.4%) and the prevalence of MRSA carriage was 0.4% (3/737). All MRSA were ST88. Isolates from HIV-positive participants (37.0%) were more frequently resistant to sulfamethoxazole/trimethoprim compared to isolates from HIV-negative participants (6.1%; p < 0.001). Similarly, trimethoprim resistance genes were more frequently detected in isolates from HIV-positive (81.5%) compared to HIV-negative participants (60.6%; p = 0.044). S. aureus in abattoir workers were representative of major sequence types in Africa, with a high proportion being toxigenic isolates. HIV-positive individuals were more frequently colonized by antimicrobial resistant S. aureus which may be explained by prophylactic antimicrobial use.

High prevalence of methicillin-resistant Staphylococcus aureus carriage among infants at the Children's Hospital, Accra, Ghana.

Infants are at risk of Staphylococcus aureus (S. aureus) colonization and infection. The aim of this study was to investigate S. aureus and methicillin-resistant S. aureus (MRSA) colonization among infants, including the prevalence, predictors of colonization, and antibiogram. The study was cross-sectional, and involved infants aged less than one year recruited at the Princess Marie Louise Children's Hospital in Accra, Ghana. Sociodemographic and clinical data of the participants were gathered with a structured questionnaire. Nasal swabs were also obtained from them and bacteriologically cultured. S. aureus was confirmed with the coagulase test, and MRSA was confirmed by polymerase chain reaction (PCR) of the mecA gene. Antimicrobial susceptibility testing of S. aureus was done using the Kirby-Bauer method. The carriage prevalence of S. aureus and MRSA were 34.9% (45/129) and 17.10% (22/129), respectively. Colonization with coagulase-negative Staphylococci (CoNS) was protective of both S. aureus (OR = 0.008; p < 0.001) and MRSA (OR = 0.052; p = 0.005) carriage. Maintenance of good hand hygiene prevented S. aureus carriage (OR = 0.16; p < 0.001). S. aureus resistance to antibiotics decreased across penicillin (96%), trimethoprim-sulfamethoxazole (61%), tetracycline (61%), erythromycin (39%), gentamicin (39%), fusidic acid (26%), rifampicin (17%), clindamycin (7%), and linezolid (0%); 68.8% S. aureus were multidrug resistant. S. aureus and MRSA prevalence were high among the infants. Colonization with CoNS and good hand hygiene maintenance were predictive of MRSA and methicillin-sensitive S. aureus (MSSA) colonization, respectively.

Risk Factors of Recurrent Infection in Patients with Staphylococcus aureus Bacteremia: a Competing Risk Analysis.

Although several clinical variables have been reported as risk factors for recurrence of Staphylococcus aureus infection, most studies have not considered competing risk events that may overestimate the risk. In this study, we performed competing risk analysis to identify risk factors related to 90-day recurrence in patients with S. aureus bacteremia (SAB) using a large cohort data from a single tertiary hospital in South Korea. All adults who experienced SAB during admission were prospectively enrolled from August 2008 to December 2019. After the day of the first positive blood culture, recurrence and all-cause mortality were assessed for 90 days. Recurrence was defined as a development of symptoms or signs of infection with or without repeated bacteremia after >7 days of negative blood culture and clinically apparent improvement. Subdistribution hazard ratios (sHR) for recurrence and all-cause mortality were estimated using Fine and Gray models. Of 1,725 SAB patients, including 885 cases (51.3%) of methicillin-resistant S. aureus (MRSA) bacteremia, 85 (5.0%) experienced recurrence during the study period. In a multivariate Fine and Gray regression model, the presence of a vascular graft (subdistribution HR [sHR], 3.48; 95% confidence interval [CI], 1.90-6.40), nasal MRSA carriage (sHR, 2.10; 95% CI, 1.28-3.44), methicillin resistance (sHR, 1.69; 95% CI, 1.00-2.84), and rifampicin resistance (sHR, 2.20; 95% CI, 1.12-4.33) were significantly associated with 90-day recurrence. In a large cohort of SAB patients with a high prevalence of MRSA, indwelling vascular graft, nasal MRSA carriage, methicillin resistance, and rifampicin resistance were potential risk factors for recurrence of S. aureus infection.

Staphylococcus aureus Nasopharyngeal Carriage and Antimicrobial Resistance among Adults with Sickle Cell Disease at the Korle Bu Teaching Hospital in Accra, Ghana.

Sickle cell disease (SCD) patients are an important risk group for Staphylococcus aureus (S. aureus) carriage and infections. Little is, however, known about the nasopharyngeal carriage epidemiology of the pathogen in this vulnerable population. The aim of this study was to evaluate S. aureus and methicillin-resistant S. aureus (MRSA) nasopharyngeal carriage prevalence, carriage determinants, and antimicrobial resistance among SCD adults in Ghana. Nasopharyngeal swabs, obtained from 200 SCD adults recruited at the Korle Bu Teaching Hospital, were cultured for S. aureus, and these isolates were subjected to antimicrobial susceptibility testing via the Kirby-Bauer method. The prevalence of S. aureus carriage was 41.5% (n = 83), and that of MRSA carriage was 1.0% (n = 2). Moreover, carriage of coagulase-negative Staphylococcus (CoNS) was the only determinant of S. aureus carriage identified (OR = 0.012, P < .0001). However, neither this variable nor the other features of the participants emerged as a determinant of MRSA carriage. The antimicrobial resistance rates decreased across penicillin (98.8%, n = 82), tetracycline (54.2%, n = 45), gentamicin (32.5%, n = 27), ciprofloxacin (21.7%, n = 18), erythromycin (18.1%, n = 15), clindamycin (10.8%, n = 9), amoxicillin-clavulanic acid (10.8%, n = 9), teicoplanin (1.2%, n = 1), and linezolid (0.0%, n = 0), and the multidrug resistance rate was 45.8% (n = 38). The nasopharyngeal carriage prevalence of S. aureus in the current study was high, while that of MRSA was low. The isolates were highly resistant to several of the antibiotics tested, but not teicoplanin and linezolid, making these antibiotics suitable for treatment of S. aureus infections among the SCD population.

AEROBIC – ANAEROBIC CUTANEOUS MICROBIOTA OF HIDRADENITIS SUPPURATIVA. A CASE REPORT

Hidradenitis suppurativa (HS) is a chronic inflammatory disease affecting intertriginous skin areas of young adults. Although HS was historically defined as an infectious disease, the role of microorganisms in its pathogenesis is now controversial. We investigated the lesion microbiota of a recently diagnosed 24-year-old male patient with axillary HS, who shared features of the metabolic syndrome. The microbiological analysis of the patient’s lesion was indicative of colonization with bacteria including aerobes – Staphylococcus (S.) aureus, S. lugdunensis, S. epidermidis, anaerobes – Anaerococcus (A.) octavius, and microaerophiles – Cutibacterium (C.) acnes; this last one was also isolated in monoculture from a patient's healthy skin control sample. In vitro antibiotic susceptibility evaluation revealed Methicillin-resistant S. aureus (MRSA) and highly susceptible S. lugdunensis and S. epidermidis. Profiles of A. octavius and C. acnes showed that both strains were susceptible to Vancomycin, Clindamycin, Doxycycline and Linezolid; the anaerobe was Benzylpenicillin-resistant and Tetracycline and the microaerophile was intrinsically Metronidazole-resistant. We conclude that the intralesional microbial diversity in this case shows low variety of species and similarities to healthy skin microbiota, although the presence of S. aureus, particularly MRSA, S. lugdunensis or C. acnes – frequently involved in chronic skin pathologies – may be relevant for the disease severity. MRSA carriage in the patient’s lesion represents a significant epidemiological risk for the healthcare environment. Antibiotic treatment in the early stages of HS should be administered with caution. Extended studies of HS microbiota could identify relevant colonization patterns for the outcome of the disease and offer important keys for selecting personalised, efficient therapeutic schemes. Keywords: hidradenitis suppurativa, cutaneous microbiome, bacterial pathogens, MRSA, Staphylococcus aureus, Cutibacterium acnes, anaerobes

Wild Animals Are Reservoirs and Sentinels of Staphylococcus aureus and MRSA Clones: A Problem with "One Health" Concern.

Background: The availability of comprehensive data on the ecology and molecular epidemiology of Staphylococcus aureus/MRSA in wild animals is necessary to understand their relevance in the “One Health” domain. Objective: In this study, we determined the pooled prevalence of nasal, tracheal and/or oral (NTO) Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus (MRSA) carriage in wild animals, with a special focus on mecA and mecC genes as well as the frequency of MRSA and methicillin susceptible S. aureus (MSSA) of the lineages CC398 and CC130 in wild animals. Methodology: This systematic review was executed on cross-sectional studies that reported S. aureus and MRSA in the NTO cavities of wild animals distributed in four groups: non-human primates (NHP), wild mammals (WM, excluding rodents and NHP), wild birds (WB) and wild rodents (WR). Appropriate and eligible articles published (in English) between 1 January 2011 to 30 August 2021 were searched for from PubMed, Scopus, Google Scholar, SciElo and Web of Science. Results: Of the 33 eligible and analysed studies, the pooled prevalence of NTO S. aureus and MRSA carriage was 18.5% (range: 0–100%) and 2.1% (range: 0.0–63.9%), respectively. The pooled prevalence of S. aureus/MRSA in WM, NHP, WB and WR groups was 15.8/1.6, 32.9/2.0, 10.3/3.4 and 24.2/3.4%, respectively. The prevalence of mecC-MRSA among WM/NHP/WB/WR was 1.64/0.0/2.1/0.59%, respectively, representing 89.9/0.0/59.1/25.0% of total MRSA detected in these groups of animals.The MRSA-CC398 and MRSA-CC130 lineages were most prevalent in wild birds (0.64 and 2.07%, respectively); none of these lineages were reported in NHP studies. The MRSA-CC398 (mainly of spa-type t011, 53%), MRSA-CC130 (mainly of spa types t843 and t1535, 73%), MSSA-CC398 (spa-types t571, t1451, t6606 and t034) and MSSA-CC130 (spa types t843, t1535, t3625 and t3256) lineages were mostly reported. Conclusion: Although the global prevalence of MRSA is low in wild animals, mecC-mediated resistance was particularly prevalent among MRSA isolates, especially among WM and WB. Considering the genetic diversity of MRSA in wild animals, they need to be monitored for effective control of the spread of antimicrobial resistance.

Staphylococcus Aureus Bacteremia Due to Central Venous Catheter Infection: A Clinical Comparison of Infections Caused by Methicillin-Resistant and Methicillin-Susceptible Strains.

Objectives: Staphylococcus aureus bacteremia has a mortality rate of 20-40% and is mainly caused by central venous catheter (CVC) infection. We aimed to investigate differences between patients with methicillin-resistant S. aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) bacteremia due to CVC infection.Methods: This retrospective study, of data collected between August 2004 and March 2016 at a single Tokyo hospital, compared the clinical background characteristics, complications, and 60-day mortality rates with positive peripheral blood cultures and positive semiquantitative cultures. MRSA carrier is defined as those with a history of MRSA detection by skin, urine, or sputum culture.Results: The median ages for the 17 MRSA and 19 MSSA patients were 72 and 55 years, respectively (P < 0.01). The occurrences of baseline disease (MRSA vs. MSSA) were 59% vs. 16% (P = 0.01), respectively, while those of complications, including septic shock, were 48% vs. 16% (P = 0.07), respectively. Catheter placement duration, time from fever onset to CVC removal, and time from fever onset to antimicrobial therapy initiation were similar in both groups. Sixty-day mortality rates were 35% and 5.3% (P = 0.04) in the MRSA and MSSA groups, respectively.Conclusion: MRSA carriers and older patients were at higher risks of CVC infection than MSSA bacteremia patients. Patients with MRSA bacteremia had higher septic shock and 60-day mortality rates despite appropriate antimicrobial therapy.

Nasal Carriage and Methicillin Resistance of Staphylococcus aureus among Schoolchildren in Sana'a City, Yemen.

Background Staphylococcus aureus (S. aureus) is a frequent cause of serious health problems with high morbidity and mortality. The risk of S. aureus infections is increased with the emergence of methicillin-resistant S. aureus (MRSA). This study aims to determine the nasal carriage rate of both S. aureus and MRSA among schoolchildren in Sana'a city. Methods This is a cross-sectional study conducted from January 2018 to May 2020. Five hundred and thirty-six students were enrolled. Their age ranged from 5 to 19 years with the mean age and standard deviation equal to 13.3 ± 3.5 years. Nasal swabs were collected from each student for culturing and methicillin susceptibility testing. Results Students with positive culture were 271 (51%) males and 265 (49%) females. S. aureus was isolated from 129 (24%) students whereas the overall prevalence of MRSA was 8 (1.5%). S. aureus was significantly recovered from students at the age group of 10–14 years (χ2 = 7.02; p=0.03), females than males (OR = 1.96; χ2 = 10.75; p=0.001), and students who were admitted into hospitals (OR = 1.6; χ2 = 4.89; p=0.03). Nevertheless, there were no significant differences between MRSA carriage and students' age (χ2 = 2.3; p=0.32), gender (OR = 1.02; χ2 = 0.001; p=0.63), and hospital admission (OR = 1.4; χ2 = 0.25; p=0.62). Conclusions The prevalence of MRSA is low among schoolchildren in Sana'a city. Age, gender, and previous hospital admission were statistically associated with nasal carriage of S. aureus but not MRSA nasal carriage.

Nasopharyngeal Carriage of Methicillin-Resistant Staphylococcus aureus (MRSA) among Sickle Cell Disease (SCD) Children in the Pneumococcal Conjugate Vaccine Era.

The aim of this cross-sectional study was to investigate Staphylococcus aureus nasopharyngeal carriage epidemiology in relation to other nasopharyngeal bacterial colonizers among sickle cell disease (SCD) children about five years into pneumococcal conjugate vaccine 13 (PCV-13) introduction in Ghana. The study involved bacteriological culture of nasopharyngeal swabs obtained from 202 SCD children recruited from the Princess Marie Louise Children’s Hospital. S. aureus isolates were identified using standard methods and subjected to antimicrobial susceptibility testing using the Kirby-Bauer disc diffusion method. Cefoxitin-resistant S. aureus isolates were screened for carriage of the mecA, pvl, and tsst-1 genes using multiplex polymerase chain reaction. The carriage prevalence of S. aureus was 57.9% (n = 117), and that of methicillin-resistant S. aureus (MRSA) was 3.5% (n = 7). Carriage of the mecA, pvl, and tsst-1 genes were respectively demonstrated in 20.0% (n = 7), 85.7% (n = 30), and 11.4% (n = 4) of the cefoxitin-resistant S. aureus isolates. PCV-13 vaccination (OR = 0.356, p = 0.004) and colonization with coagulase-negative staphylococci (CoNS) (OR = 0.044, p < 0.0001) each protected against S. aureus carriage. However, none of these and other features of the participants emerged as a determinant of MRSA carriage. The following antimicrobial resistance rates were observed in MRSA compared to methicillin-sensitive S. aureus: clindamycin (28.6% vs. 4.3%), erythromycin (42.9% vs. 19.1%), tetracycline (100% vs. 42.6%), teicoplanin (14.3% vs. 2.6%), penicillin (100% vs. 99.1%), amoxiclav (28.6% vs. 3.5%), linezolid (14.3% vs. 0.0%), ciprofloxacin (42.9% vs. 13.9%), and gentamicin (42.9% vs. 13.0%). The proportion of S. aureus isolates that were multidrug resistant was 37.7% (n = 46). We conclude that S. aureus was the predominant colonizer of the nasopharynx of the SCD children, warranting the continuous monitoring of this risk group for invasive S. aureus infections.

Molecular characterization of methicillin-resistant Staphylococcus aureus among insulin-dependent diabetic individuals in Brazil

BackgroundPeople with diabetes mellitus, especially insulin-dependent diabetic patients, are a risk group for staphylococcal infections. Asymptomatic infection with Staphylococcus aureus is common and favors dissemination of the microorganism, rendering these individuals a source of infection. This study aimed to characterize the resistance profile, clonal profile and sequence type, as well as to analyze the prevalence and risk factors for nasal and oropharyngeal carriage of methicillin-susceptible (MSSA) and methicillin-resistant S. aureus (MRSA) isolated from insulin-dependent diabetic individuals in the city of Botucatu, SP, Brazil.MethodsStaphylococcus aureus was collected from the nasopharynx and oropharynx of 312 community-dwelling insulin-dependent diabetic individuals over a period of 3 years (October 2015 to December 2018). The isolates were characterized by susceptibility profiling, detection of the mecA gene, SCCmec typing, and molecular typing by PFGE and MLST. The risk factors associated with S. aureus and MRSA carriage were determined by logistic regression analysis.ResultsThe overall prevalence of colonization with S. aureus and MRSA was 30.4% and 4.8%, respectively. Fifteen of the 112 S. aureus isolates carried the mecA gene; SCCmec type IV was identified in 10 isolates, SCCmec type I in three, and SCCmec type II in two. Among the 15 resistant isolates (MRSA), four were susceptible to oxacillin/cefoxitin by the disc diffusion method and one MSSA isolate was resistant to sulfamethoxazole/trimethoprim. The analysis of risk factors revealed a protective effect of age and lung disease, while lower-extremity ulcers were a risk factor for S. aureus. For MRSA, only male gender was significantly associated as a risk factor in multivariate analysis. Clonal profile analysis demonstrated the formation of clusters among MRSA isolates from different patients, with the identification of ST5-IV, ST5-I, and ST8-IV. Isolates carrying ST398 were identified among MSSA and MRSA (ST398-IV).ConclusionOur findings reinforce the importance of epidemiological studies of S. aureus carriage, especially in populations at high risk of infections such as diabetics. The data suggest widespread dissemination of MRSA in the population of insulin-dependent diabetic patients studied, as well as the emergence of important lineages among these individuals.

Nasopharyngeal Carriage and Antimicrobial Susceptibility Profile of Staphylococcus aureus among Children under Five Years in Accra.

This cross-sectional study investigated the Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus (MRSA) nasopharyngeal carriage epidemiology in Accra approximately five years post-pneumococcal conjugate vaccines introduction in the country. Archived nasopharyngeal swabs collected from 410 children aged under five years old were bacteriologically cultured. The resultant S. aureus isolates were subjected to antimicrobial susceptibility testing and screening for carriage of the mecA and LukF-PV (pvl) genes, following standard procedures. The data obtained were analyzed with Statistical Products and Services Solutions (SPSS) using descriptive statistics and Chi square tests of associations. The isolated bacteria decreased across coagulase-negative Staphylococci (47.3%, n = 194), S. aureus (23.2%, n = 95), Diphtheroids (5.4%, n = 22), Micrococcus species (3.7%, n = 15), Klebsiella pneumoniae (3.2%, n = 13), Moraxella species and Citrobacter species (1.5% each, n = 6), Escherichia coli, Enterobacter species, and Pseudomonas species (0.9% each, n = 2). The MRSA carriage prevalence was 0.49% (n = 2). Individuals aged 37–48 months recorded the highest proportion of S. aureus carriage (32.6%, 31/95). Resistance of S. aureus to the antibiotics tested were penicillin G (97.9%, n = 93), amoxiclav (20%, n = 19), tetracycline (18.9%, n = 18), erythromycin (5.3%, n = 5), ciprofloxacin (2.1%, n = 2), gentamicin (1.1%, n = 1), cotrimoxazole, clindamycin, linezolid, and teicoplanin (0% each). No inducible clindamycin resistance was observed for the erythromycin-resistant isolates. Three (3.2%) of the isolates were multidrug resistant, of which 66.7% (2/3) were MRSA. The pvl gene was associated with 59.14% (55/93) of the methicillin-sensitive S. aureus (MSSA) isolates, but was not detected among any of the MRSA isolates.

Prevalence and determinants of methicillin-resistant Staphylococcus aureus and methicillin-sensitive Staphylococcus aureus carrier among staff of a tertiary eye hospital in Saudi Arabia.

OBJECTIVES:The objective of this study was to estimate the prevalence and risk factors of methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) carriers among staff of a tertiary eye hospital in Saudi Arabia.METHODS:This retrospective study was conducted in 2019. Nasal and axillary swabs of health-care staff were used to determine carriers of MRSA. Bacteria were identified by culture and sensitivity tests. These isolates were grouped as antibiotic resistant, sensitive, and others not in the S. aureus group. Demographics and other determinants were associated with carrier status.RESULTS:We evaluated the carrier status of 430 staff. There were 110 (24.9%; 95% confidence interval [CI]: 21.5, 29.7) S. aureus-positive staff, 21 (11.7%; 95% CI: 11.7, 26.4) of who carried the MRSA strain. Carrier status was significantly higher among physicians (31%) compared to nurses (22.5%) and other staff (5.7%) (P < 0.001). MRSA carrier status was significantly associated with >5 years of employment at the eye hospital (P = 0.02). MRSA was significantly associated with staff who were of Indian nationality (75%) compared to other nationalities (P = 0.04) and those who were at the hospital for <5-year stay compared more than 5 years at the hospital (P = 0.001). All carriers responded to decolonization treatment.CONCLUSIONS:The high prevalence of MRSA and relatively easy treat MRSA carriers points at the need for universal screening for MRSA carriers among eye health staff.

Prevalence of nasal carriers of methicillin-resistant Staphylococcus aureus in primary health care units in Brazil.

ABSTRACTNasal carriage of Staphylococcus aureus by healthcare workers is of great clinical importance as it facilitates the contamination of medical devices and cross-transmission. However, studies regarding the epidemiology and dissemination of S. aureus and Methicillin-resistant S. aureus (MRSA) within the Primary Health Care in Brazil are scarce. The current study aimed to detect and characterize S. aureus and MRSA strains from the nasal cavities of 63 healthcare working in primary health care units in order to determine the prevalence of S. aureus and MRSA, biofilm formation and resistance profile of these isolates. PCR reactions were performed for detecting mecA, icaA and icaD genes. The phenotypic antimicrobial susceptibility was assessed by the disk diffusion method and biofilm formation by the Congo Red Agar (CRA) method. The MRSA isolates were typed for the Staphylococcal Cassette Chromosome mec (SCCmec). The prevalence of nasal carriage of S. aureus was 74.6%, of which 72.3% were MRSA carrying SCCmec type I (24.4%), III (34.1%), IV (36.6%). Two (4.9%) isolates presented a non-typeable cassette by the performed technique. The antimicrobial susceptibility evaluation evidenced penicillin resistance in 66.1% of S. aureus, erythromycin resistance in 49.2%, while 37.3% were resistant to oxacillin, 28.8% to cefoxitin, 5.1% to levofloxacin and 5.1% to clindamycin. All isolates were biofilm producers and 96.6% of the strains contained the ica biofilm-forming genes (icaA and/or icaD). We have demonstrated a high prevalence of S. aureus and MRSA carriage among health care working in Primary Health Care units, the presence of SCCmec types I, III and IV, in addition to their high ability to form biofilm, factors that possibly contribute to the dissemination and persistence of these pathogens within the primary care services. These observations highlight the importance of broadening the perspective of Health Care-Associated Infections prevention, including all health care levels, which are currently little explored. In addition, the dynamics and resistance mechanisms of S. aureus transmission still need to be further clarified to enable the implementation of more effective prevention measures.

Nasal carriage of Staphylococcus aureus by medical students: Assessment of antibiotic susceptibility and risk factors

Objective: Staphylococcus aureus (S. aureus) is the leading vector for both hospital-sourced and population-sourced infections globally and nasal carriage may be responsible for these serious infections. The aim of this study was to assess the nasal S. aureus carriage rates, antibiotic susceptibility and risk factors among preclinical period medical students.Method: A total of 183 preclinical period students from Ahi Evran University Faculty of Medicine voluntarily participated in our study. They were requested to complete a survey form containing questions about demographic information, hygiene habits and medical history and possible risk factors were recorded. S. aureus isolates proliferating from nasal swab culture samples were studied with antibiotic susceptibility tests.Results: Of the total of 183 students, 39 (21.4%) had S. aureus proliferation identified from nasal swab samples. None of these isolates were methicillin-resistant S. aureus (MRSA). Antibiotic susceptibility tests found highest resistance against penicillin (85%). There were negative correlations between nasal spray use and allergy history with nasal S. aureus carriage.Conclusions: Medical students may each be mobile sources of bacteria in hospitals, especially as MRSA carriers. According to our results, it is necessary to note the importance of training and standard infection control precautions to prevent the increase in MRSA carriage rates in the clinical period as none of our preclinical period students carried MRSA. Advanced studies are important to monitor carriage rates.

Staphylococcus aureus Population Structure and Genomic Profiles in Asymptomatic Carriers in Switzerland.

Staphylococcus aureus is a leading cause for clinical infections and food intoxications, causing over 100,000 yearly cases of bacteremia in the United States and 434 food-borne outbreaks in the European Union. Approximately 30% of the population permanently carry S. aureus asymptomatically in their nasal cavity. The risk of infection and transmission to food items or the environment is higher in individuals that are nasally colonized. In addition, S. aureus can acquire various antimicrobial resistances leading to therapeutic failure, additional medical costs, and fatalities. Methicillin-resistant S. aureus (MRSA) cause a considerable burden of disease in humans and animals. MRSA carriage has been associated with animal and in particular livestock contact. Extensive current data on the virulence gene profiles, as well as data on antimicrobial resistance determinants is crucial in developing effective strategies to mitigate the burden of disease. To this end, we screened the anterior nares of 160 test subjects (87 pupils and 73 members of farmer families) in Switzerland for S. aureus carriage. A total of 73 S. aureus isolates were obtained. Factors such as exposure to farm or companion animals and personal medical history were recorded using a questionnaire. Using a DNA microarray, isolates were assigned to clonal complexes (CCs), and virulence and resistance gene profiles were determined. The collected strains were assigned to 20 CCs, among others CC1, CC7, CC8, CC15, CC30, CC45, CC97, and CC398. Two MRSA strains and one multiresistant isolate carrying genes blaZ/I/R, InuA, aadD, tetK, and fosB were isolated from farmers with intensive exposure to animals. Strains carrying pvl, causing severe skin lesions and necrotizing pneumonia, as well as tetracycline, erythromycin, and kanamycin resistance genes were found in individuals that had taken antibiotics during the last year. A variety of superantigenic toxin genes was detected, including among others, the toxic shock syndrome toxin (tst1), and various enterotoxins (sea, sec, sel, and the egc cluster). Contact to chickens was identified as a significant factor contributing to S. aureus colonization.

Implications of Methicillin-Resistant Staphylococcus aureus Carriage on Cardiac Surgical Outcomes

Staphylococcus aureus remains the most common cause of sternal surgical site infections (SSIs). Opinions on the postoperative implications of preoperative methicillin-resistant S aureus (MRSA) colonization currently differ. This study aimed to investigate whether MRSA carriage affects postoperative outcomes and safety of operation. A total of 1,774,811 cardiac surgical patients from 2009 to 2014 were identified from the National Inpatient Sample database. Among these patients, 5798 (0.33%) were MRSA carriers. Propensity-score matching was used to determine the effect of MRSA colonization on outcomes. MRSA carriers did not differ in age or sex from noncarriers, but they more often presented for urgent surgery (P< .001). Among matched pairs, there was no difference in mortality (P= .76), stroke, SSIs, pneumonia, renal failure, cardiac complications, respiratory failure, or prolonged mechanical ventilation. MRSA infection (P < .001), MRSA septicemia (P= 0.03), and blood transfusion (P= .003) occurred more often among MRSA carriers. There was no increase in cost (P= .12), but the hospital length of stay was longer (P= .005). Predictors of MRSA infection among carriers included age older than 85 years, rural hospital location, and diabetes. Carriers with endocarditis and drug abuse were at highest risk for MRSA infection. MRSA carriers undergoing cardiac surgery are not at higher risk for mortality or SSIs and can expect outcomes similar to those of noncarriers. Higher rates of postoperative MRSA infection and septicemia among carriers, although still very low, support the need for selective preoperative screening and prophylaxis when possible.