Methicillin-resistant S. Aureus Nasal 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.

Nasal Carriage of Methicillin-resistant Staphylococcus Aureus) Mrsa) among Medical And Non-medical Students of Sheikhan-polytechnique College And Technical Institute, Iraq

Background and Aims In population, Staphylococcus aureus is present in the nasal vestibule of 35%-50% and one tenth of these are methicillin resistant S aureus (MRSA). This study aimed to investigates the prevalence of MRSA nasal carriage among students of Sheikhan-Polytechnique College (Public health and Medical laboratory technology Department) and Technical Institute (TI). Methods: During December 2018 to February 2019 data collection has been achieved. About 150 students are screened, 66 were males and 84 females with age ranged (18-24 years). &nbsp;A cross-sectional study was conducted and 150 nasal swabs were taken from students groups of several grades in various departments (Public Health, Medical laboratory technology and IT department). The &nbsp;&nbsp;samples were examined through standard microbiological methods. Antibiotic susceptibility tests for all isolates were checked for methicillin resistance using disk diffusion agar. Molecular characterization using PCR test targeting mecA gene was studied. Results: The overall prevalence of MRSA was 27(18%), (12 males and 15 &nbsp;&nbsp;females). High prevalence found among public health students 12/27(44.4%) followed by information technology 9/27(33.3%) and less 6/27(22.2) cases in laboratory technology students. Students of first grade followed by second grade of various departments recorded high rates than third and fourth grade (12, 9, 3 and 3, respectively). Moreover, MRSA was higher among those students that live within their family 19/27(70.3%) than those that live in hostels 8/27(29.6%) and negative in those that live with family relatives. Out of 28 MRSA isolate 14(51.8%) were positive for mecA gene and public health students accounted more carriage 8/14 (57.1%). Conclusions: &nbsp;This study highlighted that students of several grades of medical study are more carriers and should admit enough information concerning control measures to limit contaminate with this pathogen

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.

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.

Prevalence of Staphylococcus aureus nasal carriage and surgical site infection rate among patients undergoing elective cardiac surgery

BackgroundNasal carriers of Staphylococcus aureus are at increased risk of postoperative surgical site infection. Nasal decolonization with mupirocin is recommended in patients undergoing cardiac surgery to reduce surgical site infection. These data are still lacking in Thailand. Therefore, the aim of this study was to determine the prevalence of S. aureus nasal carriage in Thai patients undergoing elective cardiac surgery. The association of surgical site infection and S. aureus nasal carriage was also examined. MethodsThis was a prospective cohort study of 352 patients who planned to undergo elective cardiac surgery. Nasal swab culture was performed in all patients preoperatively. ResultsOf 352 patients, 46 (13.1%) had a positive nasal swab culture for methicillin-sensitive S. aureus (MSSA) and one patient (0.3%) harbored a methicillin-resistant S. aureus (MRSA) strain. The incidence of superficial and deep surgical site infection was 1.3% and 0.3%, respectively. After multivariate analysis, S. aureus nasal carriage was independently associated with superficial surgical site infection (odds ratio 13.04, 95% confidence interval 1.28–133.27; P=0.03). ConclusionsThe prevalence of MSSA and MRSA nasal carriage in Thai patients undergoing elective cardiac surgery was low. The incidence of surgical site infection was also very low in the population studied. Nevertheless, it was found that S. aureus nasal carriage increased the risk of superficial surgical site infection.

Staphylococcus aureus nasal colonization among health care workers at an Egyptian tertiary care hospital

Background: Staphylococcus aureus (S. aureus) colonization in health care workers (HCWs) is a major factor of nosocomial infections. Methicillin resistant S. aureus (MRSA) is incriminated in hospital-acquired infection. Objectives: To evaluate the colonization rates of nasal carriage of S. aureus and MRSA among HCWs at Al-Ahrar Teaching Hospital. Methods: We recruited 163 HCWs in a cross section study. S. aureus was identified phenotypically by coagulase, with DNase tests and genotypically by nuc gene detection. Antibiotics sensitivity was tested by disk diffusion. PCR for mecA was done to confirm MRSA identification. Results: Forty-eight S. aureus strain were isolated. The frequency of nasal colonization of S. aureus in HCWs was 29.44% (48/163), the frequency of MRSA isolates in HCWs was 27.6% (45/163), and frequency of MRSA isolates among S.aureus isolates was 93.8% (45/48). Prior infection (last 3 months) and living in crowded places increased significantly risk of MRSA nasal carriage by 29.3 and 79.59 folds respectively Conclusion: We demonstrated high rates of nasal carriage of S. aureus and MRSA among HCWs. Prior infection and living in crowded places were risk factors for methicillin resistance among isolated S.aureus stains.

Staphylococcus aureus including MRSA nasal carriage among hospital exposed and unexposed medical students.

Introduction:Staphylococcus aureus is one of the most common human pathogen causing a wide range of infections. It is estimated that S.aureus colonizes the anterior nares in approximately 31% of the general population at any given time. The incidence of community acquired & hospital acquired S. aureus has been increasing over the past few decades, predominantly due to continuous upsurge in the drug resistant isolates. Moreover, globally the incidence of methicillin resistant S.aureus (MRSA) is progressively increasing. Hence, it would be imperative to screen all healthcare workers, interns and admitted patients for MRSA carriage and to treat all those who are found positive for the same. With the above background, the current study was undertaken to investigate the carrier rate of S. aureus (including MRSA) among hospital unexposed & exposed medical students.Methods:A total of 181 medical students of Veer Chandra Singh Garhwali Government Institute of Medical Sciences & Research, Srinagar Garhwal, Uttarakhand. Study participants were broadly divided into two groups: hospital exposed group (n=107) and hospital unexposed group (n=74). Nasal swabs were obtained & cultured for the detection of S. aureus. Congo red agar and 0.1% Crystal Violet Assay were performed to observe the ability to form in vitro biofilm by S. aureus.Results:Out of total 181 medical students 29.28% were found to be healthy carrier of S. aureus. Among the hospital exposed group 37.38% and among hospital unexposed group 17.57% were found to be healthy carrier of S. aureus. Only one student (hospital exposed group) was found to be positive for MRSA. Beta-lactamase production was noted in 90.57% strains of S. aureus while the significant rate of slime layer production was observed in 73.58% of strains.Conclusion:Prevalence of S. aureus nasal carriage increases with the duration of exposure to the hospital environment. The nasal carriage of S. aureus in medical students indicate the potential danger of dissemination of S. aureus including MRSA from them to the hospitalized patients which in turn complicates the treatment of same.

Methicillin Resistant Staphylococcus aureus Nasal Carriage among Health Care Workers at Rawalpindi Institute of Cardiology, Rawalpindi, Pakistan

Background Staphylococcus aureus (S. aureus) is a virulent pathogen that is currently the most common cause of infections in hospitalized patients. Health care workers (HCWs) play a significant role in the epidemiology of Methicillin Resistant S. aureus (MRSA) infection. HCWs act as a vector for transmission of MRSA as they work at the interface between hospital and the community. Transmission of MRSA in health care environment is usually by contact between patients through hands, cloths or equipment of HCWs. Objectives To determine the percentage of HCW’s having MRSA carriage at a tertiary care hospital in Rawalpindi Pakistan. Materials and methods Nasal swabs from anterior nares of HCWs were cultured on Blood agar and Macconkey Agar and Mannitol Salt Agar (MSA) and incubated at 35°C for 24-48 hours. S. aureus growth was confirmed by colony morphology, gram staining and biochemical tests. MRSA were identified by observing zone of inhibition around Cefoxitin disc on Mueller Hinton Agar (MHA) according to CLSI guidelines. Results The frequency of nasal carriage of MRSA was 6.5%. High nasal carriage was seen in ITC among the nursing staff. Conclusion High frequency of MRSA nasal carriage in ITC staff reflects poor hand hygiene and urgent need for infection control measures.

Molecular characteristics of Staphylococcus aureus nasal carriage among health care workers at a Referral Hospital in Zabol, Iran.

IntroductionStaphylococcus aureus (S. aureus) is known as one of the most important hospital pathogens responsible for a wide range of infections. Limited data concerning the prevalence of nasal carriage of S. aureus and its molecular characteristics are available in Zabol province, Iran. Therefore, the aim of the present study was to determine the prevalence of nasal carriage of S. aureus and its molecular characteristics isolated from health care workers (HCWs).MethodsTotally, 251 nasal swabs were collected from HCWs at a referral hospital, from March to September 2017. Disk diffusion method was used to identify Methicillin-Resistant S. aureus (MRSA). PCR amplification method was used for the detection of following genes; sea, seb, sec, sed, see, tst, eta, etb, lukF-PV, lukS-PV and SCCmec types.ResultsOf 251 collected swabs, 31 (12.4%) cases were identified as S. aureus carriers, which 14 (14/31; 45.2%) isolates were MRSA. The most prevalent detected genes were sea and tst, with 22.6% and 9.7%, respectively. The most prevalent SCCmec type was SCCmec type IV (28.6%).ConclusionWe found that the prevalence of MRSA nasal carriage is at high level and must be considered as a significant health care problem at the investigated hospital. Strict implementation of infection-control policies and rational use of antibiotics are the main pillars for controlling the spread of S. aureus at hospital.

Comparison of Nasal Colonization of Methicillin-Resistant Staphylococcus aureus in HIV-Infected and Non-HIV Patients Attending the National Public Health Laboratory of Central Nepal.

Background Staphylococcus aureus is a cardinal source of community- and hospital-acquired infection. HIV infection is a well-recognized risk factor for methicillin-resistant S. aureus (MRSA) carriage and infection. Intrinsically developed antibiotic resistance has sharply increased the burden of MRSA which is often associated with morbidity and mortality of the patients. Moreover, nasal carriage of S. aureus plays a significant role in spread of community-associated (CA) S. aureus infections. Methods This study was conducted from June 2016 to December 2016 at National Public Health Laboratory (NPHL), Kathmandu, with an aim to assess the rate of S. aureus nasal carriage and MRSA carriage among HIV-infected and non-HIV patients. A total of 600 nonrepeated nasal swabs were analyzed following standard microbiological procedures, where 300 swabs were from HIV-infected patients while remaining 300 were from non-HIV patients. The isolates were identified on the basis of colony characteristics and a series of biochemical tests. The antibiotic susceptibility test (AST) was performed by the modified Kirby–Bauer disc diffusion method. Inducible clindamycin resistance in isolates was confirmed by the D-test method. Results Overall, out of 600 nasal swabs of patients tested, 125 (20.8%) were S. aureus nasal carriers which included 80 out of 300 (26.66%) among HIV-infected patients and 45 (15%) out of 300 among non-HIV patients, and the result was statistically significant (p=0.0043). Among the isolated S. aureus, 11 (13.8%) MRSA were confirmed in HIV-infected while 3 (6.7%) MRSA were detected from non-HIV patients. A higher number of S. aureus carriers was detected among HIV-infected males 40 (26.49%), whereas MRSA carriage was more prevalent among HIV-infected females 7 (5.1%). Among the HIV-infected, patients of age group 31–40 years were the ones with highest carriage rate 36 (45%), while in non-HIV patients, the highest rate 13 (28.9%) of carriage was detected among the patients of age group 21–30 years. Statistically significant difference was found between S. aureus carriage and HIV infection in patients (p < 0.05). Higher rate 2/3 (66.7%) of inducible clindamycin resistance in MRSA was detected from non-HIV patients in comparison to HIV-infected patients 7/11 (63.63%) while the result was statistically insignificant (p > 0.05). All the MRSA isolates (100%) were resistant against co-trimoxazole while ciprofloxacin showed high rate of sensitivity towards both MSSA and MRSA. None of the isolates were detected as VRSA. The major factors associated with nasal colonization of S. aureus were close personal contact, current smoking habit, and working or living in a farm (p < 0.05). Conclusion Regular surveillance and monitoring of MRSA nasal carriage and antibiotic susceptibility pattern are of prime importance in controlling S. aureus infections especially in high risk groups like HIV-infected patients.

NASAL COLONIZATION OF METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS AMONG CLINICAL POSTGRADUATES IN A COASTAL KARNATAKA MEDICAL COLLEGE - PREVALENCE AND ANTIBIOGRAM PATTERN

Objective: The incidence of community-acquired and hospital-acquired Staphylococcus aureus infections has been rising with increasing emergence of drug-resistant strains called methicillin-resistant S. aureus (MRSA). The prime objective of the study was to ascertain the prevalence of carriage rate of MRSA among the clinical postgraduate students of a medical college of Coastal Karnataka, India.Methods: A total of 133 clinical postgraduates have participated in the present study. Swabs from both anterior nares were collected and processed for S. aureus from the consenting participants after giving a set of questionnaires. The isolated strains of S. aureus were screened for methicillin resistance by the modified Kirby-Bauer method using cefoxitin (30 μg) disc. Antibiotic susceptibility testing for all isolates of S. aureus was also done against other antibiotics. E test was used to know vancomycin resistance for MRSA.Results: The numbers of S. aureus isolated of 133 participants were 22 (16.5%). Of 22 isolates of S. aureus, 12 were MRSA (54.5%). The MRSA carriage rate of clinical postgraduates of a medical college from Coastal Karnataka, India, was 9%. All the MRSA isolates were susceptible to vancomycin and teicoplanin. Contact with chronic patients and consumption of antibiotics in past 6 months were found to be statistically significant as the risk factor associated with the acquisition of S. aureus/MRSA carriage status among the participants. No vancomycin-resistant S. aureus was reported from the present study.Conclusion: The S. aureus and MRSA nasal carriage rates of clinical postgraduates recorded in this study were significantly high when compared with the general population. This could be due to their continuous exposure to patients in clinical settings. It is desirable that these students must receive sufficient knowledge regarding control measures to avoid the spread of MRSA infection in hospitals.

Prevalence of Nasal Carriage of Staphylococcus aureus and its Antibiotic Susceptibility among Healthcare Workers (HCWs) in Ukraine

BACKGROUND. Nasal carriage of Staphylococcus aureus among hospital personnel is a common cause of hospital acquired infections. Emergence of drug resistant strains especially methicillin resistant S. aureus (MRSA) is a serious problem in hospital environment. Therefore, the aim of this study was to determine the prevalence of nasal carriage of Staphylococcus aureus its antibiotic susceptibility among healthcare workers (HCWs) in Ukraine.&#x0D; METHODS. This cross-sectional study was conducted from January to December 2017. The study included medical workers from 19 hospitals in different Ukrainian regions. Nasal swabs were taken from 755 randomly selected HCWs. The mean age of participants was 32.41 ± 8.29 years (range 19—74 years) with a male-to- female ratio of 0.47. The isolates were identified as S. aureus based on morphology, Gram stain, catalase test, coagulase test, and mannitol salt agar fermentation. The sensitivity patterns of S. aureus strains were determined by disk diffusion method (Kirby — Bauer). The panel of antibiotics used in sensitivity tests included: penicillin, oxacillin, cefoxitin, amoxicillin/clavulanic acid, gentamicin, tobramicin, ciprofloxacin, levofloxacin, moxifloxacin, mupirocin, nitrofurantoin, vancomycin, teicoplanin, fosfomycin, clindamycin, erythromycin, rifampicin, linezolid, tetracycline, tigecycline, trimethoprim/sulphamethoxazole, and fusidic acid. Interpretative criteria were those suggested by the CLSI (Clinical and Laboratory Standards Institute). MRSA were confirmed by detection of the mecA gene by polymerase chain reaction.&#x0D; RESULTS. Nasal screening identified 31.1 % (235/755) S. aureus carriers. Of the 235 nasal carriers of S. aureus, 4 % (196/755) carried MSSA (methicillin-sensitive S. aureus) and 39/755 (16.6 %) carried MRSA. The frequency of MRSA and MSSA carriage also varied according to the department/ward. The highest prevalence of nasal carriage of MRSA was in the surgical wards. The staff of the general, pediatric, cardiovascular, neuro and orthopedic surgery wards together with the emergency department accounted for 56.4 % of all MRSA carriers. There was no significant difference between the sexes (p = 0.247), age (p = 0.817), and years of healthcare service (p = 0.15) with regard to the nasal carriage of MRSA and MSSA. In univariate analysis we divided the hospital departments into: emergency, internal medicine, pediatrics, ICUs, surgery, and non-medical units and found no significant difference between MSSA and MRSA carriers (p = 0.224). In the multivariate analysis, the occupation «nurse» was independently associated with MRSA carriage (p = 0.012, odds ratio 3.6, 95 % confidence interval 1.3—9.7). All the S. aureus isolates recovered from nasal carriers, were susceptible to linezolid, tigecycline, vancomycin, teicoplanin, and mupirocin. Susceptibility to the other antimicrobials was also on a high level: 98.3 % of strains were found susceptible to trimethoprim/sulphamethoxazole, 96.2 % — to nitrofurantoin, 95.3 % — to fusidic acid, 92.3 % — to fosfomicin, 88.5 % — to amoxicillin/clavulanic acid, 87.2 % — to tobramycin, 86.8 % — to clindamycin. Resistance to oxacyllin came up to 16.6 %.&#x0D; CONCLUSIONS. Nasal carriage of S. aureus appears to play a key role in the epidemiology and pathogenesis of infection. HCWs who are at interface between the hospital and the community may serve as agents of cross contamination of hospital acquired and community acquired MRSA. It is of importance to follow the evolution of resistance to antibiotics in this species, especially to β-lactams.

Staphylococcus aureus nasal carriage in health care workers: First report from a major public hospital in Argentina

Staphylococcus aureus causes numerous mild to severe infections in humans, both in health facilities and in the community. Patients and health care workers (HCWs) may disseminate strains during regular medical examinations or hospitalization. The aim of this study was to determine the nasal carriage rate of methicillin-susceptible and methicillin-resistant S. aureus among health care workers at Hospital Provincial del Centenario, a public general hospital in Rosario, Argentina. A transversal study was conducted on 320 health care workers. Nasal swabs were taken and presumptive S. aureus colonies were isolated. Bacterial identity and methicillin resistance status were confirmed by amplification of the nuc and mec genes. Chi square test and Fisher exact test were used for statistical analysis. Of 320 HCWs, 96 (30%) were nasal carriers of S. aureus, 20 of whom (6.3%) carried methicillin-resistant S. aureus (MRSA) and 76 (23.7%) methicillin-susceptible S. aureus (MSSA). Carriage was within thepublished values for physicians (30%) and higher for technicians (57%). Accompanying resistance (62/96, 64.6%) was detected, including resistance to fluoroquinolones (23/96, 24%), aminoglucosides (13/96, 13.5%) or to macrolides (33/96, 34.4%). All the strains were susceptible to vancomycin whereas only 3.1% (3/96), all of them on MSSA strains, were resistant to mupirocin. This study is the first one of its kind in Argentina and one of the few performed in South America, to highlight the relevance of nasal carriage of MRSA and MSSA in health care personnel and brings to light the need for consensus recommendations for regular S. aureus carriage screening as well as for decolonization strategies.

Nasal carriage of methicillin resistant Staphylococcus aureus among health care workers at Al Shifa hospital in Gaza Strip

BackgroundNasal carriage of Staphylococcus aureus among hospital personnel is a common cause of hospital acquired infections. Emergence of drug resistant strains especially methicillin resistant S. aureus (MRSA) is a serious problem in hospital environment. Therefore, the aim of this study was to determine the nasal carriage rate of S. aureus and MRSA among Health Care Workers (HCWs) at Al Shifa Hospital, the major hospital in Gaza Strip.MethodsA cross sectional study was conducted on 200 HCWs. Nasal swabs were collected during February — April 2015, and cultured on blood and mannitol salt agar. The isolates were identified as S. aureus based on morphology, coagulase test, DNase test and mannitol salt agar fermentation. Disk diffusion antibiotic susceptibility tests were performed according to the guidelines of the Clinical and Laboratory Standards Institute. MRSA were confirmed by detection of the mecA gene by PCR.ResultsOut of the 200 healthcare workers, 62 (31%) carried S. aureus, of which 51 (82.3%) were MRSA. Therefore, 25.5% of all HCWs were identified as MRSA carriers. MRSA carriage rate was highest among nurses (30.4%) whereas the carriage rate among doctors was (16%). The majority of MRSA carriers were workers of internal medicine department and surgical wards (41.3 and 35% respectively). Out of the 51 MRSA isolates identified by oxacillin disc resistance, 40 were confirmed by PCR targeting the mecA gene. Penicillin showed the highest rate of resistance among MRSA and MSSA isolates (100%).ConclusionsThe high rate of nasal MRSA carriage among healthcare workers found in this study is alarming and highlights the need for adjusted infection control measures to prevent MRSA transmission from HCWs to the vulnerable patient.

Nasal Carriage of Methicillin-resistant Staphylococcus aureus among Elderly People in Lagos, Nigeria

Objectives: Staphylococcus aureus is a lethal opportunistic pathogen capable of causing a wide range of infections, especially in debilitated hosts such as the elderly. Nasal carriers of this organism have an increased risk of becoming infected with the pathogen. The purpose of this study was to assess the prevalence of S. aureus nasal carriage, to determine the probable risk factors, and to examine the frequency of methicillin-resistant S. aureus (MRSA) among elderly people in hospital and nursing home settings in Lagos, Nigeria. Methods: Two hundred thirty nasal samples were collected from the anterior nares of individuals aged 65 years and older. Possible risk factors were assessed using well-structured questionnaires, and the samples were subjected to standard bacteriological procedures. Antibiotic susceptibility of the isolates was determined with the disk diffusion method. Detection of methicillin resistance was done with the disk diffusion test using cefoxitin 30 µg, and confirmed with OXOID MRSA CHROMagar. Results: Fifty (21.7%) S. aureus strains were identified among the samples, and antibiotic susceptibility testing showed that multidrug resistance was common. Approximately 20% were resistant to gentamicin, ofloxacin, and mupirocin. Cloxacillin, amoxicillin/clavulanate, and ceftazidime showed the least anti-staphylococcal activity, and almost half of the isolates were resistant to ceftriaxone and cefuroxime. The MRSA nasal carriage rate was 10% and colonization was favored by previous antibiotic use, hypertension, and tuberculosis. Conclusions: The occurrence of multidrug-resistant S. aureus in the elderly cohort indicates their capacity to serve as reservoirs for these strains, which could facilitate the dissemination of MRSA into the community. Therefore, decolonization and the implementation of measures to prevent the spread of this organism are necessary.

Differences in Staphylococcus aureus nasal carriage and molecular characteristics among community residents and healthcare workers at Sun Yat-Sen University, Guangzhou, Southern China.

BackgroundThe pathogenic potential and commensal nature of Staphylococcus aureus allows for easy transmission both within and outside of the hospital environment, and nasal carriage may be responsible for some serious infections. This study aimed to determine the molecular and epidemiological characteristics of nasal colonization by S. aureus in community residents (CR) and healthcare workers (HW) at Sun Yat-Sen University, Guangzhou, China.MethodsA total of 589 volunteers, both CR (n = 297) and HW (n = 292), were recruited. Each subject completed a questionnaire, and specimens were obtained from the anterior nares for S. aureus screening. Genotypic analysis included pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), staphylococcal cassette chromosome mec (SCCmec) typing, and virulence gene detection.ResultsA total of 138 S. aureus isolates were recovered from separate subjects (23.4 %, 138/589), with four isolates showing methicillin resistance (0.7 %, 4/589). The prevalence of S. aureus carriage was 25.3 % (75/297) in CR and 21.6 % (63/292) in HW. Methicillin-resistant S. aureus (MRSA) were isolated from one CR (0.3 %, 1/297) and three HW (1.0 %, 3/292). The most common risk factors for S. aureus carriage in CR were being male, age ≤ 30 years, and nasal cavity cleaning habits. Having a household member in the healthcare profession was associated with increased risk among HW. Sequence type (ST)188 and ST59 were the most prevalent among the 20 observed STs, accounting for 14.6 % and 12.2 % of all isolates, respectively. The four MRSA isolates presented four different STs, with one isolate carrying a type IVa SCCmec element and the other three isolates containing type III SCCmec. PFGE analysis grouped the 129 isolates into 23 pulsotypes, with profiles A, N, E, L, and O the most prevalent. The Panton-Valentine leucocidin gene (pvl) was identified in two of the 138 isolates, while 57.5 % of isolates carried both the Staphylococcus aureus enterotoxin A (sea) and enterotoxin B (seb) genes.ConclusionsThese data indicate a low prevalence of nasal MRSA carriage but evidence of molecular heterogeneity among S. aureus isolates from CR and HW at Sun Yat-Sen University, Guangzhou. Differences in epidemiological and molecular characteristics of S. aureus between CR and HW populations may be useful for the understanding and prevention of S. aureus infection.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-015-1032-7) contains supplementary material, which is available to authorized users.

Risk Factors for Methicillin Resistant Staphylococcus aureus Nasal Colonization of Healthy Children.

Background:Nasal colonization of healthy children with Staphylococcus aureus is an important risk factor for different infections. Detection of colonized individuals with methicillin resistant S. aureus (MRSA) and its eradication is the proper prevention strategy for infection spread in the community and health-care centers.Objectives:The aim of this study was to determine the prevalence, associated risk factors and antibiotic resistance pattern among healthy children who were nasal carriers of S. aureus.Patients and Methods:This cross-sectional study was conducted on 350 one month to 14-year-old healthy children living in Kashan/Iran. The nasal specimens were cultured in blood agar medium for S. aureus. Positive cultures were evaluated for cephalothin, co-trimoxazole, clindamycin, ciprofloxacin, oxacillin and vancomycin susceptibility by the disc diffusion method and E-test. Risk factors for nasal carriage of S. aureus and MRSA were evaluated.Results:Frequency of S. aureus nasal carriage was 92 from 350 cases (26.2%), amongst which 33 (35.9%) were MRSA. Isolates indicated an overall resistance of 52.2% to cephalothin, 33.7% to co-trimoxazol, 26.1% to ciprofloxacin, 26.1% to clindamycin, 35.9% to oxacillin and 4.3% to vancomycin. Factors associated with MRSA nasal carriage included gender (P value 0.001), age of less than four years (P value 0.016), number of individuals in the family (P value < 0.001), antibiotic use (P value < 0.001) and admission (P value < 0.001) during the previous three months, parental smoking (P value < 0.001) and sleeping with parents (P value 0.022).Conclusions:Age of less than four years, male sex, family size being more than four, antibiotic use and admission during the previous three months, parental smoking and sleeping with parents were independent risk factors for nasal colonization with MRSA.

Staphylococcus aureus nasal carriage in Ukraine: antibacterial resistance and virulence factor encoding genes

BackgroundThe number of studies regarding the incidence of multidrug resistant strains and distribution of genes encoding virulence factors, which have colonized the post-Soviet states, is considerably limited. The aim of the study was (1) to assess the Staphylococcus (S.) aureus nasal carriage rate, including Methicillin Resistant S. aureus (MRSA) strains in adult Ukrainian population, (2) to determine antibiotic resistant pattern and (3) the occurrence of Panton Valentine Leukocidine (PVL)-, Fibronectin-Binding Protein A (FnBPA)- and Exfoliative Toxin (ET)-encoding genes.MethodsNasal samples for S. aureus culture were obtained from 245 adults. The susceptibility pattern for several classes of antibiotics was determined by disk diffusion method according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. The virulence factor encoding genes, mecA, lukS-lukF, eta, etb, etd, fnbA, were detected by Polymerase Chain Reaction (PCR).ResultsThe S. aureus nasal carriage rate was 40%. The prevalence of nasal MRSA carriage in adults was 3.7%. LukS-lukF genes were detected in over 58% of the strains. ET-encoding genes were detected in over 39% of the strains and the most prevalent was etd. The fnbA gene was detected in over 59% of the strains. All MRSA isolates tested were positive for the mecA gene. LukS-lukF genes and the etd gene were commonly co-present in MRSA, while lukS-lukF genes and the fnbA gene were commonly co-present in Methicillin Sensitive S. aureus (MSSA) isolates. No significant difference was detected between the occurrence of lukS-lukF genes (P > 0.05) and the etd gene (P > 0.05) when comparing MRSA and MSSA. The occurrence of the fnbA gene was significantly more frequent in MSSA strains (P < 0.05).ConclusionsIn Ukraine, S. aureus is a common cause of infection. The prevalence of S. aureus nasal carriage in our cohort of patients from Ukraine was 40.4%. We found that 9.1% of the strains were classified as MRSA and all MRSA isolates tested positive for the mecA gene. We also observed a high prevalence of PVL- and ET- encoding genes among S. aureus nasal carriage strains. A systematic surveillance system can help prevent transmission and spread of drug resistant toxin producing S. aureus strains.

Nasal carriage of Methicillin-resistant Staphylococcus aureus among healthy population of Kashmir, India

Background: Nasal colonisation with community acquired methicillin resistant Staphylococcus aureus (CA-MRSA) is being increasingly reported, especially in places where people are in close contact and where hygiene is compromised. The aim of this study was to find out prevalence of methicillin resistant S.aureus (MRSA) colonising anterior nares of healthy subjects. Materials and Methods: Nasal swabs of healthy subjects were collected aseptically and cultured using standard microbiological protocols. Antibiotic susceptibility was done by Kirby-Bauer disc diffusion method according to CLSI guidelines. Methicillin resistance was detected by cefoxitin disc diffusion method and confirmed by minimum inhibitory concentration (MIC) and amplification of mecA gene by PCR. Strain typing of MRSA strains was done by PFGE. Results: Out of 820 samples, S.aureus was isolated from 229 (27.92%) subjects. Of the 229 isolates, 15 were methicillin resistant. All S. aureus isolates were susceptible to vancomycin. Nasal carriage of MRSA was found to be 1.83% among healthy population. The isolates were found to be polyclonal by PFGE analysis. Conclusion: High prevalence of MRSA is a cause of concern and strategies to interrupt transmission should be implemented.

High Nasal Carriage of Methicillin-ResistantStaphylococcus aureusAmong Healthy Tanzanian Under-5 Children

This study aimed to determine the prevalence of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) carriage, risk factors of colonization and antimicrobial susceptibility patterns of S. aureus strains. The study was conducted at the Muhimbili National Hospital in Dar es Salaam, Tanzania. Nasal swabs were obtained from children and S. aureus was isolated and identified using conventional culture methods. MRSA was screened and confirmed using the cefoxitin disk and multiplex real-time polymerase chain reaction, respectively. Antibiotic susceptibility was performed using the Kirby-Bauer disk diffusion method. MRSA isolates were further characterized by pulsed field gel electrophoresis (PFGE) profiling. Of 285 children included in the study, S. aureus was detected in 114 (40%). Of the 114 isolates, 12 (10.5%) were MRSA. PFGE results showed that these MRSA isolates are epidemiologically unrelated. Resistance of all S. aureus to trimethoprim-sulfamethoxazole, tetracycline, gentamicin, and ciprofloxacin was 65.8%, 23.7%, 27.2%, and 4.4%, respectively. No resistance to vancomycin was found. The prevalence of inducible clindamycin resistance, constitutive clindamycin resistance, MS phenotype (resistance to erythromycin alone), and multidrug resistance was 16.7%, 1.8%, 14.0%, and 16.8%, respectively. None of the risk factors examined was found to be significant. This is the first report of S. aureus and nasal carriage of MRSA and a high rate of S. aureus carriage was found in Tanzanian under-5 children. The study findings support the need for proper health education and effective infection control measures for healthcare workers.