CHROMagar Methicillin-resistant Staphylococcus Aureus Research Articles

Abundance and diversity of methicillin-resistant bacteria from bathroom surfaces at workplaces using CHROMagar media, 16S, and dnaJ gene sequence typing.

University campus communities consist of dynamic and diverse human populations originated from different regions of the country or the world. Their national/global movement to and from campus may contribute to the spread and buildup of methicillin-resistant (MR) bacteria, including MR Staphylococci (MRS) on high-touch surfaces, sinks, and toilets. However, studies on MR bacteria contamination of surfaces, sinks, and toilets are scarce in workplaces outside of healthcare settings. Hence, little is known whether university communities contaminate campus bathrooms by MR bacteria. This study evaluated the abundance, identity, and phylogenetics of MR bacteria grown on CHROMagar MRSA media from bathrooms at workplaces. We collected 21 sink and 21 toilet swab samples from 10 buildings on campus and cultured them on CHROMagar MRSA media, extracted DNA from MR bacteria colonies, sequenced PCR products of 16S and dnaJ primers, determined the sequence identities by BLAST search, and constructed a phylogenetic tree. Of 42 samples, 57.1% (24/42) harbored MR bacteria. MR bacteria were more prevalent on the sink (61.9%) than in the toilet (52.2%) and in male bathrooms (54.2%) than in female bathrooms (41.7%). The colony count on the bathroom surfaces of 42 samples varied in that 42.9% (18/42), 33.3, 14.3, and 9.5% of samples harbored 0, 100, and > 1000 MR bacteria colonies, respectively. Of MR bacteria sequenced, BLAST search and phylogenetic analysis showed that Staphylococcus accounted for 60% of the MR bacteria and the rest were non-Staphylococci. Of Staphylococcus carrying MR (n = 15), 53.3% were S. hemolyticus followed by S. lugdunensis (26.7%), S. epidermidis (8%), and a newly discovered S. borealis in 2020 (4%). Of non-Staphylococci MR bacteria, 20% accounted for Sphingomonas koreensis. Campus bathrooms serve as a reservoir for diverse bacteria carrying MR, which pose a direct risk of infection and a potential source of horizontal gene transfer. To reduce the health risk posed by MR bacteria in high traffic areas such as bathrooms additional environmental monitoring and improved decontamination practices are needed.

In-vitro Susceptibility of Linezolid and Teicoplanin in Methicillin-resistant Staphylococcus aureus by E-test

Introduction: Staphylococcus aureus (S. aureus) is a ubiquitous pathogen causing various infections in humans. The emergence of drug resistance in S. aureus, especially methicillin resistance, has made treating these infections increasingly tricky, with only a few antibiotics being effective. Vancomycin, Teicoplanin, and Linezolid are the antibiotics of choice for treating Methicillin-resistant Staphylococcus aureus (MRSA) infections, though occasional resistance to these antibiotics has also been reported. Aim: To know the prevalence of MRSA and subject the MRSA isolates to linezolid and teicoplanin susceptibility testing by Epsilometer test (E-test). Materials and Methods: This was a cross-sectional study done between April 2021 and March 2022. A total of 210 consecutive S. aureus isolates from various clinical samples were isolated and processed in the Department of Microbiology, Andhra Medical College, Visakhapatnam, Andhra Pradesh, India. Screening for methicillin resistance was done by cefoxitin disc diffusion testing and Chromogenic agar (CHROMagar) MRSA, with American Type Culture Collection (ATCC) S. aureus 25923 strain as a negative control and a known in-house strain was used as a positive control. All the MRSA isolates were tested for linezolid and teicoplanin susceptibility for the E-test to determine the Minimum Inhibitory Concentration (MIC). Data were entered into Microsoft Excel 2019, and International Business Machines (IBM) Statistical Package for the Social Sciences (SPSS) version 20.0 was used for analysis. Results: Out of 210 S. aureus, 100 (47.6%) were MRSA isolates. MRSA was predominantly isolated from pus (58%), sputum (19%), and urine (9%) samples. Higher resistance was observed against cotrimoxazole (72%), ciprofloxacin (54%), and amikacin (37%). Teicoplanin and linezolid were both susceptible in all of the isolates. MIC50 and MIC90 against linezolid and teicoplanin was 0.5 and 1 mcg/mL and 0.5 and 0.75 μg/mL respectively. Conclusion: MRSA isolates are increasingly becoming resistant to multiple antibiotics. Linezolid and glycopeptides are still the mainstays for treating MRSA infections, as most isolates are susceptible to these drugs.

Comparison of Different Phenotypic Methods of Detection of Methicillin-Resistant Staphylococcus aureus with Polymerase Chain Reaction

Objectives: The objective of the current study was to compare the diagnostic methods of Oxacillin Disk Diffusion, Cefoxitin Disk Diffusion, Oxacillin Resistance Screening Agar Base, and CHROM Agar MRSA with the gold-standard method of Polymerase Chain Reaction for detection of Methicillin-resistant Staphylococcus aureus.
 Methods: Two hundred pus samples were included in the study from which Staphylococcus strains were evaluated. The isolates of Staphylococcus aureus were subjected to the Oxacillin Disk Diffusion test, Cefoxitin Disk Diffusion test, Oxacillin Resistance Screening Agar Base, and CHROM Agar MRSA to detect MRSA with PCR, the reference standard. The diagnostic techniques were compared to their sensitivity, specificity, positive predictive, and negative predictive values.
 Results: The sensitivity of the Cefoxitin Disk Diffusion test was 100%, followed by CHROM Agar MRSA at 96.7%, Oxacillin Disk Diffusion at 90%, and Oxacillin Resistance Screening Agar Base at 86.7%. Most specific was the Cefoxitin Disk Diffusion test (99.4%), followed by Oxacillin Resistance Screening Agar Base (98.8%), CHROM Agar MRSA (97.7%), and the least specific was the Oxacillin Disk Diffusion test (96.5%).
 Conclusion: The Cefoxitin Disk Diffusion test was the most sensitive and specific of all four methods, next to the Polymerase Chain Reaction. However, future multicentric studies are recommended to test this method across all prevalent centers of methicillin resistance. J Microbiol Infect Dis 2022; 12(3):116-126.

Diagnostic Accuracy of CHROMagar MRSA for Detection of Methicillin-Resistant Staphylococcus Aureus (MRSA) from Screening Swab Specimens

Objective: To determine the diagnostic accuracy of CHROMagar MRSA for detecting MRSA from screening swab specimens keeping the Cefoxitin disk diffusion test as the reference method.
 Study Design: A cross-sectional validation study.
 Place and duration of study: Department of Microbiology, Armed Forces Institute of Pathology (AFIP), Rawalpindi Pakistan, from Mar to Aug 2019.
 Methodology: A total of 243 screening swab specimens, e.g., axillary, nasal and web swabs, each of hospitalized patients and healthcare workers (HCW) submitted for MRSA screening were included in the study and were processed simultaneously on blood agar, MacConkey agar and CHROMagar MRSA. The agar plates were incubated at 35°C ± 2°C for 18-24 hours in ambient air. The cefoxitin disk diffusion test followed the isolation and identification of MRSA according to the latest Clinical and Laboratory Standards Institute (CLSI) guidelines. In CHROMagar MRSA screening, after incubation, plates were examined for the presence of mauve colonies (MRSA detected), and the results were obtained and validated against the reference method of Cefoxitin disk diffusion.
 Results: Overall, the diagnostic accuracy of CHROMagar MRSA for detecting MRSA was 97.53%. Diagnostic accuracy of CHROMagar MRSA was 95.1%, 97.5% and 100% in axillary, nasal and web specimens, respectively. The rate of MRSA detection was maximum in axillary swabs, i.e., 40.7%, followed by 29.6% and 9.8% in nasal and web swabs, respectively.
 Conclusion: CHROMagar MRSA is found to be accurate for the detection of MRSA. It is reliable, easy to perform, less timeconsuming, and cost-effective. It is an affordable alternative to the conventional..............

Prevalence of Meticillin Resistance Staphylococcus Aureus in Patients with Lower Respiratory Tract Infections

Background: Lower respiratory tract infection (LRTIs) is an emerging and threatening disease of both adults and children. Methicillin resistant Staphylococcus aureus (MRSA) remains a life threatening pathogens that may colonize the lungs and cause Staphylococcal related lower respiratory tract infection. The aim of this study was to determine the prevalence and risk factors associated with MRSA infection among individuals with lower respiratory tract infections in a community setting. Method: A structured questionnaire consisting of demographic characteristics, antibiotic usage, social life habits were administered to 152 participants, comprising of 80 males and 72 females. The subjects were selected based on non- hospitalization for the past six months. Sputum samples were collected and cultured unto Mannitol Salt agar. The Staphylococcus aureus isolates were sub-cultured unto Chromagar MRSA for MRSA identification. The isolates were subjected to antibiotic susceptibility testing, using disc diffusion method. Result: The MRSA were highly resistant to Ampiclox (96.2%), Amoxcillin (92.3%), Rifampicin and Streptomycin (80.8%), Norfloxacin (76.9%), Erythromycin and Chroramphenicol (69.2%), and Levofloxacin (65.4%). Conclusion: This study showed that MRSA is implicated in LRTIs and is brought about by improper therapy and lack of awareness.

Presence of Antibiotic-Resistant Staphylococcus aureus in Fish and Seafood Originating from Points of Sale in the Tri-City Area (Poland)

Infections by methicillin-resistant Staphylococcus aureus (MRSA) is gradually increasing in the community. There is a potential public health hazard resulting from S. aureus contamination of seafood, which is mainly due to unhygienic handling, processing, and storage environments. In Poland, the limits provided in European Commission Regulation 1441/2007 refer to the presence of Escherichia coli and S. aureus in shelled and shucked products of cooked crustaceans and molluscan shellfish. This study was designed to evaluate the occurrence of MRSA in samples of fish and seafood from commercial outlets located in the Tri-City area (Poland). In this study, we investigated a 44 food samples, including fish and seafood collected from various retail outlets in the Tri-City area of Poland. The first stage of staphylococcus isolation was initial culture in Giolitti-Cantoni broth. After 24 h, if blackening had occurred at the bottom (or there was general blackening of the medium), the samples were spread plated onto a CHROMagar MRSA base. The cultures were then incubated for 24 h at a temperature of 37°C. Of the 44 samples, 26 were positive for MRSA. The samples most often contaminated with MRSA were cephalopods (6 of 9) and crustaceans (10 of 15), followed by samples taken from mollusks (4 of 7) and fish (6 of 13). The correlation between the species from which the samples were obtained and the presence of S. aureus was not significant (P > 0.05). The high frequency of occurrence of MRSA in these products points to the potential risk of transmission of diseases through the food chain. The results obtained are significant and useful for S. aureus risk assessment programs for aquatic products.

Increasing Mupirocin Resistance Among MRSA Nasal Surveillance Isolates in the Chicago Area

Background: In 2005, our healthcare system began universal admission screening for nasal colonization with MRSA and decolonization of MRSA positive patients with mupirocin. In 2010–2012, we studied the impact of nasal MRSA decolonization and concluded that it does not add benefit when contact precautions are used; plus, it resulted in increased rates of mupirocin resistance up to 9.4% in 2012. In September 2012 routine decolonization of hospitalized patients was discontinued. In the 2 years following discontinuation of mupirocin use for decolonization of MRSA carriers, the rate of mupirocin resistance gradually declined. We undertook a contemporary review of mupirocin resistance rates to ensure that the rates were stable. Methods: NorthShore University HealthSystem, Illinois, consists of 4 hospitals in the northern suburbs of Chicago, with 750 beds and 60,000 annual admissions. Admission nasal swab samples were collected from at-risk hospitalized patients based on a risk-adjusted algorithm. Nasal swabs were tested using the BD MAX MRSA assay. Positive samples were cultured onto BD BBL CHROMagar MRSA to recover the organism and were tested for the mupA gene, which confers high-level mupirocin resistance using an in-house PCR test. Data for mupirocin orders were provided by the pharmacy. Results: Mupirocin resistance rates and prescription orders are shown in Figs. 1 and 2. Conclusions: Mupirocin resistance rates plateaued between 2012 and 2014 and then increased from 9.1% in 2015 to 18.1% in 2019, despite discontinuation of routine decolonization of hospitalized patients. The reason for the increase is unclear; inpatient mupirocin orders were stable from 2015 to 2017.Funding: NoneDisclosures: None

Quantifying the Risk of Methicillin-Resistant Staphylococcus aureus (MRSA) Transmission From Patient to Healthcare Personnel in the Critical Care Setting

Background: Healthcare personnel (HCP) acquire MRSA on their gown and gloves during routine care activities for patients who are colonized or infected with MRSA at a rate of ∼15%. Certain care activities (eg, physical exam, care of endotracheal tube, wound care and bathing/hygiene) have been associated with a higher frequency of transmission from the patient to HCP gown and gloves than other activities (ie, administration of oral medicines, glucose monitoring, and manipulation of IV tubing/medication delivery). However, quantification of MRSA contamination and risk to subsequent patients is poorly defined. Objective: We sought to determine the mean MRSA colony-forming units (CFU) found on the gloves and gowns of HCP who acquire MRSA after various care activities involving patients with MRSA. Methods: We conducted a prospective cohort study at the University of Maryland Medical Center from December 2018 to October 2019. We identified patients colonized or infected with MRSA based on culture data from the prior 7 days. HCP performing prespecified care activities on eligible patients were observed. To isolate the risk of each care activity, HCP donned new gloves and gown prior to a specific care activity. Once that care activity was performed, HCP gloves and gown were swabbed prior to the any further care activities. HCP gloves were cultured with an E-swab by swabbing each digit up and down 3 times followed by 2 circles on the palm of their hands. HCP gowns were sampled by swabbing a 15 × 30-cm area along the beltline of the gown and along each inner forearm twice. E-swab liquid was then serially diluted and plated in triplicate on CHROMagar MRSA II (BD, Sparks, MD) to obtain CFU. We calculated the median CFUs and the interquartile range (IQR) for each specific care activity stratified by gown and gloves. Results: In total, 604 HCP–patient care interactions were observed. Table 1 displays the mean MRSA CFUs stratified by gown and gloves for each patient care activity of interest. Conclusions: The quantity of MRSA found on gowns and gloves varies depending on patient care activities. Recognition of differential transmission rates between various activities may allow different approaches to infection prevention, such as the use of personal protective equipment in high- versus low-risk activities and/or the use of more aggressive interventions for high-risk activities.Funding: NoneDisclosures: None

Comparison of the novel Uroquattro HB&L™ system and classical phenotypic method for rapid screening of multidrug-resistant organism colonization at the University Hospital Centre Split, Croatia

Background. Infections caused by multidrug-resistant organisms (MDRO) are difficult to treat and associated with poor outcomes for patients. Therefore, early identification and management of colonization are essential as first steps in infection prevention. Culture-based methods have been widely used for MDRO screening. The turnaround time (TAT) for the identification of carriers varies between 48-72 h with this method. The aim of our study was to compare the performance of the new rapid semiautomatic method for detection of MDRO (HB&L Uroquattro, Alifax) with standard cultivation on selective media. Methods. Twenty-one axillary, 20 nose and 19 rectal swabs were taken in duplicate on two selected days at the University Hospital Centre Split, Croatia. Swabs were cultivated and MDRO isolates were identified on selective media (Chromagar MRSA and Chromagar ESBL) according to the standard operating procedure. Novel Alifax method was performed according to manufacturer’s instructions. Results. TAT for the new method was significantly lower (6.5 h) in comparison to the classical method. With classical method, 10 extended spectrum ß-lactamases (ESBL) producing strains from 10 different rectal specimens were isolated on Chromagar ESBL media. Exactly the same specimens were positive for the presence of ESBL-producing bacteria by rapid Alifax method. On selective Chromagar MRSA media, 11 MDRO were isolated, while rapid method detected 11 MDRO from the same specimens. Conclusions. High concordance of positive and negative results obtained with classical and rapid method is encouraging. However, our study was performed on a small sample size and further research with larger sample size is needed.

JA:2021-20. Source Attribution of MRSA Exposure and Carriage among Dairy Workers

ABSTRACT Purpose: Dairy farmers experience a heavy burden of bioaerosol-related respiratory ailments. Bioaerosols are known to contain inflammagens (specifically endotoxin), and a diverse bacterial community that is associated with upper respiratory inflammation and pulmonary decrement among workers. However, identifying casual agents (beyond endotoxin) is still an area that warrants further research. Industrialization and modernization of the dairy industry has led to dramatic changes in production, work organization, and tasks. Consequently, exposure patterns have been altered. Recently, we demonstrated that the mass of dairy bioaerosols is predominantly present in particle size ranges that span 10–100 μm in aerodynamic diameter; these are known to deposit in the upper respiratory system (i.e., the nasopharyngeal region). The nose contains complex bacterial communities, and this microbiome may play a role in the inflammatory response to bioaerosols. Recently, the nasal microbiome in dairy farmers was shown to contain over two times the bacterial diversity (and abundance) as compared to non-farmers. It is believed that this diversity is protective against the colonization of methicillin-resistant Staphylococcus aureus (MRSA). In contrast, persistent nasal carriage of MRSA, specifically livestock-associated strain, has been demonstrated in swine production workers. Recent evidence shows an increase in soft tissue infections caused by livestock associated (LA)-MRSA among at risk populations. The objective of this research was to characterize the presence and carriage of Staphylococcus spp. with a focus on LA-MRSA in the nose of dairy workers. Methods: We collected nasal lavage samples before and after each shift across 5 consecutive days. The presence of MRSA in each sample was evaluated using culture-based methods, specifically tryptic soy agar, mannitol salt agar, Chromagar Staph Aureus, and Chromagar MRSA II. Antibiotic sensitivity was conducted using Kirby Disc Diffusion method using tetracycline, vancomycin, and cefoxitin. Further genetic MRSA confirmation is to be accomplished using PCR and MALDI-TOF. Results/Findings: To date, up to 4% of participants were identified to be carriers of MRSA, and up to 16% of participants were identified to be carriers of Staphylococcus aureus. Based on the results from selective media, the MRSA is attributed to mixed sources, including livestock. Confirmation of these isolates will be conducted using matrix-assisted laser desorption/ionization time-of-flight and polymerase chain reaction methods. Practical application: Based on previous pilot studies and initial results, further investigation into LA-MRSA prevalence among dairy workers is needed to help inform control strategies.

The phenotypic and genetic characterization of some virulence factors in MRSA isolated from burn patients

The present study aimed to the phenotypic and genetic detection of some virulence factors in Methicillin resistant Staphylococcus aureus (MRSA) isolated from burn patients. from a total of 38 isolates of Staphylococcus aureus, 15(39.4%) isolates of MRSA were collected from the patients in Diwaniyah Teaching Hospital during the period from June to October, 2018 in AL-Diwaniyah City. Methicillin resistant Staphylococcus aureus (MRSA) was detected by using chrom agar MRSA and polymerase chain reaction (PCR), 15 isolates (39.4%) reported resistance to methicillin antibiotic.In addition, phenotypic detection of the ability of MRSA to produce the ß-lactamase enzymes using rapid iodometric method and its ability to form the biofilm was determined by using the tube method, The results showed 15(100%) MRSA isolates were able to produce ß-lactamase enzymes and 14 (93.3%) MRSA isolates were able to biofilm production. On the other hand, All MRSA isolates were tested by using Polymerase Chain Reaction (PCR) to detection of some virulence factors genes, which include coa gene encoding production of coagulase, icaA gene encoding for biofilm production and blaZ gene encoding for the ß-lactamase enzymes. PCR results showed that MRSA isolates were posses blaZ gene (100%), icaA gene (93.3%) and coa gene (86.6%).

Comparative assessment of methicillin resistant Staphylococcus aureus diagnostic assays for use in resource-limited settings

BackgroundThe rise of methicillin-resistant Staphylococcus aureus (MRSA) is a global health concern. Paucity of data on MRSA carriage prevalence and diagnostic methods in resource-limited settings hampers efforts to define the problem and plan an appropriate response. Additionally, high variability in cost and logistical characteristics of MRSA screening methods may impede infection control efforts. We compared the performance of locally-available chromogenic agar BD CHROMagar MRSA II and two PCR-based assays (Hain GenoQuick MRSA and Cepheid Xpert SA Complete) for the detection of asymptomatic MRSA carriage in nasal swabs.ResultsDuring 2015, we enrolled 500 patients from five hospital wards at a Ugandan regional referral hospital. We found 30% prevalence of methicillin-sensitive Staphylococcus aureus (MSSA) nasal carriage, and 5.4% MRSA nasal carriage prevalence. Compared to a composite reference standard defined as a positive test result on any one of the three assays, Hain GenoQuick MRSA demonstrated the highest sensitivity (96%) followed by direct plating on CHROMagar at (70%), with the lowest sensitivity observed with Xpert SA Complete (52%). Cepheid Xpert provided the most rapid results (< 1 h) but was the most expensive (US $45–50/test). Substantially more labor was required for the Hain GenoQuick MRSA compared to Xpert SA Complete or CHROMagar tests.ConclusionMRSA nasal carriage prevalence rates were low, and high diagnostic sensitivity was achieved using Hain GenoQuick MRSA. Chromogenic media had significantly lower sensitivity, but may represent a viable local option given its lower cost compared to PCR-based assays.

Prevalence of methicillin resistant Staphylococcus aureus (MRSA) in pigs and workers at abattoirs in Trinidad and Tobago.

Methicillin resistant Staphylococcus aureus (MRSA), a major cause of zoonotic infections, has emerged globally in livestock, particularly pigs. People with occupational contact with food producing animals are at high risk of colonization. The aim of this study was to determine the prevalence of MRSA in pigs and abattoir workers throughout Trinidad and Tobago as well as their resistance to other antimicrobial agents. Nasal and skin behind the ear swabs from pigs and nasal swabs from humans were enriched in Mueller Hinton broth with 6.5% sodium chloride, followed by phenol red mannitol broth with 75 mg/L aztreonam and 5 mg/L ceftizoxime. The enriched sample was then plated on both CHROMagar MRSA and Brilliance MRSA. All incubation was at 37ºC for approximately 24 h. Suspect MRSA isolates were confirmed as MRSA using the Penicillin-Binding Protein (PBP2a) test kit and polymerase chain reaction (PCR) to detect the mecA gene. Resistance of the S. aureus and MRSA isolates to 16 antimicrobial agents was determined using the disc diffusion method. Of the 929 pigs and 44 humans sampled, MRSA strains were isolated at a frequency of 0.9% (8/929) and 2.3% (1/44) respectively. All isolates exhibited resistance to one or more of the 16 antimicrobial agents. The study demonstrated that pigs and workers at slaughter houses in Trinidad and Tobago harbour multidrug resistance S. aureus and MRSA. This is of public health significance as occupational exposure of humans can lead to an increased risk of infection and therapeutic failure.

Investigation of mecA gene, virulence traits and antibiotic resistance profiles in methicillin‐resistant Staphylococcus aureus isolates from dairy products

AbstractThis study was performed to determine the prevalence of methicillin‐resistant Staphylococcus aureus (MRSA) in raw milk and dairy products and the presence of virulence traits in the isolates obtained and to assess their resistance to several antibiotics. MRSA was detected by CHROMagar MRSA II in 148 (22.8%) of 650 samples. Ninety‐eight isolates were confirmed as MRSA, 86 of these isolates were phenotype‐positive, 9 were phenotype/mecA‐positive, and 3 were phenotype‐negative but mecA‐positive. However, the virulence genes were not found in any MRSA strains. According to the results of antibiotic susceptibility tests, 100, 44.9, and 29.6% of strains were resistant to penicillin, tetracycline, and clindamycin, respectively. A low prevalence (1.02%) of resistance was observed against vancomycin and chloramphenicol antibiotics. Furthermore, multidrug resistance was seen among MRSA strains isolated from cheese, butter and buttercream samples. In contrast with other studies, we identified a high‐level vancomycin‐resistant MRSA strain in one buttercream sample and the intermediate‐level vancomycin resistance in six different multiple‐resistant MRSA strains from food of dairy origin.Practical applicationsRecently, MRSA has been isolated from foods of animal origin and become one of the rising public health concerns worldwide. This study focused on the prevalence of MRSA in raw milk and dairy products, the presence of genes encoding virulence factors that allow it to cause the disease and their antibiotic susceptibility patterns. Consequently, we revealed the emergence of resistance to vancomycin and multiple antibiotics among MRSA strains. The isolation of high‐level vancomycin‐resistant MRSA strain is an important finding because vancomycin continues to be the first‐line treatment agent for MRSA infections.

Prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in broilers and workers at 'pluck shops' in Trinidad.

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is a cause of zoonotic infections in many countries. People with occupational contact with food animal production are at risk of colonization. The aim of this study was to determine the prevalence of MRSA and their frequency of resistance to other antimicrobial agents from broilers and workers at the 'pluck shops' in Trinidad. For isolation of MRSA, choanal, cloacal and pharyngeal swabs taken from broilers and nasal swabs from humans were enriched then plated on CHROMagar MRSA and Brilliance MRSA. MRSA was confirmed using the PBP2a test kit, resistance to oxacillin and cefoxitin and polymerase chain reaction (PCR) for the mecA gene. Antimicrobial resistance of the MRSA isolates to 16 antimicrobial agents was determined using the disc diffusion method. Of the 287 broilers and 47 humans sampled, MRSA was isolated at a frequency of 2 (0.7%) and 0 (0.0%) respectively. All the MRSA isolates exhibited resistance to one or more of the 16 antimicrobial agents. The study demonstrated that broilers at 'pluck shops' in Trinidad harbor MRSA. This is the first isolation of MRSA from poultry in Trinidad, West Indies,and this finding is of public health significance since occupational exposure of humans can lead to increased risk of acquiring MRSA infections.

The Effect of Low Power Ultrasonic Wave Exposure to Suppress Methicillin-Resistant Staphylococcus aureus (MRSA) In Vitro

The incidence of methicillin-resistant Staphylococcus aureus (MRSA) infection keeps increasing in every part of the world. Currently, the infection prevalence of MRSA has reached 70% in Asia. In Indonesia in 2006 the prevalence was 23.5%; the infection prevalence of MRSA in RS Atmajaya Jakarta reached 47%, in RSUP Dr. Moh. Husin Palembang reached 46%, and RSUD Abdul Moeloek Lampung in 2013 reached 38.4%. MRSA is multiresistant to antibiotics and is hard to kill compared to most other negative gram bacteria. The purpose of this research is to find the lethal power and exposure of ultrasonic waves to kill MRSA, monitoring its ef-fects via changes in shape, size, structure and Gram staining as indicators. The observations were done mac-roscopically by culturing the MRSA in a petri dish filled with Chromagar MRSA medium, while the morpho-logical observations of MRSA were done by SEM, changes in the structure using TEM, and changes in the color of MRSA cells using Gram staining. Ultrasonic wave exposure, at a lethal power = 8.432 watt, killed a significant percentage of MRSA over the control (p = 0.000). The death indicators of the MRSA due to expo-sure to ultrasonic waves of various power were: changes in shape of MRSA affected by ultrasonic power (p = 0.005), changes in size is not affected by ultrasonic power (p= 0.470), the stain of MRSA cell staining from purple to pink affected by ultrasonic power (p = 0.000), all compared with the control. MRSA died due to ne-crosis, with physical evidence of the MRSA death such as mechanical stress marked by swollen MRSA cell, shift cell wall, crack and tears, cavitation marked by pieces of MRSA cell in the field of view due to explosions inside the cell, change to an irregular cell shape, and changes in color from black to transparent.

Methicillin-resistant Staphylococcus aureus (MRSA) screening of hospital dental clinic surfaces.

We assessed the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) strains on surfaces of hospital dental clinics. Specimens were obtained from 5 clinically symptoms-free patients of five different specialties clinics (Implantology, Pediatric Dentistry, Prosthetics, Restorative Dentistry, and Oral Medicine) of the Dental Clinic Hospital of King Saud University before and after each patient. A Q-tip swabs were used from 10 surfaces in each clinic (Arm rest of dental chair, floor beneath dental chair, sink/faucet, towel dispenser, instrument table handle, light handle, X-ray viewer, paper dental records, head rest, and bench). Specimens were cultured in CHROMagar MRSA medium. Prevalence of MRSA colonization was compared between periods before and after patients visited each clinic for treatment. The results showed that the prevalence of MRSA was remarkably increased after patients visited the area. The results indicate that dental clinics should be considered as possible reservoirs of MRSA in the hospital setting.

Prevalence and risk factors for Staphylococcus aureus and methicillin-resistant Staphylococcus aureus nasal carriage inpatients in a tertiary care hospital's chest clinic in Turkey.

We aimed to determine the prevalence and associated risk factors for nasal methicillin-sensitive and methicillin-resistant Staphylococcus aureus (MSSA/MRSA) carriage among patients admitted to a chest clinic of a tertiary care hospital in this study. Nasal samples were taken from anterior nares were cultured in CHROMagar S. aureus plates, MRSA was determined by disc diffusion method (cefoxitin 30 μg) according to the Clinical and Laboratory Standards Institute guidelines and CHROMagar MRSA plates. A questionnaire was applied to determine the demographic characteristics of the participants and risk factors for carriage. Fisher's exact test, univariate and multivariate logistic regression analysis were used. A P < 0.05 indicated a statistically significant difference. This is a cross-sectional study covering all the patients (n = 431) admitted to Kayseri Training and Research Hospital's Chest Clinic from January 1st to 31st 2014. Of all these patients 55 (12.8%) were nasal S. aureus carriers. MRSA positivity was in five among these patients. In multivariate analysis, being under 65 years of age (odds ratio [OR], 1.9; 95% confidence interval [CI], 1.0-3.3), and having prosthesis (OR, 4.8; 95% CI, 1.6-13.9) were found as risk factors for MSSA colonization. The prevalence of nasal carriage of MSSA was low in our study population. The only risk factors playing role in carriage were found as being under the age of 65 and having prosthesis.

Automated Scoring of Chromogenic Media for Detection of Methicillin-Resistant Staphylococcus aureus by Use of WASPLab Image Analysis Software

Recently, systems have been developed to create total laboratory automation for clinical microbiology. These systems allow for the automation of specimen processing, specimen incubation, and imaging of bacterial growth. In this study, we used the WASPLab to validate software that discriminates and segregates positive and negative chromogenic methicillin-resistant Staphylococcus aureus (MRSA) plates by recognition of pigmented colonies. A total of 57,690 swabs submitted for MRSA screening were enrolled in the study. Four sites enrolled specimens following their standard of care. Chromogenic agar used at these sites included MRSASelect (Bio-Rad Laboratories, Redmond, WA), chromID MRSA (bioMérieux, Marcy l'Etoile, France), and CHROMagar MRSA (BD Diagnostics, Sparks, MD). Specimens were plated and incubated using the WASPLab. The digital camera took images at 0 and 16 to 24 h and the WASPLab software determined the presence of positive colonies based on a hue, saturation, and value (HSV) score. If the HSV score fell within a defined threshold, the plate was called positive. The performance of the digital analysis was compared to manual reading. Overall, the digital software had a sensitivity of 100% and a specificity of 90.7% with the specificity ranging between 90.0 and 96.0 across all sites. The results were similar using the three different agars with a sensitivity of 100% and specificity ranging between 90.7 and 92.4%. These data demonstrate that automated digital analysis can be used to accurately sort positive from negative chromogenic agar cultures regardless of the pigmentation produced.

Occurrence and Zoonotic Importance of Methicillin-Resistant Staphylococcus aureus in raw Milk and Some Dairy Products at Ismailia City, Egypt

This study was undertaken to determine the occurrence and the zoonotic importance of methicillin resistant Staphylococcus aureus (MRSA) in raw milk of sheep, goats and buffaloes, some dairy products and dairy workers at Ismailia City, Egypt. A total of 150 samples were collected randomly and cultured on Baird Parker agar and CHROMagar MRSA. Culturing on Baird Parker agar, the results revealed that 46.7 % of raw goat milk, 40% of raw sheep milk, 40% of raw buffaloes' milk, 80% of yogurt, 36.7% of ice cream, 63.3% of Kareish cheese and 63.3% of human swabs' samples were contaminated by coagulase positive Staphylococcus aureus. The isolation rates of MRSA on CHROMagar MRSA in relation to the number of the examined samples and the number of S. aureus isolates were (33.3 and 71.4%), (20 and 50%), (13.3 and 33.3%), (40 and 50%), (13.3 and 36.4%), (33.3 and 52.6%) and (13.3 and 21.1%) from the examined milk samples (goat, sheep, and buffaloes), yogurt, ice cream, Kareish cheese and human swabs' samples, respectively. PCR results showed that all the isolates that were classified as MRSA on CHROMagar contained mec A gene. Results of the disk diffusion test revealed that the resistance rates of MRSA strains to penicillin, gentamycin, vancomycin, clindamycin, amikacin, erythromycin and oxacillin were 91.2%, 67.6%, 14.7%, 94.1%, 91.2%, 82.4% and 100%, respectively. The effectiveness of some hand cleansing agents against the selected MRSA isolates was assessed. It was found that hand gel rub based on alcohol and triclosan together was the most effective agent. The findings of the present study necessitate exerting more efforts for effective control of MRSA in dairy products.