Oxacillin Disk Research Articles

Comparison of Phenotypic and Genotypic Characterization Methods for the Detection of Methicillin-Resistant Staphylococcus Aureus.

IntroductionMethicillin-resistant Staphylococcus aureus (MRSA) is associated with high morbidity and mortality due to the development of antimicrobial resistance secondary to irrational use of antibiotics, nonadherence to infection control practices, and increased use of intravascular devices in healthcare systems. Detection of MRSA is critical in clinical microbiology laboratories as it helps identify MRSA carriers and avoid treatment failure in patients. Hence, this study compared various phenotypic methods with the standard genotyping method to determine a method that permits rapid and accurate detection of MRSA.Materials & MethodsStaphylococcus aureus (S. aureus) was initially identified based on colony morphology, Gram staining, standard biochemical tests, and antibiotic susceptibility using disk diffusion. MRSA was identified based on the detection of the mecA gene by polymerase chain reaction (PCR) and subsequent gel electrophoresis. Disk diffusion using cefoxitin or oxacillin and mannitol salt agar with 6-µg/ml oxacillin were used for phenotypic detection of MRSA. The D test was used to detect inducible clindamycin resistance in S. aureus isolates.ResultsOf the 100 S. aureus isolates analyzed, 37% were identified as MRSA by PCR and the cefoxitin disk diffusion method; however, only 31% were detected by the oxacillin disk diffusion method and 29% by the mannitol salt agar method. The sensitivity of the cefoxitin disk diffusion test, oxacillin disk diffusion, and mannitol salt agar methods was 86.05%, 83.78%, and 70.73%, respectively. Specificity was 100% for all the three phenotypic methods (p < 0.001). Notably, inducible clindamycin resistance was found in 37.2% of the MRSA isolates, indicating potential challenges in treatment.ConclusionAmong the three phenotypic methods tested, the cefoxitin disk diffusion method had 100% sensitivity and specificity, which is similar to that of PCR-based MRSA detection. Hence, the cefoxitin disk diffusion method is recommended for use in clinical laboratories, where molecular methods are not available as it is both cost-effective and easy to perform.

Systematic Review of Plasmid AmpC Type Resistances in Escherichia coli and Klebsiella pneumoniae and Preliminary Proposal of a Simplified Screening Method for ampC.

Beta-lactamase (BL) production is a major public health problem. Although not the most frequent AmpC type, AmpC-BL is increasingly isolated, especially plasmid AmpC-BL (pAmpC-BL). The objective of this study was to review information published to date on pAmpC-BL in Escherichia coli and Klebsiella pneumoniae, and on the epidemiology and detection methods used by clinical microbiology laboratories, by performing a systematic review using the MEDLINE PubMed database. The predictive capacity of a screening method to detect AmpC-BL using disks with cloxacillin (CLX) was also evaluated by studying 102 Enterobacteriaceae clinical isolates grown in CHROMID ESBL medium with the addition of cefepime (FEP), cefoxitin (FOX), ertapenem (ETP), CLX, and oxacillin with CLX. The review, which included 149 publications, suggests that certain risk factors (prolonged hospitalization and previous use of cephalosporins) are associated with infections by pAmpC-BL-producing microorganisms. The worldwide prevalence has increased over the past 10 years, with a positivity rate ranging between 0.1 and 40%, although AmpC was only detected when sought in a targeted manner. CMY-2 type has been the most prevalent pAmpC-BL-producing microorganism. The most frequently used phenotypic method has been the double-disk synergy test (using CLX disks or phenyl-boronic acid and cefotaxime [CTX] and ceftazidime) and the disk method combined with these inhibitors. In regard to screening methods, a 1-µg oxacillin disk with CLX showed 88.9% sensitivity, 100% specificity, 100% positive predictive value (PPV), 98.9% negative predictive value (NPV), and 98.9% validity index (VI). This predictive capacity is reduced with the addition of extended-spectrum beta-lactamases, showing 62.5% sensitivity, 100% specificity, 100% PPV, 93.5% NPV, and 94.1% VI. In conclusion, there has been a worldwide increase in the number of isolates with pAmpC-BL, especially in Asia, with CMY-2 being the most frequently detected pAmpC-BL-producing type of microorganism. Reduction in its spread requires routine screening with a combination of phenotypic methods (with AmpC inhibitors) and genotypic methods (multiplex PCR). In conclusion, the proposed screening technique is an easy-to-apply and inexpensive test for the detection of AmpC-producing isolates in the routine screening of multidrug-resistant microorganisms.

Patterns of antimicrobial, multidrug and methicillin resistance among Staphylococcus spp. isolated from canine specimens submitted to a diagnostic laboratory in Tennessee, USA: a descriptive study

BackgroundMultidrug- and methicillin-resistant staphylococci are both veterinary and public health concerns due to their zoonotic potential. Therefore, the objective of this study was to investigate patterns of antimicrobial, multidrug, and methicillin resistance among four Staphylococcus spp. commonly isolated from canine clinical specimens submitted to the Clinical Bacteriology Laboratory at the University of Tennessee College of Veterinary Medicine (UTCVM).MethodsResults of antimicrobial susceptibility testing and mecA polymerase chain reaction (PCR) for isolates of four common Staphylococcus spp. isolates were obtained from the Bacteriology Laboratory at the UTCVM between 01/01/2006 and 12/31/2017. Cochran-Armitage trend test was used to assess temporal trends of antimicrobial resistance (AMR), multidrug resistance (MDR), and methicillin resistance. Kappa test of agreement was used to assess agreement between the results of PCR and disk diffusion tests.ResultsMost of the 7805 isolates were S. pseudintermedius (6453 isolates), followed by S. coagulans (860), S. aureus (330), and S. schleiferi (162). Among S. pseudintermedius isolates, 45.5% were MDR, and 30.8% were methicillin-resistant (MRSP). There was a significant temporal increase in MRSP (p = 0.017). Chloramphenicol resistance increased among both MRSP and methicillin-susceptible (MSSP) isolates (p < 0.0001). Among S. aureus isolates, 40.9% were MDR, 37.4% were methicillin-resistant (MRSA), and the proportion of MRSA isolates increased significantly (p = 0.0480) over time. There was an increasing temporal trend in the proportion of MDR isolates among MSSP (p = 0.0022), but a decrease among MRSP (p < 0.0001) and MRSA (p = 0.0298). S. schleiferi had the highest percentage (56.9%) of methicillin-resistant isolates. Oxacillin disk diffusion was superior to cefoxitin for the detection of mecA-mediated resistance and had almost perfect agreement with mecA PCR assay for S. pseudintermedius (95.4% agreement, kappa (κ) = 0.904; p < 0.0001), S. coagulans (95.6%, κ = 0.913; p < 0.0001) and S. schleiferi (97.7%, κ = 0.945; p < 0.0001). However, cefoxitin disk diffusion was superior to oxacillin disk diffusion and had almost perfect agreement with mecA PCR assay for S. aureus (95.3%, κ = 0.834; p < 0.0001).ConclusionsThe levels of resistance and increasing temporal trends are concerning. These findings have implications for treatment decisions and public health due to the zoonotic potential of staphylococci. Continued surveillance and use of antibiograms to guide clinical decisions will be critical.

Sources and Risk factors of a Novel MRSA Spa Type Circulating in Neonatal Intensive Care Unit

Background: Methicillin-Resistant Staphylococcus aureus is a major source of colonization and infection affecting premature neonates in Neonatal Intensive Care Unit. Objectives: to determine the prevalence, risk factors, and resistant profiles in neonates, their mothers, and healthcare personnel. In addition, to confirm the clonal similarity of neonatal Methicillin-Resistant S. aureus to their mothers or healthcare personnel. Materials and Methods: Samples were screened and identified for Methicillin-Resistant S. aureus colonization by gram stain, biochemical tests, oxacillin disk diffusion test, and resistance pattern. PCR was used to detect the presence of nuc and mecA gene. DNA fingerprinting was conducted using a standard spa typing technique. Results: Healthcare personnel colonization was high (27.9%) compared to neonatal and maternal colonization (15F%, 9.7%, respectively) and was found to be the only significant risk factor for neonatal MRSA colonization. Fifteen different spa types were identified and the novel t12492 was predominant among neonates and was reported for the first time. There was no demonstrated distribution correlation with sources of colonization. Colonization appeared to originate from multiple sources. Conclusion: Findings suggest conducting periodical molecular investigations of colonization of MRSA in healthcare personnel. Surveillance, molecular analysis of strains, reinforcement of an inclusive infection control program and antibiotic control could be useful in preventing MRSA transmission.

Comparison of Different Phenotypic Methods Including E-Test, Cefoxitin and Oxacillin Disk Diffusion for Detection of Methicillin Resistant Staphylococcus aureus

Introduction: Methicillin-Resistant Staphylococcus aureus (MRSA) has spread throughout the world as a hospital and communityacquired illness. Although a variety of strategies have been employed, laboratory identification of MRSA remains a difficulty. Aim: To examine several phenotypic approaches for accuracy results, with an (Epsilometer) E-test based method serving as the gold standard for MRSA identification. Materials and Methods: A prospective observational study was conducted in the Microbiology department of Santosh Medical College, Ghaziabad, Uttar Pradesh, India, from August 2020 to July 2021. Total of 384 isolates S.aureus were identified by using the required samples including pus, swab, blood, wound and urine, etc., which were collected from the Microbiology department and the comparison was done between E-test serving as the gold standard for MRSA identification with Cefoxitin Disk Diffusion (CDD)/ Oxacillin Disk Diffusion method (ODD). The diagnostic kit for using E-Test in collected samples was purchased from Himedia Laboratries Pvt., Ltd., Mumbai, India (EM0065). The data was calculated by using MS-Excel. Results: A total of 113 strains were revealed to be MRSA in clinical specimens out of 384 isolated S.aureus. The gold standard method was chosen to be the E-Test, which had found a high sensitivity of 79.8% and a specificity of 94.2%. Compared to the cefoxitin/oxacillin disc diffusion method, isolates including MRSA were highly susceptible to Tiecoplanin and Linezolid. Conclusion: The present study concludes that E-Test (strip) method is a high sensitivity and highly specific for detecting MRSA in comparison to other disk methods used in this study. Due to less number of sample size and lesser time period more studies are needed to establish this fact.

Nasal colonization of methicillin resistant staphylococcus aureus among slaughterhouse workers in Dar es salaam, Tanzania

Introduction: Methicillin resistant Staphylococcus aureus (MRSA) is a zoonotic pathogen that is associated with serious and sometimes fatal infections in humans. The pathogen has ability to acquire resistance to most antibiotics. Working in slaughterhouses increase the chance of workers to contract this pathogen. This study aimed to determine the prevalence of MRSA and its associated factors among slaughterhouse workers in Dar es Salaam, Tanzania. Methods: A cross-sectional study was conducted from June-July 2018 involving workers from 4 registered slaughterhouses. Social demographics and other information was collected using a semi-structured questionnaire. Swabs were collected and inoculated in Mannitol salt agar for S. aureus isolation. The isolates were tested for antimicrobial susceptibility using 10µg Oxacillin discs implanted on Muller Hinton Agar plates. Binary logistic regression was employed to determine the association between prevalence of MRSA and independent variables. Results: MRSA was isolated from 39,2% of the 258 enrolled slaughterhouse workers. MRSA colonization was more likely in persons who have been working for more than 21 years (p=0,014) and smokers (p=0,02). On-job training (adjOR=0,417; 95% CI: 0,202-0,858, p= 0,018) was protective against MRSA nasal colonization. Conclusion: Our study has demonstrated the occurrence of MRSA in slaughterhouse workers in Dar es salaam, Tanzania. It is more prevalent in persons who have been working for a long time in slaughterhouses. In addition, provision of on-job training is protective against MRSA nasal colonization. More studies are required to confirm whether the MRSA detected were livestock-associated.

Prevalence and Characterization of Methicillin-Resistant Staphylococcus aureus from Meat Retail Shops and Meat Handlers in the Buea Municipality, Cameroon

Aim: Methicillin-resistant Staphylococcus aureus (MRSA) is a notorious multidrug-resistant biovar of S. aureus associated with infections that result in high morbidity and mortality in humans and animals. Its persistence in both host and non-host environments adds a major ecological dimension to the problem, thereby making it a one health challenge. This study determined the prevalence and antibiotic resistance patterns of MRSA from meat retail shops and meat handlers in the Buea municipality in addition to basic hygiene practices implemented in the meat retail shops.&#x0D; Study Design: In this cross-sectional study, a total of 260 samples (comprising 52 swabs each from weighing balances, butchering slabs, cutting knives, hands of meat handlers and meat samples) were randomly obtained and subjected to microbiological analysis. Data on sociodemographic characteristics of meat handlers and basic hygiene practices were captured in a questionnaire.&#x0D; Methodology: After enrichment, each sample was inoculated on mannitol salt agar and DNA extracted from presumptive S. aureus isolates for detection of the nuc gene. MRSA was identified by oxacillin disk diffusion and confirmed by amplification of the mecA gene. All MRSA isolates were challenged with 10 commonly used antibiotics using the Kirby-Bauer disk diffusion method.&#x0D; Results: A total of 27 MRSA isolates were recovered from hand swabs (5.8%), meat (15.4%), knives swabs (21.2%) and butchering slabs (9.6%). All (100%) MRSA were resistant to ampicillin and cefepime followed by ofloxacin (92.6%), ciprofloxacin (81.5%) and vancomycin (37%). High susceptibility was observed for gentamicin (100%) and amikacin (100%). All isolates were multidrug-resistant and comprised 11 antibiotypes. Most meat handlers (71.2%) did not have basic meat safety training, while 90.4% of the meat retail shops did not have a nearby water source.&#x0D; Conclusion: Our results indicate that meat retail shops could be a potential reservoir of MRSA in the environment and meat handlers need more basic meat safety training.

Evaluation of cefoxitin disc diffusion test as a rapid phenotypic method for detection of methicillin resistance

: Accuracy and promptness in the detection of methicillin resistance are of key importance in ensuring correct antibiotic treatment in infected patients and control of MR staphylococci in the hospital environment. The aim of this study was to detect MRSA phenotypically by oxacillin screen agar and Oxacillin MIC method and to evaluate cefoxitin disc diffusion test as a screening tool for MRSA detection. In the present study, a total of 50 isolates of from various clinical samples collected were used for the detection of Methicillin resistant (MRSA). Methicillin resistance was determined by oxacillin disc diffusion, cefoxitin disc diffusion the oxacillin screen agar test and MIC. Out of 50 isolates 21 (42%) isolates were detected as MRSA based on MIC method, which is considered as gold standard method for the detection of MRSA. All the isolates of MRSA were 100% susceptible to vancomycin and linezolid. rnIn the present study, cefoxitin diffusion method has given 100% sensitivity and specificity in concordance with MIC method. However, the oxacillin screen agar method showed 95.24% sensitivity and 96.55% specificity. As per our study and previous reports elsewhere on phenotypic detection of MRSA, cefoxitin is more potent inducer of the regulatory system and an accurate surrogate marker for the detection of MRSA in the routine susceptibility testing.

Methicillin-resistant Staphylococcus aureus in urinary tract infections; prevalence and antimicrobial resistance

Introduction: The newly-launched strain of the Staphylococcus aureus, methicillin-resistant S. aureus, is considered the most emerging bacterium in-hospital infections globally. Objectives: The current research focused on the prevalence and virulence features of methicillin-resistant S. aureus (MRSA) bacteria recovered from urinary tract infections (UTIs) cases. Patients and Methods: A total of 710 urine specimens were taken from hospitalized patients who suffered from UTIs. S. aureus was recovered from urine specimens using the microbial culture. S. aureus antimicrobial susceptibility was assessed toward oxacillin and cefoxitin antimicrobial disk to determine the MRSA strains. The polymerase chain reaction (PCR) assessed the distribution of antimicrobial resistance encoding genes. S. aureus antimicrobial resistance was evaluated by disk diffusion. Results: Fifty-five out of 710 (7.7%) urine specimens were positive for the MRSA bacteria. The uppermost antibiotic resistance was obtained against penicillin (100%), ceftaroline (100%), gentamicin (87.2%), erythromycin (76.3%), and ciprofloxacin (69.0%). BlaZ (100%) and tetK (85.4%) had the higher frequency amid examined antimicrobial resistance-encoding genes. Conclusion: The high prevalence of MRSA isolates harboring antimicrobial resistance-encoding genes in the UTIs suggests that diseases caused by them need more expansion healthcare monitoring with essential demand for novel antimicrobials.

ANTIMICROBIAL SUSCEPTIBILITY PATTERN OF STAPHYLOCOCCUS AUREUS STRAINS IN ISLAMABAD, PAKISTAN

Objective: To investigate the prevalence of S. aureus in hospitalized patients of Islamabad.&#x0D; Study Design: Cross-sectional study.&#x0D; Study Duration: Pakistan Institute of Medical Science, Applied Microbiology and Biotechnology Lab, COMSATS Institute of Information Technology, Islamabad, from Sep 2017 to Sep 2018.&#x0D; Methodology: A total of 500 samples were collected. The isolates were divided into four study groups according to their source of origin i.e. group 1 (dermal group), group 2 (nasal group), group 3 (blood group) and group 4 (urine group). Gram staining, catalase test and DNA se media analysis were done for validation of S. aureus. Disc diffusion test (for antibiotic susceptibility), Oxacillin disc test (to differentiate between methicillin-resistant Staphylococcus aureus and methicillin-susceptible staphylococcus aureus) and minimal inhibitory concentration (for susceptibility to vancomycin), were performed.&#x0D; Results: Degree of the prevalence of staphylococcus aureus was 21%, 17%, 9% and 8% in group 1, 2, 3 &amp; 4 respectively. The overall prevalence of staphylococcus aureus was 19.5% in all isolates. The disc diffusion test showed the descending resistance pattern of isolates i.e. 100, 94, 94, 76, 58, 55, 47, 43, 40 and 37% for penicillin, ciprofloxacin, Kanamycin, erythromycin, tetracycline, oxazolidinone, sulfamethoxazole, doxycycline, clindamycin, and cipoxin respectively. Minimal inhibitory concentration found only one sample resistant at 2ug/l concentration of Vancomycin. Moreover, Oxacillin disc test showed 52% methicillin-susceptibleStaphylococcus aureus while 48.2% methicillin-resistant staphylococcus aureus among all isolates.&#x0D; Conclusion: There is an increase in the frequency of methicillin-resistant staphylococcus aureus. Single vancomycin resistant staphylococcus aureus strain was also isolated.

Prevalence of Mastitis and Phenotypic Characterization of Methicillin-Resistant Staphylococcus aureus in Lactating Dairy Cows of Selected Dairy Farms in and Around Adama Town, Central Ethiopia.

Background:The emergence of Methicillin resistant Staphylococcus aureus (MRSA) poses a serious public health threat. Strains of Staphylococcus aureus resistant to β-lactam antibiotics are known as MRSA. MRSA has gained attention as community pathogen. MRSA has been increasingly reported as emerging problem in veterinary medicine. However, little is known in Ethiopia. This study was, therefore, conducted to identify MRSA, to determine its drug susceptibility patterns, and mastitis infection in dairy cattle in and around Adama town, Central Ethiopia.Methods:A cross-sectional study was conducted to estimate the occurrence of MRSA in mastitic dairy cows in and around Adama town, central Ethiopia. A total of 384 lactating cows were included from the conveniently selected dairy farms in the study area. Approximately 10 ml of milk was aseptically collected from clinical and subclinical mastitic cows into sterile universal bottles after discarding the first 3 milking streams. Then, Staphylococcus aureus was isolated using the conventional bacteriological procedure. Resistance to methicillin was detected using the Kirby-Bauer disc diffusion antibiotic susceptibility method. Oxacillin disc was used to detect methicillin resistant Staphylococcus aureus strains. Antimicrobial susceptibility test was conducted against MRSA strains using streptomycin (S, 10 µg), amoxicillin (Am, 25 µg), kanamycin (k, 30 µg), nalidixic acid (NA, 30 µg), oxytetracycline (OT, 30 µg) sulphonamide (S, 300 µg) and ceftriazole (CRO, 30 µg).Results:The study found that the prevalence of mastitis was 121(31.5%). Among this 37(30.6%) were clinical mastitis and 84 (69.4%) of them were sub-clinical mastitis. Of 121 mastitis cases, Staphylococcus aureus was isolated in 37 (30.6%) of mastitic cow milk samples. The prevalence of mastitis was significantly affected by breed, age, floor type and hygienic status of the milkers (P < .05). Moreover, 32.4% of Staphylococcus aureus isolates were resistant to oxacillin. A total of 75% percent of MRSA isolates were resistant to amoxicillin, 66.7% were resistant to oxytetracycline, and 50% were resistant to sulphonamide. However, 75% of MRSA isolates were susceptible to kanamycin, 58.3% were susceptible to streptomycin, and 50% were susceptible to nalidixic acid.Conclusion:The study revealed that relatively high number of strains are resistant to the antibiotics commonly used in the therapeutic protocol of many human and animal infections. Therefore, antimicrobial susceptibility test should be carried out at a regular basis and proper hygienic practices should be introduced at farm level. Creating public awareness about transmission, prevention and control of MRSA should also be considered.

Prevalence pattern of MRSA from a rural medical college of North India: A cause of concern.

Introduction:Methicillin-resistant Staphylococcus aureus (MRSA) has become a global challenge. The shift of this organism form hospital settings to community setting and increasing resistance to non-β-lactams antibiotics have further aggravated the crisis. This trend in MRSA has necessitated the knowledge and sensitization about this agent among physicians in rural and peripheral settings.Material and Methods:Present study was undertaken at Department of Microbiology at rural medical college of North India from January 2017 to December 2019 (3 years). All the clinical samples collected with aseptic precautions were processed as per standard protocol. All the Staphylococcus aureus isolates cultured were subjected to antimicrobial susceptibility testing as per CLSI guidelines 2019. Screening for MRSA was done by CLSI recommended methods, such as cefoxitin disc (30 μg), oxacillin disc (1 μg), and oxacillin screen agar as per CLSI recommendation.Results:A steady increase in number of MRSA isolates was observed from year 2017 to 2019 with overall prevalence being 33.7%. Most MRSA isolates were obtained from pus samples. Cefoxitin disc diffusion method is a dependable detection method compared to oxacillin disc diffusion and oxacillin screen agar for identification of MRSA.Conclusion:The rising trend of MRSA impresses upon the acute need of stringent infection control practices namely strict compliance to hand hygiene, prevention of misuse and overuse of antibiotics and a continuous surveillance program for MRSA. Also sensitization about this agent among the primary health physician is the need of hour to implement the control measures and limit its spread in communities.

Methicillin-resistant Staphylococcus schleiferi subspecies coagulans associated with otitis externa and pyoderma in dogs.

Background:Dermatological infections are the most common cases in the daily pet clinic. Since its discovery in 1990, Staphylococcus schleiferi subspecies coagulans have been reported more frequently in canine otitis externa and pyoderma and even in cases of zoonoses.Aim:Detect the presence of S. schleiferi subsp. coagulans of canine otitis externa and pyoderma, its antimicrobial resistance, and the presence of mecAgen.Methods:Three-hundred-thirty-one swabs from dogs with otitis externa and pyoderma were cultured on bacteriological agar for bacterial isolation and subsequent biochemical and molecular identification. The identified S. schleiferi subsp. coagulans were evaluated for their antimicrobial susceptibility using the Kirby–Bauer technique, including an oxacillin disk, and subsequently, a PCR was run to identify which ones had the mecA gene.Results:Thirty-four (22.97%) and twelve (6.56%) isolates were identified as S. schleiferi subspecies coagulans from otitis externa and pyoderma, respectively. Fluoroquinolones, the most widely used group of antibiotics in Peru, showed a susceptibility of 58.82% (20/34) in cases of otitis externa and 50% (6/12) in cases of canine pyoderma. Meanwhile, nitrofurantoin was the antibiotic with the best efficacy in both cases, with 97% (33/34) in otitis externa and 83% (10/12) in pyoderma. Furthermore, 40% (13/34) of S. schleiferi subsp. coagulans isolated from otitis externa were resistant to methicillin, and 85.29% (29/34) had the mecA gene. On the other hand, the only methicillin-resistant isolate from pyoderma was also the only one with a mecA gene.Conclusion:This study is the first report of S. schleiferi subsp. coagulans in Peru, finding a higher percentage than reported in other South American countries.

Isolation, characterisation and antibiotic susceptibility of staphylococcal isolates with special reference to methicillin-resistant Staphylococcus aureus from the anterior nares of healthcare workers in A tertiary healthcare centre

Background: Staphylococcus aureus (S. aureus) and its resistant form methicillinresistant S. aureus (MRSA) is one of the most common nosocomial pathogens causing a wide range of infections in humans. The anterior nares are the main ecological niche for S. aureus. Nasal carriage of S. aureus acts as an important reservoir of infection among the colonised healthcare workers and they transmit the infection to the community. The aim of the present study was to estimate the nasal colonisation of S. aureus (with special reference to MRSA) in healthcare workers (doctors and nursing staff) and its antibiotic susceptibility pattern. Methods: A descriptive study was planned in the Department of Microbiology, JLN Medical College, Ajmer (Rajasthan, India) after due approval from the institutional ethics committee. A total of 170 healthcare workers of either sex aged between 18 to 60 years were screened for S. aureus. Identification was done using standard microbiological techniques, by studying their morphology, colony and biochemical characteristics. MRSA was detected by cefoxitin disc diffusion test, oxacillin disc diffusion test, minimum inhibitory concentration (MIC) of oxacillin by E-test and oxacillin screen agar test. The observations were described in proportions and Chisquared test was used to find independence. Statistical significance was considered at 5 %. Results: Among 170 samples, 159 (93.53 %) samples (50 doctors and 109 nursing staff) had staphylococci colonisation. Among these 159 isolates, 34 (21.38 %) were S. aureus. Further, 8 (5.03 %) S. aureus isolates were resistant to both cefoxitin and oxacillin and had oxacillin MIC values ≥ 4 µg/mL and were considered MRSA. All the MRSA were detected in the nursing staff (males: 5.50 %, females: 1.83 %). All S. aureus and MRSA isolates were found sensitive to linezolid, vancomycin and mupirocin (minimum inhibitory concentration ≤ 4 µg/mL). Conclusion: Screening and treatment of healthcare workers colonised with MRSA should be an important component of hospital infection control policy. These measures will prevent spread of infection to patients and the community and thereby reduce the morbidity, mortality and healthcare costs associated with nosocomial infections.

Evaluation of Surrogate Tests for the Presence of mecA-Mediated Methicillin Resistance in Staphylococcus capitis, Staphylococcus haemolyticus, Staphylococcus hominis, and Staphylococcus warneri.

Testing of staphylococci other than Staphylococcus aureus (SOSA) for mecA-mediated resistance is challenging. Isolates of Staphylococcus capitis, Staphylococcus haemolyticus, Staphylococcus hominis, and Staphylococcus warneri were evaluated by cefoxitin and oxacillin broth microdilution (BMD), disk diffusion (DD), and PBP2a immunoassay, and the results were compared to mecA PCR results. No phenotypic susceptibility test correlated well with PCR results across all species, although the PBP2a immunoassay yielded 100% correlation. Oxacillin BMD testing by current Clinical and Laboratory Standards Institute (CLSI) SOSA breakpoints led to 2.1% very major errors (VMEs) and 7.1% major errors (ME). Adjusting this breakpoint up by a dilution (susceptible, ≤0.5 μg/ml; resistant, ≥1.0 μg/ml) led to 2.8% VMEs and 0.3% MEs. Among species evaluated, S. haemolyticus had unacceptable VMEs with this new breakpoint (6.4%), as did S. hominis (4.0%). MEs were acceptable by this new breakpoint, ranging from 0 to 1.2%. Oxacillin DD yielded high ME rates (20.7 to 21.7%) using CLSI or European Committee on Antimicrobial Susceptibility Testing breakpoints. VMEs ranged from 0 to 5.3%. Cefoxitin BMD led to 4.9% VMEs and 1.6% MEs. Cefoxitin DD performed best when interpreted with the CLSI SOSA breakpoint, with 1.0% VMEs and 2.9% MEs. This study led CLSI to adjust the oxacillin MIC breakpoints for SOSA. Laboratories should be aware that no individual phenotypic test correlates well across all species of SOSA with mecA PCR results. Molecular testing for mecA or evaluation for PBP2a is the preferred approach.

Nasal carriage of methicillin-resistant Staphylococcus aureus among healthcare undergraduates in Malaysia

Staphylococcus aureus is a common component of skin flora of healthy adults. However, it can cause serious infections such as bloodstream infections, pneumonia, or bone and joint infections. Methicillin-resistant Staphylococcus aureus (MRSA) is known to cause hospital- (HA-MRSA) and community-acquired (CA-MRSA) infections worldwide. Asia is reported to have highest prevalence rates of HA-MRSA and CA-MRSA. As there were very less number of epidemiological studies being done in Malaysia, this study aimed to determine the prevalence of MRSA infection among the healthcare undergraduates who will be engaging with patients soon. We analyzed nasal swabs of students from a private medical institution in Klang Valley, Malaysia. Methicillin-resistance was accessed by sensitivity to the Oxacillin and Cefoxitin disks. In a total of 151 healthcare undergraduates, 117 of them were found positive for Staphylococcus aureus. Among the latter, 21 samples (13.9%) were resistant to Oxacillin and Cefoxitin. Our data shows significant high percentage of MRSA infection and therefore prevention strategies for MRSA need to be developed for the healthcare students before they engage with patients in clinic setting. Keywords: MRSA, nasal swab, healthcare undergraduates, Oxacillin.

Antimicrobial Susceptibility Testing and Phenotypic Detection of MRSA Isolated from Diabetic Foot Infection.

BackgroundDiabetic foot infection (DFI) is a common and costly complication of diabetes that may be caused by various bacteria with multi-resistant genes. The aim of this study is to evaluate the efficacy of phenotypic methods for identification of methicillin-resistant Staphylococcus aureus (MRSA) with genotypic detection of MRSA-related genes.MethodsIn this cross-sectional study, swab samples were collected from patients with DFI from hospitals in Sulaimani/Iraq in April–July 2019. All the samples were processed for microbiological assessment and further MRSA phenotypic and genotypic testing.ResultsA total of 46 swab samples were collected from diabetic foot ulcers of 29 males and 17 females. Most samples (93.5%) showed positive growth, with higher proportions of monomicrobial (23; 53.5%) than mixed-bacterial infections (20; 46.5%) and S. aureus as the predominant pathogen. Conventional methods of MRSA detection, such as cefoxitin disc diffusion, can predict methicillin resistance in 45.8% of the cases. Real-time/conventional PCR showed that 41.6% of Staphylococcus aureus were positive for the mecA gene, while none of the isolates was positive for PVL.ConclusionStaphylococcus aureus was the predominant pathogen in DFI. Although cefoxitin and oxacillin disc diffusion methods can help in the prediction of MRSA, real-time PCR is a reliable method for MRSA detection and confirmation.

English

Methicillin-resistant Staphylococcus aureus (MRSA) is a major hospital acquired pathogen. In Cameroon, there is limited data on nasal carriage of MRSA and its antibiotic susceptibility testing and risk factors for multi resistance to antibiotics in hospitalized patients and medical staff . A prospective, qualitative, cross-sectional hospital-based study was carried out. Anterior nasal swabs were taken from 579 participants and bacterial strains were identified by conventional method and antibiotic susceptibility testing. Methicillin resistance was confirmed with cefoxitin and oxacillin disks. Of the 579 samples analysed, 53.0% were positive for S. aureus, 45.4% were MRSA. MRSA constituted 85.7% of all the S. aureus identified. The prevalence of MRSA in nasal carriage was significantly higher in females (49.6%) than in males (34.0%). The overall prevalence of MRSA in nasal carriage in both medical staff and hospitalized patients was 45.4%. The prevalence of MRSA in nasal carriage was significantly higher in RHL (49.0%) and RHB (48.5%) compared to the UTHY (36.3%). The prevalence of MRSA in nasal carriage was significantly higher in the surgical ward (59.7%) and paediatric ward (45.2%) compared to the other units. Among the MRSA isolates, the maximum sensitivity was observed with vancomycin (97.0%) and minocycline (95.1%), while the least sensitivity was observed with penicillin (0.0%) and ampicillin (0.8%). Binary logistic regression model showed that being aged 35 years an above and being hospitalized for more than 15 days were strongly associated with MDR to MRSA. Nasal carriage of MRSA is increasing rapidly and call for urgent preventive measures. Key words: Healthcare personnel, adult patients, nasal carriage, antibiotic susceptibility, risk factors, health care personnel, adult, patients, multi drug resistance (MDR), methicillin-resistant Staphylococcus aureus (MRSA).

MecA gene and methicillin-resistant Staphylococcus aureus (MRSA) isolated from dairy farms in East Java, Indonesia

Abstract. Ramandinianto SC, Khairullah AR, Effendi MH. 2020. MecA gene and methicillin-resistant Staphylococcus aureus (MRSA) isolated from dairy farms in East Java, Indonesia. Biodiversitas 21: 3562-3568. Milk Borne Disease (MBD) can be caused by a variety of pathogenic bacteria, one of which is Staphylococcus aureus which has a large impact on aspects of public health. The therapy used to treat staphylococcal infection is Oxacillin preparations that can inhibit bacterial wall synthesis, but the adaptation of the mecA gene to staphylococcal cassette chromosome mec (SCCmec) causes the emergence of strains of methicillin-resistant S. aureus (MRSA). The purpose of this study was to detect the level of MRSA strain contamination in dairy cows in East Java by comparing the mecA gene, Oxacillin, and Cefoxitin Disc Diffusion Methods and Oxacillin Resistance Screen Agar (ORSA) detection methods. A total of 150 cow's milk samples were taken at 3 village dairy farms in East Java, samples were added to the enrichment media Buffer Pepton Water (BPW) and then isolates were planted and purified using Mannitol Salt Agar (MSA). The detection of MRSA was carried out by the Kirby Bauer disc diffusion preparation Cefoxitin 30 μg and Oxacillin 30 μg then confirmed by ORSA and the presence of mecA gene by the polymerase chain reaction (PCR) method. The results showed that from a total of 92 S. aureus isolates using Oxacillin disc test, 24 resistant isolates were obtained, using Cefoxitin disc test, 17 isolates were obtained, and using the ORSA test 18 MRSA isolates were obtained. MRSA isolates tested by PCR obtained evidence of 2 isolates of mecA gene. It can be concluded that the Oxacillin disc test was the highest sensitivity for detecting MRSA strain isolate, however, mecA gene was the golden standard to detect MRSA on the dairy farms.

Detection of Enterotoxin type B gene on Methicillin Resistant Staphylococcus aureus (MRSA) isolated from raw milk in East java, Indonesia

Background and Aim: Methicillin resistant Staphylococcus aureus (MRSA) has an exponential rate of spread throughout the world and its occurrence rates have been detected in animal / food samples of animal origin. The methicillin resistance (MR) strain is a significant factor in the potential virulence of Staphylococcus aureus such as the presence of Stapylococcal enterotoxin B (SEB) which induces a super antigenic effect. This study aims to detect the presence of SEB gene in MRSA isolates that isolated from cow milk in East Java province. Materials and Methods: Raw cow's milk ingredients were inoculated in enrichment media and mannitol salt agar (MSA) which were then tested using oxacillin and cefoxitin disc diffusion combined with oxacillin screen agar (ORSA) test to detect MRSA strains. All MRSA strains were detected by the SEB gene by the polymerase chain reaction (PCR) method. Results: In this study confirmed 18 MRSA from 150 samples of cow's milk and detected 4 MRSA isolates having SEB gene with product size 478 bp. In Conclusion: Detection of MRSA carrying the SEB gene in milk can have an impact on the public sector / animal health (milk borne disease) and the economy on livestock. It is very necessary to further analyze the relationship between various virulence factors in MRSA isolates that have the potential to be transmitted through cow's milk in East Java Keywords: Methicillin resistant Staphylococcus aureus(MRSA), Stapylococcal enterotoxin B (SEB), food safety, milk borne disease