Cefoxitin Disc Diffusion Method Research Articles

Expression of norA, norB and norC efflux pump genes mediating fluoroquinolones resistance in MRSA isolates.

Although fluoroquinolones are used to treat methicillin-resistant Staphylococcus aureus (MRSA)-induced infections, acquisition of antibiotic resistance by bacteria has impaired their clinical relevance. We aimed to evaluate the frequency of norA, norB, and norC efflux pump genes-mediating fluoroquinolones resistance and measure their expression levels in MRSA isolates. 126 S. aureus isolates were collected from different clinical samples of adult hospitalized patients and identified by conventional microbiological methods. MRSA was diagnosed by cefoxitin disc diffusion method and minimum inhibitory concentration (MIC) of ciprofloxacin by broth microdilution method. The expression levels of efflux pump genes were measured by quantitative real-time polymerase chain reaction (qRT-PCR). 80 (63.5%) MRSA isolates were identified and showed high level of resistance to erythromycin (80%), gentamicin (75%), clindamycin (65%) and ciprofloxacin (60 %). norA, norB and norC were detected in 75%, 35% and 55% of the MRSA isolates respectively. norC was the most commonly overexpressed gene measured by qRT-PCR, occurring in 40% of MRSA isolates, followed by norA (35%) and norB (30%). The expression of these genes was significantly higher in ciprofloxacin-resistant than quantitative real-time PCR ciprofloxacin-sensitive MRSA isolates. This study showed high prevalence and overexpression of efflux pump genes among MRSA isolates which indicates the significant role of these genes in the development of multidrug resistance against antibiotics including fluoroquinolones.

Tetracycline susceptibility in multidrug resistant Staphylococcus aureus isolated from clinical samples in tertiary care hospitals of Kathmandu, Nepal.

Staphylococcus aureus, being an opportunistic pathogen, is frequently associated with various infections in human. The clinical sector feels challenge regarding the management of multidrug resistant S. aureus. Besides the B-lactam antibiotics, Glycopeptides, Tetracycline, Quinolones, Macrolide-lincosamide streptogramin B family of antibiotics are also commonly prescribed to deal with such infections as an alternative drug. Therefore, this study was conducted to assess tetracycline susceptibility in multidrug resistant S. aureus in clinical samples. This study was conducted over the period of 15 months from March 2020–May 2021. The clinical samples were collected from the three different tertiary care hospitals of Kathmandu, Dirghayu Guru Hospital, Chabahil, Bhaktapur Cancer Hospital, Bhaktapur, and Shankarapur Hospital, Jorpati. The sample processing and laboratory work was carried out in the Microbiology Laboratory of Dirghyau Guru Hospital to determine the proportion of different phenotypes of MDR among S. aureus and their association with methicillin resistance. Two hundred sixty six isolates of S. aureus were included in the study. Methicillin resistance was detected by cefoxitin disc diffusion method. Among 2004 clinical samples processed, 266 (13.27%) isolates were S. aureus. The multidrug resistant strain isolated from OPD was 56.84% (54/95) and from inpatient was 43.15% (41/95). Among the 266 S. aureus, 28.94% MRSA and 71.05% MSSA isolates were detected. Tetracycline resistance was found in 9.8% of total S. aureus isolates whereas 27.36% (26/95) among MDR S. aureus isolates. Resistance to Tetracycline was higher in MRSA as compared to MSSA. Detection rate of MRSA in this study shows the necessity to improve health care practices to control MRSA infections. Tetracycline can be used as an alternative antibiotic against the S. aureus infection.

Isolation and antimicrobial resistance patterns of Methicillin‐resistantStaphylococcus aureus from raw cow's milk in dairy farms of Wolaita Sodo Town, Southwest, Ethiopia

AbstractStaphylococcus aureus is a pathogenic bacterium‐contaminating milk and milk products causing food poisoning primarily due to its enterotoxins. A cross‐sectional study was conducted from November 2021 to June 2022 in Wolaita Sodo Town, to detect Methicillin‐resistant Staphylococcus aureus (MRSA) in raw cow's milk and assess their resistance levels to different antimicrobials. Purposive sampling was used to select 34 dairy farms. Accordingly, 419 raw milk samples from the farm and collection centers were collected. Isolates of S. aureus showing resistance to Cefoxitin were classified as MRSA. From the total 419 samples, 22.19% (93/419) were contaminated with S. aureus in dairy cows. The prevalence of S. aureus in raw milk, bulk milk from the farm, and bulk tank milk from the collection centers was 16.9%, 2.1%, and 3.1%, respectively. The risk of S. aureus contamination in dairy farm owners and milkers who do not take food safety training was 5.303 times higher than the risk of S. aureus contamination in dairy farm owners and milkers who take food safety training. The risk of S. aureus contamination in dairy farms kept under poor management system was 7.34 times more than that of dairy farms kept under good management. The cefoxitin disk diffusion method was used to detect MRSA, 57.14% being resistant to Cefoxitin in total while approximately 87.5% were sensitive to Sulfamethoxazole‐trimethoprim and Gentamycin, while Erythromycin registered 75%, Ciprofloxacin 62.5%, Chloramphenicol 62.5%, and Tetracycline 25%. This study revealed that MRSA exhibited a notable multidrug resistance pattern, encompassing resistance to multiple drugs, with a prevalence of 75%. Significantly, the hands of milkers and the milking containers emerged as pivotal sources of contamination. This underscores the crucial importance of maintaining stringent hygienic practices during the milking process, with particular emphasis on thorough cleaning and decontamination of utensils.

The Prevalence, Epidemiological, and Molecular Characterization of Methicillin-Resistant Staphylococcus aureus (MRSA) in Macau (2017-2022).

Macau, recognized as a global tourism hub and the world's most densely populated region, provides a unique environment conducive to methicillin-resistant Staphylococcus aureus (MRSA) transmission in healthcare and community settings, posing a significant public health concern both locally and globally. The epidemiology and molecular characteristics of MRSA in the distinct city of Macau remain largely unelucidated. This five-year longitudinal study (2017-2022) examined the local prevalence and molecular typing of MRSA in Macau, with future MRSA type distribution predicted through ARIMA modeling. We subsequently analyzed the epidemiological characteristics of MRSA, including specimen source, clinical department, collection year, season, patient age, sex, and the annual number of tourists. Comprehensive antibiotic resistance profiles of the strains were also assessed. Of 504 clinically isolated S. aureus strains, 183 (36.3%) were identified as MRSA by the cefoxitin disk diffusion method and validated through multi-locus sequence typing (MLST). The MRSA detection rate showed an upward trend, increasing from 30.1% in 2017 to 45.7% in 2022. SCCmec type IV was predominant (28.9%), followed by types II (25.4%), III (22.1%), and V (22.1%). The primary sources of MRSA isolates were sputum (39.2%) and secretions (25.6%). Older age emerged as a risk factor for MRSA infection, whereas no significant associations were found with seasonal variations, gender, or the annual number of tourists. Despite displaying universal resistance to cefoxitin, oxacillin, and benzylpenicillin, MRSA isolates in Macau remained fully sensitive to vancomycin, tigecycline, quinupristin, nitrofurantoin, and linezolid. Continuous surveillance and analysis of MRSA distribution in Macau could provide invaluable insights for the effective management of MRSA prevention and control measures within healthcare settings.

Bacteriological Profile and Antibiogram of Aerobic Blood Culture Isolates among Suspected Blood Stream Infections: A Cross-sectional Study

Introduction: Bloodstream Infections (BSIs) are important causes of morbidity and mortality worldwide. Blood culture is the most important diagnostic tool for BSI. The epidemiology and outcome of BSI are constantly changing due to increasing antimicrobial resistance, changing patterns of antibiotic drug usage, and the increased use of transient or permanent medical devices. Thus, regular monitoring of the bacterial aetiology of BSI and their antibiograms is necessary. Aim: To determine the bacteriological profile and antibiotic susceptibility patterns among suspected BSI patients. Materials and Methods: A hospital-based cross-sectional study was carried out in the Department of Microbiology, Jawaharlal Nehru Institute of Medical Sciences (JNIMS), Imphal, Manipur, India, from September 2018 to August 2020. A total of 481 suspected BSI patients were included in the study. The blood culture samples were collected under aseptic conditions and cultured for seven days. The isolates were identified using conventional biochemical tests, and the antibiotic susceptibility pattern was determined by the Kirby-Bauer disk diffusion method and the epsilometer test (E-test). Methicillin resistance among the staphylococcal isolates was detected using the cefoxitin disk diffusion method. Data analysis was performed using EpiInfoTM version 7.0, and the Chi-square test was used as a statistical test. Results: A total of 150 (31.2%) blood samples were culture positive out of the 481 samples processed from suspected BSI patients. The predominant isolates were gram-positive, accounting for 113/150 (75.3%), while gram-negatives accounted for 37/150 (24.7%). Staphylococcus aureus, Pseudomonas aeruginosa, and Coagulase Negative Staphylococci (CoNS) were the primary pathogens isolated. Methicillin resistance was detected in 59 (54.6%) of the staphylococcal isolates {52 (54.7%) were Methicillin Resistant S. aureus (MRSA), and out of the 13 CoNS isolates, 7 (53.9%) were Methicillin Resistant CoNS (MRCoNS)}. The most susceptible drugs for gram-positives were vancomycin and linezolid, while aminoglycosides and imipenem were the most susceptible drugs for gram-negatives. Conclusion: The study highlighted the prevalence and pattern of aerobic bacterial isolates in BSI cases at JNIMS Hospital, as well as, the antibiotic susceptibility patterns of the isolates. Regular epidemiological studies of BSIs, regarding the pathogens and their antibiotic susceptibility patterns, are necessary to guide clinicians in choosing appropriate empirical therapy and to update the hospital antibiotic policy from time to time. This promotes rational antibiotic use and reduces resistance among bacteria.

Study of Methicillin-resistant Staphylococcus aureus Isolated from Various Clinical Specimens from Tertiary Care Hospital

ABSTRACT Introduction: Staphylococci are Gram-positive bacteria, with a diameter of 0.5–1.5 μm and individual cocci, which are divided in more than one plane from the grape-like cluster. In the genus staphylococci, 32 species and 8 subspecies are present in many of which are present as a commensal in the human body. Staphylococci are frequently found as a normal flora of skin mucosal, surface of respiratory, upper elementary, and urogenital tract of the human body. In immunocompromised condition, the infection can be spread by skin-to-skin contact and also by excretion such as saliva aerosol releasing during sneezing and coughing. Infection of staphylococci may also spread from the animal product such as nonpasteurized milk and milk products. Over the last few decades, Staphylococcus aureus has emerge as the most dangerous organism, which is known as methicillin-resistant S. aureus (MRSA). Some strains show vancomycin resistance by S. aureus in hospitalized patients. The present study was conducted to study the prevalence and antibiogram of MRSA isolates in a clinical sample from Acharya Vinoba Bhave Rural Hospital. Materials and Methods: This study was conducted in the Department of Microbiology at Jawaharlal Nehru Medical College (Datta Meghe Institute of Higher Education and Research), Wardha, from August 2020 to December 2021. The samples received in the microbiology laboratory were inoculated on blood agar and MacConkey’s agar, and incubated for 24 h at 37°C for staphylococcal isolation. A total of 145 Staphylococcal aureus were isolated and confirmed by Gram stain and various biochemical tests such as catalase test, oxidase test, coagulase test, and mannitol salt agar. Antibiotic susceptibility test was examined on the Mueller–Hinton agar plate using the modified Kirby–Bauer disc diffusion method. Screening of methicillin resistant was performed by cefoxitin (30 μg) disc diffusion method and interpreted according to CLSI guideline. Results: The prevalence of MRSA was 76 (52.41%) to methicillin-susceptible S. aureus. The highest MRSA was found in the age group >50 years (26.31%). Out of 76 MRSA isolates from different departments, the medicine and orthopedic departments show maximum MRSA as 19.74% each followed by pediatrics (17.11%) and surgery (13.16). Out of 76 MRSA isolates, vancomycin showed 93.42% sensitivity followed by linezolid (85.52%), Gentamicin (71.05%), tetracycline (56.57%), clindamycin (46.05%), and erythromycin (31.57%). Conclusion: With the advancement of new therapeutic agent, MRSA is also being easily resistant. Due to increasing cases of MRSA, there is an increase in the rate of morbidity and mortality. Moreover, except vancomycin, other drugs are resistant, as their MIC is not in the susceptible range. Thus, the results of this study indicate that vancomycin is a suitable medication to take when MRSA cases rise. In such cases, MRSA can be controlled by regular monitoring and checking the irrational use of antibiotics.

Assessing Tetracycline susceptibility in multidrug-resistant Staphylococcus aureus: A clinical study in Kathmandu

Introduction: Staphylococcus aureus, recognized as an opportunistic pathogen, is frequently implicated in diverse human infections. Managing multidrug-resistant S. aureus poses a significant challenge in the clinical sector. Beyond B-lactam antibiotics, healthcare practitioners commonly prescribe Glycopeptides, Tetracycline, Quinolones, and Macrolide-Lincosamide-Streptogramin B antibiotics as alternative treatments for such infections. Consequently, this study was undertaken to evaluate the susceptibility of multidrug-resistant S. aureus to tetracycline in clinical samples. Methods: The study spanned 15 months, from March 2020 to May 2021, during which clinical samples were collected from three distinct hospitals in Kathmandu-Dirghayu Guru Hospital, Chabahil; Bhaktapur Cancer Hospital, Bhaktapur; and Shankarapur Hospital, Jorpati. Sample processing and laboratory work were conducted in the Microbiology Laboratory of Dirghyau Guru Hospital to assess the prevalence of different multidrug-resistant (MDR) phenotypes among S. aureus and their correlation with Methicillin resistance. The study included 266 isolates of S. aureus, and Methicillin resistance was determined using the Cefoxitin disc diffusion method. Results: Among 2004 clinical samples processed, 266 (13.27%) isolates were S. aureus. The multidrug resistant strain isolated from Outpatient department was 56.84% (54/95) and from inpatient department, the data was 43.15% (41/95). Among the 266 S. aureus, 28.94% Methicillin resistant S. aureus (MRSA) and 71.05% Methicillin sensitive S. aureus (MSSA) isolates were detected. Tetracycline resistance was found in 9.8% of total S. aureus isolates whereas 27.36% (26/95) among multidrug resistant S. aureus isolates. Resistance to Tetracycline was higher in MRSA as compared to MSSA. Conclusion: The detection rate of MRSA emphasizes the urgency to improve healthcare practices to control the spread of MRSA infections. Tetracycline can be used as a viable alternative antibiotic for combating S. aureus infections, particularly in Kathmandu.

Antibiotic resistance and Staphylococcal super antigenic determinants in methicillin resistant Staphylococcus aureus isolated from anterior nares of dental students

Background: Staphylococcus aureus primarily inhabits the human anterior nares. Asymptomatic Methicillin-resistant Staphylococcus aureus (MRSA) nasal carriage in healthcare professionals makes them potential MRSA reservoirs. Since identification and decolonization would promote cross-contamination reduction and curb communal transmission, this study was designed to identify MRSA nasal carriers among dental students and detect staphylococcal super antigenic determinants among them. Methods: Staphylococci isolates (n=52) from dental students(n=42) were investigated in the study. Following initial microbial speciation and antimicrobial susceptibility determination using standard identification methods, the MRSA strains were identified phenotypically using cefoxitin disc (30 µg). Genes encoding the virulence determinants, namely, TSST (test), enterotoxins (sea and seb), and cytotoxin (pvl), were looked for by PCR. Results: Only 15.09% of isolates were identified as Staphylococcus aureus, and all of them (n=8) were scored as MRSA using the cefoxitin disc diffusion method. None of the tested isolates showed the presence of virulence determinants in standard molecular techniques. Conclusion: Lower prevalence of S. aureus, MRSA, coupled with the absence of virulence determinants in the strains, suggests strategies for better surveillance. Tracking virulence-causing genes in nasal carrier S. aureus strains could enhance efforts to prevent infection outbreaks.

Variations In The Genotypic And Phenotypic Characteristics Of Methicillin-Resistant Staphylococcus Aureus (Mrsa) From Students Attending Poultry Farms In Umuahia, Abia State, Nigeria

Staphylococcus aureus causes significant epidemiologic and therapeutic challenges with various skin and soft tissue infections, the main forms of disease manifestation. The public health importance of this organism has been heightened by the emergence and spread of species that are resistant to treatment usually referred to as methicillin-resistant S. aureus (MRSA). This study was carried out to detect mecA and mecC genes in phenotypically determined MRSA isolates. Nasal swab samples of the subjects were cultured on mannitol salt agar and the isolates were identified as S. aureus using a combined morphological and biochemical characteristic. Antibiotic susceptibility profile was performed using the disk diffusion susceptibility method whilst phenotypic detection of MRSA isolates was by Cefoxitin disk diffusion method as per CLSI guidelines. Genomic DNA was extracted from the isolates using commercial kits. The extracted DNA was subjected to multiplex PCR to amplify the 163-bp and 188-bp fragment of the mecA and mecC genes respectively in a Pielter thermal cycler. The susceptibility pattern of MRSA isolates showed that the organisms were highly resistant to Augmentin 29 (93.5%), ceftazidime 18 (58.1%), Streptomycin 19 (76%) whilst high levels of susceptibility were seen for Ofloxacin 27 (87.1%), Levofloxacin 28 (90.3%), and Gentamicin 24 (77.4%). The antibiotic resistance profiles in MRSA isolates were recorded as follows: ciprofloxacin 6 (16.2%), Augmentin 32 (86.4%), erythromycin 13 (35.1%), Ceftazidime 22 (59.4%). Of the 10 MRSA isolates that were subjected to PCR, one isolate was found to harbor the 188-bp of mecC gene whilst mecA was absent from the screened isolates. The detection of mecC MRSA in the present study highlights the diagnostic importance of screening for mecC in mecA negative MRSA. We suggest that surveillance for MRSA should include screening for mecC gene where mecA is not detected in resistant isolates. Stamford Journal of Microbiology, 2023. Vol. 13, Issue 1, p. 6-10

Evaluating the incidence of ampC-lactamase genes, biofilm formation, and antibiotic resistance among hypervirulent and classical Klebsiella pneumoniae strains.

Both immunocompetent and healthy individuals can become life-threateningly ill when exposed to the hypervirulent (hvKp) strains of Klebsiella pneumoniae (Kp). The main objectives of this study were to evaluate the presence of ampC-lactamase genes, biofilm formation, and antibiotic resistance in clinical strains of hvKp and cKp (classical K. pneumoniae). Kp strains were collected from patients referred to Shahidzadeh Hospital in Behbahan city, Khuzestan Province, Iran. Several techniques were used to identify hvKp. The hypermucoviscosity phenotype was determined using the string test. Isolates that developed dark colonies on tellurite agar were assumed to be hvKp strains. If any of the iucA, iutA, or peg-344 genes were detected, the isolates were classified as hvKp. Phenotypic and genotypic detection of AmpC β-lactamases of hvKp strains was performed by combined disk method and PCR, respectively. In addition, crystal violet staining was used to determine the biofilm formation of these isolates. For this study, 76 non-duplicative isolates of Kp were collected. Overall, 22 (28.94%) strains had positive string test results, and 31 (40.78%) isolates were grown in tellurite-containing medium. The genes iucA and iutA or peg-344 were found in 23.68% of all Kp strains and in 50% of tellurite-resistant isolates, respectively. The most effective antibiotics against hvKp isolates were tetracycline (85.52%) and chloramphenicol (63.15%). Using the cefoxitin disc diffusion method, we observed that 56.57% (43/76) of the strains were AmpC producer. A total of 30.26% (n=23/76) of the isolates tested positive for at least one ampC gene, including blaDHA (52.63%, n=40), blaCIT (40.78%, n=31), blaACC (19.76%, n=15), blaMOX (25%, n=19), and blaFOX (43.42%, n=33). Biofilm formation analysis revealed that most hvKp isolates were weak (n=6, 40%) and moderate (n=5, 33.33%) biofilm producers. Healthcare practitioners should consider the possibility of the existence and acquisition of hvKp everywhere. The exact mechanisms of bacterial acquisition are also unknown, and it is unclear whether the occurrence of infections is related to healthcare or not. Thus, there are still many questions about hvKp that need to be investigated.

Exploring the virulence potential of immune evasion cluster genes in methicillin-resistant Staphylococcus aureus from cancer patients

Methicillin-resistant Staphylococcus aureus (MRSA) is accountable for a plethora of infections, ranging from minor cutaneous manifestations to grave metastatic conditions. The dissemination of MRSA among cancer patients poses a substantial public health hazard on a global scale. This study explores the association between MRSA and bacteriophage-encoded immune evasion cluster (IEC) genes. This investigation employed a total of 168 pathogenic MRSA collected from 38 cancer and 130 non-cancer patients. A cefoxitin disc diffusion method followed by PCR analysis was used to identify the mecA gene. In this study, we employed singleplex and multiplexed PCR techniques to detect specific IEC genes. No association (p = 0.98) was observed between the sex and age of patients and MRSA isolates. However, MRSA isolates demonstrated a notable association (p = 0.01) with pus samples in non-cancer patients and skin swabs in cancer patients. The resistance profiles of MRSA strains from cancer and non-cancer patients did not show significant differences (p > 0.05). Notably, the sea gene was found to be more prevalent in MRSA isolates from cancer patients, displaying a significant association (p = 0.03). Additionally, this study identified two novel and distinct combinations of IEC types, namely V1 (sea, chp, scn) and V2 (sea, scn). Cancer patients had higher multidrug resistance and toxin gene abundance than non-cancer patients. The identification of two novel IEC patterns underscores the urgent need to control MRSA dissemination in hospitals and monitor emerging clones.

Molecular Detection of Hospital-Acquired Methicillin-Resistant Staphylococcusaureus Isolated From Teaching Hospitals in Damascus, Syria

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is an established pathogen responsible for hospital-acquired infections (HAIs). Accurate MRSA diagnosis is of paramount importance to facilitate early and effective treatment and to manage its transmission effectively. The primary objective of our study was to determine the precise prevalence of hospital-acquired MRSA (HA-MRSA) in select teaching hospitals in Damascus by detecting the presence of the mecA gene. Methods: One hundred Staphylococcus aureus isolates were collected from various clinical specimens obtained from inpatients admitted to three major teaching hospitals in Damascus, Syria, including Al-Moussat, Al-Assad, and Tishreen Military Hospitals. These patients met the established criteria for HAIs. The isolates were collected between December 2021 and August 2022. Genus and species confirmation were conducted via polymerase chain reaction (PCR), employing the 16SrDNA gene specific to the Staphylococcus genus and the nuc gene specific to S. aureus. Methicillin resistance was assessed using cefoxitin disc diffusion (CDD) in accordance with Clinical and Laboratory Standards Institute (CLSI) recommendations. The presence of the mecA gene was also detected through PCR. Results: Out of the collected isolates, 67% exhibited resistance to cefoxitin, as determined by the CDD, while 66% were found to be positive for the mecA gene. CDD demonstrated a sensitivity of 100% and a specificity of 97%. Conclusion: This investigation revealed a notably high incidence of HA-MRSA infections within the teaching hospitals under scrutiny. The CDD method displayed significant sensitivity and specificity, making it a dependable alternative to the mecA PCR for MRSA detection. This finding holds substantial importance for the effective implementation of infection control initiatives and strategies aimed at eradicating MRSA and curtailing its spread within our hospital facilities.

STUDY OF SPECIES IDENTIFICATION AND ANTIMICROBIAL SUSCEPTIBILITY OF VARIOUS CLINICAL ISOLATES OF COAGULASE – NEGATIVE STAPHYLOCOCCI

BACKGROUND- Interest in CoNS is increasing because of their role as pathogens in certain clinical conditions and their marked resistance to antibiotics. Frequent isolation of CoNS from the blood, other normally sterile body fluids, intravenous catheters and various tissues presents a recurrent interpretative challenge to both the clinician and microbiologist. The ubiquity of these organisms does present problems when one is faced with making a decision as to whether their isolation in clinical laboratory represents true infection or merely contaminant .AIM-The aim of this study was to isolate, identify and speciate coagulase negative staphylocci (CoNS) from clinical specimens, along with to find their resistance to antimicrobial agents with reference to their methicillin resistance .MATERIAL & METHOD - Various clinical specimens like blood, pus, wound swab, ascitic / synovial fluid, urine, cerebro spinal fluid were processed in laboratory following the standard protocol for isolation, identification and speciation of coagulase negative staphylococci. RESULT- Present study found, S. epidermidis to be most prevalent species of coagulase negative staphylocci from clinical isolates with 47.58% strains, followed by S. haemolyticus 26.06%, and S. lugdunensis 8.54%. S. saprophyticus was the most common of CoNS species from urinary tract infection cases. Methicillin resistant CoNS (MRCoNS) were detected by cefoxitin disk diffusion method Out of 234 strains of CoNS, 153 strains (65.38%) were detected as MRCoNS. Most of the MRCoNS were found to be resistant to penicillin (100%), ceftazidime (99.35%), amoxicillin-clavulanic acid (98.69%), cotrimoxazole (92.81%), gentamicin (88.23%).Susceptibility to vancomycin and pristinamycin was 86.93 % and 99.35% respectively while all the MRCoNS isolates were susceptible to linezolid. CONCLUSION - Vancomycin is the mainstay of therapy in MDR MRCoNS infections and should be used judiciously. Looking at the possibility of emergence of resistance to the drug, newer agents like linezolid and pristinamycin might provide a valuable option for the treatment of MRCoNS infections. There is a need to have the knowledge and monitoring of antibiotic sensitivity pattern and formulation of definite antibiotic policy to improve the empirical approaches to the therapy of serious infections caused by CoNS

Prevalence of Methicillin Resistance Staphylococci (MRS) from Neonatal Septicemia and Comparative Evaluation of Newer Rapid Latex Agglutination Method with Conventional Methods for diagnosis of MRS

Background & Aims: Neonatal septicemia is a major cause of neonatal mortality in developing countries. Rapid treatment with antimicrobials is very crucial for essential outcome. Methicillin Resistance Staphylococcus (MRS) are important cause of nosocomial infection, which causes septicemia especially in neonates. They are frequently resistance to other antibiotics also. So, rapid, sensitive and specific procedures are required urgently to initiate timely treatment. This study was undertaken to perform comparative evaluation of conventional methods with rapid agglutination method in diagnosis of MRS and to estimate the prevalence of MRS among neonatal septicemia cases. Materials and Method: This study was done in one of the major tertiary care hospitals in Ahmedabad, Gujarat. All the blood samples collected from the patients with sign and symptoms of septicemia, from January 2012 to July 2012, were cultured and identified by standard microbiological method. MRS detection was done by conventional methods and latex agglutination method. Results: Staphylococcus coagulase negative constituted 61.96% and S.aureus 4.33% of total bacterial isolates. Methicillin resistance in S.aureusand in CONS, was 44.44% and 25.91% respectively. Prevalence of MRS among neonates was 32.72%. The sensitivity and specificity of oxacillin disk was 68% and 100% respectively for detection of MRS. Latex agglutination test method shows sensitivity and specificity of 100% for detection of MRS. Conclusion: Along with cefoxitin disc diffusion method, latex agglutination method is to be used for early diagnosis & treatment and forprevention of over use of vancomycinfor methicillin resistant staphylococci. Keywords:Septicemia, MRS, Blood culture, S.aureus, Cefoxitin, CoNS

Methicillin-resistant Staphylococcus aureus causing ocular infections in a tertiary care center in north India

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is often the cause of serious ocular infections that are difficult to treat, and these ocular infections are a significant public health problem. Aims and Objective: The study aimed to determine the prevalence and antimicrobial susceptibility pattern of MRSA in ocular infections. Materials and Methods: The patients were recruited from the outpatient and inpatient departments from July 2018 to February 2021 from the Institute of Ophthalmology and study was done in the Department of Microbiology, JNMC, AMU, Aligarh (UP). MRSA was identified by Cefoxitin disk diffusionmethod. Polymerase chain reaction was used for detection of mecA gene. Results: Seventy-six S. aureus were found in 350 patients with clinically suspected various bacterial infections. Among all S. aureus, 41 (53.94%) were MRSA. Maximum 10 (24.4%) MRSA were isolated from lacrimal apparatus infection followed by 7 (17%) in lid infection, and 6 (14.6%) in keratitis. All MRSA isolates were positive for mec A gene. MRSA isolates showed 85.3% sensitivity to amikacin and 100% to vancomycin. Fluoroquinolones showed resistance to the majority of MRSA strains. Conclusion: MRSA is the main pathogen of ocular infections, resistant to a wide range of antibiotics. The monitoring of antibiotic sensitivity patterns, regular surveillance of associated ocular diseases, and strict antibiotics policy should be followed in an institute.

“Evaluation Of Several Phenotypic Methods Of Antibiotic Susceptibility Pattern For The Detection Of MRSA With Molecular Profiling RT-PCR With The Detection Of MecA Gene”

INTRODUCTION:- Methicillin-resistant Staphylococcus aureus (MRSA) is a well-recognized public health problem throughout the world and community MRSA strains are now epidemic in India and others countries. The resistance rates of S. aureus infection and multidrug resistant strains are increasing, making the clinical anti-infective treatment and diagnosis more difficult.
 AIM:- To evaluate several phenotypic methods of the antibiotic susceptibility pattern for the detection of MRSA with Molecular Profiling Rt-PCR with the detection of MecA gene.
 MATERIALS AND METHODS:- The present study was a prospective observational study carried out at the Department of Microbiology, Santosh Medical College, Ghaziabad in a tertiary care hospital over a 12-month period from August 1, 2020 to July 31, 2021. Both IPD and OPD clinical sample comprised 385 clinical isolates as Staphylococcus aureus from various clinical specimens were included. Antibiotic susceptibility by the Kirby-Baure disc diffusion methods was performed according to the Clinical and Laboratory Standard Institute (CLSI) guidelines. Detection of MRSA by various methods like, Cefoxitin Disk diffusion Method, Oxacillin Disk diffusion method, E-Test method and detection of MecA gene by RT-PCR was carried out.
 RESULT:- In the present study out of 384 clinical samples, the majority of isolates from MRSA were found to be resistant to (E-Test) strip Oxacillin 114 (29.7%), followed by cefoxitin 113 (29.4%) and disc diffusion oxacillin 99 (25.8%). However, we observed a high incidence of resistance to other antibiotics such as Erythromycin 265 (69.0%), followed by Clotrimozole 228 (59.4%), Tetracyclin 144 (37.5), Vancomycin 102 (26.6%) and Refampicin 102 (26.6%). We also observed that Linezolid 354 (92.2%) followed by Teicoplanin 325 (84.6%), Gentamycin 272 (70.8%), Clindamycin 249 (64.8%) and Amoxyclave 281 (73.2%). In this study molecular RT-PCR test for the detection of mecA gene observed more in pus with 36 samples out of 113 followed by blood 17, urine 33, Sputum 05, pleural fluid 04, wound swab 16, Vaginal swab 06, CSF 01, Throat swab 2.
 CONCLUSION:- The gold standard assay for determining methicillin resistance is the PCR technique for detecting the mecA gene. But Because PCR is still time intensive and expensive, and it is not yet available in the 95% of routine clinical laboratories the phenotypic methods is still the choice where E-test is more reliable method than the disc diffusion method in detecting the drug resistance and can be utilised on a regular basis for better results.

Distribution of Leukocidins, Exfoliative Toxins, and Selected Resistance Genes Among Methicillin-resistant and Methicillin-sensitive Staphylococcus aureus Clinical Strains in Egypt

Background: Infection with Staphylococcus aureus (S.aureus) is an increasing health problem worldwide. This pathogen has multiple virulence factors that contribute to its pathogenesis in a wide range of diseases. The present study aimed to investigate the prevalence of leukocidins, exfoliative toxins, and common antimicrobial resistance genes among Methicillin-Resistant Staphylococcus aureus (MRSA) and Methicillin-Sensitive Staphylococcus aureus (MSSA) strains collected from various clinical sources in Egypt. Methods: Isolates were identified as S.aureus by the standard microbiological methods. Methicillin resistance was detected phenotypically by cefoxitin disc diffusion method and genotypically by PCR for detection of mecA gene. PCR was also used to detect the presence of leukocidin genes (LukD, LukE, LukF-PV, and LukS-PV), exfoliative toxin genes (eta and etb), and antibiotic resistance genes (tetK, tetM, ermA, ermC, msrA, and aacA-aphD). Results: About 50.5% of tested isolates were methicillin resistant by cefoxitin disc assay, while mecA gene was amplified in 64.6% of isolates. The highest prevalent toxin gene was lukE (93%) and the least prevalent one was eta (1%). The resistance genes tetK and tetM were detected in nearly 50% of the tested strains but lower prevalence rates were recorded for aacA-aphD, msrA, ermA, and ermC genes. Conclusion: Methicillin resistance was highly prevalent among tested S.aureus strains. Regarding the studied virulence and resistance genes, no significant difference was detected between MRSA and MSSA strains, except for ermA gene p<0.05 which was highly prevalent in MRSA strains. So, the variation between MRSA and MSSA strains in the response to treatment may be attributed to the resistance of MRSA strains to all β-lactams in addition to other possible acquired resistance mechanisms. Accordingly, fewer options of antimicrobial medications are available to treat MRSA infections.

Nasal carriage of meticillin-resistant Staphylococcus aureus among children living with HIV attending Infectious Diseases Clinics in Kano, Nigeria

SummaryBackgroundChildren living with HIV (CLWH) are at risk of colonisation and infection with meticillin-resistant Staphylococcus aureus (MRSA). All S. aureus isolates from CLWH with bloodstream infections in Kano were MRSA.AimTo estimate the prevalence of nasal colonisation with S. aureus and MRSA in CLWH in Kano State and to determine associated risk factors.MethodsA cross-sectional study was performed in the infectious diseases clinics of two public hospitals in Kano involving 214 CLWH/caregiver pairs. Children were selected from clinic registers by simple random sampling and an interviewer-administered questionnaire used to elicit factors associated with MRSA carriage from the caregivers. Clinical records were reviewed for patients' medical histories. Standard laboratory techniques were used to isolate S. aureus from nasal swabs collected from CLWH. MRSA was detected using the cefoxitin disc diffusion method and PCR for mecA gene detection. We measured the prevalence of S. aureus and MRSA carriage in the CLWH and calculated adjusted odds ratios (AOR) for factors associated with MRSA.ResultsNasal S. aureus carriage in CLWH was 18.7% (40/214). Cefoxitin disc diffusion identified 6/214 (2.8%) of CLWH were MRSA carriers, while PCR identified that 9/214 (4.2%) of CLWH were MRSA carriers. Recent hospitalisation (AOR: 61.04; 95% CI: 9.01–413.38) and recent antibiotic therapy (AOR: 7.52; 95% CI: 1.07–52.95) were independent risk factors for MRSA colonisation.ConclusionsThe rate of MRSA nasal colonisation among CLWH in Kano was similar to that reported in other studies in Africa. Infection prevention and control measures including MRSA screening and decolonisation, as well as education for CLWH and their carers should be introduced to reduce MRSA spread.

Prevalence of Methicillin Resistant Staphylococcus aureus and its Associated SCCmec Types among Healthcare workers and Patient Visitors from Western Maharashtra, India

Staphylococcus aureus is one of the major pathogen causing infections in human ranging from mild to severe life-threatening conditions. Methicillin-Resistant Staphylococcus aureus (MRSA) is an important nosocomial pathogen with high morbidity and mortality in both hospital and community settings. Total 600 nasal swabs were collected from patient visitors and Healthcare workers. Of these, 184 S.aureus (30.66%) were isolated. All S.aureus isolates screened for MRSA and 73 (39.67%) isolates showed MRSA by Cefoxitin disc diffusion method and PCR. 21 (28.76%) isolates detected pvl gene of the 73 isolated MRSA i.e., CA-MRSA. All MRSA isolates were typed into SCCmec element (I to V). Of these SCCmec type III was found more prevalent than other SCCmec types and 3 isolates were not typeable. MRSA still remains a significant problem in public Healthcare settings. Screening of MRSA among Healthcare Workers and patient visitors is mandatory to prevent the spread of CA-MRSA in hospitals.

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.