Staphylococcal Isolates Research Articles

Guardians of resistance and virulence: detection of mec, femA, Van, pvl, hlg and spa genes in methicillin and vancomycin-resistant Staphylococcus aureus from clinical and food samples in Southwestern Nigeria.

Staphylococcus aureus strains are highly virulent and associated with an eclectic range of severe nosocomial and community-acquired infections. This study assessed methicillin- and vancomycin-resistant Staphylococcus aureus (MRSA/VRSA) from clinical and ready-to-eat (RTE) food sources, screened for antibiotic resistance; and molecular determinants of antibiotic and virulence genes. Altogether, 465 clinical and RTE food samples were analyzed via conventional microbiological techniques and S. aureus identification was confirmed by nuc gene detection. Phenotypic screening for methicillin and vancomycin-resistance was by agar-screen cum micro-broth dilution respectively, while antibiotic susceptibility testing was done by the disc-diffusion technique. VanA/vanB/VanC1, femA, mecA/mecC; pvl/hlg and spa gene detection was via Polymerase chain reaction. Phenotypically, 211 Staphylococcal isolates were recovered, 138 (65.4%) of them carrying the nuc gene - all 138 (100.0%) were VRSA, while 59/138 (42.8%) were MRSA phenotypically. Overall, 114/138 (82.6%), 7/138 (5.1%), and 6/138 (4.3%) of isolates had the femA, mecA, and mecC genes, while van genes were detected in only 3 (2.2%) isolates, with virulence determinants pvl, hlg, and spa gene carriage in 8 (5.8%), 10 (7.2%), and 77 (55.8%) isolates respectively. In all, 11.6% carried resistance-associated genes, 55.8% carried virulence genes, and co-detection of resistance and virulence genes was observed in 12.3%. Overall, 96/138 (69.6%) were multidrug-resistant (MDR), while one strain was extremely drug-resistant (XDR). MAR Indices ≥ 0.2 was observed in 83.3% of isolates. This study highlights virulence levels of MRSA and VRSA circulating strains in Osogbo, contributing to their sustained surveillance, and improving available data for successive epidemiology investigations. This study also reports the occurrence of the mecC gene in S. aureus isolates from RTE foods and human samples in Southwestern Nigeria.

Comparative Study of Staphylococcus aureus Biofilm Formation among Clinical Isolates and Nasal Colonisers

Staphylococcus aureus (S. aureus) a noted versatile facultative commensal with pathogenic potential. This facultatively anaerobic cocci lives a commensal lifestyle in about a quarter of the world’s population awaiting a breach in the immune barrier to establish as a debilitating pathogen. This bacterium produces biofilms which acts as adhesive molecule enhancing the bacterial virulence and gives it an ability to withstand antibiotics, thereby causing tremendous burden on the healthcare community in terms of patient mortality and morbidity. This study assesses the biofilm producing ability among clinical isolates of staphylococci in comparison to colonizing staphylococci isolated from anterior nares of healthcare personnel. The present cross-sectional observational study was conducted in a tertiary care hospital in Mysore, India. In this study, 50 pathogenic isolates of S. aureus were assessed for phenotypic biofilm production. Additionally, 100 healthcare personnel were screened for nasal colonisation with S. aureus and the colonizing isolates were also screened for phenotypic biofilm formation. Phenotypic biofilm formation was evident among 22% of the pathogenic isolates. 23% of clinical S. aureus isolates demonstrated methicillin resistance (MRSA). There was no significant association of MRSA status with biofilm production (p > 0.05). Out of the 100 healthcare professionals screened for nasal carriage of S. aureus, 30% were colonized with S. aureus. Biofilm production among colonizing S. aureus isolates was found to be 26.6%. Methicillin resistance was a whopping 40% among the colonising strains. MRSA carriage was found to be highest among those healthcare personnel who had worked for an average of 20-30 years in the hospital environment. The Present study showed no significant association of biofilm production with the pathogenic potential of the S. aureus isolates (p > 0.05). Additionally, there was no significant association of methicillin resistance with the pathogenicity of the isolate. In conclusion, the interplay of virulence genes, biofilm forming ability, drug resistance of the isolate in coordination with the host immune status dictate the fate of the colonising as well as clinical isolates of S. aureus.

Presence of Methicillin-Resistant Staphylococci and Carbapenemase-Positive Acinetobacter Isolates on Surfaces in German Dog Daycare Facilities and Correlation with Cleaning Practices.

Many bacteria, including methicillin-resistant staphylococci and opportunistic pathogens such as Acinetobacter (A.) species, in particular members of the A. calcoaceticus-A. baumannii (Acb) complex, are known to survive in environmental settings. This increases the risk of bacterial spreading and transmission to animals and humans, especially in institutions with a high animal population density. This study aimed to identify the presence of multidrug-resistant (MDR) staphylococci and Acinetobacter species in dog daycare facilities (DDFs). The surfaces of 16 DDFs were sampled and information about cleaning practices was obtained. After microbial identification, the detected isolates were investigated by multiplex PCR for antimicrobial resistance genes. In 200 location samples, 38 staphylococci and 109 Acinetobacter spp. isolates were identified. Methicillin-resistant genes were confirmed in 18 staphylococci isolates from four DDFs, including Staphylococcus (S.) equorum, S. saprophyticus, S. cohnii, S. lentus, and S. haemolyticus. Eight A. radioresistens isolates comprising the blaOXA-23 carbapenemase gene and seventeen isolates belonging to the Acb complex were also isolated. This is the first investigation for MDR pathogens in DDFs, a close human-animal interaction environment. Though the role of DDFs in the transmission and spreading of MDR bacteria is not known, the findings should contribute to the public awareness and underscore the necessity of adequate cleaning protocols.

Characterization and complete genome sequence of highly lytic phage active against methicillin-resistant Staphylococcus aureus (MRSA) isolated from Egypt

BackgroundMethicillin-Resistant Staphylococcus aureus (MRSA) is one of the most resistant bacteria to antibiotics. S. aureus is an important, widespread pathogen that can cause a variety of infectious diseases in humans and animals. Phages have been recognized as natural, safe, highly specific and effective alternatives agents to antibiotics for preventing and treating bacterial infections caused by MRSA. Therefore, this study aims at the characterization of a novel isolated lytic phage, vB_SauP_ASUmrsa123.MethodsIsolates of Staphylococcus aureus MRSA were obtained on Mannitol Salt Agar and Baird Parker Agar plates and confirmed using VITEK 2. Sewage and clinical samples were used to isolate specific phages for S. aureus MRSA, and plaque assays were used for host range determination on Luria-Bertani (LB) media. The phage morphology of the isolated phage was determined by transmission electron microscopy. The phage’s whole genome sequencing was identified.ResultsA total of 25 isolates of Staphylococci were obtained from different clinical sources and showed typical colonies on Baird-Parker and Mannitol Salt Agar plates. The VITEK 2 automated system revealed that all 25 isolates were confirmed as S. aureus (MRSA). Two of the most antibiotics-resistant isolates were further confirmed using 16S ribosomal RNA sequencing. A lytic phage was detected against the MRSA isolates tested In Vitro, namely vB_SauP_ASUmrsa123. The phage belonged to Rountreeviridae family based on morphological properties observed by TEM and the host range of the isolated phage was tested on the 25 clinical MRSA isolates in Vitro. The one-step growth curve of the isolated phage showed that the latent period was about 55 min, and the burst size was estimated at 167 PFU. The whole genome sequencing and annotation of genes revealed that phage vB_SauP_ASUmrsa123 contained a linear dsDNA with a size of about 17,155 bp with predicted 24 ORFs. Analysis of its genome provides valuable information approximately the variety of phages belonging to the staphylococcal phages class I.ConclusionA lytic Podo Phage vB_SauP_ASUmrsa123 was identified against S. aureus MRSA isolates and its genome was sequenced. The phage was found to be eligible for potential application in biocontrol.

Occurrence of virulence genes icaADBC and antibiotic resistance genes blaZ, mecA, and aac(6’)-Ie-aph (2’’)-Ia in coagulase-negative staphylococci isolates from neonates with sepsis at a regional referral hospital in Dar es Salaam, Tanzania

BackgroundCoagulase-negative staphylococci (CoNS) have been linked to severe conditions such as bloodstream infection, with biofilm formation regarded as the major virulence mechanism. This study determined virulence genes (VGs) (icaA, icaB, icaC, and icaD) responsible for biofilm formation and antibiotic resistance genes (ARGs) (blaZ, mecA, and aac(6’)-Ie-aph(2’’)-Ia) in CoNS isolated from blood samples of 70 neonates with sepsis in Dar es Salaam, Tanzania. We used VITEK®MS (BioMérieux, France) for speciation and phenotypically detected biofilm production using the Congo red agar. Polymerase chain reaction was performed for ARGs and VGs detection; principal component analysis was used to ascertain their relationship.ResultsOut of 70 CoNS, Staphylococcus epidermidis, 27 (36.8%) was the most commonly isolate, subsequently to Staphylococcus haemolyticus, 24 (34.3%). The intercellular adhesion genes (ica) were detected in all isolates, with IcaD found in 70 (100.0%), followed by icaB 69 (98.6%), icaC 69 (98.6%), and icaA 65 (92.9%). Four virulence gene combinations (icaADBC, icaBCD, icaACD, and icaABD) were detected, predominantly icaADBC 63 (90.0%). Sixty-one (87.1%) isolates harbored three ARGs, mostly the mecA gene 69 (98.6%), followed by blaZ 67 (95.7%) and aac (6’)-Ie-aph (2’’)-Ia, 65 (92.7%). We observed a moderate positive correlation between mecA and icaA genes (r = 0.4341). Sixty-five (97.0%) isolates resistant to penicillin harbored blaZ genes, and all 62 (100%) resistant to oxacillin harbored mecA genes. Of the 66 isolates resistant to gentamycin, 62 (93.9%) harbored the aac (6’)-Ie-aph (2’’)-Ia gene. The mecA gene contributed most of the resistance, followed by aac(6’)-Ie-aph(2’’)-Ia genes. However, the icaA and icaD genes significantly influenced the virulence of CoNS.ConclusionsMost CoNS isolated from blood samples of neonates with sepsis harbor a variety of clinically relevant virulence and resistance genes, indicating their ability to cause severe infections that are difficult to treat. Significantly, 59 (84.3%) isolates were phenotypically penicillin, gentamycin, and oxacillin resistant; the antibiotics recommended in the national guidelines for empiric treatment of neonatal sepsis.

Time to positivity of Coagulase Negative Staphylococcus In Neonatal Blood Cultures as an adjunct tool to help discriminate between sepsis and contamination.

To assess the usefulness of time to positivity (TTP) to distinguish between sepsis and contamination in coagulase-negative staphylococci (CoNS) isolates. Unicentric retrospective observational. Medical records of 168 patients with suspected sepsis and positive blood culture for CoNS were reviewed. Patients were subdivided into sepsis (29%) and probable contamination (71%). Logistic regression analyses were performed to evaluate different risk factors and clinical signs and symptoms associated with sepsis. TTP cut-off value that best discriminated sepsis from contamination was found to be 18 h. Regression analysis revealed that TTP ≤ 18 h, gestational age ≤32 weeks, taquycardia/bradycardia and hypoactivity/lethargy were independent predictors of sepsis. TTP is useful in distinguishing sepsis from contamination, especially in neonates with lower gestational age (<32 weeks). The clinical signs that most increase the discriminatory power of TTP are the presence of tachycardia/bradycardia or hypoactivity.

MIC trends of vancomycin and teicoplanin among methicillin resistant CoNS isolates from new born blood cultures in a tertiary care centre in Southern India.

Coagulase-negative-Staphylococci (CoNS) are important etiological agent of bacteraemia in newborn babies. Methicillin resistant CoNS infections have only limited treatment options. The antimicrobial susceptibility pattern of Methicillin Resistant CoNS isolates from newborn blood cultures was studied with special reference to MICs of Vancomycin and Teicoplanin. The study population included Methicillin Resistant Coagulase Negative Staphylococcal isolates (MRCoNS) from newborn blood cultures, during a one-year period. Minimum inhibitory concentration (MIC) of Vancomycin and Teicoplanin in Methicillin resistant CoNS isolates was determined by macrobroth dilution method as per CLSI guidelines and by automated methods. Coagulase Negative Staphylococci were the etiological agent in 73.7% (n=56) cases of neonatal bacteremia. Methicillin resistance in newborn CoNS was found to be 58.9%. All the MRCoNS isolates had vancomycin and teicoplanin MICs in the susceptible range. There were MRCoNS isolates with MICs in the upper limit of susceptible range for both vancomycin and teicoplanin, which can result in poor clinical response. Continuous large scale multi-centre surveillance studies with special attention to study the MIC pattern of the high-end anti-MRSA agents like vancomycin, teicoplanin, linezolid are to be carried out. This will help the clinicians to judiciously prescribe the antibiotics, which is very essential for antimicrobial stewardship.

Prevalence of pathogens and antimicrobial resistance of isolated Staphylococcus spp. in bovine mastitis milk in South Korea, 2018-2022.

Staphylococcus spp. are one of the most predominant isolates in milk samples of dairy cows with mastitis worldwide. The aims of this study were to investigate the prevalence of bacterial pathogens in bovine mastitis milk samples in South Korea and the antimicrobial resistance profiles of staphylococcal isolates. In total, 1,245 strains were isolated from 1,260 mastitis quarter milk samples (with somatic cell counts ≥200,000 cells/mL) from 66 dairy farms between 2018 and 2022. The bacterial genus with the highest prevalence in bovine mastitis milk samples was Staphylococcus spp. (33.9%), followed by Streptococcus spp. (11.5%). S. aureus and non-aureus staphylococci (NAS) accounted for 11.0% and 89.0% of staphylococcal isolates, respectively. S. chromogenes was the most prevalent species among the 22 NAS species detected. S. aureus showed the highest resistance rates to penicillin (25.0%) and ampicillin (20.8%), whereas NAS showed the highest resistance rates to penicillin (18.3%), tetracycline (11.4%) and erythromycin (10.1%). Sixteen multidrug-resistant (MDR) isolates were only isolated from NAS, and the most commonly detected antimicrobial resistance gene in the 16 MDR isolates was mecA (75.0%), followed by tetK (62.5%), blaZ (50.0%), ermC (50.0%), and lnuA (43.8%). In conclusion, NAS were the most common isolates from mastitis milk in South Korea and MDR isolates carried a variety of antibiotic resistance genes. Our study suggests that continuous monitoring of the distribution and antimicrobial resistance in Staphylococcus spp., particularly NAS, is needed to improve the effectiveness of management and treatment strategies in dairy farms.

Phenotypic and genotypic detection of macrolide resistance among clinical isolates of Staphylococci, Zagazig University Hospitals, Egypt

Phenotypic and genotypic detection of macrolide resistance among clinical isolates of Staphylococci, Zagazig University Hospitals, Egypt

Biofilm Eradication and Inhibition of Methicillin-Resistant Staphylococcus Clinical Isolates by Curcumin-Chitosan Magnetic Nanoparticles.

Biofilm-producing methicillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococci (MR-CoNS) pose clinical challenges in treating healthcare-associated infections. As alternative antimicrobial options are needed, in this study, we aimed to determine the effect of curcumin-chitosan magnetic nanoparticles (Cur-Chi-MNP) on the biofilms of staphylococcal clinical isolates. MRSA and CoNS clinical isolates were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Antimicrobial susceptibility testing was performed using the broth microdilutions. Nanoparticles were synthesized by the co-precipitation of magnetic nanoparticles (MNP) and encapsulated by the ionotropic gelation of curcumin (Cur) and chitosan (Chi). Biofilm inhibition and eradication by nanoparticles, with and without the addition of oxacillin (OXA), were assessed in Staphylococcus strains. Cur-Chi-MNP showed antimicrobial activity against planktonic cells of MRSA and MR-CoNS strains and inhibited MRSA biofilm. The addition of OXA to Cur-Chi-MNP increased the biofilm inhibition and eradication activity against all staphylococcal strains (P = 0.0007), and higher biofilm activity was observed in the early biofilm stages. Cur-Chi-MNP showed antimicrobial and biofilm inhibitory activities against S. aureus. Addition of OXA increased biofilm inhibition and eradication activity against all staphylococcal strains. A combination treatment of Cur-Chi-MNP and OXA could potentially be used to treat staphylococcal biofilm-associated infections in the early stages before the establishment of biofilm bacterial cells.

Microbial profiling, antimicrobial resistance surveillance, and molecular detection of MecA gene in Staphylococcal strains from donor human milk: Insights from a milk bank investigation

PurposeDonor human milk (DHM) from milk banks provides vital nutrition to vulnerable infants. Understanding its microbial profile and antimicrobial resistance patterns is crucial for ensuring its safety and efficacy. This study aimed to profile the microbial composition, detect antibiotic resistance, and identify the presence of mecA gene in Staphylococcal strains from DHM samples. Materials and methodA total of 151 DHM samples were collected from a regional human milk bank in North India. Microbial identification was performed using MALDI TOF MS, and antimicrobial susceptibility testing was conducted using the disc diffusion method. Molecular methods, including PCR, were employed for mecA gene detection. ResultsThe study revealed a diverse microbial profile, with Staphylococcus species being predominant. Acinetobacter and Pseudomonas species were also prevalent, raising concerns due to their association with healthcare-associated outbreaks. High rates of antibiotic resistance were observed across both Gram-positive and Gram-negative bacteria, with resistance to commonly used antibiotics such as penicillin, clindamycin, erythromycin, and ceftriaxone. The mecA gene, associated with methicillin resistance, was detected in a significant proportion of Staphylococcal isolates. ConclusionThe study underscores the importance of rigorous microbial analysis and antimicrobial susceptibility testing in assessing the safety of DHM. The presence of diverse microbial species, including antibiotic-resistant strains and the mecA gene in Staphylococcal strains, emphasizes the need for stringent hygiene practices and continuous surveillance in milk banks. Implementing comprehensive screening protocols and adhering to best practices in milk handling and pasteurization are crucial for safeguarding the health of vulnerable infants reliant on donor milk.

ANTIBIOTICS SENSITIVITY PATTERN OF FOOD-BORNE BACTERIA AMONGST CARRIERS, FOOD HANDLERS IN A NIGERIAN UNIVERSITY

Antibiotics sensitivity patterns of food-borne bacteria amongst food handlers in a Nigerian University was carried out in this study. 100 food handlers actively participated in this research. Percutaneous and nasal swabs were collected and samples were placed on MacConkey, blood and chocolate agar media, incubated at 37 0 C for 24 h, followed by biochemical identification of isolates. Antibiotics multi-disc were used to test bacteria susceptibility. Among bacteria isolates, 14% showed very poor sensitivity. Sensitivity to ampicillin, flucloxacillin, rifampicin and streptomycin was &lt; 50%. Prevalence of food-borne pathogens was 76 % for percutaneous and 51 % for nasal samples. Isolates-sex difference was not statistically significant p &gt; 0.05. Staphylococci isolates had the highest prevalence, 64 % and 45 % from percutaneous and nasal samples, respectively. Thirty (30 %) participants had similar isolates from both sampling regions. Antibiotics multi-resistant strains of bacteria are prevalent in our environment. Food handlers can be potential reservoirs and means of transmission of antibiotics multi-resistant food-borne bacteria.

Genetic identification of methicillin resistant Staphylococcus aureus (MRSA) isolated from diabetic foot ulcers and evaluating the inhibition activity of reuterin against this bacteria.

To genetically diagnose the isolates of methicillin-resistant staphylococcus aureus taken from patients with severe diabetic foot infections, and to test the inhibitory effect of reuterin on the growth of these bacteria. The experimental study was conducted from June to November 2021 at the Diabetes Unit of Al-Faihaa General Hospital, Basrah, Iraq, and comprised 62 foot ulcer swabs from the necrotic lesions of patients with type 2 diabetes. The swabs were cultivated first in brain heart infusion broth media, and then streaked on Mannitol salt agar and staphylococcus chromogeneic agar media for phenotypic and genetic analysis. The genetic identification of bacteria was confirmed by deoxyribonucleic acid extraction, and methicillin-resistant staphylococcus aureus was confirmed by the presence of plasmid mecA gene. The inhibition activity of reuterin towards methicillin-resistant staphylococcus aureus was determined using the minimum inhibitory concentration test. All data was analyzed with SPSS version 23. A total of 62 swabs were taken from the necrotic lesions of type 2 diabetes mellitus (T2DM) patients with diabetic foot ulcers. Of the total isolates, 9(14.5%) gave mauve to purple colour on staphylococcus chromogeneic agar, which was then genetically confirmed as methicillin-resistant staphylococcus aureus. The minimum inhibitory concentration value of these bacteria was 10μl/ml at 16mm inhibition zone diameter. There was no cytotoxicity of reuterin to human red blood cells. Reuterin was found to be a natural antimicrobial substance suitable for use to disinfect diabetic foot wounds from bacterial contamination and infection, especially those caused by methicillin-resistant staphylococcus aureus.

Genomic portraits of methicillin-resistant staphylococci (MRS) from food fish unveiled the genes associated with staphylococcal food poisoning (SFP), virulence and antimicrobial resistance

BackgroundCharacteristics of non-clinical strains of methicillin-resistant Staphylococcus aureus (MRSA) especially from fishery environment are poorly understood. This research, in addition to comprehensive characterisation, sought to delineate the genetic relatedness between the MRSA strains originating from clinical as well as non-clinical settings. Out of 39 methicillin-resistant staphylococcal isolates from 197 fish samples, 6 (Three each of methicillin-resistant S. haemolyticus (MRSH) and MRSA) with distinct resistance profiles were selected for whole-genome sequencing. Using respective bioinformatics tools, MRSA genomes were comprehensively characterized for resistome, virulomes, molecular epidemiology and phylogenetic analysis. Simultaneously, MRSH genomes were specifically examined to characterize antimicrobial resistance genes (ARGs), owing to the fact that MRSH is often recognized as a reservoir for resistance determinants.ResultsThree MRSA clones identified in this study include ST672-IVd/t13599 (sequence type-SCCmec type/spa type), ST88-V/t2526, and ST672-IVa/t1309. Though, the isolates were phenotypically vancomycin-sensitive, five of the six genomes carried vancomycin resistance genes including the VanT (VanG cluster) or VanY (VanM cluster). Among the three MRSA, only one harbored the gene encoding Panton-Valentine Leukocidin (PVL) toxin, while staphylococcal enterotoxin (SEs) genes such as sea and seb, associated with staphylococcal food poisoning were identified in two other MRSA. Genomes of MRSH carried a composite of type V staphylococcal cassette chromosome mec (SCCmec) elements (5C2 & 5). This finding may be explained by the inversion and recombination events that may facilitate the integration of type V elements to the SCC elements of S. aureus with a methicillin-susceptible phenotype. Phylogenetically, MRSA from a non-clinical setting displayed a considerable relatedness to that from clinical settings.ConclusionThis study highlights the genetic diversity and resistance profiles of MRSA and MRSH, with non-clinical MRSA showing notable relatedness to clinical strains. Future research should explore resistance gene transfer mechanisms and environmental reservoirs to better manage MRSA spread.

Identification, Antibiotic Profiling of Potential Pathogenic Bacteria from Fomites in Neonatal Intensive Care Units in a Tertiary Teaching Hospital of North Karnataka

This study was taken up to determine the prevalence of potential pathogens in most touched fomites in Neonatal Intensive Care Units (NICUs) and to determine their antibiogram. Fifty swabs each were collected from fomites from In-born (for babies born in our center) and out-born (for babies born elsewhere, brought to our center) NICUs, before and after cleaning. Samples were processed using standard Microbiological techniques. Antibiogram was determined by Kirby-Bauer disc diffusion method. From In-born NICU, before cleaning, 42 (84%) samples yielded growth with 48 bacterial isolates of which 31 (64.6%) were pathogens and after cleaning, 40 (80%) samples yielded growth with 41 bacterial isolates, of which 30 (73.1%) were pathogens. Most frequent isolates were non-fermenting gram-negative bacilli (NFGNB) and Klebsiella pneumoniae before and after cleaning, respectively. Prevalence of bacteria from In-born NICU before and after the cleaning was statistically significant (p = 0.025). From Out-born NICU, before cleaning, 42 (84%) samples yielded growth with 45 bacterial isolates, of which 25 (55.55%) were pathogens. Samples collected after cleaning; 42 (84%) samples yielded growth with 43 bacterial isolates of which 19 (44.18%) were pathogens. Most frequent isolates were NFGNB and Klebsiella pneumoniae from In-born NICU and K. pneumoniae and Escherichia coli from Out-born NICU before and after cleaning, respectively. Overall prevalence of pathogens was significant (p = 0.007). Staphylococcal isolates were resistant to Methicillin. NFGNB exhibited highest resistance (55.9%) towards Gentamicin. Significant decrease in the frequency of pathogens after cleaning indicates stringent practice of sterilization protocol would be essential in hospital environment.

Epidemiology and vancomycin susceptibility pattern of methicillin resistant coagulase negative Staphylococcal (CoNS) isolates from skin swabs of the surgical patients in the National Hospital of Sri Lanka

Epidemiology and vancomycin susceptibility pattern of methicillin resistant coagulase negative Staphylococcal (CoNS) isolates from skin swabs of the surgical patients in the National Hospital of Sri Lanka

Virulence, Susceptibility Profile, and Clinical Characteristics of Pathogenic Coagulase-Negative Staphylococci.

Background Coagulase-negative staphylococci (CoNS) are emerging as clinically significant pathogens. A high proportion of methicillin resistance along with intensebiofilm-producing abilityrender CoNS-related infections challenging to treat. This study was undertaken to investigate the mechanisms of methicillin resistance, identify genes encoding for virulence, and their association with clinical outcomes among clinical isolates of Staphylococci in a tertiary care center. Methods A total of 203 clinical isolates were included in this study. Susceptibility to various antibiotics was determined by the disc diffusion method. Methicillin resistance was screened using cefoxitin disc, mecAand mecC genes were detected using polymerase chain reaction (PCR). PCR was performed to detect five virulence genes:atlE, aap, fbe, embp, and icaAB. Staphylococcal cassette chromosome mec (SCCmec) types were identified by multiplex PCR. Statistical analysis was performed using SPSS software (IBM Inc., Armonk, New York). The Chi-squared test was used to compare the distribution of virulence genes among methicillin-susceptible resistant CoNS. A p-value of less than 0.5 was considered significant. Results In the current study, 60% (122/203) of CoNS were methicillin-resistant, and SCCmec type Iwas the most common. Among the 203 CoNS, 24.6% (50/203) isolates harbored one or more virulence genes in them. Conclusion CoNS have relatively low virulence as only 24.6% of isolates carried the virulence genes. Nevertheless, the variety of diseases linked to these species indicates the necessity for accurate identification and precise reporting ofantimicrobial susceptibility to avoid adverse outcomes.

Microbiological profile of patients with orthopedic implant-associated infection in the post-COVID period

Background. The etiological structure of implant-associated infection and antibiotic resistance of pathogens are important when choosing empirical antibiotic therapy. COVID-19 pandemic and increased consumption of antibiotics by the population could provoke an increase in antibiotic resistance.The aim of the work. To compare the spectrum of leading pathogens of implantassociated infection in the pre- and post-Covid period and to assess antibiotic resistance.Materials and methods. A continuous retrospective study of biomaterial samples from traumatology and orthopedic patients with implant-associated infection was carried out for 2018–2019 and 2021–2022. The sample consisted of 548 microorganism strains (n = 237 and n = 317, respectively) in 442 cases of infectious complications. The antibiotic resistance of all isolated microorganisms, including those from microbial associations, was assessed.Results. The leading pathogen of monomicrobial implant-associated infection in both study periods was Staphylococcus epidermidis (33–37 %). In 2021–2022, the proportion of microbial associations increased (from 12.5 to 17.5 %; p = 0.147) with the appearance of fungi in the microbial landscape. In the post-Covid period, the increase in Staphylococcus aureus resistance to tetracycline and doxycycline was revealed; the isolation of methicillin-resistant strains among Staphylococcus aureus decreased from 4 cases (out of 187) to 3 (out of 232); 100 % sensitivity to rifampicin and co-trimoxazole was maintained. An increase in Staphylococcus epidermidis resistance to all tested antibiotics was detected (statistically significant increase in resistance to fluoroquinolones; p = 0.002–0.003) with the isolation of methicillin-resistant strains in 80.5% and 80.9% of cases, respectively. All staphylococcal isolates were susceptible to vancomycin and linezolid. Enterobacteriaceae representatives showed a decrease in resistance to carbapenems and an increase in resistance to co-trimoxazole; in Pseudomonas aeruginosa and Acinetobacter baumannii, there is an increase in resistance to carbapenems and fluoroquinolones. All gram-negative microorganisms were sensitive to colistin.Conclusion. The high frequency of isolation of methicillin-resistant staphylococci determines the choice of vancomycin for empirical therapy. Increasing resistance of staphylococci to fluoroquinolones may limit their use. Increasing resistance of gram-negative bacteria and a narrow spectrum of antibiotics acting on carbapenemase producers may reduce the effectiveness of therapy.

Prevalence, genetic characteristics, and antimicrobial resistance of staphylococcal isolates from oral cavity and skin surface of healthy individuals in northern Japan

BackgroundOral cavity is an ecological niche for colonization of staphylococci, which are a major bacterial species causing community-acquired infections in humans. In this study, prevalence, and characteristics of staphylococci in oral cavity and skin of healthy individuals were investigated in northern Japan. MethodsSaliva from oral cavity and swab from skin surface of hand were collected and cultured on selective media. Species of the isolates were identified genetically, and ST was determined for S. aureus and S. argenteus. Genes associated with antimicrobial resistance were detected by PCR. ResultsAmong 166 participants, a total of 75 S. aureus isolates were obtained from 61 individuals (37 %), and recovered more frequently in oral cavity (n = 48) than skin (n = 27). Among 23 STs identified in S. aureus isolates, ST8 (CC8), ST15 (CC15), and ST188 (CC1) were the most common (10 isolates each), with STs of CC1 being dominant (17 isolates). Methicillin-resistant S. aureus (MRSA) was isolated in the skin of two individuals and belonged to ST1 and ST6. Resistance to erythromycin and gentamicin associated with erm(A) and aac(6’)-Ie-aph(2”)-Ia, respectively, was more commonly found in ST5 and ST8 isolates. One S. argenteus isolate (ST2250, mecA-negative) was recovered from oral cavity of a participant (0.6 %). A total of 186 isolates of coagulase-negative staphylococci (CoNS) were recovered from 102 participants and identified into 14 species, with S. warneri being the most common (n = 52), followed by S. capitis (n = 42), S. saprophyticus (n = 20) and S. haemolyticus (n = 19). mecA was detected in S. saprophyticus, S. haemolyticus, and S. caprae, while arginine-catabolic mobile element (ACME) in only S. capitis and S. epidermidis. ConclusionS. aureus was more prevalent in oral cavity than skin surface, belonging to three major STs, with CC1 being a dominant lineage. The prevalence of antimicrobial resistance was distinct depending on CoNS species.

In Vitro Antimicrobial Activity of Taurolidine against Isolates Associated with Catheter-Related Bloodstream Infections

Background: Taurolidine exhibits broad antimicrobial activity and is a component of a recently FDA approved catheter lock solution (DefenCath®, taurolidine 13,500 μg/mL and heparin 1000 Units/mL) indicated for reducing the risk of catheter-related bloodstream infections (CRBSI) in adult patients receiving chronic hemodialysis through a central venous catheter (HD-CVC). FDA approval was based on a Phase 3 randomized trial (LOCK-IT-100) in which DefenCath showed a 71% reduction in CRBSI risk among HD-CVC patients as compared with heparin alone. Although individual isolates from the clinical program were not available for testing, this study evaluated the in vitro antimicrobial activity of taurolidine against a set of recent clinical isolates representative of those recovered from the LOCK-IT-100 trial and/or those commonly associated with CRBSI. Methods: 420 bacterial and 50 yeast isolates were selected from the SENTRY Antimicrobial Surveillance Program. All isolates were collected from the bloodstream of patients in the U.S. between 2018-2023. Isolates were tested for susceptibility to taurolidine and comparators using Clinical and Laboratory Standards Institute (CLSI) broth microdilution guidelines. JMI Laboratories produced susceptibility test panels for testing. CLSI-recommended quality control strains were also tested concurrently. MIC values were determined after 24 hours. Results: Taurolidine exhibited broad antimicrobial activity against all isolates tested (see table). Against gram-positive bacteria, taurolidine MIC50/90 values ranged from 256-512/512-1,024 μg/mL for S. aureus, Coagulase-negative Staphylococcus, Enterococcus species, and Viridans group streptococci. This activity was maintained regardless of methicillin susceptibility for Staphylococcal isolates or vancomycin resistance among Enterococcal species. Against gram-negative bacteria, taurolidine MIC50/90 values ranged from 256-1,024/512-2,048 μg/mL for Enterobacterales, P. aeruginosa, S. maltophilia, A. baumannii-calcoaceticus, and B. cepacia. This activity was maintained in both multidrug resistant Enterobacterales and P. aeruginosa isolates. Among Candida isolates, taurolidine MIC50/90 values ranged from 256-512/512 μg/mL for C. glabrata and C. parapsilosis while taurolidine MIC50/90 values of 4,096/4,096 μg/mL were observed for C. albicans. Conclusions: Taurolidine activity was very similar among a large collection of gram-positive, gram-negative, and yeast organisms. MIC90 values for all species/groups were ≤2,048 μg/mL, except C. albicans where an MIC90 of 4,096 μg/mL was observed. The activity of taurolidine was unaffected by resistance to antibiotics (i.e. methicillin, vancomycin, or multi-drug resistance) among gram-positive or gram-negative organisms. Based on these data, catheter lock solutions containing the broad-spectrum antimicrobial taurolidine at 13,500 μg/mL have the potential to prevent CRBSI caused by a variety of species, including those observed in the recent LOCK-IT-100 clinical trial and other common bloodstream pathogens