Methicillin-resistant Staphylococcus Aureus Isolates Research Articles

Characterization of Antibiotic Resistance and Virulence Traits Present in Clinical Methicillin-Resistant Staphylococcus aureus Isolates.

Methicillin-resistant Staphylococcus aureus (MRSA) is a notorious superbug which poses serious health threats to humanity. The severity of the infections depends on the prevalence of virulence factors and antibiotic resistance. In this study, attempts have been made to nominate the two most virulent and multidrug-resistant MRSA isolates demonstrating the preliminary features of intestinal adhesion for the futuristic applications of probiotics and postbiotics as antagonists to combat MRSA infections. In this context, six clinical isolates of MRSA were polyphasically characterized for their identity, multidrug resistance, and few selected virulence determinates such as hemolytic activity and production of coagulase, nuclease, and capsule. The gut colonizing ability of MRSA isolates was assessed by mucoadhesion, auto-aggregation, and cell surface hydrophobicity. An antibiogram of MRSA isolates suggested the resistance towards several antibiotics with multiple antibiotic resistance (MAR) index >0.5 (12/241, 12/206, and 5/255) as well as their genome portraying mecA mediated methicillin resistance. Besides exhibiting strong biofilm formation ability, all the isolates exhibited positive responses towards tested virulence assays coupled with their genome displaying Coa, NucA, and CapE genes. On the other hand, isolates exhibited different levels of auto-aggregation (37.90 ± 1.8 to 51.53 ± 3.1%) and mucin adhesion ability (68.93 ± 0.61% to 86.62 ± 1.96%) with a significant (P ≤ 0.05) variation in adhesion to different hydrocarbons. Finally, multivariate Principal Component Analysis and Hierarchical Cluster Analysis (HCA) heatmap using Euclidean distance measurement indicated MRSA 12/206 and 5/255 as most resistant and virulent isolates with the potential to adhere to the hydrophobic gut niche.

Antibacterial of Cinnamon Bark (Cinnamomum burmannii) Essential Oil Against Methicillin-Resistant Staphylococcus aureus

This study aimed to determine the in vitro antibacterial activities of essential oil from cinnamon bark (Cinnamomum burmannii) on Methicillin-resistant Staphylococcus aureus (MRSA) isolated from raw milk. Essential oil from cinnamon bark obtained from the steam distillation method and essential oil was made in a series dilution with a concentration of 1%, 2%, 4%, and 8%. The antibacterial activities were tested using the disk diffusion method. Results showed from five isolates of MRSA, one isolate was sensitive of essential oil with a concentration 2% and all of the isolate was sensitive with a concentration 4% and 8%. The antibacterial activity showed by inhibition zones on MRSA. The results suggest that the activity of the essential oils of cinnamon bark has an antibacterial effect on MRSA and it is developed as phytopharmaca.

The First Report of a Methicillin-Resistant Staphylococcus aureus Isolate Harboring Type IV SCCmec in Thailand.

Methicillin-resistant Staphylococcus aureus (MRSA) is mostly found in Thailand in the hospital as a nosocomial pathogen. This study aimed to report the genetic characterization of a clinical community-acquired MRSA (CA-MRSA) isolate collected from hospitalized patients in Thailand. Among 26 MRSA isolates, S. aureus no. S17 preliminarily displayed the presence of a staphylococcal cassette chromosome mec (SCCmec) type IV pattern. The bacterial genomic DNA was subjected to whole-genome sequencing. Panton–Valentine leukocidin (PVL) production, virulence toxins, and antibiotic resistance genes were identified, and multi-locus sequence typing (MLST) and spa typing were performed. The strain was matched by sequence to MLST type 2885 and spa type t13880. This strain carried type IV SCCmec with no PVL production. Five acquired antimicrobial resistance genes, namely blaZ, mecA, Inu(A), tet(K), and dfrG conferring resistance to β-lactams, lincosamides, tetracycline, and trimethoprim, were identified. The detected toxins were exfoliative toxin A, gamma-hemolysin, leukocidin D, and leukocidin E. Moreover, there were differences in seven regions in CR-MRSA no. S17 compared to CA-MRSA type 300. In summary, we have reported the ST2885-SCCmec IV CA-MRSA clinical strain in Thailand for the first time, highlighting the problem of methicillin resistance in community settings and the consideration in choosing appropriate antibiotic therapy.

A Molecular Insight into the Synergistic Mechanism of Nigella sativa (Black Cumin) with β-Lactam Antibiotics against Clinical Isolates of Methicillin-Resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) infection is detrimental to hospitalized patients. With diminishing choices of antibiotics and the worry about resistance to colistin in synergistic combined therapy, there are suggestions for the use of herbal derivatives. This investigation evaluated the synergistic effects of Nigella sativa (NS) in combination with beta-lactam (β-lactam) antibiotics on extreme drug-resistant (XDR) MRSA isolates. NS concentrations of 10, 7.5, 5.0, 2.5, 1.0, and 0.1 µg/mL, alone and in combination with β-lactam antibiotics, were used to determine the antimicrobial susceptibility of MRSA isolates by the well diffusion method. Time–kill assays were performed using a spectrophotometer, with time–kill curves plotted and synergism ascertained by the fractional inhibitory concentration (FIC). Scanning and transmission electron microscopy were used to gain insight into the mechanism of action of treated groups. Isolates were inhibited by the NS concentrations, with differences in the zones of inhibition being statistically insignificant at p < 0.05. There were statistically significant differences in the time–kill assay for the MRSA isolates. In addition, NS combined with augmentin showed better killing than oxacillin and cefuroxime. The mechanism of action shown by the SEM and TEM results revealed cell wall disruption, which probably created interference that led to bacterial lysis.

Phenotype-Genotype Characterization and Antibiotic-Resistance Correlations Among Colonizing and Infectious Methicillin-Resistant Staphylococcus aureus Recovered from Intensive Care Units.

IntroductionMethicillin-resistant Staphylococcus aureus (MRSA) presents a profound hazard to public health. MRSA colonizing skin, mucous membranes, and the anterior nares without clinical symptoms is termed “colonizing MRSA”. Upon manifestation of clinical symptoms, it is termed “infectious MRSA”. Here, we characterize and differentiate colonizing and infectious MRSA, and analyze the phenotypic-genotypic and antibiotic susceptibility correlations.MethodologyClinical MRSA isolates were recovered from intensive care units (ICUs) of two major Egyptian hospitals and their biofilm formation ability was tested. Antibiograms against 16 antibiotics were determined, in addition to the minimum inhibitory concentrations (MICs) of vancomycin and linezolid. The entire collection was typed by enterobacterial repetitive intergenic consensus (ERIC)-PCR, as well as multi-locus sequence typing (MLST). Representative resistance and virulence genes were detected by PCR amplification.ResultsForty-nine isolates were confirmed as MRSA, of which 30 isolates were infectious and 19 were colonizing. Versatile resistance patterns were observed in both groups of isolates. We report a higher tendency for biofilm-formation and borderline minimum inhibitory concentrations among infectious isolates. A Positive antibiotic correlation was observed between susceptibility to protein synthesis inhibitors and cell wall inhibitors. Positive correlations were observed between isolation site and rifampicin resistance: nasal samples were enriched in rifampicin-resistant isolates, while urine and blood samples were enriched in susceptible ones. Furthermore, biofilm formation ability was slightly associated with amikacin resistance, and an association between teicoplanin resistance and the presence of the Panton-Valentine leukocidin gene was the only significant phenotype-genotype correlation observed. Finally, ERIC typing and MLST had congruent results.ConclusionLinezolid and vancomycin are still the most convenient choice for MRSA treatment. ERIC PCR and MLST show promising typing combination that could be easily used periodically for tracking the genotypic changes of MRSA, especially within the healthcare facilities. Several correlations were established between groups of antibiotics and the genotypes/phenotypes of the selected isolates.

Microbiological evaluation in oral health units: detection of antibiotic resistant bacteria

Introduction The environment in oral health care units can represent an important source of transmission of infections, which can be acquired through aerosols, bleeding, saliva and respiratory secretions [1]. It is increasingly important to prevent cross-infection in dental clinics [2]. Resistance to antibiotics is a serious public health problem. Presence of resistant microorganisms in health care units is a worrying reality, but little is known about oral health care units [3]. The aim of this study was the detection of microorganisms resistant to antibiotics at the Clínica Dentária Egas Moniz, in the dentist’s chair, trays and lamp handles. Materials and methods Environmental samples were collected at the dental clinic with a swab. Sampling was made at trays, chairs and lamp handles, at the end of the appointments. All samples were inoculated in Trypticase soy agar (TSA), Mannitol salt agar (MSA) and MacConkey agar. All the bacteria that grew in MSA and were mannitol positive were inoculated in chromogenic agar, because we wanted to detect Methicillin resistant Staphylococcus aureus (MRSA). Results Of the 123 samples obtained in 41 working stations, only two (1.6%) lactose negative bacteria were found. One was isolated from a tray and the other from a lamp handle, in two different working stations. We found 51 mannitol positive Staphylococcus samples (41.5%), were isolated from 36 different working stations, being 14 samples identified as MRSA (11.4%). These MRSA were isolated from 13 different working stations. In our study, we cannot identify if there was a preferential location for the presence of MRSA, but we found it mainly at trays and dentist’s chairs. Discussion and conclusions There was a low contamination by Enterobacteriaceae. However, a percentage of MRSA isolation of 11.4% was obtained. There are few similar studies. Although, in a study where 95 surfaces from 7 different university dental clinics were evaluated, 8 MRSA were found, which corresponds to 8.4%. Comparing to our study, we obtained a slightly higher percentage. These results demonstrate that oral health care units are also sites of contamination, where bacteria with resistance to antibiotics can circulate. They also reinforce the need for good hygiene and disinfection of the site between appointments.

EVALUATION OF SOME ANTIBIOTIC RESISTANCE IN STAPHYLOCOCCUS AUREUS ISOLATED BY MEDICAL LABORATORIES ADEN, YEMEN

The study was carried out to determine antibacterial resistance profiles of methicillin-resistant Staphylococcus aureus (MRSA) isolates from clinical samples of patients during the duration, from January 2019 to July 2020 in five governmental and private medical laboratories of Aden governorate, Yemen. A total of 267 MRSA isolates were tested with a disc diffusion method from 4 clinical specimens. The isolates were examined for methicillin resistance using vancomycin, erythromycin, amikacin, and gentamicin.
 The results revealed a large number of MRSA isolates showed resistance to erythromycin (43.5%) and Vancomycin (28%). A lower number of MRSA isolates showed resistance to amikacin (6.25%), gentamicin (11.75%). A majority of MRSA isolates were from urine specimen (162) followed by (56) wounds, (34) pus, and (25) semen specimens. The highest proportion of MRSA isolates were obtained from Al-medina medical laboratory (31%) and Alborg laboratory (24%).

Presence of Methicillin-Resistant Staphylococcus aureus (MRSA) on Healthcare Workers' Attire: A Systematic Review.

Contaminated healthcare workers’ (HCW) clothing risk transferring methicillin-resistant Staphylococcus aureus (MRSA) in healthcare facilities. We performed a systematic review in Pubmed and Scopus for 2000–2020 according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines to analyze evidence of MRSA on HCW attire. The primary study outcome was MRSA isolation rates on HCW clothing in healthcare settings. Out of 4425 articles, 23 studies were included: 18 with 1760 HCWs, four with 9755 HCW–patient interactions and one with 512 samples. There was a notable variation in HCWs surveyed, HCW attires, sampling techniques, culture methods and laundering practices. HCW attire was frequently colonized with MRSA with the highest rates in long-sleeved white coats (up to 79%) and ties (up to 32%). Eight studies reported additional multidrug-resistant bacteria on the sampled attire. HCW attire, particularly long-sleeved white coats and ties, is frequently contaminated with MRSA. Banning certain types and giving preference to in-house laundering in combination with contact precautions can effectively decrease MRSA contamination and spread.

Increased Incidence and Plasma-Biofilm Formation Ability of SCCmec Type IV Methicillin-Resistant Staphylococcus aureus (MRSA) Isolated From Patients With Bacteremia.

In Japan, Staphylococcal cassette chromosome mec (SCCmec) type IV methicillin-resistant Staphylococcus aureus (MRSA) is an increasingly prominent cause of bacteremia, but the virulence of most of these strains is unclear. We aimed to investigate the relationship between the molecular characteristics and the ability to form biofilms in the presence of blood plasma (plasma-biofilms) of MRSA strains isolated from bloodstream infections. In this study, the molecular characteristics and biofilms of MRSA strains isolated from blood cultures between 2015 and 2017 were analyzed by PCR-based assays, crystal violet staining, and confocal reflection microscopy methods. Among the 90 MRSA isolates, the detection rate of SCCmec type II clones decreased from 60.7 to 20.6%. The SCCmec type IV clone replaced the SCCmec type II clone as the dominant clone, with a detection rate increasing from 32.1 to 73.5%. The plasma-biofilm formation ability of the SCCmec type IV clone was higher than the SCCmec type II clone and even higher in strains harboring the cna or arcA genes. Plasma-biofilms, mainly composed of proteins, were formed quickly and strongly. Our study demonstrated the increased plasma-biofilm formation ability of SCCmec type IV strains.

Antibiotic Sensitivity to Methicillin and Methicillin Plus Macrolide- Lincosamide-Streptogramins Resistant Staphylococcus Aureus

This study was conducted from May 2018 to Oct 2019 to determine the culture and sensitivity pattern of Methicillin resistant Staphylococcus aureus (MRSA) and MRSA with Macrolide Lincosamide and Streptogramin-B (MLS-B) antibiotics in a tertiary care hospital of Nowshera. A total of 235 isolates were studies and 86 samples showed MRSA. The prevalence rate of MRSA was 89/235 (37.87%). Out of 86 isolates with MRSA, 19 (22.09%) were also resistant to MLS-B antibiotics.Regarding gender specification, 52 (60.5%) were females and 34 (39.5%) were males. The mean age with standard deviation of patients was 29 + 6.8 years. The sensitivity pattern to MRSA was; Vancomycin 100%, Linezolid 100%, Rifampicin 86.04%, Clindamycin, 73.25%, Fusidic acid 60.46%, Erythromycin 44.18%., Doxycyclin 32.55%, levofloxacin 16.27%, Gentamycin 13.95% and Ciprofloxacin 11. 62%. Sensitivity of Vancomycin & Linezolid was 100% in MRSA and MLS-B resistant isolates, and should be kept reserved for MRSA cases to avoid misuse of antibiotics and to reduce resistance.

Prevalence and Multidrug Resistance Pattern of Methicillin Resistant S. aureus Isolated from Frozen Chicken Meat in Bangladesh.

Infections by methicillin-resistant Staphylococcus aureus (MRSA) are continuously expanding within the community. Chicken meat is usually contaminated by MRSA, and this contaminated chicken meat is an important source of foodborne infections in humans. In this study, a cross-sectional supershop survey was conducted to determine the prevalence and antimicrobial resistance pattern of MRSA in 113 domestic frozen chicken meat samples purchased from nine branded supershops available in five divisional megacities of Bangladesh. The study also focused on the determination of methicillin resistance gene in MRSA isolates. S. aureus was identified by standard culture-based and molecular methods, and subjected to antimicrobial susceptibility testing. MRSA was screened by cefoxitin disk diffusion test. Methicillin resistance gene was identified by PCR. Of samples, 54.9% were positive for S. aureus, and, of these, 37.1% isolates were identified as MRSA. All the isolates were multidrug resistant (MDR): 52.2% were resistant to 6–8 antimicrobial classes, and 47.8% isolates to 9–12 classes. Three (3.2%) isolates of S. aureus were possible extensively drug resistant. The highest rates of resistance were observed against cefoxitin (100%), followed by nalidixic acid, ampicillin and oxacillin (97.7%), colistin (91.3%), amoxicillin-clavulanic acid and amoxicillin (87%), penicillin-G and cloxacillin (82.6%), oxytetracycline (78.3%), and cefixime (73.9%). Screening of methicillin resistance gene revealed that 43.5% isolates of MRSA were positive for mecA gene. The high prevalence of MDR MRSA in frozen chicken meat samples in this study emphasizes the need for better sanitary education of food handlers in hygienic practices focusing on their potential role as reservoirs and spreaders of MRSA.

Shedding of methicillin-resistant Staphylococcus aureus and multidrug-resistant gram-negative bacilli during outpatient appointments and procedures outside hospital rooms

Limited information is available on the frequency of and risk factors for shedding of health care-associated pathogens in settings outside patient rooms. We conducted a cohort study of hospitalized or recently discharged patients with methicillin-resistant Staphylococcus aureus (MRSA) (N = 39) or multidrug-resistant gram-negative bacilli (MDR-GNB) (N = 11) colonization to determine the frequency of environmental shedding during appointments outside hospital rooms or during outpatient clinic visits. Chi-square tests were performed to identify patient-level factors associated with environmental shedding. Spa typing was performed for environmental and nasal MRSA isolates. Of 50 patients enrolled, 39 were colonized with MRSA and 11 with MDR-GNB. Shedding during 1 or more appointments occurred more often for patients colonized with MRSA versus MDR-GNB (15 of 39, 38.5% versus 0 of 11, 0%; P = .02). The presence of a wound with a positive culture for MRSA was associated with shedding of MRSA during appointments (11 of 15, 73.3% with shedding versus 4 of 24, 16.7% with no shedding; P = .008). Eighty percent of environmental MRSA isolates were genetically related to concurrent nasal isolates based on spa typing. Environmental shedding of MRSA occurs frequently during appointments outside hospital rooms or during outpatient clinic visits. Decontamination of surfaces and strategies that reduce shedding of MRSA could reduce the risk for transmission in these settings.

The Prevalence of Staphylococcus aureus and the Occurrence of MRSA CC398 in Monkey Feces in a Zoo Park in Eastern China.

Simple SummaryThe increasing observation of methicillin-resistant Staphylococcus aureus (MRSA) in wildlife species has raised the concern of its impact on the animal health and the potential of zoonotic transmission. The molecular types of MRSA and S. aureus in wild animals has been found to mix with several molecular types from humans and livestock, indicating a dynamics of S. aureus transmission between these animals and humans. Thus, it is important to investigate the epidemiological relationship of MRSA between zoo animals and humans. To investigate the prevalence and transmission of S. aureus in non-human primates and their living environment, we conducted this study on all the non-human primates in a zoo park located in eastern China. Fecal samples from non-human primates and samples from their living environments were selectively enriched and conducted for S. aureus isolation. The whole genome analysis showed that these two MRSA t034/CC398 isolates were found from a monkey fecal sample and its living environment. The virulence factor analysis showed that these two MRSA isolates carried virulence factors relating to the cell adherence, biofilm formation, toxins, and human-associated immune evasion cluster. The further phylogenetic analysis revealed that these two MRSA isolates have a close genomic relationship with the human-associated clinical isolates from China, which indicates a potential risk of bidirectional transfer of MRSA between monkeys and humans.Methicillin-resistant Staphylococcus aureus (MRSA) is one of the important antibiotic resistant pathogens causing infections in humans and animals. The increasing observation of MRSA in wildlife species has raised the concern of its impact on animal health and the potential of zoonotic transmission. This study investigated the prevalence of S. aureus in fecal samples from non-human primates in a zoo located in Jiangsu, China, in which 6 out of 31 (19.4%) fecal samples, and 2 out of 14 (14.3%) indoor room floor swab samples were S. aureus-positive. The antibiotic susceptibility tests of the eight isolates showed that the two isolates were resistant to both penicillin and cefoxitin, the three isolates were resistant only to penicillin, while three isolates were susceptible to all detected antibiotics. The two isolates resistant to cefoxitin were further identified as MRSA by the presence of mecA. Five different spa types were identified including t034 of two MRSA isolates from Trachypithecus francoisi, t189 of two methicillin-susceptible S. aureus (MSSA) isolates from Rhinopithecus roxellana, t377 of two MSSA isolates from Colobus guereza, and two novel spa types t19488 and t19499 from Papio anubis. Whole genome sequencing analysis showed that MRSA t034 isolates belonged to ST398 clustered in clonal complex 398 (CC398) and carried the type B ΦSa3 prophage. The phylogenetic analysis showed that the two MRSA t034/ST398 isolates were closely related to the human-associated MSSA in China. Moreover, two MRSA isolates contained the virulence genes relating to the cell adherence, biofilm formation, toxins, and the human-associated immune evasion cluster, which indicated the potential of bidirectional transfer of MRSA between monkeys and humans. This study is the first to report MRSA CC398 from monkey feces in China, indicating that MRSA CC398 could colonize in monkey and have the risk of transmission between humans and monkeys.

Prevalence of PVL and LucED Genes in Methicillin-Resistant and Susceptible Isolates of Staphylococcus aureus Isolated from Burn Patients in Kermanshah, Iran

Background: The main pathogen causing various nosocomial infections, especially in burn patients, is Staphylococcus aureus. An important virulence factor of this bacterium is leukocidin, which binds to white blood cells and leads to apoptosis and necrosis. Objectives: In the present research, we aimed at investigating the prevalence of the panton-valentine leukocidin (PVL) and LucED genes in methicillin-susceptible and resistant isolates of S. aureus isolated from burn patients in Kermanshah, Iran. Methods: Overall, 73 isolates of S. aureus were collected from burn wounds and identified by specific biochemical tests. After determining the susceptibility patterns of the isolates by the disc diffusion method, the frequencies of the PVL and LucED genes were assessed using specific primers and polymerase chain reactions. Results: The rates of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible Staphylococcus aureus (MSSA) isolates were 58.9% (43 isolates) and 41.1% (30 isolates), respectively. In MRSA isolates, the highest antibiotic resistance was to penicillin (100%) and gentamicin (81.4%). Moreover, the frequencies of the LucED and PVL genes were 76.7% (56 isolates) and 27.4% (20 isolates), respectively, and the highest frequency of the LucED and PVL genes was observed in MRSA (81.4%) and MSSA (40%) isolates, respectively. Conclusions: Increased multidrug resistance pattern among S. aureus isolates with leukocidin production has led to treatment failure and severe infections. The development of infections can be prevented by the identification of isolates carrying the leukocidin gene, and early detection of MRSA isolates is feasible by using the PVL gene.

Human DNA methylation signatures differentiate persistent from resolving MRSA bacteremia

Persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia is life threatening and occurs in up to 30% of MRSA bacteremia cases despite appropriate antimicrobial therapy. Isolates of MRSA that cause antibiotic-persistent methicillin-resistant S. aureus bacteremia (APMB) typically have in vitro antibiotic susceptibilities equivalent to those causing antibiotic-resolving methicillin-resistant S. aureus bacteremia (ARMB). Thus, persistence reflects host-pathogen interactions occurring uniquely in context of antibiotic therapy in vivo. However, host factors and mechanisms involved in APMB remain unclear. We compared DNA methylomes in circulating immune cells from patients experiencing APMB vs. ARMB. Overall, methylation signatures diverged in the distinct patient cohorts. Differentially methylated sites intensified proximate to transcription factor binding sites, primarily in enhancer regions. In APMB patients, significant hypomethylation was observed in binding sites for CCAAT enhancer binding protein-β (C/EBPβ) and signal transducer/activator of transcription 1 (STAT1). In contrast, hypomethylation in ARMB patients localized to glucocorticoid receptor and histone acetyltransferase p300 binding sites. These distinct methylation signatures were enriched in neutrophils and achieved a mean area under the curve of 0.85 when used to predict APMB using a classification model. These findings validated by targeted bisulfite sequencing (TBS-seq) differentiate epigenotypes in patients experiencing APMB vs. ARMB and suggest a risk stratification strategy for antibiotic persistence in patients treated for MRSA bacteremia.

Methicillin-Resistant Staphylococcus aureus Clonal Complex 398 as a Major MRSA Lineage in Dogs and Cats in Thailand.

The aim of this study was to present molecular and antimicrobial resistance characteristics of methicillin-resistant Staphylococcus aureus (MRSA) clonal complex (CC) 398 isolated from diseased dogs and cats in Thailand. A total of 20 MRSA isolates of 134 Staphylococcus aureus isolated from canine and feline clinical samples during 2017–2020 were CC398, consisting of sequence type (ST) 398 (18 isolates), ST5926 (1 isolate), and ST6563 (1 isolate) by multilocus sequence typing. spa t034 and staphylococcal cassette chromosome mec (SCCmec) V were predominantly associated with ST398. Intraclonal differentiation was present by additional spa (t1255, t4653), non-detectable spa, composite SCCmec with a hybrid of ccrA1B1+ccrC and class A mec complex, and DNA fingerprints by pulsed-field gel electrophoresis. The isolates essentially carried antimicrobial resistance genes, mediating multiple resistance to β-lactams (mecA, blaZ), tetracyclines [tet(M)], aminoglycosides [aac(6′)-Ie-aph(2′)-Ia], and trimethoprim (dfr). Livestock-associated MRSA ST398 resistance genes including lnu(B), lsa(E), spw, fexA, and tet(L) were heterogeneously found and lost in subpopulation, with the absence or presence of additional erm(A), erm(B), and ileS2 genes that corresponded to resistance phenotypes. As only a single CC398 was detected with the presence of intraclonal variation, CC398 seems to be the successful MRSA clone colonizing in small animals as a pet-associated MRSA in Thailand.

Effects of cefazolin-containing niosome nanoparticles against methicillin-resistant Staphylococcus aureus biofilm formed on chronic wounds

The ability of biofilm formation in methicillin-resistant Staphylococcus aureus (MRSA) causes significant mortality and morbidity in wound infections. Nanoparticles because of the drug concentration increment at the point of contact of nanoparticles and bacteria, and slower release of the drug at the desired location are considered as proper tools to overcome the therapeutic problem of antimicrobial-resistant infections. This study was aimed to evaluate the anti-biofilm activity of cefazolin-loaded nanoparticles against MRSA isolates. The 27 clinical isolates of MRSA were collected from patients with pressure sores and diabetic ulcers referred to Loghman Hospital in Tehran—Iran. MRSA isolates were detected by polymerase chain reaction (PCR) and biochemical tests. Cefazolin-loaded niosome was synthesized using the thin-film hydration method and were characterized by zeta potential measurement and transmission electron microscopy (TEM). The round-shaped cefazolin-loaded niosomes had a diameter of 100 nm and a −63 mV zeta potential. The cefazolin-containing niosomes removed 1, 3, and 5 d old biofilms at the concentration of 128 µg ml−1, 128 µg ml−1, and 256 µg ml−1, respectively. Histological results indicated that BALB/c mice receiving cefazolin-loaded niosomes were treated effectively faster than those treated by cefazolin or untreated group. In conclusion, the cefazolin-loaded niosome could be considered as a promising candidate for the treatment of biofilm-mediated infections of MRSA.

Detection of a cfr-positive MRSA CC398 strain in a pig farmer in Spain

ObjectiveTo characterize one linezolid- and methicillin-resistant Staphylococcus aureus (MRSA) isolate recovered from a nasal sample of a pig farmer patient. MethodsThe detection of linezolid resistance mechanisms was performed by PCR and sequencing. The antimicrobial resistance and virulence profile was investigated, and the molecular typing was performed by molecular techniques. The transference of cfr gene was assessed by conjugation experiments and its genetic environment was investigated by specific PCRs. ResultsThe linezolid-resistant MRSA isolate was typed as t011-ST398/CC398-SCCmecV-agrI and carried the cfr gene. The isolate was multidrug-resistant but lacked the virulence genes studied. The cfr gene was co-located with the fexA gene on a Tn558 variant and was successfully transferred by conjugation. ConclusionWe report the first description of LA-MRSA-CC398 carrying the cfr gene in Spain. This finding highlights the importance of surveillance programmes to determine the presence and spread of the cfr gene in the livestock and clinical settings.

Predominance of PVL-negative community-associated methicillin-resistant Staphylococcus aureus sequence type 8 in newly diagnosed HIV-infected adults, Tanzania

Difficult-to-treat infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are of concern in people living with HIV infection as they are more vulnerable to infection. We aimed to identify molecular characteristics of MRSA colonizing newly diagnosed HIV-infected adults in Tanzania. Individuals newly diagnosed with HIV infection were recruited in Dar es Salaam, Tanzania, from April 2017 to May 2018, as part of the randomized clinical trial CoTrimResist (ClinicalTrials.gov identifier: NCT03087890). Nasal/nasopharyngeal isolates of Staphylococcus aureus were susceptibility tested by disk diffusion method, and cefoxitin-resistant isolates were characterized by short-reads whole genome sequencing. Four percent (22/537) of patients carried MRSA in the nose/nasopharynx. MRSA isolates were frequently resistant towards gentamicin (95%), ciprofloxacin (91%), and erythromycin (82%) but less often towards trimethoprim-sulfamethoxazole (9%). Seventy-three percent had inducible clindamycin resistance. Erythromycin-resistant isolates harbored ermC (15/18) and LmrS (3/18) resistance genes. Ciprofloxacin resistance was mediated by mutations of the quinolone resistance-determining region (QRDR) sequence in the gyrA (S84L) and parC (S80Y) genes. All isolates belonged to the CC8 and ST8-SCCmecIV MRSA clone. Ninety-five percent of the MRSA isolates were spa-type t1476, and one exhibited spa-type t064. All isolates were negative for Panton-Valentine leucocidin (PVL) and arginine catabolic mobile element (ACME) type 1. All ST8-SCCmecIV-spa-t1476 MRSA clones from Tanzania were unrelated to the globally successful USA300 clone. Carriage of ST8 MRSA (non-USA300) was common among newly diagnosed HIV-infected adults in Tanzania. Frequent co-resistance to non-beta lactam antibiotics limits therapeutic options when infection occurs.

Assessment of indoor air bacterial load and antibiotic susceptibility profile of bacteria from some hospitals in Dutse, Jigawa State

Indoor air microbial communities play significant roles on the increase in hospitals acquired infections globally. In view of the importance of indoor air bacterial quality in the transmission of nosocomial infections, a study was conducted to assess the air bacterial load and antibiotic susceptibility profile of bacteria from some hospitals in Dutse, Jigawa State. A total of 114 air samples were collected and analyzed using standard procedures from wards and units of Rasheed Shekoni Teaching Hospital Dutse, General Hospital Dutse and Primary Health Care Centre Shuwarin. Settling platetechnique was employed and sampling was done twice daily (Morning and Afternoon). Aerobic mesophilic bacterial counts were conducted. Isolates were identified according to standard methods. The Medical Surgical Ward (MSW) revealed the highest airborne bacterial count (2.770x103 CFU/m3). General Hospital Dutse was found to have a higher indoor bacterial load than Rasheed Shekoni Teaching Hospital and Primary Healthcare Centre Shuwarin. Airborne Gram positive cocci were the most frequently detected (100%) in all the indoor environments. Staphylococcus aureus, Klebsiella pneumoniae, Proteus mirabilis and Escherichia coli were the bacterial species identified in the study. It was observed that the bacterial isolates were more susceptible to gentimicin. The findings revealed the presence of five (5) methicillin resistant staphylococcus aureus isolates (MRSA) 60% in Male Medical Ward (MMW), 20% in Female Medical Ward (FMW), and 20% in Post-natal Ward (PNW). In conclusion, 84.2% of the hospitals’ units were having aerobic mesophilic bacterial counts within the acceptable limits. It is recommended that disinfection of male, female and post-natal wards should be intensified.