Genomic characterization of methicillin-resistant Staphylococcus aureus isolated from patients attending regional referral hospitals in Tanzania.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) colonization increases the risk of subsequent infection by MRSA strain complex interlinking between hospital and community-acquired MRSA which increases the chance of drug resistance and severity of the disease. OBJECTIVE: Genomic characterization of Staphylococcus aures strains isolated from patients attending regional referral hospitals in Tanzania. METHODOLOGY: A laboratory-based cross-sectional study using short read-based sequencing technology, (Nextseq550,Illumina, Inc. San diego, California, USA). The samples used were collected from patients attending selected regional referral hospitals in Tanzania under the SeqAfrica project. Sequences were analyzed using tools available in the center for genomic and epidemiology server, and visualization of the phylogenetic tree was performed in ITOL 6.0. SPSS 28.0 was used for statistical analysis. RESULTS: Among 103 sequences of S. aureus, 48.5% (50/103) carry the mecA gene for MRSA. High proportions of MRSA were observed among participants aged between 18 and 34 years (52.4%), in females (54.3%), and among outpatients (60.5%). The majority of observed MRSA carried plasmids rep5a (92.0%), rep16 (90.0%), rep7c (90.0%), rep15 (82.0%), rep19 (80.0%) and rep10 (72.0%). Among all plasmids observed rep5a, rep16, rep20, and repUS70 carried the blaZ gene, rep10 carried the erm(C) gene and rep7a carried the tet(K) gene. MLST and phylogeny analysis reveal high diversity among MRSA. Six different clones were observed circulating at selected regional hospitals and MRSA with ST8 was dominant. CONCLUSION: The study reveals a significant presence of MRSA in Staphylococcus aureus strains from Tanzanian regional hospitals, with nearly half carrying the mecA gene. MRSA is notably prevalent among young adults, females, and outpatients, showing high genetic diversity and dominance of ST8. Various plasmids carrying resistance genes indicate a complex resistance profile, highlighting the need for targeted interventions to manage MRSA infections in Tanzania.

Clinical features and prognosis of prosthetic valve endocarditis due to Staphylococcus aureus.

PURPOSE: Staphylococcus aureus prosthetic valve endocarditis (SAPVE) is a serious infection with high mortality. The main objective of this study was to identify factors associated with in-hospital mortality. METHODS: From January 2008 to December 2021, consecutive patients from a Spanish cohort of infective endocarditis with a definitive diagnosis of SAPVE were analyzed. RESULTS: During the study period, 219 cases of definitive SAPVE were diagnosed, which accounted for 16.7% of a total of 1309 cases of definitive prosthetic valve endocarditis (PVE). Patients presented advanced age and marked comorbidity. There was a higher incidence of persistent bacteremia, septic shock, stroke, and acute kidney injury than in cases of PVE caused by other microorganisms. Methicillin resistance was not associated with differences in clinical presentation, echocardiographic findings, or mortality. Only 50.6% of the patients with surgical indications (88 patients) underwent surgery. Overall, in-hospital mortality was 47.9%. The variables associated with in-hospital mortality were age (OR:1.03, 95% CI: 1.00-1.05; p = 0.016), heart failure (OR:2.86, 95% CI: 1.53-5.32; p = 0.001), acute kidney injury (OR:2.42, 95%CI:1.28-4.58; p = 0.006), stroke (OR:3.53, 95%CI:1.79-6.96; p < 0.001) and surgery indicated but not performed (OR:2.01, 95%CI:1.06-3.8; p = 0.030). On the other hand, the performance of surgery per se in patients with SAPVE, regardless of whether there was a surgical indication according to the guidelines, was not associated with a reduction in in-hospital mortality. CONCLUSIONS: SAPVE is characterized by high mortality, which is more marked in patients who present a surgical indication but do not undergo surgery.

Improving the treatment of bacterial infections caused by multidrug-resistant bacteria through drug repositioning.

Drug repurposing (repositioning) is a dynamically-developing area in the search for effective therapy of infectious diseases. Repositioning existing drugs with a well-known pharmacological and toxicological profile is an attractive method for quickly discovering new therapeutic indications. The off-label use of drugs for infectious diseases requires much less capital and time, and can hasten progress in the development of new antimicrobial drugs, including antibiotics. The use of drug repositioning in searching for new therapeutic options has brought promising results for many viral infectious diseases, such as Ebola, ZIKA, Dengue, and HCV. This review describes the most favorable results for repositioned drugs for the treatment of bacterial infections. It comprises publications from various databases including PubMed and Web of Science published from 2015 to 2023. The following search keywords/strings were used: drug repositioning and/or repurposing and/or antibacterial activity and/or infectious diseases. Treatment options for infections caused by multidrug-resistant bacteria were taken into account, including methicillin-resistant staphylococci, multidrug-resistant Mycobacterium tuberculosis, or carbapenem-resistant bacteria from the Enterobacteriaceae family. It analyses the safety profiles of the included drugs and their synergistic combinations with antibiotics and discusses the potential of antibacterial drugs with antiparasitic, anticancer, antipsychotic effects, and those used in metabolic diseases. Drug repositioning may be an effective response to public health threats related to the spread of multidrug-resistant bacterial strains and the growing antibiotic resistance of microorganisms.

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

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

Molecular detection of multidrug and methicillin resistance in Staphylococcus aureus isolated from wild pigeons (Columba livia) in South Africa.

Staphylococcus aureus is an important human and veterinary pathogen. The present study aimed to determine the prevalence of antibiotic resistance among S. aureus isolated from samples obtained from free-flying wild pigeons and houseflies from different locations surrounding a local hospital in the Greater Durban area in KwaZulu-Natal Province, South Africa. Environmental fecal samples were obtained from wild pigeons that inhabits the grounds of a local public hospital located on the South Beach area, Durban, South Africa. Housefly samples were collected from three different locations (Kenneth Stainbank Nature Reserve, Montclair/Clairwood, and Glenwood/Berea) in the greater Durban area, all within a close proximity to the hospital. Following enrichment, identification, and antimicrobial resistance profiling, S. aureus isolates were subjected to DNA extraction using the boiling method. It was found that 57 out of 252 samples (22.62%) were positive for S. aureus. The Kirby-Bauer disk diffusion method of antibiotic susceptibility testing was performed and revealed that antibiotic resistance rates to penicillin and rifampicin were the most common, with both returning 48 (84.2%) out of the 57 S. aureus isolates being resistant to penicillin and rifampicin. Antibiotic resistance rates to clindamycin, linezolid, erythromycin, tetracycline, cefoxitin, and ciprofloxacin were 82.5%, 78.9%, 73.7%, 63.2%, 33.3%, and 15.8% respectively. Antibiotic resistance genes were detected using primer-specific PCR and it was found that the prevalence rates of tetM, aac(6')-aph(2″), mecA, tetK, ermc, and blaZ genes were 66.7%, 40.4%, 40.4%, 38.6%, 24.6%, and 3.51% respectively. Statistical analysis revealed significant (p < 0.05) relationships between the tetM, aac(6')-aph(2″), and ermC genes and all parameters tested. A significant correlation between the aac(6')-aph(2″) gene and the tetM (0.506) and ermC (-0.386) genes was identified. It was found that 23 (40.3%) S. aureus isolates were mecA positive, of which 10 (52.6%) out of 19 cefoxitin-resistant isolates were mecA positive and 13 (35.1%) out of 37 cefoxitin-sensitive isolates were mecA positive. The results of the present study demonstrated the detection of methicillin and multidrug resistant S. aureus isolated from samples obtained from wild pigeons and houseflies in the surroundings of a local public hospital in the Greater Durban area in South Africa. The findings of the study may account for the emergence of multidrug-resistant staphylococcal infections. The findings highlight the significant role of wild pigeons and houseflies in the spread of drug-resistant pathogenic S. aureus including MRSA. The conclusions of the present study highlight the improtant role of wildlife and the environment as interconnected contributors of One Health.

Proteomic assay for rapid characterisation of Staphylococcus aureus antimicrobial resistance mechanisms directly from blood cultures.

PURPOSE: Staphylococcus aureus is one of the most common pathogens causing bloodstream infection. A rapid characterisation of resistance to methicillin and, occasionally, to aminoglycosides for particular indications, is therefore crucial to quickly adapt the treatment and improve the clinical outcomes of septic patients. Among analytical technologies, targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) has emerged as a promising tool to detect resistance mechanisms in clinical samples. METHODS: A rapid proteomic method was developed to detect and quantify the most clinically relevant antimicrobial resistance effectors in S. aureus in the context of sepsis: PBP2a, PBP2c, APH(3')-III, ANT(4')-I, and AAC(6')-APH(2''), directly from positive blood cultures and in less than 70 min including a 30-min cefoxitin-induction step. The method was tested on spiked blood culture bottles inoculated with 124 S.aureus, accounting for the known genomic diversity of SCCmec types and the genetic background of the strains. RESULTS: This method provided 99% agreement for PBP2a (n = 98/99 strains) detection. Agreement was 100% for PBP2c (n = 5/5), APH(3')-III (n = 16/16), and ANT(4')-I (n = 20/20), and 94% for AAC(6')-APH(2'') (n = 16/17). Across the entire strain collection, 100% negative agreement was reported for each of the 5 resistance proteins. Additionally, relative quantification of ANT(4')-I expression allowed to discriminate kanamycin-susceptible and -resistant strains, in all strains harbouring the ant(4')-Ia gene. CONCLUSION: The LC-MS/MS method presented herein demonstrates its ability to provide a reliable determination of S. aureus resistance mechanisms, directly from positive blood cultures and in a short turnaround time, as required in clinical laboratories.

Methicillin-resistant coagulase-positive staphylococci in new, middle-aged, and old veterinary hospitals in southern Thailand: A preliminary study.

Background and Aim: Methicillin-resistant coagulase-positive staphylococci (MRCoPS) cause pyoderma, dermatitis, and nosocomial infection. Numerous factors, including indiscriminate antimicrobial use (AMU) in veterinary medicine, cleaning practices, and AMU in hospitals, contribute to MRCoPS. However, the relationship between hospital age and MRCoPS has not yet been investigated. This study aimed to estimate the prevalence of MRCoPS in the treatment and operation rooms of new, middle-aged, and old veterinary hospitals. Materials and Methods: Samples were collected from small animal hospitals in Surat Thani, Nakhon Si Thammarat, and Songkhla in Thailand. Hospitals were defined as those that had been in operation for 5 years (new, n = 5), 5-15 years (middle-aged, n = 6), or >15 years (old, n = 3). Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used to identify 280 samples, and duplex polymerase chain reaction was used to identify resistance genes (mecA and blaZ). The VITEK2® automated system was then used to determine the minimum inhibitory concentration. Results: A total of 57 Staphylococcus species were identified and classified as coagulase-positive staphylococci (CoPS) (22/57, 38.60%) or coagulase-negative staphylococci (35/57, 61.40%), respectively. Nine of the 22 CoPS (40.90%) harbored the mecA gene, and 21 isolates (95.45%) harbored the blaZ gene. Interestingly, more MRCoPS was found in new hospitals (six isolates) than in middle-aged (one isolate) and old hospitals (two isolates), although there was no statistically significant difference in the presence of MRCoPS across new, middle-aged, and old veterinary hospitals (p = 0.095), Kruskal-Wallis test. There is a need for further detailed studies, including an increase in the number of hospitals in various locations. Conclusion: MRCoPS is a nosocomial pathogen that causes zoonotic and recurrent infections in veterinary hospitals. The prevalence of MRCoPS tended to be higher in new hospitals. Areas with heavy animal contact, such as hospital floors, are areas of particular concern, and cleaning/disinfection of these areas must be highlighted in hygiene regimens.

Antibiotic Susceptibility of Staphylococcus Aureus with VanA and MecA Genes.

BACKGROUND: Staphylococcus aureus (S.aureus) is an emerging antibiotic resistant bacterium responsible for various infections in human. Resistance to methicillin and vancomycin are of prime concern in S. aureus. The study aims to determine the minimum inhibitory concentration (MIC) of Vancomycin and evaluate the existence of mecA and vanA genes, associated with antibiotic resistance. METHODS: Clinical specimens from three Kathmandu hospitals were processed and S. aureus was identified using conventional microbiological procedures. MRSA was phenotypically identified with cefoxitin (30µg) disc diffusion, while vancomycin susceptibility was assessed using the Ezy MICTM stripes. The mecA and vanA genes were detected by polymerase chain reaction (PCR). RESULTS: Out of 266 S. aureus samples from various clinical specimen subjected for analysis, 77 (28.9%) were found methicillin-resistant (MRSA) and 10 (3.8%) were observed vancomycin-resistant (VRSA). Vancomycin resistant isolates showed a significant correlation between resistance to ampicillin, chloramphenicol, and cefoxitin. The mecA gene was found in 39 of the MRSA isolates, having 50.64% of MRSA cases, while the vanA gene was detected in 4 of the VRSA cases, constituting 40% of VRSA occurrences. CONCLUSIONS: The strains with higher vancomycin minimum inhibitory concentration values (≥ 1.5 µg/ml) displayed increased resistance rates to various antibiotics compared to strains with lower minimum inhibitory concentration values (< 1.5 µg/ml). The presence of vanA genes was strongly associated (100%) with vancomycin resistance, while the 10.3% mecA gene was identified from MRSA having resistance towards vancomycin also.

The Home Environment Is a Reservoir for Methicillin-Resistant Coagulase-Negative Staphylococci and Mammaliicocci.

Coagulase-negative staphylococci (CoNS) and mammaliicocci are opportunistic human and animal pathogens, often resistant to multiple antimicrobials, including methicillin. Methicillin-resistant CoNS (MRCoNS) have traditionally been linked to hospitals and healthcare facilities, where they are significant contributors to nosocomial infections. However, screenings of non-hospital environments have linked MRCoNS and methicillin-resistant mammaliicocci (MRM) to other ecological niches. The aim of this study was to explore the home environment as a reservoir for MRCoNS and MRM. A total of 33 households, including households with a dog with a methicillin-resistant staphylococcal infection, households with healthy dogs or cats and households without pets, were screened for MRCoNS and MRM by sampling one human, one pet (if present) and the environment. Samples were analyzed by a selective culture-based method, and bacterial species were identified by MALDI-TOF MS and tested for antibiotic susceptibility by the agar disk diffusion method. Following whole-genome sequencing, a large diversity of SCCmec elements and sequence types was revealed, which did not indicate any clonal dissemination of specific strains. Virulome and mobilome analyses indicated a high degree of species specificity. Altogether, this study documents that the home environment is a reservoir for a variety of MRCoNS and MRM regardless of the type of household.

A Web-Based Dynamic Nomogram to Predict the Risk of Methicillin-Resistant Staphylococcal Infection in Patients with Pneumonia.

The aim of this study was to create a dynamic web-based tool to predict the risks of methicillin-resistant Staphylococcus spp. (MRS) infection in patients with pneumonia. We conducted an observational study of patients with pneumonia at Cho Ray Hospital from March 2021 to March 2023. The Bayesian model averaging method and stepwise selection were applied to identify different sets of independent predictors. The final model was internally validated using the bootstrap method. We used receiver operator characteristic (ROC) curve, calibration, and decision curve analyses to assess the nomogram model's predictive performance. Based on the American Thoracic Society, British Thoracic Society recommendations, and our data, we developed a model with significant risk factors, including tracheostomies or endotracheal tubes, skin infections, pleural effusions, and pneumatoceles, and used 0.3 as the optimal cut-off point. ROC curve analysis indicated an area under the curve of 0.7 (0.63-0.77) in the dataset and 0.71 (0.64-0.78) in 1000 bootstrap samples, with sensitivities of 92.39% and 91.11%, respectively. Calibration analysis demonstrated good agreement between the observed and predicted probability curves. When the threshold is above 0.3, we recommend empiric antibiotic therapy for MRS. The web-based dynamic interface also makes our model easier to use.

Factors associated with foreign body infection in methicillin-resistant Staphylococcus aureus bacteremia.

Background: We aimed to compare patient characteristics, MRSA sequence types, and biofilm production of MRSA strains that did and did not cause a foreign body infection in patients with MRSA bloodstream infections (BSI). Methods: All adult patients with MRSA BSI hospitalized in two hospitals were identified by clinical microbiology laboratory surveillance. Only patients who had at least one implanted foreign body during the episode of BSI were included. Results: In July 2018 - March 2022, of 423 patients identified with MRSA BSI, 118 (28%) had ≥1 foreign body. Among them, 51 (43%) had one or more foreign body infections. In multivariable analysis, factors associated with foreign body infection were history of MRSA infection in the last year (OR=4.7 [1.4-15.5], p=0.012) community-associated BSI (OR=68.1 [4.2-1114.3], p=0.003); surgical site infection as source of infection (OR=11.8 [2-70.4], p=0.007); presence of more than one foreign body (OR=3.4 [1.1-10.7], p=0.033); interval between foreign body implantation and infection <18 months (OR=3.3 [1.1-10], p=0.031); and positive blood culture ≥48h (OR=16.7 [4.3-65.7], p<0.001). The most prevalent sequence type was ST8 (39%), followed by ST5 (29%), and ST105 (20%) with no significant difference between patients with or without foreign body infection. Only 39% of MRSA isolates formed a moderate/strong biofilm. No significant difference was observed between patients with foreign body infection and those without foreign body infection. In multivariable analysis, subjects infected with a MRSA isolate producing moderate/strong in vitro biofilm were more likely to have a history of MRSA infection in the last year (OR=3.41 [1.23-9.43]), interval between foreign body implantation and MRSA BSI <18 months (OR=3.1 [1.05-9.2]) and ST8 (OR=10.64 [2-57.3]). Conclusion: Most factors associated with foreign body infection in MRSA BSI were also characteristic of persistent infections. Biofilm-forming isolates were not associated with a higher risk of foreign-body infection but appeared to be associated with MRSA genetic lineage, especially ST8.

In Vitro and Ex Vivo Investigation of the Antibacterial Effects of Methylene Blue against Methicillin-Resistant Staphylococcus aureus.

Methylene blue (MB) is a water-soluble dye that has a number of medical applications. Methicillin-resistant Staphylococcus aureus (MRSA) was selected as a subject for research due to the numerous serious clinical diseases it might cause and because there is a significant global resistance challenge. Our main goal was to determine and analyze the antibacterial effects of MB against S. aureus both in vitro and ex vivo to enhance treatment options. A total of 104 MRSA isolates recovered from various clinical specimens were included in this study. Minimum inhibitory concentration (MIC) values of MB against MRSA isolates were determined by the agar dilution method. One randomly selected MRSA isolate and a methicillin-susceptible S. aureus strain (S. aureus ATCC 25923) were employed for further evaluation of the antibacterial effects of MB in in vitro and ex vivo time-kill assays. A disc diffusion method-based MB + antibiotic synergy assay was performed to analyze the subinhibitory effects of MB on ten isolates. MICs of MB against 104 MRSA isolates, detected by the agar dilution method, ranged between 16 and 64 µg/mL. MB concentrations of 4 and 16 µg/mL showed a bactericidal effect at 24 h in the ex vivo time-kill assays and in vitro time-kill assays, respectively. We observed a significant synergy between cefoxitin and methylene blue at a concentration of 1-2 µg/mL in two (20%) test isolates. Employing MB, which has well-defined pharmacokinetics, bioavailability, and safety profiles, for the treatment of MRSA infections and nasal decolonization could be a good strategy.

Susceptibility to postbiotics - enterocins of methicillin-resistant Staphylococcus aureus strains isolated from rabbits.

There is a major problem with the rising occurrence of highly virulent and multiply-resistant strains, including methicillin-resistant Staphylococcus aureus (MRSA), because of their difficult treatment. This study aimed to evaluate the antibacterial and antibiofilm effect of new enterocins (Ent) against potential pathogenic MRSA strains isolated from rabbits. Staphylococci were identified with PCR and screened for methicillin/oxacillin/cefoxitin resistance (MR) using the disk diffusion method and the PBP2' Latex Agglutination Test Kit. Enzyme production, hemolysis, DNase activity, slime production, and biofilm formation were tested in MRSA strains. The susceptibility of MRSA to eight partially-purified enterocins (Ent) produced by E. faecium and E. durans strains was checked using agar spot tests. The antibiofilm activity of Ents was tested using a quantitative plate assay. Out of 14 MRSA, PBP testing confirmed MR in 8 strains. The majority of MRSA showed DNase activity and ß-hemolysis. Slime production and moderate biofilm formation were observed in all strains. MRSA were susceptible to tested Ents (100-12,800 AU/mL; except Ent4231). The antibiofilm effect of Ents (except Ent4231) was noted in the high range (64.9-97.0%). These results indicate that enterocins offer a promising option for the prevention and treatment of bacterial infections caused by biofilm-forming MRSA.

Validation of a new risk stratification system-based management for methicillin-resistant Staphylococcus aureus bacteraemia: analysis of a multicentre prospective study.

PURPOSE: Distinguishing between complicated and uncomplicated Staphylococcus aureus bacteraemia (SAB) is therapeutically essential. However, this distinction has limitations in reflecting the heterogeneity of SAB and encouraging targeted diagnostics. Recently, a new risk stratification system for SAB metastatic infection, involving stepwise approaches to diagnosis and treatment, has been suggested. We assessed its applicability in methicillin-resistant SAB (MRSAB) patients. METHODS: We retrospectively analysed data of a 3-year multicentre, prospective cohort of hospitalised patients with MRSAB. We classified the patients into three risk groups: low, indeterminate, and high, based on the new system and compared between-group management and outcomes. RESULTS: Of 380 patients with MRSAB, 6.3% were classified as low-, 7.6% as indeterminate-, and 86.1% as high-risk for metastatic infection. No metastatic infection occurred in the low-, 6.9% in the indeterminate-, and 19.6% in the high-risk groups (P < 0.001). After an in-depth diagnostic work-up, patients were finally diagnosed as 'without metastatic infection (6.3%)', 'with metastatic infection (17.4%)', and 'uncertain for metastatic infection (76.3%)'. 30-day mortality increased as the severity of diagnosis shifted from 'without metastatic infection' to 'uncertain for metastatic infection' and 'with metastatic infection' (P = 0.09). In multivariable analysis, independent factors associated with metastatic complications were suspicion of endocarditis in transthoracic echocardiography, clinical signs of metastatic infection, Pitt bacteraemia score ≥ 4, and persistent bacteraemia. CONCLUSIONS: The new risk stratification system shows promise in predicting metastatic complications and guiding work-up and management of MRSAB. However, reducing the number of cases labelled as 'high-risk' and 'uncertain for metastatic infection' remains an area for improvement.

[Prevalence and risk factors for methicillin-resistant Staphylococcus aureus infection in children]. / Prevalencia y factores de riesgo de infección por Staphylococcus aureus resistente a meticilina en niños.

OBJECTIVE: The objectives of this work were to know the prevalence of methicillin-resistant S. aureus (MRSA) infections in the paediatric population of our health department, to describe the risk factors for infection by MRSA compared to those produced by methicillin-susceptible S. aureus (MSSA) and to know the antibiotic sensitivity profile of MRSA and MSSA isolates. METHODS: A retrospective, descriptive and analytical study of infections produced by MRSA versus those produced by MSSA was carried out during the years 2014 to 2018. Risk factors for MRSA infection were studied using a binary logistic regression model. RESULTS: 162 patients with S. aureus infections were identified. Of these, 25 (15.4%) were MRSA. The highest percentages of MRSA infection occurred among children who required hospital admission (23.4%). In the univariate analysis the need of hospital admission, antibiotic treatment in the last 3 months, the kind of infection and past MRSA infection or colonisation reached statistical significance. However, only the need of hospital admission and antibiotic treatment in the last 3 months maintained statistical significance in the binary logistic regression model. Correct antibiotic treatment was only prescribed in 26.7% of the MRSA infection cases admitted to the hospital. CONCLUSIONS: Our results suggest the need to review empirical local treatment regimen using drugs active against MRSA in infections of probable staphylococcal origin admitted to the hospital, especially if they have received antibiotic treatment in the last 3 months.

Accuracy of the GeneXpert® MRSA/SA SSTI test to diagnose methicillin-resistant Staphylococcus spp. infection in bone fixation and fusion and management of infected non-unions.

INTRODUCTION: The GeneXpert® MRSA/SA SSTI (Methicillin Resistant Staphylococcus aureus/S. aureus skin and soft tissue infection) PCR test allows early detection of methicillin resistance in staphylococci. This test was developed for skin infections and has been evaluated for prosthetic joint infections but, to our knowledge, has not been evaluated for hardware infections outside of arthroplasties. Furthermore, we conducted a retrospective study in patients with non-prosthetic osteosynthesis hardware aiming: (1) to identify the diagnostic values of the PCR test compared to conventional cultures and the resulting rate of appropriate antibiotic therapy; (2) to identify the rate of false negative (FN) results; (3) to identify and compare the rates of failure of infectious treatment (FN versus others); (4) to search for risk factors for FN of the PCR test. HYPOTHESIS: The PCR test allowed early and appropriate targeting of antibiotic therapy. MATERIAL AND METHODS: The results of PCR tests and conventional cultures for osteoarticular infections of non-prosthetic hardware over four years (2012-2016) were compared to identify the diagnostic values of using the results of conventional culture as a reference and the rate of appropriate antibiotic therapies. Infectious management failures between the results of the FN group and the others were compared, and variables associated with a FN of the PCR test were identified. RESULTS: The analysis of 419 PCR tests allowed us to establish a sensitivity of 42.86%, a specificity of 96.82%, a positive predictive value of 60% and a negative predictive value of 93.83%. Using the results of the PCR test for the targeting of postoperative antibiotic therapy, it was suitable for staphylococcal coverage in 90.94% (381/419). The rates of patients for whom infectious treatment failed were not significantly different between the FN group and the other patients (20.8% versus 17.7%, respectively; Hazard Ratio=1.12 (95%CI 0.47-2.69, p=0.79)). A skin opening during the initial trauma (p=0.005) and a polymicrobial infection were significantly associated with a risk of FN from the PCR test (p<0.001). CONCLUSION: The PCR test makes it possible to reduce the duration of empirical broad-spectrum antibiotic therapy during the treatment of an infection of osteosynthesis hardware but causes a lack of antibiotic coverage in 9.06% of cases. LEVEL OF EVIDENCE: III; diagnostic case control study.

Safety and effectiveness of fifth generation cephalosporins for the treatment of methicillin-resistant staphylococcus aureus bloodstream infections: a narrative review exploring past, present, and future.

INTRODUCTION: Methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI) is a major issue in healthcare, since it is often associated with endocarditis or deep site foci. Relevant morbidity and mortality associated with MRSA-BSIs forced the development of new antibiotic strategies; in particular, this review will focus the attention on fifth-generation cephalosporins (ceftaroline/ceftobiprole), that are the only ß-lactams active against MRSA. AREAS COVERED: The review discusses the available randomized controlled trials and real-world observational studies conducted on safety and effectiveness of ceftaroline/ceftobiprole for the treatment of MRSA-BSIs. Finally, a proposal of MRSA-BSI treatment flowchart, based on fifth-generation cephalosporins, is described. EXPERT OPINION: The use of anti-MRSA cephalosporins is an acceptable choice either in monotherapy or combination therapy for the treatment of MRSA-BSIs due to their relevant effectiveness and safety. Particularly, their use may be advisable in combination therapy in case of severe infections (including endocarditis or persistent bacteriemia) or in monotherapy in subjects at higher risk of drugs-induced toxicity with older regimens. On the contrary, caution should be taken in case of suspected/ascertained central nervous system infections due to inconsistent data regarding penetration of these drugs in cerebrospinal fluid and brain tissues.

Clinical and bacteriological profiles of neonatal sepsis in a tertiary hospital, south-western Nigeria.

Introduction: Antibiotic-resistant bacteria complicate treatment options in neonatal sepsis, especially in developing countries. This study determined the epidemiology and bacteriological characteristics of neonatal sepsis at a tertiary hospital, in southwest Nigeria. Methods: This was a cross-sectional study from December 2017 to April 2019 among admitted babies with clinical neonatal sepsis. Blood culture was performed by semi-automated system, sepsis biomarker assay (serum procalcitonin) by a semi-quantitative kit while proforma was used to capture clinico-demographic data. Bacterial identification, antibiotic susceptibility patterns, determination of genetic elements mediating resistance, were performed by standard methods and polymerase chain reaction protocols, respectively. Quantitative data were expressed as frequencies, mean; bivariate and multivariate analyses were performed by Chi-square or Fishers' exact test and logistic regression. Results: Of the 192 cases of neonatal sepsis enrolled, 42.7% (82/192) were blood culture positive. Factors associated with blood culture positivity included respiratory rate ≥60 bpm (60/82; p<0.03), lethargy/unconsciousness (59/82; FE=7.76; p<0.001), grunting respiration (54/82; p=0.04), meconium passage before birth (17/82; p=0.03) and prolonged rupture of membranes ≥24 hours (50/82; FE=6.90; p=0.01). On the other hand, mortality in the neonates was associated with elevated serum procalcitonin assay (>0.5 ng/mL) χ2=13.58; p=0.03] and Gram-negative bacteremia (χ2=24.64; p<0.001). The most common bacterial isolates were Staphylococcus aureus (42/82), coagulase-negative Staphylococcus spp. (17/82), Enterobacter spp. (8/82), and Acinetobacter spp. (6/82). Methicillin resistance was present in 85.7% (36/42) of Staphylococcus aureus and 52.9% (9/17) of coagulase-negative Staphylococcus, while extended-spectrum beta-lactamase (ESBL) and AmpC enzymes were present in (21.1%; 4/19) of the Gram-negative bacilli. Conclusions: Almost half of the cases of clinically diagnosed neonatal sepsis have bacterial etiologic confirmation of sepsis. Gram-negative bacteremia and high serum procalcitonin predict mortality in neonatal sepsis. There was high resistance to common antibiotics for the treatment of neonatal sepsis in our settings.

Molecular Epidemiology and Comparative Genome Analysis of Clinically-isolated MRSA Strains in Indonesia.

Objective: Most strains of methicillin-resistant Staphylococcus aureus (MRSA) analyzed to date have been from industrialized countries, with information lacking on the epidemiology of MRSA in other regions of the world. The present study describes the molecular epidemiology of MRSA strains collected at a referral hospital in Surabaya City, Indonesia in 2015-2016. The similarity of strains isolated in Indonesia to known lineages of MRSA was investigated. Materials: Of 45 MRSA strains isolated in Surabaya, 10 were selected by antibiotic resistance patterns and clinical features, while excluding duplicates. Methods: Whole genome sequencing was performed using a next-generation sequencer, and the complete genome sequence of one of these 10 strains was also determined by the PacBio system. The strains were subjected to molecular epidemiological analyses, including the presence of drug-resistance and virulence-related genes, the determination of sequence types and staphylococcal cassette chromosome mec (SCCmec) types and mutual phylogenetic relationships, using standard analytical tools. Results: The molecular types of these MRSA strains showed significant diversity. Complete sequencing of the genome of strain IDSA1 showed that it belonged to the ST239 group, while also having unique mobile genetic elements. Conclusions: Despite the small number of MRSA strains collected in a limited area and over a short period of time, these strains were found to have arisen in many other regions of the world, suggesting that they had migrated into Indonesia through human movement. These strains also showed molecular differentiation after migrating into Indonesia.

Genomic characterization, antimicrobial resistance profiles, enterotoxin, and biofilm production of methicillin-resistant Staphylococcus aureus isolated from clinical and animal products origins in Eastern Turkey / Caracterização genômica perfis de resistência antimicrobiana, produção de enterotoxinas e biofilme Staphylococcus aureus resistente à meticilina isolado de origem clínica e de produtos de origem animal no leste da Turquia

Staphylococcus aureus is an opportunistic and ubiquitous pathogen found in the skin, nares, and mucosal membranes of mammals. Increasing resistance to antimicrobials including methicillin has become an important public concern. One hundred and eight (108) S. aureus strains isolated from a total of 572 clinical and animal products samples, were investigated for their biofilm capability, methicillin resistance, enterotoxin genes, and genetic diversity. Although only one strain isolated from raw retail was found as a strong biofilm producer, the percentage of antimicrobial resistance pattern was relatively higher. 17.59% of S. aureus strains tested in this study were resistant to cefoxitin and identified as methicillin-resistant S. aureus (MRSA) isolates. mecA and mecC harboring S. aureus strains were detected at a rate of 2.79% and 0.93%, respectively. In addition, staphylococcal enterotoxin genes including Sea, Seb, Sec, and Sed genes were found to be 18.5%, 32.4%, 6.5% and 3.7%, respectively. The phylogenetic relationship among the isolates showed relationship between joint calf and cow milk isolates. Multi locus sequence typing (MLST) revealed three different sequence types (STs) including ST84, ST829, and ST6238. These findings highlight the development and spread of MRSA strains with zoonotic potential in animals and the food chain throughout the world.

Staphylococcus aureus é um patógeno dúctil e ubíquo encontrado na pele, narinas e membranas mucosas de mamíferos. O aumento da resistência aos antimicrobianos, incluindo a meticilina, tornou-se uma importante preocupação pública. Cento e oito (108) cepas de S. aureus isoladas de um total de 572 amostras clínicas e de produtos animais foram investigadas por sua capacidade de biofilme, resistência à meticilina, genes de enterotoxinas e diversidade genética. Embora apenas uma cepa isolada do cru tenha sido encontrada como forte produtora de biofilme, a porcentagem do padrão de resistência antimicrobiana foi relativamente maior. Parte das cepas (17,59%) de S. aureus testadas neste estudo eram resistentes à cefoxitina e identificadas como isolados de MRSA. mecA e mecC abrigando cepas de S. aureus foram detectados a uma taxa de 2,79% e 0,93%, respectivamente. Além disso, verificou-se que os genes da enterotoxina estafilocócica, incluindo os genes Sea, Seb, Sec e Sed, eram 18,5%, 32,4%, 6,5% e 3,7%, respectivamente. A relação filogenética entre os isolados mostrou relação entre os isolados de bezerro e leite de vaca. A tipagem de sequência multiloco (MLST) revelou três tipos de sequência diferentes (STs), incluindo ST84, ST829 e ST6238. Essas descobertas destacam o desenvolvimento e a disseminação de cepas de MRSA com potencial zoonótico em animais e na cadeia alimentar em todo o mundo.