Multidrug-resistant Methicillin-resistant S. Aureus Research Articles

Respiratory microorganisms in acute pharyngitis patients: Identification, antibiotic prescription patterns and appropriateness, and antibiotic resistance in private primary care, central Malaysia.

Acute pharyngitis (AP) is a common reason for private primary care consultations, thus providing an avenue for widespread antibiotic intake among the community. However, there is limited data on the antibiotic prescription appropriateness and resistance information in the Malaysian private primary care setting, therefore, this study aimed to investigate the prevalence of isolated viruses and bacteria, antibiotic resistance patterns, antibiotic prescription patterns and appropriateness by general practitioners (GPs) and factors affecting antibiotic resistance and antibiotic prescription patterns. To investigate, a cross-sectional study was conducted among 205 patients presenting with AP symptoms at private primary care clinics in central Malaysia from 3rd January 2016 to 30th November 2016. Throat swabs were collected from 205 AP patients for two purposes: (i) the detection of four common respiratory viruses associated with AP via reverse-transcription real-time PCR (qRT-PCR); and (ii) bacterial identification using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS). Bacterial isolates were then subjected to antibiotic susceptibility screening and McIsaac scoring was calculated post-prescription based on GP selection of criteria. Generalized estimating equations analysis with multiple logistic regression was conducted to identify factors associated with presence of virus and antibiotic prescription. The results showed that 95.1% (195/205) of patients had at least one of the four viruses, with rhinovirus (88.5%) being the most prevalent, followed by adenovirus (74.9%), influenza A virus (4.6%) and enterovirus (2.1%). A total of 862 non-repetitive colonies were isolated from the culture of throat swabs from 205 patients who were positive for bacteria. From a total of 22 genera, Streptococcus constitutes the most prevalent bacteria genus (40.9%), followed by Neisseria (20%), Rothia (13.0%), Staphylococcus (11%) and Klebsiella (4.9%). Only 5 patients carried group A beta-hemolytic streptococci (GABHS). We also report the presence of vancomycin-resistant S. aureus or VRSA (n = 9, 10.1%) among which one isolate is a multidrug-resistant methicillin-resistant S. aureus (MDR-MRSA), while 54.1% (n = 111) were found to carry at least one antibiotic-resistant bacteria species. Application of the McIsaac scoring system indicated that 87.8% (n = 180) of patients should not be prescribed antibiotics as the majority of AP patients in this study had viral pharyngitis. The antibiotic prescription appropriateness by applying post-prescription McIsaac scoring was able to rule out GABHS pharyngitis in this sample with a GABHS culture-positive sensitivity of 40% (n = 2/5) and specificity of 90% (180/200). In conclusion, antibiotic-resistant throat isolates and over-prescription of antibiotics were observed and McIsaac scoring system is effective in guiding GPs to determine occurrences of viral pharyngitis to reduce unnecessary antibiotic prescription.

Phenotypic detection of methicillin resistance, biofilm production, and inducible clindamycin resistance in Staphylococcus aureus clinical isolates in Kathmandu, Nepal

IntroductionMethicillin resistance, inducible clindamycin resistance (ICR), biofilm production, and increased minimum inhibitory concentration (MIC) of vancomycin in Staphylococcus aureus are major causes of antibiotic treatment failure and increased morbidity and mortality. The surveillance of such isolates and the study of their antimicrobial pattern are essential in managing the infections caused by these isolates. This study aimed to determine methicillin resistance, biofilm production, and ICR in S. aureus isolates from a tertiary care hospital in Kathmandu, Nepal.Materials and methodsA total of 217 S. aureus isolated from different samples were processed following standard laboratory procedures. Antibiotic susceptibility testing was performed by the Kirby–Bauer disk diffusion technique. Methicillin-resistant S. aureus (MRSA) were identified by the cefoxitin disk diffusion test, and biofilm producers were examined using the microtiter plate technique. D-test and E-test were performed to determine inducible clindamycin resistance and minimum inhibitory concentration of vancomycin, respectively.ResultsAmong the 217 S. aureus isolates, 78.3% were multidrug-resistant (MDR), 47.0% were MRSA, 62.2% were biofilm producers, and 50.7% showed ICR. All MRSA isolates exhibited MIC levels of vancomycin within the susceptible range. Biofilm producers and MRSA isolates showed elevated antimicrobial resistance. MRSA was significantly associated with MDR. Biofilm-producing and multidrug-resistant MRSA isolates showed significantly higher MIC levels of vancomycin (p = 0.0013 and < 0.0001, respectively), while ICR was significantly higher in MDR (p = 0.0001) isolates.ConclusionHigh multidrug resistance, MRSA, and ICR in this study call for routine evaluation of antibiotic susceptibility patterns of S. aureus. Vancomycin can be used to treat serious staphylococcal infections. Clindamycin should be prescribed only after performing the D-test. Drugs like teicoplanin, chloramphenicol, doxycycline, amikacin, and levofloxacin can treat MRSA infections.

N-Butanol Potentiates Subinhibitory Aminoglycosides against Bacterial Persisters and Multidrug-Resistant MRSA by Rapidly Enhancing Antibiotic Uptake.

Potentiation of traditional antibiotics is of significance for combating antibiotic-resistant bacteria that have become a severe threat to human and animal health. Here, we report that 1 min co-treatment with n-butanol greatly and specifically enhances the bactericidal action of aminoglycosides by 5 orders of magnitude against stationary-phase Staphylococcus aureus cells, with n-propanol and isobutanol showing less potency. This combined treatment also rapidly kills various S. aureus persisters, methicillin-resistant S. aureus (MRSA) cells, and numerous Gram-positive and -negative pathogens including some clinically isolated multidrug-resistant pathogens (e.g., S. aureus, Staphylococcus epidermidis, and Enterococcus faecalis) in vitro, as well as S. aureus in mice. Mechanistically, the potentiation results from the actions of aminoglycosides on their conventional target ribosome rather than the antiseptic effect of n-butanol and is achieved by rapidly enhancing the bacterial uptake of aminoglycosides, while salts and inhibitors of proton motive force (e.g., CCCP) can diminish this uptake. Importantly, such n-butanol-enhanced antibiotic uptake even enables subinhibitory concentrations of aminoglycosides to rapidly kill both MRSA and conventional S. aureus cells. Given n-butanol is a non-metabolite in the pathogens we tested, our work may open avenues to develop a metabolite-independent strategy for aminoglycoside potentiation to rapidly eliminate antibiotic-resistant/tolerant pathogens, as well as for reducing the toxicity associated with aminoglycoside use.

Synergism of a Novel 1,2,4-oxadiazole-containing Derivative with Oxacillin against Methicillin-Resistant Staphylococcus aureus.

Staphylococcusaureus is an important opportunistic pathogen that causes many infections in humans and animals. The inappropriate use of antibiotics has favored the diffusion of methicillin-resistant S. aureus (MRSA), nullifying the efforts undertaken in the discovery of antimicrobial agents. Oxadiazole heterocycles represent privileged scaffolds for the development of new drugs because of their unique bioisosteric properties, easy synthesis, and therapeutic potential. A vast number of oxadiazole-containing derivatives have been discovered as potent antibacterial agents against multidrug-resistant MRSA strains. Here, we investigate the ability of a new library of oxadiazoles to contrast the growth of Gram-positive and Gram-negative strains. The strongest antimicrobial activity was obtained with compounds 3 (4 µM) and 12 (2 µM). Compound 12, selected for further evaluation, was found to be noncytotoxic on the HaCaT cell line up to 25 µM, bactericidal, and was able to improve the activity of oxacillin against the MRSA. The highest synergistic interaction was obtained with the combination values of 0.78 μM for compound 12, and 0.06 μg/mL for oxacillin. The FIC index value of 0.396 confirms the synergistic effect of compound 12 and oxacillin. MRSA treatment with compound 12 reduced the expression of genes included in the mec operon. In conclusion, 12 inhibited the growth of the MRSA and restored the activity of oxacillin, thus resulting in a promising compound in the treatment of MRSA infection.

Antibacterial and anti-biofilm properties of Aptosimum albomarginatum(Marloth&amp; Engl.) and Dicoma schinzii(O. Hoffm.) crude methanolic extracts against S. aureus and MRSA.

Background: The effectiveness of phytomedicine is often questioned by scientists. This study therefore aimed to test crude methanolic extracts from two traditional medicinal plants currently being used in Namibia for their antibacterial and anti-biofilm activity against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). Materials and methods: Aptosimum albomarginatum (Marloth &amp; Engl.) roots and Dicoma schinzii (O. Hoffm.) roots and leaves were used to prepare crude methanolic extracts by maceration, filtration, rotary evaporation and freeze-drying. Thin layer chromatography (TLC) was used to detect flavonoids, saponins and anthraquinones in the plant material. For antibacterial activity, two S. aureus reference strains (one susceptible and one multi-drug resistant MRSA) and 10 S. aureus nasal isolates from school children were used in disk diffusion assays with crude methanolic plant extracts. The microtiter plate assay with crystal violet stain was used to determine if these extracts could inhibit and/or eradicate bacterial biofilms. Results: Aptosimum albomarginatum root extract displayed moderately antibacterial activity against five nasal isolates (one MRSA isolate) and two reference strains, of which one was multi-drug resistant MRSA. This extract was also the best biofilm inhibition agent, with highly active inhibition (86.0%) observed in S. aureus ATCC 33591 (MRSA). Dicoma schinzii root extract had moderate antibacterial activity against six nasal isolates and the two reference strains; its leaf extract was moderately active against two nasal isolates. The D. schinzii leaf extract moderately inhibited biofilms in two nasal isolates and S. aureus ATCC 25923. Flavonoids and saponins detected in both the roots and leaves of the two plants may have contributed to the extracts’ antibacterial and antibiofilm activity. Conclusion: Aptosimum albomarginatum roots and D. schinzii roots and leaves displayed anti-staphylococcal activity, indicating potential use against staphylococcal infections involving the bacteria under study. Noteworthy is both antibacterial and anti-biofilm properties of A. albomarginatum root extract against MRSA.

Regional analysis of telavancin and comparator antimicrobial activity against multidrug-resistant Staphylococcus aureus collected in the USA 2014-2016.

The in vitro antimicrobial activities of telavancin and comparator antimicrobials were evaluated against recent Staphylococcus aureus (S. aureus) clinical isolates collected in the United States of America (USA). A total of 15882 S. aureus isolates were collected (2014-2016) as part of the SENTRY Antimicrobial Surveillance Program from sites located in all US Census Bureau divisions. Broth microdilution MIC values were measured using current reference methods. Data were stratified by year and census division, and resistance rates were analysed for significant trends. Previously published data on methicillin-resistant S. aureus (MRSA) and multidrug-resistant (MDR) MRSA isolates (collected 2011-2013) were merged with the current isolate set to examine longer term resistance trends. Telavancin antimicrobial activity against MRSA and MDR MRSA isolates (MIC50/90 values, 0.03/0.06μg/mL for both subsets) remained unchanged over the 3-year surveillance period, and all isolates were susceptible to telavancin. No difference in telavancin activity was noted when MIC data were stratified by year or US Census Bureau division. When merged data (2011-2016) were analysed, the MRSA rate decreased for the entire USA and six individual census divisions, although the overall rate remained considerable. The overall US MDR MRSA rate also remained considerable and was unchanged from 2011-2016. The sustained potent activity of telavancin against US S. aureus isolates (100% susceptible) and the high rates of MRSA and MDR MRSA in the USA support the continued use of telavancin to treat indicated serious infections caused by S. aureus.

Prevalence, antimicrobial susceptibility and characterization of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus isolated from dairy industries in north-central and north-eastern Greece

Staphylococcus aureus is an important cause of food intoxication, whereas methicillin-resistant S. aureus (MRSA) constitutes a serious public-health concern due to its ability to colonize and infect humans and animals. S. aureus and MRSA have often been isolated from milk and dairy products. The objectives of this study were to estimate the prevalence and the antimicrobial resistance of S. aureus and MRSA in four Greek dairy industries, to identify virulence factors of MRSA isolates and to describe their genetic diversity, in order to identify possible epidemiological links and evaluate the risk of MRSA dissemination to the community. S. aureus was isolated from 67 out of 305 (22.0%) dairy industry samples (bulk-tank milk, dairy products, employee nasal swabs and equipment/surface swabs). Almost all (99%) of the 227 corresponding S. aureus isolates (approximately 4 isolates per positive sample) were resistant to at least one antimicrobial and 22% were multi-drug resistant (MDR). MRSA were isolated from 11 different samples (3.6%) originating from three of the dairy plants. All MRSA isolates were capable of forming biofilms, while staphylococcal enterotoxin (SE) genes were detected in 91% of the MRSA isolates, with sec being the most frequent. All of the MRSA isolates harbored the mecA gene but the mecC and Pandon-Valentine leucocidin (PVL) genes were not detected. Pulse-Field Gel Electrophoresis (PFGE) analysis showed genetic diversity among the MRSA isolates and indicated clonal circulation in one of the dairy plants. Seven spa types were identified among the MRSA isolates with the most prevalent (t065) isolated only in one dairy plant. Certain spa types (t065, t337 and t3536) were isolated for the first time in Greece. The presence of MDR, biofilm-forming and enterotoxigenic MRSA strains in dairy plant facilities may lead to their dissemination to the community, but also to staphylococcal food poisoning, when conditions are favorable. The study's findings highlight the need for continuous monitoring of the dairy production chain, the need for re-evaluating the implemented cleaning and sanitizing processes and the adoption of preventive strategies in order to minimize public-health risks.

Prevalence and pattern of antibiotic resistance of Staphylococcus aureus isolated from door handles and other points of contact in public hospitals in Ghana

BackgroundStudies have implicated Staphylococcus aureus as the leading cause of septicemia in the Tamale metropolis of Ghana. The aim of this study was to determine the prevalence and antibiotic susceptibility of S. aureus and Methicillin Resistant S. aureus (MRSA) in the environments of three hospitals in Ghana.MethodsA total of 120 swab samples were taken from door handles, stair railings and other points of contact at Tamale Teaching Hospital, Tamale Central Hospital and Tamale West Hospital. The swab samples were directly plated on Mannitol Salt and Baird Parker agar plates and incubated at 37 °C (± 2) for 18–24 h. An antibiotic susceptibility test was performed using the Clinical Laboratory Standard Institute’s guidelines. Isolates resistant to both cefoxitin and oxacillin were considered to be MRSA.ResultsA total of 47 (39%) positive S. aureus samples were isolated from all three hospitals, of which, eight (17%) were putative MRSA isolates. One MRSA isolate was resistant to all the antibiotics used (cefoxitin, oxacillin, ciprofloxacin, erythromycin, tetracycline, ampicillin, streptomycin and sulfamethoxazole-trimethoprim). Five of the MRSA isolates were multi-drug resistant, whilst the other three were resistant to only two antibiotics. All the multi-drug resistant MRSA isolates were resistant to at least four antibiotics. The percentage of isolates resistant to oxacillin, ampicillin, ciprofloxacin, tetracycline, streptomycin, erythromycin, and sulfamethoxazole/trimethoprim were 17, 13, 9, 28, 89, 13 and 11% respectively.ConclusionThe high multi-drug resistance of MRSA in hospital environments in Ghana reinforces the need for the effective and routine cleaning of door handles in hospitals. Further investigation is required to understand whether S. aureus from door handles could be the possible causes of nosocomial diseases in the hospitals.

Molecular Characteristics of Staphylococcus aureus Causing Bovine Mastitis between 2014 and 2015.

Staphylococcus aureus is highly pathogenic and can cause diseases in both humans and domestic animals. In animal species, including ruminants, S. aureus may cause severe or sub-clinical mastitis. This study aimed to investigate the molecular profile, antimicrobial resistance, and genotype/phenotype correlation of 212 S. aureus isolates recovered from cases of bovine mastitis from 2014 to 2015 in the Shanghai and Zhejiang areas of China. Nineteen sequence types (STs) were determined by multi-locus sequence typing, while the dominant ST was ST97, followed by ST520, ST188, ST398, ST7, and ST9. Within 14 methicillin-resistant S. aureus (MRSA) isolates and 198 methicillin-susceptible S. aureus (MSSA) isolates, ST97 was the predominant MSSA clone and ST9-MRSA-SCCmecXII-spa t899 was the most common MRSA clone. The MRSA strains showed much higher rates of resistance to multiple antibiotics than did MSSA strains. Compared with other MSSA strains, MSSA ST398 was more resistant to clindamycin, erythromycin, and ciprofloxacin. No isolates were resistant to vancomycin, teicoplanin, or linezolid. The molecular profiles of the virulence genes varied in different strains. ST520 strains carried seg-sei-sem-sen-seo genes, and ST9 and ST97 harbored sdrD-sdrE genes. Virulence phenotype analysis showed diversity in different clones. Biofilm formation ability was significantly enhanced in ST188 and ST7, and red blood cell lysis capacity was relatively strong in all S. aureus strains of animal origin except ST7. Our results indicate that MSSA was the predominant S. aureus strain causing bovine mastitis in eastern regions of China. However, the presence of multidrug resistant and toxigenic MRSA clone ST9 suggests that comprehensive surveillance of S. aureus infection should be implemented in the management of animal husbandry products.

The clinical and molecular epidemiology of Staphylococcus aureus infections in Fiji

BackgroundThere are few data describing the microbiology and genetic typing of Staphylococcus aureus that cause infections in developing countries.MethodsIn this study we observed S. aureus infections in Pacific Island nation of Fiji in both the community and hospital setting with an emphasis on clonal complex (CC) genotyping and antimicrobial susceptibility.ResultsS. aureus was commonly found in impetigo lesions of school children and was recovered from 57% of impetigo lesions frequently in conjunction with group A streptococcal infection. Methicillin-resistant S. aureus (MRSA) comprised 7% (20/299) of isolates and were all non-multi-resistant and all genotyped as CC1. In contrast, there was a diverse selection of 17 CCs among the 105 genotyped methicillin-susceptible S.aureus (MSSA) strains. Isolates of the rare, phylogenetically divergent and non-pigmented CC75 lineage (also called S.argenteus) were found in Fiji.From hospitalized patients the available 36 MRSA isolates from a 9-month period were represented by five CCs. The most common CCs were CC1 and CC239. CC1 is likely to be a community-acquired strain, reflecting what was found in the school children, whereas the CC239 is the very successful multi-drug resistant MRSA nosocomial lineage. Of 17 MSSA isolates, 59% carried genes for Panton-Valentine leukocidin. The S. aureus bacteraemia incidence rate of 50 per 100,000 population is among the highest reported in the literature and likely reflects the high overall burden of staphylococcal infections in this population.ConclusionsS. aureus is an important cause of disease in Fiji and there is considerable genotypic diversity in community skin infections in Fijian schoolchildren. Community acquired- (CA)- MRSA is present at a relatively low prevalence (6.7%) and was solely to CC1 (CA-MRSA). The globally successful CC239 is also a significant pathogen in Fiji.

Chorioamnionitis and Neonatal Sepsis from Community-associated MRSA

Chorioamnionitis and Neonatal Sepsis from Community-associated MRSA

Nabi Biopharm Sells PentaStaph™ to GSK

Nabi Biopharmaceuticals agreed to sell PentaStaph™ (Pentavalent S. aureus vaccine) and related assets to GlaxoSmithKline (GSK) for US$46 M. The vaccine is a potential development in the fight against the multidrug resistant bacterium, S. aureus, and MRSA (methicillin-resistant S. aureus). Troubled Nabi is also on the lookout for a potential acquirer.

Community Case of Methicillin-resistantStaphylococcus aureusInfection

Community Case of Methicillin-resistant<i>Staphylococcus aureus</i>Infection