Antibiotic resistance and molecular typing of clinical Staphylococcus aureus isolates from Malaysian military hospital

Objective:To determine the antibiotic resistance profile(ARP)of Staphylococcus(S.)aureus isolates and molecular typing of the methicillin-resistant S.aureus(MRSA)isolates from Tuanku Mizan Armed Forces Hospital(TMAFH),Kuala Lumpur.Methods:The ARP and presence of the pvl gene were determined for 209 S.aureus isolates from clinical specimens.Of these,123 were methicillin-susceptible S.aureus(MSSA)isolates and 86 were MRSA isolates.All MRSA isolates were characterized using SCCmec typing and spa typing.Descriptive analysis was performed to compare the demographic data with the phenotypic and genotypic variables of the S.aureus isolates.Results:No vancomycin-intermediate and-resistant S.aureus(VISA and VRSA,respectively)were detected among the study isolates.The MSSA isolates showed low resistance rates to all tested antibiotics,were commonly invasive(28/42,66.7%),and mostly harboured pvl(35/42,83.3%).Meanwhile,MRSA isolates showed high resistance to penicillin(86/86,100%),ampicillin(86/86,100%),sulbactam/ampicillin(86/86,100%),cefuroxime(81/86,94.19%),cefoperazone(76/86,88.37%),azithromycin(56/86,65.12%),and erythromycin(54/86,62.79%).The majority of MRSA isolates were of SCCmec type IVh(65/86,75.58%),spa type t032(55/85,63.95%),and grouped into spaCC-t022(66/85,77.65%).The t032 type was found to be associated with resistance traits to azithromycin and erythromycin(P<0.05).We also found several spa types that are typically associated with hospital-,community-,and livestock-associated MRSA co-existing in our MRSA population.Conclusions:This study reflected the consistent absence of VISA and VRSA and corroborated the clonal shifting of MRSA isolates in the Malaysian MRSA isolates.

Antimicrobial drug resistance of Staphylococcus aureus in dairy products

Objective:To evaluate the prevalence of multidrug resistant Staphylococcus aureus(S.aureus) in dairy products.Methods:Isolation and identification of S.aureus were performed in 3 dairybased food products.The isolates were tested for their susceptibility to 5 different common antimicrobial drugs.Results:Of 50 samples examined,5(10%) were contaminated with 5. aureus.Subsequently,the 5 isolates were subjected to antimicrobial resistance pattern using five antibiotic discs(methicillin,vancomycin,kanamycin,chloramphenicol and tetracycline).Sample 29 showed resistance to methicillin and vancomycin.Sample 18 showed intermediate response to tetracycline.The other samples were susceptible to all the antibiotics tested.Conclusions:The results provide preliminary data on sources of food contamination which may act as vehicles for the transmission of antimicrobial-resistant Staphylococcus.Therefore,it enables us to develop preventive strategies to avoid the emergence of new strains of resistant S.aureus.

In-vitro antimicrobial activity of marine actinobacteria against multidrug resistance Staphylococcus aureus

Objective:To investigate the antibacterial aclivily of marine actinobacteria against multidrug resistance Staphylococcus aureus(MDRSA).Methods:Fifty one actinobacterial strains were isolated from salt pans soil,costal area in Kothapattanam,Ongole,Andhra Pradesh.Primary screening was done using cross-streak method against MDRSA.The bioaclive compounds are extracted from efficient actinobacteria using solvent extraction.The antimicrobial activity of crude and solvent extracts was perfomied using Kirby-Bauer method.MIC for ethyl acetate extract was determined by modified agar well diffusion method.The potent actinobacteria are identified using Nonomura key,Shirling and Gottlieb 1966 with Bergey's manual of determinative bacteriology.Results:Among the fifty one isolates screened for antibacterial activity,SRB25were found efficient against MDRSA.The ethyl acetate extracts showed high inhibition against test organism.MIC test was performed with the ethyl acetate extract against MDRSA and found to be 1 000μg/mL.The isolaled actinobacteria are identified as Streptomyces sp with the help of Nonomura key.Conclusions:The current investigation reveals that the marine actinobacteria from salt pan environment can be able to produce new drug molecules against drug resistant microorganisms.

Change in drug resistance of staphylococcus aureus

Objective To analyze the change in drug resistance of staphylococcus aureus(SAU) in the PLA general hospital from January 2008 to December 2012, and to provide solid evidence to support the rational use of antibiotics for clinical applications. Methods The SAU strains isolated from clinical samples in the hospital were collected and subjected to the Kirby-Bauer disk diffusion test. The results were assessed based on the 2002 American National Committee for Clinical Laboratory Standards(NCCLS) guidelines. Results SAU strains were mainly isolated from sputum, urine, blood and wound excreta and distributed in penology, neurology wards, orthopedics and surgery ICU wards. Except for glycopeptide drugs, methicillinresistant staphylococcus aureus(MRSA) had a higher drug resistance rate than those of the other drugs and had significantly more resistance than methicillin-sensitive staphylococcus aureus(MSSA)(P<0.05). In the dynamic observation of drug resistance, we discovered a gradual increase in drug resistance to fourteen test drugs during the last five years. Conclusion Drug resistance rate of SAU stayed at a higher level over the last five years; moreover, the detection ratio of MRSA keeps rising year by year. It is crucial for physicians to use antibiotics rationally and monitor the change in drug resistance in a dynamic way.

Genetic characterization of antimicrobial resistance in Staphylococcus aureus isolated from bovine mastitis cases in Northwest China

Staphylococcus aureus is the most common etiological pathogen of bovine mastitis. The resistant strains make the disease difficult to cure. The aim of this study was to characterize the genetic nature of the antimicrobial resistance in S. aureus cultured from bovine mastitis in Northwest China in 2014. A total of 44 S. aureus were isolated for antimicrobial resistance and resistance-related genes. Antimicrobial resistance was determined by disc diffusion and the corresponding resistance genes were detected by PCR. Phenotype indicated that S. aureus isolates were resistant to penicillin （84.09%）, erythromycin （20.45%）, tetracycline （15.91%）, gentamicin （9.09%）, tobramycin （6.82%）, kanamycin （6.82%） and methicillin （2.27%）. 9.09% of the S. aureus isolates were classified as multidrug resistant. In addition, genotypes showed that the isolates were resistant to rifampicin （100%, rpoB）, penicillin （95.45%, blaZ）, tetracycline （22.73%, tetK, tetM, alone or in combination）, erythromycin （22.73%, ermB or ermC）, gentamicin/tobramycin/kanamycin （2.27%, aacA-aphD）, methicillin （2.27%, mecA） and vancomycin （2.27%, vanA）. Resistance to tetracycline was attributed to the genes tetK and tetM （r=0.558, P〈0.001）. This study noted high-level geno- and phenotypic antimicrobial resistance in S. aureus isolates from bovine mastitis cases in Northwest China.

A report on infection dynamics of inducible clindamycin resistance of Staphylococcus aureus isolated from a teaching hospital in India

Objective:To investigate the infection of hospital-and community-acquired"erythromycininduced clindamycin resistant"strains or D-test positives of clinical isolates of Staphylococcus aureus(S.aureus)(with and without methicillin resistance)in a hospital.Methods:Strains of S.aureus isolated from clinical specimens were subjected to D-test and antibiotic profiling.Results:Of the total 278 isolates,140(50.35%)were D-test positives and the rest were D-test negatives.Further,of 140(100%)pesitives,87(62.14%)and 53(37.85%)strains were from males and females,respectively.Of 140(100%)pesitives,117(83.57%)were methicillin resistant S.aureus and23(16.42%)were methicillin sensitive S.aureus;of 140 strains,103(73.57%)strains front persons with and 37(26.42%)were without related infections;of 140 strains,91(65%)and 49(35%)were from hospital-and community-acquired samples,respectively.In 140 strains,118(84.28%)with comorbidities and 22(15.71%)without comorbidities cases were recorded;similarly,persons with prior antibiotic uses contributed 108(77.14%)and without 32(22.85%)positive strains.These binary data of surveillance were analyzed by a univariate analysis.It was evident that the prior antibiotic uses and comorbidities due to other ailments were the determinative factors in D-test positivity,corroborated by low P values,P=0.001 1 and 0.0024,respectively.All isolates(278)were resistant to17 antibiotics of nine groups,in varying degrees;the minimum of 28%resistance for vancomycin and the maximum of 97%resistance for gentamicin were recorded.Further,of 278 strains,only42(15.1%)strains were resistant constitutively to both antibiotics,erythromycin resistant and clindamycin resistant,while 45(16.2%)strains were constitutively sensitive to both antibiotics(erythromycin sensitive,and clindamycin sensitive).Further,of the rest 191(68.7%)strains were with erythromycin resistant and clindamycin resistant,of which only 140(50.35%)strains were D-test positives,while the rest 51(18.34%)strains were D-test negatives.Conclusions:In view of high prevalence of D-test positive S.aureus strains,and equally high prevalence of multidrug resistant strains both in community and hospital sectors,undertaking of D-test may be routinely conducted for suppurative infections.

Determining of antibiotic resistance profile in Staphylococcus aureus isolates

Objective:To determine the pattern of antibiotic resistance among Staphylococcus aureus(S. aureus) isolates from clinical specimens and to identify community-acquired methicillin-resistant Staphylococcus aureus(CA-MRSA) in specimens that have been collected from patients referring to one of the hospitals of Ahvaz.Methods:S.aureus isolates from a hospital in Ahvaz were screened for resistance to various antibiotics including methicillin.The susceptibility of the isolates was determined by Kirby-Bauer disc diffusion method.The MRSA was also treated with ethidium bromide to find the origin of resistance.Results:Among the bacterial isolates,all of 11 S.aureus were resistant to methicillin and cefixime,2 were resistant to ciprofloxacin,6 were resistant to tetracycline and the reminder were sensitive or intermediate to other antibiotics.The treated isolates were reminded resistant to methicillin and this suggested that the plasmid was not the origin of resistance in these isolates.Conclusions:These results showed that infection due to MRSA is widespread in Ahvaz and with respect to the spread of vancomycin resistance among MRSA and appearance of overwhelming infections.It is necessary to identify continuously the profile of antibiotic resistance among S.aureus isolates in other regions and finding appropriate antibiotic for infection control and eradication.

Surface-engineered liposomes for dual-drug delivery targeting strategy against methicillin-resistant Staphylococcus aureus(MRSA)

This study focused on the encapsulation of vancomycin(VAN) into liposomes coated with a red blood cell membrane with a targeting ligand, daptomycin–polyethylene glycol–1,2-distearoyl-sn-glycero-3-phosphoethanolamine, formed by conjugation of DAPT and Nhydroxysuccinimidyl-polyethylene glycol-1,2-distearoyl-sn-glycero-3-phosphoethanolamine.This formulation is capable of providing controlled and targeted drug delivery to the bacterial cytoplasm. We performed MALDI-TOF, NMR and FTIR analyses to confirm the conjugation of the targeting ligand via the formation of amide bonds. Approximately 45% of VAN could be loaded into the aqueous cores, whereas 90% DAPT was detected using UV–vis spectrophotometry. In comparison to free drugs, the formulations controlled the release of drugs for > 72 h. Additionally, as demonstrated using CLSM and flow cytometry, the resulting formulation was capable of evading detection by macrophage cells. In comparison to free drugs, red blood cell membrane–DAPT–VAN liposomes, DAPT liposomes, and VAN liposomes reduced the MIC and significantly increased bacterial permeability, resulting in > 80% bacterial death within 4 h. Cytotoxicity tests were performed in vitro and in vivo on mammalian cells,in addition to hemolytic activity tests in human erythrocytes, wherein drugs loaded into the liposomes and RBCDVL exhibited low toxicity. Thus, the findings of this study provide insight about a dual antibiotic targeting strategy that utilizes liposomes and red blood cell membranes to deliver targeted drugs against MRSA.

Antimicrobial resistance and underlying mechanisms in Staphylococcus aureus isolates

Objective: To investigate the antimicrobial susceptibility of 97 clinical Staphylococcus aureus(S. aureus) strains against 14 antimicrobials and corresponding resistance mechanisms.Methods: The antimicrobial susceptibility of the isolates was determined using a disk diffusion method and antimicrobial resistance genes were screened by polymerase chain reaction. Mutations responsible for ciprofloxacin and rifampicin resistance were investigated by polymerase chain reaction and DNA sequencing.Results: All isolates were found to be susceptible to vancomycin. Various rates of resistance to penicillin(83.5%), ampicillin(77.3%), erythromycin(63.9%), tetracycline(16.5%), amoxicillin/clavulanic acid(16.5%), ciprofloxacin(15.5%), trimethoprim/sulfamethoxazole(15.5%), oxacillin(13.4%), fusidic acid(12.4%), rifampin(6.2%), clindamycin(6.2%), gentamicin(6.2%) and mupirocin(5.2%) were determined. In addition,different combinations of resistance genes were identified among resistant isolates.Ciprofloxacin resistant isolates had mutations in codon 84(Ser84 Leu) and 106(Gly106 Asp) in the gyr A gene. Mutations in grl A were mostly related to Ser80 Phe substitution. Leu466 Ser mutation in the rpo B gene was detected in all rifampin resistant isolates. All methicillin resistant S. aureus isolates were SCCmec type V.Conclusions: In conclusion, it was determined that the isolates were resistant to different classes of antimicrobials at varying rates and resistance was mediated by different genetic mechanisms. Therefore, continuous monitoring of resistance in S. aureus strains is necessary to control their resistance for clinically important antimicrobials.

Emergence of staphylococcal cassette chromosome mec type Ⅰ with high-level mupirocin resistance among methicillin-resistant Staphylococcus aureus

Objective: To investigate the molecular epidemiology and antimicrobial resistance patterns of methicillin-resistant Staphylococcus aureus(MRSA) among healthcare workers and patients.Methods: MRSA isolates were recovered from nasal swabs collected at a tertiary care hospital of Nepal and confirmed on the basis of Gram staining, conventional biochemical tests, and PCR amplification of mec A gene. PCRs were also used for detection of the different resistance genes and staphylococcal cassette chromosome(SCC) mec types.Antibiotic susceptibility patterns of isolates were assessed by disc diffusion method and minimum inhibitory concentrations were determined by E-test.Results: A total of 29 MRSA were isolated from 536 nasal swabs(5.4%) of health care workers and patients at a tertiary care hospital in Nepal. All isolates were susceptible to amikacin, gentamicin, vancomycin(minimal inhibitory concentrations < 2 mg/m L), tigecycline, tetracycline, nitrofurantoin, rifampicin, quinupristin-dalfopristin, and linezolid. Among the 29 MRSA isolates, resistance to erythromycin(72%), ciprofloxacin(75%), co-trimoxazole(62%), clindamycin(10%), and chloramphenicol(10%) was found, and fifteen isolates(51%)exhibited high-level mupirocin resistance(minimal inhibitory concentrations > 1 024 mg/m L).Fourteen isolates were found harboring the mup A gene and one isolate was found carrying the novel mup B gene. High prevalence(68%) of SCCmec I type was found, followed by SCCmec V(13%) and SCCmec III(3%) among all the MRSA isolates.Conclusions: We found the emergence of SCCmec type I with high-level mupirocin resistance among MRSA in Nepal. Data also suggest that MRSA SCCmec type V strain has spread from the community to the hospital.

High Prevalence of Ciprofloxacin Resistance in Community Associated <i>Staphylococcus aureus</i>in a Tertiary Care Indian Hospital

We have studied the nature of ciprofloxacin resistance in methicillin sensitive and resistant Staphylococcus aureus among patients in a tertiary care hospital in Bengaluru, South India. All the isolates were highly resistant to ciprofloxacin. Molecular characterization of these samples performed using Staphylococcal Cassette Chromosome typing and multilocus sequence typing showed that 37.5% of total isolates and 59% of MRSA were sequence type (ST)772 and the rest were other STs. This indicates high prevalence of CA-MRSA in this tertiary care hospital serving the Indian community. Mutations responsible for ciprofloxacin resistance among these isolates in DNA gyrase (gyrA and gyrB) and topoisomerase IV (grlA and grlB) were analyzed by PCR amplification of specific fragments and sequencing. We found that for ST772 and five other STs present in this collection, single mutation in the gyrA gene, Ser-84→Leu, was sufficient for the high resistance. In vitro generation of ciprofloxacin resistance in two sensitive ST772 isolates by exposure to increasing antibiotic concentrations also resulted in the same single mutation of gyrA. The factors responsible for high ciprofloxacin resistance are varied and are dependent on the genetic background of the isolates and the environment. This is the first report on the mechanism of ciprofloxacin resistance among the most prevalent Indian CA-MRSA.

Antibacterial Activity of Exogenous Glutathione and Its Synergism on Antibiotics in Methicillin-Associated Multidrug Resistant Clinical Isolates of Staphylococcus aureus

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most problematic human pathogens. Antibiotic treatment of MRSA often associated with resistance to multiple classes of antibiotics is extremely challenging and urgently demands action to treat MRSA. Glutathione (GSH) is a biogenic thiol-compound that maintains an optimal intracellular redox-potential required for various normal cellular processes. Antibacterial activity of exogenous GSH has been reported in some bacterial pathogens but is largely unknown in MRSA. Aim: This study aimed to understand antibacterial activity of GSH, its role in antibiotic susceptibility, and a potential antibacterial mechanism in clinical isolates of S. aureus. Materials and Methods: Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), checkerboard, time-killing, and bacterial killing assays were performed for 14 clinical isolates of S. aureus including 10 MRSA and two type strains (ATCC 700699 and 35556). Results: MIC and MBC levels for the clinical and type strains were 15 - 20 mM and 25 - 40 mM of GSH, respectively. Subinhibitory concentrations of GSH synergistically enhanced susceptibility of all tested-antibiotics, resulting in sensitizing all-tested S. aureus. Bacterial-killing produced by GSH-mediated acidity was significantly higher than that by hydrochloric acid-mediated acidity. Conclusion: Overall results concluded that GSH exhibited antibacterial activity on S. aureus regardless of antibiotic susceptibility and synergistically enhanced antibiotic susceptibility. Additionally, GSH-mediated acidity was one of the antibacterial mechanisms. These findings suggest that GSH may be a potential antimicrobial agent or adjuvant for the conventional anti-MRSA regimens.

A Review of <i>Staphylococcus aureus</i>and the Emergence of Drug-Resistant Problem

There are various bacteria living in this world. The most common one is Staphylococcus aureus. Almost everyone has heard of it. It is easy to find their habitats, such as hospitals, homes, parks, schools etc. Some of them are difficult to be eliminated because of drug-resistant mutations. Hence, lots of researchers devoted their efforts to eliminate them. This review illustrates the characteristics of the Staphylococcus aureus and the main threat of their drug-resistant strains, especially methicillin-resistant S. aureus. What’s more, the article also highlights the plight in the drug development.

Ophthalmic methicillin-resistant <i>Staphylococcus aureus</i>infections: Sensitivity and resistance profiles of 65 isolates in central California

Purpose: To capture the sensitivity and resistance trends of ophthalmic Methicillin-resistant Staphylococcus aureus (MRSA) in a heterogenous demographic. Methods: Between 1/1/2004-12/31/2011, ophthalmic MRSA infections were searched in the electronic medical record system ofCommunityRegionalMedicalCenterinFresno,California. We reviewed whether the infection was community-acquired or hospital-acquired, culture site, and sensitivity/resistance profiles. Results: The ophthalmic MRSA isolates tested for vancomycin, sulfamethoxazole-trimethoprim, and gentamycin were 100% sensitive to these to these antibiotics. Tetracycline and rifampin had the next highest sensitivity to resistance ratio, followed by clindamycin. More cases were community-acquired than hospital acquired. Almost half of the hospital-acquired cases were in newborns. Most hospital acquired infections were post-ophthalmic surgery. Conclusion: There is an increasing trend of community- acquired ophthalmic MRSA infection with eyelid involvement being the most common manifestation. Hospital-acquired cases are common in newborns and post-ophthalmic surgery. Have a high index of suspicion for MRSA infection with suspected “insect bites”. Vancomycin, sulfamethoxazole-trimethoprim, gentamycin, tetracycline, and rifampin are good choices to treat ophthalmic MRSA infection. There may be emerging resistance to clindamycin, at least in theCentral Californiaregion. If MRSA infection is suspected, erythromycin and fluoroquinolones should be avoided.

Screening for Panton-Valentine Leukocidin Toxin Genes in Multi-Drug Resistant Methicillin-Resistant <i>Staphylococcus aureus</i>Nasal Isolates from Healthy School Children in Mariental, Namibia

Panton-Valentine leukocidin (PVL) is one of the toxins responsible for increased virulence of Staphylococcus aureus. In school settings where children are in close contact with each other, S. aureus strains, including those that may produce PVL, can be transmitted and spread in the community. Twenty-two multi-drug resistant MRSA nasal isolates from children enrolled in five schools in the town of Mariental and the multi-drug resistant American Type Culture Collection MRSA reference strain S. aureus ATCC 33591 (PVL-negative control) were used for molecular assays. Plasmid deoxyribonucleic acid (DNA) of isolates was amplified by polymerase chain reaction (PCR) and amplified PCR products were electrophoresed on a 2.5% (w/v) agarose gel containing 12 μl 0.5 μg/ml ethidium bromide and 1× TAE (Tris-acetate-EDTA) buffer at 90 volts for 50 minutes. The developed gel was viewed for the PVL-associated lukS and lukF genes that amplified at 151 bp and 406 bp, respectively. Our results indicated that seven nasal isolates had PVL toxin gene(s). From the seven isolates, three were tested positive for both lukS and lukFgenes, one tested positive for only lukS, and three tested positive for only lukF. Two of the isolates harbouring both lukS and lukF genes shared the same antibiotic resistance pattern and one of them could also produce enterotoxin A. One of the isolates with only lukF gene could produce enterotoxins B and C. These toxin-producing isolates can be expected to be more virulent than non-producers. Children should be educated on the importance of regular handwashing with soap and water to prevent the spread of potentially virulent staphylococci amongst them and the wider community. This work warrants a larger study to be carried out to investigate PVL toxin and its associated infections in Staphylococcus from school children in Namibia.

Prevalence, Resistance to Quinolones/Fluoroquinolones of <i>Staphylococcus aureus</i>Strains Isolated in the Hospital and University Center of Brazzaville, Republic of Congo

Staphylococcus aureus is a gram-positive pathogenic bacterium responsible for various infections including skin suppurations. Quinolones are sometimes used last in infections. The Staphylococcus aureus objective of this study was to determine the prevalence and assess the level of resistance to quinolones of Staphylococcus aureus trains isolated in the Hospital and University Center of Brazzaville (CHU-B). 40 strains of Staphylococcus aureus from various biological products were isolated and identified by bacteriological methods. The study of the resistance of these different strains to antibiotics (Quinolones/Fluoroquinolones) was carried out by the phenotypic method, by antibiogram. A total of 40 Staphylococcus aureus strains were isolated including 13 (32.50%) community strains, 27 (67.5%) clinical strains distributed as follows: neonatal and pediatric service 29.62% and 25.92%, surgery 18.51%, contagious 14.81%, emergencies 7.4% and delivery block 3.7%. 60% of strains were isolated in women and 40% in men. The average age of those infected was 16 years and older. 90% strains were resistant to Nalidixic acid (AN), 72.5% to Ofloxacin (OFL), 67.5% to Ciprofloxacin (CIP), 70% to Norfloxacin (NOR), 62.5% to Levofloxacin (LEV), 47.5% to Moxifloxacin (MXF), and 40% strains were resistant to all antibiotics tested.

Analysis of the Clinical Characteristics and Antibiotics Resistance of Community-acquired Methicillin-resistant Staphylococcus aureus

The purpose of this investigation is to study the clinical characteristics of infections by community-acquired methicillin-resistant Staphylococcus aureus (MRSA) and the condition of antibiotics resistance of the clinical isolates in order to guide for the rational use of antibiotics. With the clinical isolates from cases of hospital-acquired MRSA at the same period as controls, the clinical characteristics of infections by community-acquired MRSA in Hangzhou area and the pattern of non-β-lactamase antibiotics resistance were determined in this study. It was found that the average age of patients with community-acquired MRSA infections was 30.89±13.3, in comparison with those of the hospital-acquired patients of 56.0±11.8, appearing to be younger than those of the latter, and the former showing no any basic illness. Both of the former and the latter were sensitive to vancomycin (100% vs 100%), and they had the same degrees of sensitivity to rifampicin, fosfomycin, and STM/TMP (86.8% vs 88.1%, P >0.05; 81.6% vs 82.9%, P >0.05; and 52.6% vs 61.9%, P >0.05, respectively). The former was more sensitive to netimycin, clindamycin, erythromycin and minocycline than those of the latter (73.7% vs 50.5%, P <0.01; 60.5% vs 45.7%, P <0.05; 28.9% vs 11.4%, P <0.01; and 81.6% vs 58.6%, P <0.01 respectively). Meanwhile, the incidence of multi-resistant strain of isolates in the former was significantly lower than that of the latter (31.6% vs 81.0%, P <0.01). In conclusion, it appears that the strains of clinical isolates isolated from patients with the community-acquired MRSA infections show different clinical characteristics and antimicrobial susceptibility in comparison with those of the hospital-acquired cases of infection, and this necessitates an alteration in the chemotherapy of infections suspected to be caused by community-acquired MRSA.

Detection and Characterization of Methicillin Resistant Staphylococcus aureus from Toilet and Classroom Door Handles in Selected Secondary Schools in Nairobi County

Background: Staphylococcus aureus is found on all surfaces especially in public areas like hospitals and schools and on frequently touched areas like toilet and classroom door handles. Methicillin resistant Staphylococcus aureus (MRSA) is a strain of Staphylococcus aureus which is resistant to methicillin. There are two types of MRSA: Community acquired methicillin resistant Staphylococcus aureus (CA-MRSA) and hospital acquired methicillin resistant Staphylococcus aureus (HA-MRSA). MRSA in the community presents a significant reservoir that could enter into healthcare facilities and spread among patients and also a risk for immune compromised persons in the community. Methodology: The study aimed at determining the prevalence of MRSA isolated from toilet and classroom door handles as a potential source of infection to the students and the workers in selected schools in Nairobi, Kenya. The study also compared the prevalence of MRSA between boarding and non-boarding girls, boys and mixed (both girls and boys in the same school) secondary schools. Twelve secondary schools in Nairobi County were randomly selected and 306 samples from both the toilet and classroom door handles were collected using sterile swabs and transported to the laboratory. Isolation of Staphylococcus aureus was done by the use of selective media Mannitol salt agar, antibiotic susceptibility of isolates was done by disk diffusion method, and molecular detection of mecA and PVL genes were done by polymerase chain reaction (PCR). Results: The prevalence of S. aureus was 20% and 15% were MRSA positive by both Antimicrobial Susceptibility Test and PCR detection. 20% showed the presence of PVL genes, 8% showed the presence of both genes and 56% of isolates with mecA gene had PVL genes. Conclusion: The presence of MRSA in this study emphasizes the need to formulate hygiene measures to prevent possible spread of MRSA and other transmissible pathogens to students and workers in the schools.

Effect of Nano - Titanium Dioxide with Different Antibiotics against Methicillin-Resistant Staphylococcus Aureus

The different investigation has been carried out on the biological activities of titanium dioxide nanoparticle but the effect of this nano product on the antibacterial activity of different antibiotics has not been yet demonstrated. In this study the nano size TiO2 is synthesized using citric acid and alpha dextrose and the enhancement effect of TiO2 nanoparticle on the antibacterial activity of different antibiotics was evaluated against Methicillin-resistant Staphylococcus aureus (MRSA). During the present study, different concentrations of nano-scale TiO2 were tested to find out the best concentration that can have the most effective antibacterial property against the MRSA culture. Disk diffusion method was used to determine the antibacterial activity of these antibiotics in the absence and presence of sub inhibitory concentration of TiO2 nano particle. A clinical isolate of MRSA, isolated from Intensive Care Unit (ICU) was used as test strain. In the presence of sub-inhibitory concentration of TiO2 nanoparticle (20 μg/disc) the antibacterial activities of all antibiotics have been increased against test strain with minimum 2 mm to maximum 10mm. The highest increase in inhibitory zone for MRSA was observed against pencillin G and amikacin (each 10 mm). Conversely, in case of nalidixic acid, TiO2 nanoparticle showed a Synergic effect on the antibacterial activity of this antibiotic against test strain. These results signify that the TiO2 nanoparticle potentate the antimicrobial action of beta lactums, cephalosporins, aminoglycosides, glycopeptides, macrolids and lincosamides, tetracycline a possible utilization of nano compound in combination effect against MRSA.

Genotypic Characterization of Methicillin-resistant Staphylococcus aureus Isolated from Pigs and Retail Foods in China

Objective To investigate the genotypic diversity of Methicillin-resistant Staphylococcus aureus （MRSA） isolated from pigs and retail foods from different geographical areas in China and further to study the routes and rates of transmission of this pathogen from animals to food. Methods Seventy-one MRSA isolates were obtained from pigs and retail foods and then characterized by multi-locus sequencing typing （MLST）, spa typing, multiple-locus variable number of tandem repeat analysis （MLVA）, pulsed-field gel electrophoresis （PFGE）, and antimicrobial susceptibility testing. Results All isolated MRSA exhibited multi-drug resistance （MDR）. Greater diversity was found in food-associated MRSA （7 STs, 8 spa types, and 10 MLVA patterns） compared to pig-associated MRSA （3 STs, 1 spa type, and 6 MLVA patterns）. PFGE patterns were more diverse for pig-associated MRSA than those of food-associated isolates （40 vs. 11 pulse types）. Among the pig-associated isolates, CC9-ST9-t899-MC2236 was the most prevalent clone （96.4%）, and CC9-ST9-t437-MC621 （20.0%） was the predominant clone among the food-associated isolates. The CC9-ST9 isolates showed significantly higher antimicrobial resistance than other clones. Interestingly, CC398-ST398-t034 clone was identified from both pig- and food-associated isolates. Of note, some community- and hospital-associated MRSA strains （t030, t172, t1244, and t4549） were also identified as food-associated isolates. Conclusion CC9-ST9-t899-MC2236-MDR was the most predominant clone in pigs, but significant genetic diversity was observed in food-associated MRSA. Our results demonstrate the great need for improved surveillance of MRSA in livestock and food and effective prevention strategies to limit MDR-MRSA infections in China.