ANTIBIOTIC RESISTANCE PATTERN OF ISOLATES FROM WOUND AND SOFT TISSUE INFECTIONS

Two-hundred and eighty bacterial isolates from wound and soft tissue infections were studied for species identification and antibiotic resistance pattern. Amongst them 122 isolates were from community acquired infection and 158 were from nosocomial infections. The common community acquired pathogens were Staphylococcus aureus (67.8%) and Streptococcus pyogenes (10.7%), whereas Staphylococcus aureus (60.1%) and E. Coli (8.9%) were common in nosocomial infection. Only two anaerobes (Cl perfringens) were isolated. Penicillin resistance was found to be 87% and 92% for Staphylococccus aureus in community acquired and noscomial infections respectively. 85% of Proteus isolates were resistant to ampicillin. There was relatively lower level of resistance by all isolates to cefotaxime. Gentamicin showed higher rate of resistance than netilmicin and amikacin. Resistance of E. coli isolates to fluoroquinolones being 79% for norfloxacin, 81% for ciprofloxacin and 60% for ofloxacin. The study showed a higher resistance of methicillin resistant Staphylococcus aureus (MRSA) to other antibiotics. Amikacin and ofloxacin were the best recommended drugs for empirical therapy for all organisms, the susceptibility rate being 80.7% and 80.4%.KEY WORDS: Antibiotic resistance, Soft tissue infections, Wound infections     

The antimicrobial activity of ceftobiprole against Methicillin-resistant Staphylococcus aureus and multi-drug resistant Pseudomonas aeruginosa : A large tertiary care university hospital experience in Riyadh,Saudi Arabia

Objectives:To assess the antibacterial activity of ceftobiprole against Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (P. aeruginosa) from various body specimen types and different patterns of resistance.Methods:A retrospective cohort study with a total of 49 MRSA and 99 P. aeruginosa isolated in the Microbiology Laboratory at King Saud University Medical City, Riyadh, Saudi Arabia, between 2018-2019, were used. Isolates were randomly selected from various specimen types. The minimum inhibition concentration (MIC) of ceftobiprole was determined by E-test. Breakpoints carried out by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) were used to assess antibiotic susceptibility.Results:Approximately 100% of the MRSA isolates were susceptible with MIC50/90 value of 1/1.5 mg/L while 69.8% of multi-drug resistant (MDR) P. aeruginosa isolates were resistant with MIC50/90 value of 16/32 mg/L.Conclusion:The excellent activity of ceftobiprole against MRSA would have major implications in management of the patients with serious infections, as an empirical treatment or alternative to vancomycin. Ceftobiprole has a very low activity against MDR P. aeruginosa, and its susceptibility should be tested prior to use for treatment.     

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 dairy-based 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 S. 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.     

Prevalence of inducible clindamycin resistance in Staphylococcus aureus isolated from clinical samples

Background

Therapy for Staphylococcal infections may be complicated by the possibility of inducible macrolide-lincosamide-streptogramin B resistance (MLSBi). We studied the prevalence of MLSBi in community associated (CA) and hospital associated (HA) Staphylococcus aureus isolates from clinical samples.

Methods

A total of 305 strains of S. aureus comprising 140 (45.9%) [95% CI 40.36–51.52] methicillin resistant S. aureus (MRSA) and 165 (54%) [95% CI 48.48–59.64] methicillin-sensitive S. aureus (MSSA) were identified by conventional methods. The double disc test (D test) was applied by placing erythromycin and clindamycin discs to investigate inducible and constitutive MLSBi resistant phenotypes.

Results

16.6% of MRSA showed constitutive resistance and 37.5% inducible MLSBi resistance. Community associated MRSA (CA-MRSA) represented 10% of all isolates and had lower prevalence of MLSBi than hospital associated MRSA (HA-MRSA).

Conclusion

Routine screening for inducible MLSBi resistance by double disc test can screen for potential treatment failures such that clindamycin can be used effectively and judiciously when indicated for staphylococcal infections especially for treating skin and soft tissue infections (SSTIs) in CA-MRSA due to low prevalence of MLSBi among CA-MRSA.     

PCR-based identification of methicillin–resistant Staphylococcus aureus strains and their antibiotic resistance profiles

ObjectiveTo evaluated the PCR for mecA gene compared with the conventional oxacillin disk diffusion method for methicillin-resistant Staphylococcus aureus (S. aureus) identification.MethodsA total of 292 S. aureus strains were isolated from various clinical specimens obtained from hospitalized patients. Susceptibility test to several antimicrobial agents was performed by disk diffusion agar according to Clinical and Laboratory Standards Institute guidelines. The PCR amplification of the mecA gene was carried out in all the clinical isolates.ResultsAmong antibiotics used in our study, penicillin showed the least anti-staphylococcal activity and vancomycin was the most effective. The rate of methicillin-resistant S. aureus prevalence determined by oxacillin disk diffusion method was 47.6%; whereas, 45.1% of S. aureus isolates were mecA-positive in the PCR assay.ConclusionsThis study is suggestive that the PCR for detection of mecA gene is a fast, accurate and valuable diagnostic tool, particularly in hospitals in areas where methicillin-resistant S. aureus is endemic.     

Staphylococcus aureus sensitivity to various antibiotics — A national survey in Ireland 1993

The sensitivity ofStaphylococcus aureus (S. aureus) to methicillin, penicillin, gentamicin, erythromycin, ciprofloxacin, fusidic acid and mupirocin was tested in 1152 clinical isolates from nine hospital microbiology departments. In all cases standard methods for culture and sensitivity were employed using either the Stokes’ or a modified Stokes’ method for susceptibility testing. The isolates were recovered from 1150 patients (606 men, 544 women; mean age: 41 years) and only those deemed relevant to the patient’s clinical condition were included. Of the total 1152 isolates, 454 were regarded as hospital acquired, 506 were community acquired and the source of the remaining 192 isolates was unknown. The overall percentages ofS. aureus sensitive to the tested antibiotics were as follows: methicillin 85%, penicillin 8%, gentamicin 89%, ciprofloxacin 85%, erythromycin 80%, fusidic acid 96%, mupirocin 98%. The sensitivity of the methicillin resistant strains to the other antibiotics tested was generally low except for fusidic acid and mupirocin, both of which retain good activity against methicillin resistantS. aureus (MRSA). Participating investigators     

Incidence of Community-associated Methicillin-resistant Staphylococcus aureus Infections in a Regional Hospital

Background and Objective: Since the early 2000s, the incidence of methicillin-resistant Staphylococcus aureus (MRSA) infections among the community of people lacking known healthcare risk factors has increased. This MRSA infection is referred to as community-associated MRSA (CA-MRSA) infection and is distinct from hospital-associated MRSA (HA-MRSA) infection, which occurs among people with known healthcare risk factors. Understanding the epidemiology of CA-MRSA infections is critical; however, this has not been investigated in detail in Japan. Our objective was to investigate the incidence of CA-MRSA infections in a regional hospital.Patients and Methods: We investigated CA-MRSA isolates and infections in a rural regional hospital by reviewing medical records of one year. Infections were classified as CA-MRSA if no established risk factors were identified.Results: During 2008, 31 Staphylococcus aureus (S. aureus) isolates were detected in 29 unique patients, with 1 methicillin-sensitive S. aureus (MSSA) isolates obtained from 19 patients (66%) and MRSA obtained from 10 patients (34%). In the 10 patients with MRSA, the number of HA-MRSA and CA-MRSA cases were nine (32% of patients with S. aureus isolates) and one (3%), respectively. The patient with CA-MRSA was diagnosed with cellulitis due to CA-MRSA. All nine patients with HA-MRSA exhibited colonization.Conclusion: We observed a CA-MRSA case in a regional hospital in Japan, suggesting that incidence trends of CA-MRSA should be considered in future research and treatment.     

耐甲氧西林金黄色葡萄球菌抗生素耐药和耐药基因的检测

目的探讨北京地区社区感染和院内感染中金黄色葡萄球耐药情况变化。方法用琼脂稀释法检测了471株从北京地区收集的金黄色葡萄球菌对11种抗生素的敏感水平(其中422株菌株从1993年至2000年门诊脓疱疮患儿分离获得,49株从2000年烧伤病房住院患者分离获得)。用聚合酶链反应方法对上述菌株进行了mecA耐药基因的检测。结果引起社区感染的耐甲氧西林金黄色葡萄球菌(MRSA)的比率由1993年的12.2%上升至2000年的29.8%,对甲氧西林均表现为低度耐药。引起院内感染的金黄色葡萄球菌对甲氧西林的耐药率为63.3%,表现为高度耐药。所有的金黄色葡萄球菌对青霉素100%耐药,对红霉素、四环素、克林霉素和氯霉素的耐药率分别约80%、70%、60%和50%。引起社区感染的金黄色葡萄球菌中未发现庆大霉素和利福平耐药菌株,对环丙沙星的耐药率由1993年的2.4%上升至2000年的21.3%;引起院内感染的金黄色葡萄球菌中对庆大霉素、环丙沙星和利福平的耐药率分别为63.3%、63.3%和57.1%。所有的金黄色葡萄球菌均对夫西地酸和万古霉素敏感。2000年分离的多重耐药菌株比例较1993年有所增加。PCR对mecA耐药基因的测定结果显示,所有对甲氧西林高度耐药的金黄色葡萄球菌mecA耐药基因均呈阳性;对甲氧西林低度耐药的金黄色葡萄球菌mecA耐药基因均呈阴性。结论在本实验所及范围内,北京地区金黄色葡萄球菌的耐药率逐渐上升,mecA耐药基因测定是筛选耐药MRSA菌株的快速、简易手段。     

Distribution of sasX,qacA/B and mupA genes and determination of genetic relatedness of methicillin-resistant Staphylococcus aureus among clinical isolates and nasal swab samples from the same patients in a hospital in Malaysia

INTRODUCTIONThis study determined the distribution of sasX, qacA/B and mupA genes from methicillin-resistant Staphylococcus aureus (MRSA) isolated from clinical samples and nasal swab samples of the same patients and analysed their genetic relatedness.METHODSPolymerase chain reaction was used to detect the presence of sasX, qacA/B and mupA genes from 47 paired MRSA isolates. A paired isolate was defined as one nasal swab (colonising) isolate and clinical isolate that caused infection in the same patient. 22 selected paired isolates were subjected to multilocus sequence typing (MLST). The genetic relatedness among the isolates and association between the putative genes with epidemic sequence types (STs) were investigated.RESULTS7 (14.9%, n = 14) paired isolates were positive for the sasX gene. qacA/B genes were positive in 7.4% (n = 7) of the isolates, from three paired isolates and one clinical isolate whose paired colonising isolate was negative. The paired sample of three patients were positive for both genes. The mupA gene was not detected in all the isolates. MLST revealed two epidemic STs, ST22 and ST239, and a novel ST4649. sasX and qacA/B genes were found in ST239 in 29.5% (n = 13) and 13.6% (n = 6) of cases, respectively. Gene co-existence occurred in 13.6% (n = 6) of MRSA ST239 and 2.3% (n = 1) of MRSA ST4649.CONCLUSIONsasX and qacA/B genes were present in the MRSA isolates, while the mupA gene was undetected. ST22 and ST239 were the major MRSA clones. The circulating MRSA genotypes conferred different virulence and resistance determinants in our healthcare settings.     

Prevalence of methicillin-resistant Staphylococcus aureus nasal colonization among medical students in Jeddah,Saudi Arabia

Objectives:

To identify Methicillin-resistant Staphylococcus aureus (MRSA) nasal carriage status among medical students during their clinical rotations.

Methods:

This cross-sectional study detected the prevalence of MRSA among medical students at King Abdulaziz University (KAU), Jeddah, Saudi Arabia, using molecular approaches. Nasal swabs were collected from 150 internship and sixth-year medical students between September 2014 and January 2015, and compared with the control group of 32 third-year medical students who were not exposed to clinical work. Polymerase chain reaction (PCR) screening was performed to identify Staphylococcus aureus (S. aureus) nuc gene, and an additional PCR was performed on S. aureus positive samples to detect the presence of mecA gene.

Results:

Out of 150 students screened, 38 were nasal carriers of S. aureus. The prevalence of methicillin-sensitive S. aureus (MSSA) carriers was 18.7% (n=28), whereas 10 students (6.7%) were mecA-positive, representing MRSA carriers. Interns carry MRSA more than 6th year students and students who were not exposed to clinical work (p<0.05), while MSSA is found more in students who were not exposed to clinical work (p<0.01).

Conclusion:

We found MRSA carriers among medical students at KAU, which showed a possible contribution of this group to transmit infection to hospitalized patients. Medical students must receive sufficient knowledge regarding control measures to avoid spread of this infection in hospitals.Staphylococcus aureus (S. aureus) is a key pathogen, which is implicated in nosocomial and community acquired infections.1,2 Infection caused by S. aureus can be endogenous, where the infectious organism is found in the patient’s body, or exogenous, where the organism is transmitted from an external source. The organism is normally found as a commensal in the anterior nares of healthy individuals. Immuno-compromised patients are at high risk of acquiring infection. Therefore, nasal colonization of hospital staff, students, and visitors who are in direct contact with this type of patients can be a potential source of transmitting infection.3,4 More clinical attention has been given to staphylococcal infection due to the ability of this organism to rapidly develop resistance to a wide range of antibiotics.5 After the identification of ß-lactamase, the core cause of penicillin resistance in S. aureus, newer semi-synthetic penicillinase-resistant ß-lactams, exemplified by methicillin, were introduced to counteract the penicillinase-producing S. aureus strains.6 However, very shortly after its introduction, strains of S. aureus resistant to methicillin were reported.7 These are known as methicillin-resistant Staphylococcus aureus (MRSA). Since the early 1960s, multi-resistant strains of S. aureus have emerged in hospitals and the community, which are now resistant to methicillin and a wide range of currently available antibiotics. According to national nosocomial surveillance system in 2003,8 60% of nosocomial infections caused by S. aureus from the intensive care units were resistant to methicillin. This limits the therapeutic options to very few agents such as vancomycin and teicoplanin. However, the overuse of vancomycin resulted in emergence of MRSA that shows decreased susceptibility to these agents.9,10 The prevalence rate of MRSA had reached 50% in the United States hospitals.11 In the United Kingdom, MRSA accounted for 44% of S. aureus isolated from health care workers. In Japan, MRSA accounted 60-70% of S. aureus isolated from inpatients.12,13 In Saudi Arabia, the MRSA nasal carriage rate among healthcare workers was reported as 76%.14 However, a 20-year literature search did not reveal any data for the prevalence of MRSA carriers among medical students in Saudi Arabia. Thus, healthcare workers are at higher risk of colonization by MRSA than the general public, apparently due to increased exposure to this organism. Moreover, they can be a major source of transmission during contact with their patients if infection control measures are not complied. The presence of MRSA in health institutes is directly proportional to high rate of infections caused by this strain. This may lead to a relative increase in treatment cost and length of hospital stay. Therefore, screening for MRSA in hospitals is an important factor for building up successful infection control strategies.15,16 Medical students would be a key target group to introduce awareness of hospital-acquired infections. Therefore, prevalence studies need to be carried out to screen this group to assess their carriage status during their clinical rotations. In Saudi Arabia, such studies have not been frequently carried out. These students can be exposed to patients and other healthcare workers during their clinical rotation and can be potential nasal carriers for spreading MRSA within hospitals. Therefore, this study aims to identify the MRSA nasal carriage status among medical students during their clinical rotations at King Abdulaziz University (KAU) Hospitals, Jeddah, Saudi Arabia.     

Community-acquired methicillin-resistant Staphylococcus aureus in a rural American Indian community

CONTEXT: Until recently, methicillin-resistant Staphylococcus aureus (MRSA) infections have been acquired primarily in nosocomial settings. Four recent deaths due to MRSA infection in previously healthy children in the Midwest suggest that serious MRSA infections can be acquired in the community in rural as well as urban locations. OBJECTIVES: To document the occurrence of community-acquired MRSA infections and evaluate risk factors for community-acquired MRSA infection compared with methicillin-susceptible S aureus (MSSA) infection. DESIGN: Retrospective cohort study with medical record review. SETTING: Indian Health Service facility in a rural midwestern American Indian community. PATIENTS: Patients whose medical records indicated laboratory-confirmed S aureus infection diagnosed during 1997. MAIN OUTCOME MEASURES: Proportion of MRSA infections classified as community acquired based on standardized criteria; risk factors for community-acquired MRSA infection compared with those for community-acquired MSSA infection; and relatedness of MRSA strains, determined by pulsed-field gel electrophoresis (PFGE). RESULTS: Of 112 S aureus isolates, 62 (55%) were MRSA and 50 (45%) were MSSA. Forty-six (74%) of the 62 MRSA infections were classified as community acquired. Risk factors for community-acquired MRSA infections were not significantly different from those for community-acquired MSSA. Pulsed-field gel electrophoresis subtyping indicated that 34 (89%) of 38 community-acquired MRSA isolates were clonally related and distinct from nosocomial MRSA isolates found in the region. CONCLUSIONS: Community-acquired MRSA may have replaced community-acquired MSSA as the dominant strain in this community. Antimicrobial susceptibility patterns and PFGE subtyping support the finding that MRSA is circulating beyond nosocomial settings in this and possibly other rural US communities.     

A STRATEGY FOR RAPID IDENTIFICATION OF METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS NASAL CARRIER STATUS

Methicillin Resistant Staphylococcus aureus (MRSA) is a multi drug resistant organism responsible for severe outbreaks of life threatening infections in hospitals which are difficult to treat They are spread by nasal carriage among the hospitalised patients, staff and visitors. Mannitol cloxacillin salt agar (MCSA) is a single tube method to identify MRSA. However, tubes showing growth and change in colour on biochemical characterisation often do not prove to be MRSA. In this study we have combined two strategies for the rapid identification and isolation of MRSA by culture in MCSA and multiplex PCR for mecA and femB genes. Anterior nasal swabs obtained from nursing staff and patients admitted to a large referral hospital, were inoculated into MCSA. Of the 100 tubes inoculated, 8 tubes showed change in colour and growth. On conventional testing 4 were MRSA, 3 were methicillin sensitive S aureus (MSSA) and 1 was Methicillin Sensitive Coagulase Negative S aureus (MSCNS). Genotyping by multiplex PCR revealed 5 MRSA, 2 MSSA and 1 MRCNS. The Multiplex PCR technique to rapidly identify presence of mecA and femB genes showed presence of both mecA and femB bands in all MRSA. The methicillin sensitive organisms showed absence of mecA gene while coagulase negative organisms showed absence of the fern B gene. Combining MSCA with multiplex PCR for mec A and fem B genes made the test both rapid and specific. Use of this strategy would enable rapid screening of nasal carriers and early implementation of hospital infection control measures.KEY WORDS: Mannitol cloxacillin salt agar, Methicillin Resistant S aureus, Methicillin Sensitive Coagulase Negative S aureus, Methicillin Sensitive S aureus     

In vitro vancomycin susceptibility amongst methicillin resistant Staphylococcus aureus

Background

Vancomycin is drug of choice for treatment of Methicillin Resistant Staphylococcus aureus (MRSA) infections. S. aureus with reduced vancomycin susceptibility (SA-RVS) is on rise. Current guidelines of detection of SA-RVS are based on MIC (Minimum Inhibitory Concentration) by broth or agar dilution methods. Vancomycin MIC by E test (Epsilometer Test) is an alternative. A study was undertaken to know the prevalence of SA-RVS and compare vancomycin MIC by agar dilution and E test.

Methods

A prospective study was undertaken at tertiary care hospital; 232 clinical MRSA isolates were included. Vancomycin MIC was undertaken by agar dilution method and E test.

Results

All isolates were sensitive to Linezolid. Two MRSA isolates had vancomycin MIC ≥4 μg/ml; vancomycin MIC50 and MIC90 of MRSA isolates was 0.5 and 0.2 μg/ml respectively by agar dilution method. There was agreement over 93.5% isolates in vancomycin susceptibility by agar dilution and E test. E test had sensitivity and positive predictive value of 1.0 (CI – 0.34–1.0) and 0.5 (CI – 0.17–0.83) respectively compare to agar dilution method.

Conclusions

MRSA isolates continues to be susceptible to vancomycin and Linezolid. E test was found equally suitable in initial screening for vancomycin susceptibility. Due to geographic variation in prevalence, there is need of ongoing surveillance of SA-RVC.     

Characterization of Staphylococcus aureus Isolated from Clinical Specimens by Matrix Assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry

ObjectiveTo develop a matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) approach to identify Staphylococcus aureus (S. aureus) and differentiate methicillin-resistant S. aureus (MRSA) from methicillin-sensitive S. aureus (MSSA).MethodsA total of 100 S. aureus strains isolated from clinical specimens and farm workers were collected and analyzed by MALDI-TOF-MS. And data obtained were interpreted with biotyper software.ResultsNinety-two strains were identi?ed by MALDI-TOF-MS as S. aureus at a level of secure genus and probable species, and 4 strains were identified at probable genus after their cultivation, spectral collection and data preprocessing. One strain was identified as S. aureus with lower score. It was revealed that identification of S. aureus by MALDI-TOF-MS was highly correlated with typing by biochemical and serological methods with an accuracy as high as 97%. The biotyper cluster analysis showed that 100 isolates were divided into 2 types at the distance level of 400. Higher peak intensity in the mass of both 3784 Da and 5700 Da was observed in MRSA, whereas that was absent from MSSA.ConclusionMALDI-TOF-MS is considered as a simple, rapid and highly reproducible technique with high-throughput and accuracy for the identification of S. aureus and it can reliably differentiate MRSA from MSSA.     

In vitro antibacterial activity of leaf extracts of Zehneria scabra and Ricinus communis against Escherichia coli and methicillin resistance Staphylococcus aureus

ObjectiveTo evaluate the antibacterial activities of the crude leaves extracts of Zehneria scabra (Z. scabra) and Ricinus communis (R. communis) against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and methicillin resistance S. aureus.MethodsThe crude powdered leaves of Z. scabra and R. communis were extracted successively by organic solvents in increasing polarity [benzene, chloroform:acetone (1:1), 70% alcohol and distilled water]. The antibacterial susceptibility of the crude leaves extracts of were tested against standard strains of E. coli (ATCC 25922) and S. aureus (ATCC 2923) and clinical isolates of E. coli, S. aureus and methicillin resistance S. aureus using agar well diffusion method.ResultsIn Z. scabra and R. communis leaf extracts, the most sensitive standard strain was S. aureus with an inhibition zone of (14.00±1.20) mm and (15.90±2.13) mm, respectively. The minimum inhibitory concentration (MIC) values of Z. scabra extracts against test organisms ranged from 1.95 mg/mL for extract 3 in clinical and standard strains of S. aureus to 250 mg/mL for extract 1 and 4 in clinical and standard strains of E. coli. The MIC values of R. communis extracts against test organisms ranged from 1.95 mg/mL for extract 2 and 3 standard strains of S. aureus to 250 mg/mL for extract 1 in clinical isolate of E. coli. Most of the minimum bactericidal concentration and MIC values of plant extracts were almost similar particularly in R. communis, or minimum bactericidal concentration equal to one dilution factor less than MIC value of the extracts mainly in Z. scabra.ConclusionsThe potency of plant extracts against test organisms were depend on different organic solvents used. Clinical isolate of bacterial pathogens showed less zones of diameter compared to the standard strains. Gram-positive had wide inhibition zones than Gram-negative bacteria. Further studies should be carried out to isolate the pure compounds and standardization of the methods of plant extracts for an in vitro testing.     

Effect of ethanolic extract of Ecballium elaterium against Staphylococcus aureus and Candida albicans

Objective

To evaluate the antimicrobial activity of ethanolic extract of Ecballium elaterium (E. elaterium) fruits alone against Staphylococcus aureus (S. aureus) strains and Candida albicans (C. albicans) strains, or in combination with penicillin against Staphylococcus areus strains.

Methods

Evaluation of the antimicrobial activity or synergy interaction was carried out using microdilution method.

Results

The results showed that ethanolic extract of E. elaterium fruits has antimicrobial activity against methicillin resistant S. aureus (MRSA), methicillin sensitive S. aureus (MSSA) and C. albicans. This extract showed a significant decrease in minimum inhibitory concentrations (MIC) of penicillin against both MRSA and MSSA strains. Fractional inhibitory concentration index (FIC) between penicillin and ethanolic extract of E. elaterium fruits against these test strains was less than 0.5.

Conclusions

This study suggests that ethanolic extract of E. elaterium fruits has antimicrobial activity against S. aureus and C. albicans and there is a possibility of concurrent use of penicillin and E. elaterium extract in combination in the treatment of infections caused by MRSA and MSSA strains. A wider study is needed to identify the effective components, the mode of action and the possible toxic effect in vivo of these ingredients.     

In?vitro vancomycin susceptibility amongst methicillin resistant Staphylococcus aureus

Background

Vancomycin is drug of choice for treatment of Methicillin Resistant Staphylococcus aureus (MRSA) infections. S. aureus with reduced vancomycin susceptibility (SA-RVS) is on rise. Current guidelines of detection of SA-RVS are based on MIC (Minimum Inhibitory Concentration) by broth or agar dilution methods. Vancomycin MIC by E test (Epsilometer Test) is an alternative. A study was undertaken to know the prevalence of SA-RVS and compare vancomycin MIC by agar dilution and E test.

Methods

A prospective study was undertaken at tertiary care hospital; 232 clinical MRSA isolates were included. Vancomycin MIC was undertaken by agar dilution method and E test.

Results

All isolates were sensitive to Linezolid. Two MRSA isolates had vancomycin MIC ≥4 μg/ml; vancomycin MIC50 and MIC90 of MRSA isolates was 0.5 and 0.2 μg/ml respectively by agar dilution method. There was agreement over 93.5% isolates in vancomycin susceptibility by agar dilution and E test. E test had sensitivity and positive predictive value of 1.0 (CI – 0.34–1.0) and 0.5 (CI – 0.17–0.83) respectively compare to agar dilution method.

Conclusions

MRSA isolates continues to be susceptible to vancomycin and Linezolid. E test was found equally suitable in initial screening for vancomycin susceptibility. Due to geographic variation in prevalence, there is need of ongoing surveillance of SA-RVC.     

Bacteriophage types of methicillin-resistant Staphylococcus aureus in a tertiary care hospital

Background

Phage typing had been utilised extensively to characterise methicillin-resistant Staphylococcus aureus (MRSA) outbreak strains in the past. It is an invaluable tool even today to monitor emergence and dissemination of MRSA strains.

Aims

The aim of this study was to determine the prevalent phage types of MRSA in south India and the association between phage types, antibiotic resistance pattern and risk factors.

Method

A total of 48 non-duplicate MRSA strains recovered from various clinical samples during January to December, 2010 were tested against a panel of anti-staphylococcal antibiotics. Phage typing was carried out at the National Staphylococcal Phage Typing Centre, New Delhi. Out of 48, 32 hospitalised patients were followed up for risk factors and response to empirical and post sensitivity antibiotic therapy. The risk factors were compared with a control group of 30 patients with methicillin sensitive Staphylococcus aureus (MSSA) infection.

Results

Amongst the five prevalent phage types, 42E was most common (52%), followed by a non-typable variant (22.9%), 42E/47/54/75 (16.6%), 42E/47 (6.2%) and 47 (2%). Phage type 42E was the predominant strain in all wards and OPDs except in the ICU where 42E/47/54/75 was most common. Although not statistically significant, strain 42E/47/54/75 (n=8) showed higher resistance to all drugs, except ciprofloxacin and amikacin, and were mostly D-test positive (87.5%) compared to the 42E strain (32%). Duration of hospital stay, intravenous catheterisation and breach in skin were the most significant risk factors for MRSA infection.

Conclusion

We found MRSA strain diversity in hospital wards with differences in their antibiotic susceptibility pattern. The findings may impact infection control and antibiotic policy significantly.     

耐甲氧西林金黄色葡萄球菌临床感染分布及耐药性分析

目的了解山西省长治医学院附属和平医院耐甲氧西林金黄色葡萄球菌(MRSA)临床感染分布和耐药现状。方法常规进行细菌的分离培养和鉴定,采用纸片扩散法行药物敏感试验;采用头孢西丁纸片扩散法行MRSA菌株鉴定;采用双纸片扩散法(D试验)检测诱导型克林霉素耐药情况。结果耐药率>50.0%的有8种,其中青霉素、红霉素、克林霉素(包括2株D试验阳性株)、阿奇霉素、环丙沙星、左旋氧氟沙星、庆大霉素耐药率均达到100.0%。敏感率>50.0%的仅4种,其中万古霉素、替考拉宁敏感率为100.0%。MRSA对12种抗菌药物共有6种耐药表型,其中对青霉素、红霉素、克林霉素、阿奇霉素、环丙沙星、左旋氧氟沙星、庆大霉素、复方新诺明是其主要的耐药模式。38株MRSA中检测出对红霉素耐药、克林霉素敏感菌株共2株,D试验阳性株2株(100.0%)。结论 MR-SA菌株表现为多重耐药,耐药性有上升趋势。万古霉素仍是目前对抗NRSA感染的首选用药。