Prevalence of methicillin resistant Staphylococcus aureus in Karnataka

This study was undertaken to find out the prevalence of methicillin resistant Staphylococcus aureus (MRSA) infection in our hospital and to compare their antibiotic susceptibility pattern with methicillin sensitive Staphylococcus aureus (MSSA). 100 strains of Staphylococcus aureus isolated from various clinical samples were screened for MRSA by disc diffusion method using 1 gm oxacillin disc. Antibiotic sensitivity testing was done by Kirby-Bauer's disc diffusion method. Out of these, 43% were identified as MRSA and the remaining 57% were MSSA. There was a marked difference in antibiotic sensitivity pattern of these M RSA versus the MSSA isolates. None of the MRSA isolate was found to be sensitive to amoxycillin while 36.8% of MSSA were sensitive to this antibiotic. 9.3%, 18.6%, 34.9% and 95.3% of MRSA were sensitive to cotrimoxazole, cloxacillin, ciprofloxacin and chloramphenicol, while 75.4%, 92.9%, 91.2% and 94.7% of MSSA were sensitive to these antibiotics respectively. Sensitivity to macrolide group of antibiotics like erythromycin and roxithromycin were seen in 7% and 14% of MRSA in comparison to 85.9% and 91.2% of MSSA respectively. Amongst the aminoglycosides like gentamicin and amikacin, the sensitivity of MRSA was found to be 18.6% and 46.5% and that of MSSA was 98.2% and 94.7% respectively. Sensitivity to cephalosporins like cephalexin and cefotaxime was seen in 23% and 25.5% of MRSA, whereas 100% of MSSA were sensitive to these antibiotics. All Staphylococcus aureus isolates were found to be uniformly sensitive to vancomycin. Majority of the isolates belonged to phage group III and the common phage types were 54, 54/75 and 54/75/85.     

Antibody-directed photodynamic therapy of methicillin resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a world-wide public health problem, causing nosocomial and community-acquired infections. Furthermore, MRSA is increasingly resistant to many conventional antimicrobials, so there is a real need to develop alternative approaches for MRSA decolonization and treatment. Previously, we have demonstrated that MRSA can be killed with an immunoglobulin G (IgG)-SnCe6 conjugate and red light, but effectiveness was dependent on the particular strain and the growth phase. In this investigation, we used an antibody raised against MRSA to make an Ab-SnCe6 conjugate capable of targeting many MRSA strains in all growth phases. To suspensions of important epidemic MRSA, each grown to stationary, lag, or exponential phase, the Ab-SnCe6 conjugate was added and samples exposed to red light. Survivors were then enumerated. This treatment was very effective at killing all the different MRSA strains tested, in all growth phases. The Ab-SnCe6 conjugate was able to kill EMRSA-16 selectively in a mixed suspension of EMRSA-16 and Escherichia coli, and was much better at killing EMRSA-16 than a coagulase-negative staphylococcus, S. epidermidis. These results demonstrate that photodynamic therapy of MRSA is very effective when the photosensitizer is targeted to the pathogen using a suitable antibody and may be a good candidate for a novel treatment of MRSA infections.     

Studies on clinical isolates of coagulase-negative staphylococci resistant to methicillin. Evidence of cross-resistance between methicillin and cephalothin

The in vitro susceptibility to cephalothin and cefuroxime of 195 isolates of methicillin-resistant coagulase-negative staphylococci was determined by the agar-diffusion test, using 7.5% NaCl-supplemented agar. The distribution of the inhibition zone diameters for isolates of S. epidermidis (S. biotype 1) as well as for S. haemolyticus (S. biotype 4) was trimodal. While 4% of the isolates were found susceptible to cefuroxime, 39% of the S. epidermidis/S. hominis (S. biotype 1) isolates and 34% of the S. haemolyticus (S. biotype 4) isolates were found susceptible to cephalothin by this method. Eight of these isolates (six S. epidermidis, two S. haemolyticus) were selected for susceptibility testing by the tube-dilution method, together with four isolates (three S. haemolyticus, one S. epidermidis) found resistant to cephalothin by the agar-diffusion test. The first-mentioned isolates were all found susceptible to cephalothin with MICs less than or equal to 2 micrograms/l, while the last-named all were resistant with MICs greater than or equal to 16 micrograms/ml. Population analyses revealed sub-populations of highly resistant bacteria in all methicillin-resistant isolates of S. epidermidis (S. biotype 1), as well as in all isolates of S. haemolyticus (S. biotype 4). We thus concluded that methicillin-resistance in isolates of coagulase-negative staphylococci implies resistance to cephalosporins and that the difference between S. epidermidis and S. haemolyticus as regards cephalosporin-susceptibility is quantitative and not qualitative. Eighty-nine per cent of the 195 methicillin-resistant isolates in this study were resistant to penicillin and at least one more antibiotic. We therefore think that resistance to penicillin and one or more non-beta-lactam antibiotics strongly suggests methicillin-resistance and that such isolates should be further tested on hypertonic media.     

Antimicrobial susceptibility pattern among methicillin resistant Staphylococcus isolates in Assam

Prevalence of methicillin resistant Staphylococcus aureus from a referral hospital in Assam was studied. Methicillin resistance among the Staphylococcus aureus isolates was 52.9% and 15% among the coagulase negative staphylococci. Resistance to all antibiotics tested among the methicillin resistant and methicillin sensitive staphylococci was found to be 23.2% and 6.6% respectively. Higher resistance to multiple antibiotics in methicillin resistant strains as compared to methicillin sensitive strains was found to be statistically significant. Ciprofloxacin resistance among the strains was still lower in comparison to the findings from other parts of the country.     

脉冲场凝胶电泳分析耐甲氧西林金黄色葡萄球菌

目的探索一种准确、快速、可靠的分子生物学分型方法，研究耐甲氧西林的金黄色葡萄球菌（ＭＲＳＡ）的流行病学。方法建立脉冲场凝胶电泳（ＰＦＧＥ）的分子生物学分型方法。将细菌包埋于琼脂块中，原位溶解细菌，ＳｍａⅠ消化染色体ＤＮＡ，经脉冲场凝胶电泳（ＰＦＧＥ）分离，比较染色体限制性内切酶图谱，确定菌株的亲缘关系。结果３８株ＭＲＳＡ的ＰＦＧＥ谱分１０组（Ａ～Ｊ），以Ａ型为主，Ａ型又有Ａ１～Ａ４四个亚型。１９９５年１１月～１９９６年３月发生了Ａ１亚型株暴发流行，从１８位住院病人共分离到２２株。暴发流行株在住院病人、各病房及各医院之间进行传播。结论对ＭＲＳＡ的流行病学进行研究，ＰＦＧＥ是一种准确、可靠、重复性好的分子生物学分型方法。     

Comparison of methods for the isolation of methicillin resistant Staphylococcus aureus.

The control of methicillin resistant Staphylococcus aureus (MRSA) relies on the rapid and sensitive detection of carriage. The roles of an enrichment broth, duration of incubation, and Baird-Parker medium containing ciprofloxacin (BPC) were evaluated in comparison with standard media in a centre where the prevalence of ciprofloxacin resistance among MRSA is over 98%. Screening swabs from 402 sites were plated onto BPC, mannitol salt agar (MSA), and MSA with methicillin (MMSA). The swabs were enriched in Tryptone-T broth with 6% salt for 24 hours and the broths subcultured onto BPC, MSA, and MMSA. MRSA was isolated from 134 swabs. Significantly more isolates were obtained by incubating culture plates for 42 hours rather than 18 hours, by the use of broth enrichment, and by addition of methicillin or ciprofloxacin to media. BPC was the most sensitive medium (107 isolates (80%) by direct culture at 42 hours), grew the fewest contaminants, and allowed provisional reporting of 73% of isolates at 18 hours by colonial appearance and use of Staphaurex Plus rapid latex reagent. This may allow the introduction of infection control measures a day earlier than when other established methods are used.     

A case of methicillin resistant Staphylococcus aureus necrotizing pneumonia with pulmonary cryptococcosis

A 37-year-old healthy man was transferred to the emergency department of this hospital because of fever and hemoptysis. A radiograph of the chest revealed a cavitary lesion in the right upper lobe. Computed tomography of the chest showed necrotizing cavitary pneumonia. Urgent throacoscopic lobectomy was performed. Sputum and intraoperative pleural pus grew methicillin resistant Staphylococcus aureus (MRSA). The pathological examination reportedly revealed cryptococcal infection. He had a full recovery after intravenous linezolid treatment.     

Advantage and limitations of nitrofurantoin in multi-drug resistant Indian scenario

Infections caused by antibiotic resistant pathogens are of significant concern and are associated with higher mortality and morbidity. Nitrofurantoin is a broad-spectrum bactericidal antibiotic and is effectively used to treat urinary tract infections (UTIs) caused by E. coli, Klebsiella sp., Enterobacter sp., Enterococcus sp. and Staphylococcus aureus. It interfere with the synthesis of cell wall, bacterial proteins and DNA of both Gram positive and Gram negative pathogens. Nitrofurantoin has been used successfully for treatment and prophylaxis of acute lower urinary tract infections. With the emergence of antibiotic resistance, nitrofurantoin has become the choice of agent for treating UTIs caused by multi-drug resistant pathogens.     

耐甲氧西林金黄色葡萄球菌SCCmec基因分型及药敏分析

Objective To investigate the SCCmec genotyping, subtype and antimicrobial susceptibility tests in methicillin resistant staphylococcus aureus to guide the clinical treatment and provide the proof for molecular epidemiology. Methods To detect mecA gene and SCCmec genetyping and subtype in 50 MRSA by PCR. According to CLSI's guideline, antimicrobial susceptibility tests were performed with disk diffusion. Results All 50 MRSA had meeA genes. 45 strains were SCCmecⅢ types; 3 strains were SCCmecⅢA types;2 straius were SCCmec Ⅱ types. There were no SCCmec Ⅰ and SCCmecⅣ types. SCCmec Ⅱ ,SCCmecⅢ and SCCmecⅢ A type strains were all multiresistant. Conclusion 50 MRSA are all multiresistant. SCCmec Ⅲ are the main types.     

耐甲氧西林金黄色葡萄球菌SCCmec基因分型及药敏分析

Objective To investigate the SCCmec genotyping, subtype and antimicrobial susceptibility tests in methicillin resistant staphylococcus aureus to guide the clinical treatment and provide the proof for molecular epidemiology. Methods To detect mecA gene and SCCmec genetyping and subtype in 50 MRSA by PCR. According to CLSI's guideline, antimicrobial susceptibility tests were performed with disk diffusion. Results All 50 MRSA had meeA genes. 45 strains were SCCmecⅢ types; 3 strains were SCCmecⅢA types;2 straius were SCCmec Ⅱ types. There were no SCCmec Ⅰ and SCCmecⅣ types. SCCmec Ⅱ ,SCCmecⅢ and SCCmecⅢ A type strains were all multiresistant. Conclusion 50 MRSA are all multiresistant. SCCmec Ⅲ are the main types.     

耐甲氧西林金黄色葡萄球菌SCCmec基因分型及药敏分析

Objective To investigate the SCCmec genotyping, subtype and antimicrobial susceptibility tests in methicillin resistant staphylococcus aureus to guide the clinical treatment and provide the proof for molecular epidemiology. Methods To detect mecA gene and SCCmec genetyping and subtype in 50 MRSA by PCR. According to CLSI's guideline, antimicrobial susceptibility tests were performed with disk diffusion. Results All 50 MRSA had meeA genes. 45 strains were SCCmecⅢ types; 3 strains were SCCmecⅢA types;2 straius were SCCmec Ⅱ types. There were no SCCmec Ⅰ and SCCmecⅣ types. SCCmec Ⅱ ,SCCmecⅢ and SCCmecⅢ A type strains were all multiresistant. Conclusion 50 MRSA are all multiresistant. SCCmec Ⅲ are the main types.     

Epidemic of Staphylococcus aureus nosocomial infections resistant to methicillin in a maternity ward

Methicillin-resistant Staphylococcus aureus (MRSA) nosocomial infections frequently occur in the hospital environment, but their incidence is less often observed in neonates. In the present investigation, seventeen cases were recorded over a nine-week period (two cases per week). Pulsed field gradient gel electrophoresis confirmed the clonal character of the strain. The hypothesis of manually-transmitted infection due to contamination from multiple sources was reinforced by the fact the epidemic persisted in spite of the elimination of the main human infectious source and an absence of risk factors determined by the case-control study. The role of environmental factors in the persistence of this outbreak of MRSA infection has been considered.     

耐甲氧西林金黄色葡萄球菌SCCmec基因分型及药敏分析

Objective To investigate the SCCmec genotyping, subtype and antimicrobial susceptibility tests in methicillin resistant staphylococcus aureus to guide the clinical treatment and provide the proof for molecular epidemiology. Methods To detect mecA gene and SCCmec genetyping and subtype in 50 MRSA by PCR. According to CLSI's guideline, antimicrobial susceptibility tests were performed with disk diffusion. Results All 50 MRSA had meeA genes. 45 strains were SCCmecⅢ types; 3 strains were SCCmecⅢA types;2 straius were SCCmec Ⅱ types. There were no SCCmec Ⅰ and SCCmecⅣ types. SCCmec Ⅱ ,SCCmecⅢ and SCCmecⅢ A type strains were all multiresistant. Conclusion 50 MRSA are all multiresistant. SCCmec Ⅲ are the main types.     

耐甲氧西林金黄色葡萄球菌SCCmec基因分型及药敏分析

Objective To investigate the SCCmec genotyping, subtype and antimicrobial susceptibility tests in methicillin resistant staphylococcus aureus to guide the clinical treatment and provide the proof for molecular epidemiology. Methods To detect mecA gene and SCCmec genetyping and subtype in 50 MRSA by PCR. According to CLSI's guideline, antimicrobial susceptibility tests were performed with disk diffusion. Results All 50 MRSA had meeA genes. 45 strains were SCCmecⅢ types; 3 strains were SCCmecⅢA types;2 straius were SCCmec Ⅱ types. There were no SCCmec Ⅰ and SCCmecⅣ types. SCCmec Ⅱ ,SCCmecⅢ and SCCmecⅢ A type strains were all multiresistant. Conclusion 50 MRSA are all multiresistant. SCCmec Ⅲ are the main types.     

耐甲氧西林金黄色葡萄球菌SCCmec基因分型及药敏分析

Objective To investigate the SCCmec genotyping, subtype and antimicrobial susceptibility tests in methicillin resistant staphylococcus aureus to guide the clinical treatment and provide the proof for molecular epidemiology. Methods To detect mecA gene and SCCmec genetyping and subtype in 50 MRSA by PCR. According to CLSI's guideline, antimicrobial susceptibility tests were performed with disk diffusion. Results All 50 MRSA had meeA genes. 45 strains were SCCmecⅢ types; 3 strains were SCCmecⅢA types;2 straius were SCCmec Ⅱ types. There were no SCCmec Ⅰ and SCCmecⅣ types. SCCmec Ⅱ ,SCCmecⅢ and SCCmecⅢ A type strains were all multiresistant. Conclusion 50 MRSA are all multiresistant. SCCmec Ⅲ are the main types.     

耐甲氧西林金黄色葡萄球菌SCCmec基因分型及药敏分析

Objective To investigate the SCCmec genotyping, subtype and antimicrobial susceptibility tests in methicillin resistant staphylococcus aureus to guide the clinical treatment and provide the proof for molecular epidemiology. Methods To detect mecA gene and SCCmec genetyping and subtype in 50 MRSA by PCR. According to CLSI's guideline, antimicrobial susceptibility tests were performed with disk diffusion. Results All 50 MRSA had meeA genes. 45 strains were SCCmecⅢ types; 3 strains were SCCmecⅢA types;2 straius were SCCmec Ⅱ types. There were no SCCmec Ⅰ and SCCmecⅣ types. SCCmec Ⅱ ,SCCmecⅢ and SCCmecⅢ A type strains were all multiresistant. Conclusion 50 MRSA are all multiresistant. SCCmec Ⅲ are the main types.