Open Access Short Research Article

Community-Associated and Health care-Associated Methicillin-Resistant Staphylococcus aureus in Children: A Microbiological and Epidemiological Study

Ana Luísa N. Erthal, Amanda M. Alves, Maria Fernanda B. Pereira, Marcelo J. Mimica

Microbiology Research Journal International, Page 1262-1266
DOI: 10.9734/BMRJ/2014/9726

Aims: Novel methicillin-resistant Staphylococcus aureus have been causing infections in the community and are now invading hospitals. In this study we aimed to determine, using epidemiological and microbiological parameters, the characteristics of circulating S. aureus clinical isolates.

Methods: From July 2009 to April 2012, S. aureus isolates from children hospitalized in Santa Casa de São Paulo, a tertiary care-center in São Paulo, Brazil, were included.  All isolates grew in cultures from sterile sites and we included only one isolate per patient.

Results: Fifty-five isolates were included during the study period, 47 from blood, six from abscesses, one from pleural fluid and one from spinal fluid. Among these isolates, 34 were methicillin susceptible S. aureus (MSSA) and 21 were methicillin-resistant S. aureus (MRSA). Eleven patients were excluded (5 MSSA and 6 MRSA) because clinical charts were not available for review, reducing the total to 29 MSSA and 15 MRSA isolates.  After searching for risk factor for healthcare-associated infections, 11 of the 15 MRSA isolates were epidemiologically considered health care-associated MRSA (HCA-MRSA) and 4 community-associated MRSA (CA-MRSA). Using the microbiological classification (multiresistance), five were considered as HCA-MRSA and 10 were CA-MRSA. Interestingly, of the 11 isolates considered as epidemiological HCA-MRSA (presence of any risk factor), six had a microbiological profile (non-multiresistant) consistent with CA-MRSA circulating clones. 

Conclusion: Our results clearly show that the boundaries between CA-MRSA and HCA- are increasingly difficult to determine

Open Access Original Research Article

Partial Purification and Antimycobacterial Screening of the Ethyl Acetate Extract of Alcaligenes faecalis BW1

Ilham Zahir, Abdellah Houari, Mohammed Iraqui, Saad Ibnsouda

Microbiology Research Journal International, Page 1178-1188
DOI: 10.9734/BMRJ/2014/10595

Aims: The focus of this study was to evaluate the antimycobacterial activity of Alcaligenes faecalis BW1 extract and to purify it partially.

Study design: Partial purification of A. faecalis BW1 extract was performed by using thin layer chromatography and active substances responsible for the biological activity were localized.

Place and Duration of Study: The study was carried out at laboratory of Microbial Biotechnology, Department of Biology, Faculty of Sciences and Technical, University Sidi Mohamed Ben Abdellah, BP 2202, Road of Immouzer, Fez, Morocco, during the period from January 2011 to July 2011.

Methodology: Crude extract of A. faecalis BW1 was obtained by using ethyl acetate as an organic solvent and its antimycobacterial effect was investigated by agar discs diffusion method. The extract was then fractionated by thin layer chromatography and the bioactivity was assessed with a bioautography technique followed by spots elution tests.

Results: The results showed that A. faecalis BW1 produced compounds with antimycobacterial activity. All the detected spots by thin layer chromatography inhibited the growth of M. smegamtis.

Conclusion: Various metabolites of A. faecalis BW1 are responsible for the sought effect or they could act synergistically to inhibit mycobacterial growth. These compounds could be used after their total purification in further work against mycobacterial infections.

Open Access Original Research Article

Effect of Different Carbon and Nitrogen Sources on Growth and Indole Acetic Acid Production by Rhizobium Species Isolated from Cluster Bean [Cyamopsis tetragonoloba (L.)]

G. Nalini, Y. R. K. V. Tirupati Rao

Microbiology Research Journal International, Page 1189-1197
DOI: 10.9734/BMRJ/2014/6871

Five Rhizobium strains (Cb1, Cb2, Cb3, Cb4 and Cb5) were isolated from root nodules of cluster bean [Cyamopsis tetragonoloba (L.)] on yeast extract mannitol agar (YMA) medium. All the five Rhizobium isolates have shown the Indole Acetic Acid( IAA) production in culture medium supplemented with L-tryptophan. The IAA content in culture supernatant was estimated by using the colorimetric method (13). All the five Rhizobium isolates produced maximum amount of IAA in medium supplemented with 2.5mg/ml L- tryptophan concentration. Production of IAA was maximum at 72h of incubation when bacteria reached the stationary phase. The cultural conditions were optimized for maximum IAA production by using different carbon and nitrogen sources as well as changing the incubation period. Glucose and L-asparagine were found to be the best carbon and nitrogen sources, respectively for maximum IAA production. The cell wall affecting agent, penicillin increased the IAA production up to 77.95% in Cb4, 59.52% in Cb5 and 37.84% in Cb3 isolates, over the control. Among the five isolates studied, isolate Cb4 showed better performance in IAA production.

Open Access Original Research Article

Optimization of the Production of α-L-Rhamnosidase by Aspergillus niger in Solid State Fermentation Using Agro-Industrial Residues

Adriana Casavechia Petri, Joao Batista Buzato, Maria Antonia P. C. Celligoi1, Dionisio Borsato

Microbiology Research Journal International, Page 1198-1210
DOI: 10.9734/BMRJ/2014/6862

The enzyme α-L-rhamnosidase specifically cleaves terminal rhamnose residues from a wide variety of natural products. This property endows this enzyme with important biotechnological potential as a-L-rhamnosidase could be employed in a variety of applications, including removing bitterness from citrus fruit juices, improving the aroma of wines and converting clinically important steroids. This work optimized α-L-rhamnosidase solid-state fermentation production from Aspergillus niger 426 using statistical methods. Firstly, a statistical mixture-design with three components to determine the best ratio of nutrients for enzyme production was carried out. The optimal conditions consisted of growing the fungi in media containing 0.14 g of cane sugar bagasse, 1.25 g of soybean hulls and 3.05 g of rice straw; these conditions achieved a maximum α-L-rhamnosidase activity of 1.92 U / mL. Next, a 3² Box-Behnken design to optimize culture moisture levels and nutrient solution pH values for enzyme production was carried out. α-L-rhamnosidase activity increased to 3.02 U / mL when medium moisture was   75.5% and  pH value of 4.0.

Open Access Original Research Article

Etiology and Drug Resistance Pattern of Ventilator Associated Pneumonia in an Iranian 1000- Bed Tertiary Care Hospital

H. Bahrami, M. Rahbar, N. Rahimifard, H. Haji Mehdipour, H. Rastegar, H. R. Ahmadi Ashtiani, F. Bagheri, M. Saremi

Microbiology Research Journal International, Page 1211-1218
DOI: 10.9734/BMRJ/2014/7543

Aim: The aim of this study was to determine etiology and drug resistance pattern of most frequency isolates of microorganisms responsible for VAP in an Iranian 1000-bed tertiary care hospital in Tehran Iran.

Place and Duration: This study was conducted in microbiology laboratory of Milad Hospital in Tehran, Iran from November 2010 to December 2011.

Methodology: Ventilator Associated Pneumonia (VAP) was defined as any lower respiratory tract infection that developed 48 hours after mechanical ventilation. Tracheal aspirate specimens were collected and processed according standard microbiological procedures. Bacterial identification and susceptibility testing were performed using disk diffusion standard procedures as recommended by CLSI.

Results: One hundred and one patients developed at least one episode of nosocomial pneumonia were subject of our study. Of 101 patients 61 patients were male and 40 female patients. The mean time for hospitalization in ICUs and ventilation duration were 16 and 9, 5 days respectively. Old age, History of previous use of antibiotics and duration of ventilation times were the most important risk factors for VAP. In total 126 microorganisms were isolated from VAP cases. Acinetobacer baumannii with 46 (36.5%) isolates was the predominant organism followed by Staphylococcus aureus with 31 (24. 60% and Pseudomonas aeruginosa with 19 (15%) isolates. Other isolated organisms included Klebsiella pneumoniae and E. coli. The majority isolated organism included Acinetobacter baumannii and Pseudomonas aeruginosa were resistant to many antibiotics including the third generation of cephalosporins and nearly 50% isolates were resistant to amikacin. Colistin was the most effective antibiotic against multidurug resistant (MDR) isolates. We found a high rate of methicillin resistant Staphylococcus aureus (93.54%). All isolates of S. aureus were susceptible to vancomycin.

Conclusion: Our study revealed that A. baumannii, S. aureus and P. aeruginosa were the major etiological agents of VAP in our hospital. The majority isolates were resistant to routinely used antibiotics including the third generation of cephalosporins. We also observed a high rate of MRSA among our isolates.

Open Access Original Research Article

In vitro Photodynamic Antimicrobial Activity of Protoporphyrin IX in the Presence of Hydrogen Peroxide against Staphylococcus aureus and Pseudomonas aeruginosa

Fathi Awad, Chandrasekaran Ramprasath, Kanniyappan Udayakumar, Narayanasamy Mathivanan, Prakasa Rao Aruna, Singaravelu Ganesan

Microbiology Research Journal International, Page 1219-1234
DOI: 10.9734/BMRJ/2014/10482

Aims: This study reports on In vitro investigation of photodynamic antimicrobial activity of     protoporphyrin IX (PPIX) in the presence and absence of Hydrogen peroxide (H2O2) against S. aureus and P. aeruginosa.

Place and Duration of Study: Department of Medical Physics, Anna University, Chennai between December 2013 and February 2014.

Methodology: A light-emitting diode (LED) was used as a light source to irradiate PPIX. The antibacterial effect was analyzed by standard plate counting method. Steady-state fluorescence spectroscopy technique was used to monitor the damage at protein level.

Results: We found that the antibacterial effect is dependent on PPIX concentration as well as H2O2 concentration and light dose. PPIX-H2O2 combination showed higher bacterial reduction of 6.5 log10 and 2.7 log10 for S. aureus and P. aeruginosa respectively, when the light dose increased to 70 J/cm2. Fluorescence spectroscopic characterization showed       a considerable change in the intensity of emission of tryptophan present in the microorganisms between pre- and post- APDT.

Conclusion: PPIX-H2O2 is a promising combination for APDT against Gram positive and Gram negative bacteria. The LED seems to be a very good option for PDT because of its low cost and miniature in size.

Open Access Original Research Article

Retrospective Analysis of Gram-Negative Bacteria Isolated at a Tertiary Hospital in Maiduguri, Nigeria

K. O. Okon, S. T. Balogun, U. M. Askira, Y. B. Jibrin, C. U. Aguoru, T. M. Isyaka, P. E. Ghamba

Microbiology Research Journal International, Page 1235-1247
DOI: 10.9734/BMRJ/2014/9302

Background: Gram negative bacteria accounts for significant proportion of hospital and community associated infections responsible for significant proportion of hospital admission, and associated increased level of antibiotic resistance pattern. Based on this information, we retrospectively analyzed the prevalence and resistance pattern of gram negative bacteria isolated from clinical specimens submitted in a tertiary hospital in Maiduguri, Nigeria.

Methodology: Bacteriological data of gram negative bacteria isolates recovered from clinical specimens submitted to medical microbiology laboratory of University of Maiduguri Teaching Hospital (UMTH) between 2007-2011were extracted and analyzed. A total of 36,800clinical specimens were examined.

Results: The prevalence level of gram-negative bacteria isolates was 24.09% (8865/36,800), majority (29.16%, n=2585) of the isolates were recovered from wound specimens. Escherichia coli accounted for 31.8% (n=2823) of the total isolates. High susceptibility was observed with fluoroquinolones, aminoglycosides and cephalosporin tested, and resistance with cotrimoxazole and chloramphenicol. Overall, 7.6% (n=671) of the gram negative isolates exhibited multidrug resistance pattern, Escherichia coli accounted for 39.9% (268/671) of the  multidrug resistant isolates.

Conclusion: The study highlights epidemiological characteristics of the gram-negative bacteria isolated in our hospital, with prevalence level of 24.09% and diverse isolation pattern which affirmed gram-negative bacteria clinical implication in hospital and community associated infections. In addition, the multidrug resistance pattern level of 7.6% is an indication for laboratory personnel to be aware of possible emergence of multidrug resistant strain among gram-negative isolated in the hospital

Open Access Original Research Article

Optimization of Nutritional Parameters for the Production of L-Methionine from Newly Isolated Bacillus cereus Strain

K. S. Dike, C. E. Obiukwu, I. A. Ekwealor

Microbiology Research Journal International, Page 1248-1261
DOI: 10.9734/BMRJ/2014/2444

Aims: This study evaluated nutritional parameters for optimum methionine production
Study Design: Methionine was assayed using the colorimetric method of Greenstein and Wintz (1961).

Place and Duration of Study: Department of Applied Microbiology and Brewing, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria, between April 2010 and November 2011.

Methodology: Bacillus cereus RS 16 was previously isolated from a soil ecovar in Owerri, Nigera. It was maintained on nutrient agar (Oxoid) slants at 4ºC. Bacillus cereus 16 was confirmed by 16Sr RNA conducted at Macrogen Incoporated Korea. Methionine production was carried out in a submerged medium. A 10% (v/v) seed culture was used to inoculate a 100ml Erlenmeyer flask containing 30 ml of fermentation medium in a rotatory shaking incubator at 170 rpm and 30ºC. Growth and methionine accumulation was determined from the broth. Nutritional parameters were studied to determine optimum methionine production

Results: Glucose and ammonium chloride were the best carbon and nitrogen source for L-methionine production. Maximum methionine (4.55mg/ml) were obtained with 80.0g glucose, 20.0g ammonium chloride, 20.0g calcium carbonate, 0.1.g DL-ornithine monohydrate, 0.1g peptone, 0.5g potassium dihydrogen phosphate, 0.5g potassium hydrogen phosphate, 0.01g magnesium sulphate heptahydrate, 0.001g manganese sulphate tetrahydrate, 0.001g ferrous sulphate heptahydrate at 72h fermentation period. There was a remarkable increase of methionine level to 4.55 mg/ml after optimization compared to methionine level of 1.92 mg/ml before optimization

Conclusion: This present investigation has determined optimum parameters for maximum production of L- methionine by the newly isolated mesophilic bacterium Bacillus cereus strain RS 16. This information has enabled formulation of media composition for maximum methionine production by this organism

 

This present investigation has determined optimum parameters for maximum production of L- methionine by the newly isolated mesophilic bacterium Bacillus cereus strain RS 16. This information has enabled formulation of media composition for maximum methionine production by this organism., was deleted after optimization because it was supposed to be in the conclusion

Open Access Original Research Article

Growth Kinetics of a Native Toxigenic Isolate of Bacillus Cereus under the Influence of Incubation Temperature, pH and Sodium Chloride in Broth System

S. V. Desai, M. C. Varadaraj

Microbiology Research Journal International, Page 1267-1284
DOI: 10.9734/BMRJ/2014/11745

Aims: The growth behavior of vegetative cells and spores of a native toxigenic food isolate of Bacillus cereus CFR 1534 was studied under the influence of incubation temperature, pH and sodium chloride.

Place and Duration of Study: The study was undertaken in the Department of Human Resource Development, CSIR-Central Food Technological Research Institute, Mysore 570020, India. The duration of study was during the period October 2009 to February 2010.

Methodology: The experimental design was a central composite design (CCD) based on 3 factors and 5 levels. The factors for vegetative cells were incubation temperature (12-48ºC), pH level (5.5-7.5) and sodium chloride (2-6%). With spores, the ranges of pH and NaCl levels were the same, while incubation temperature range was 22 to 42ºC.

Results: Multiple regression analysis of experimental data relating to lag phase duration (LPD) and growth rate (GR) of B. cereus across the influencing factors in broth system revealed that LPD of vegetative cells and spores was primarily influenced by incubation temperature. In vegetative cells of B. cereus, the LPD was in the range of 3.1 to 31.5 h with the highest being observed at 48ºC and pH 6.5. The GR had the lowest of 0.2/h to highest of 2.2/h at 30ºC and pH 7.5. With spores, the lowest LPD of 5.8 h was at 42ºC and highest of 20.5 h at 22ºC and that of GR was in the range of 0.2/h at 22ºC to 0.7/h at 32ºC. Experimental tubes of vegetative cells with GR estimates of 1.3/h and above revealed positive reactions for toxigenic traits of haemolytic and lecithinase activities associated with B. cereus.

Conclusion: In the case of vegetative cells, incubation temperature in the range of 12-20ºC resulted in higher LPD, while in spores, higher LPD was observed with incubation temperatures of 22-26ºC. This could provide a basis to design protocols for a safe food in the food chain

Open Access Original Research Article

Effect of Fermentation on Nutrient and Anti-Nutrient Contents of Ground-Cooked Lima Bean (Phaseolus lunatus) Seeds using Bacillus subtilis and Bacillus pumilus

Kehinde Tope Adegbehingbe, Fatusa Clement Adetuyi, Felix Akinsola Akinyosoye

Microbiology Research Journal International, Page 1285-1298
DOI: 10.9734/BMRJ/2014/11511

Aim: This study investigated the effect of single cultures of Bacillus subtilis and B. pumilus on nutrient and anti-nutrient contents of ground-cooked Lima bean seeds.

Methodology: Lima bean seeds were ground and fermented naturally as well as with single starters of B. subtilis and B. pumilus (previously isolated from naturally fermented Lima bean seeds) for nine days. Microbial analyses, pH, total titratable acidity and the temperature of the fermenting samples were carried out on daily basis, nutritional composition at two day intervals while the anti-nutrient contents were determined before and after the fermentation period. 

Results: Higher microbial counts were observed in starter fermented samples than the naturally fermented samples. The pH increased throughout the fermentation period with the highest in B. subtilis fermented sample but was not significantly higher (P<.05) than B. pumilus fermented sample while the total titratable acidity which however decreased mostly in B. subtilis was also not significantly different from B. pumilus fermented sample. Temperature increased up to the fifth day in both starter samples but higher in B. subtilis fermented substrate but up to seventh day in naturally fermented sample. Starter culture fermented samples had the highest moisture, fat and ash contents at the end of the fermentation while the protein values increased in all the samples with the highest in B. subtilis fermented sample (25.34%) while B. pumilus and naturally fermented sample contained 24.32% and 22.22% respectively. Oxalate, phytic acid and cyanide were more reduced in naturally fermented sample than the starter fermented samples while the highest reductions were observed in saponin and tannin contents of B. subtilis fermented sample. Organoleptic parameters were rated better in the Lima bean seeds fermented with starter cultures than the naturally fermented sample.

Conclusion: This study revealed that Lima bean seeds fermented with single starter cultures of B. subtilis and B. pumilus enhanced the nutrient contents and organoleptic qualities of the products.