Open Access Original Research Article

Change in Expression of Genes Involved in the G-Protein Signaling Pathway (GP-SP) is Associated with Voriconazole-Resistance (VCZ-R) in Aspergillus Species

Suganthini Krishnan Natesan, Lulu Farhana, Wenjuan Wu

Microbiology Research Journal International, Page 1-5
DOI: 10.9734/MRJI/2018/44716

Background: Invasive infections due to Aspergillus species continue to be associated with a significant morbidity in immuno-compromised patients. Despite the availability of several azoles [isavuconazole (ISZ), posaconazole (POS), voriconazole (VCZ) and itraconazole (ITZ)], mortality remains high. Studies from various cancer and transplant centers around the world have reported the emergence of azole-resistance in clinical and environmental isolates of Aspergillus fumigatus and Aspergillus flavus. The major mechanism of high-level azole- resistance in Aspergillus species reported so far is mutation and/or overexpression of target site namely cyp51A, that encodes lanosterol demethylase of the fungal cell wall. However, some azole-resistant isolates have not exhibited either of these mechanisms, suggesting other novel non-cyp51 related mechanisms of triazole- resistance.

Aim: To evaluate the possible role of G-protein signaling pathway genes in VCZ-R in Aspergillus species.

Materials and Methods: CLSI based susceptibility, and cyp51 gene-specific PCR experiments were performed on wild type and specific mutant strains of Aspergillus species to analyse the phenotypic alterations and changes in triazole-susceptibility pattern in Aspergillus species.

Results: Voriconazole inhibits conidiation in A. flavus, possibly through its effect on several genes involved in the GP-SP. Mutations or changes in expression of these genes contribute to VCZ-R in A. flavus. Loss of conidiation and pigmentation with switch to pure vegetative growth, exclusively by hyphal elongation, is associated with VCZ-R in A. flavus.

Conclusion: Our results suggest that VCZ inhibits conidiation by targeting one of the critical genes in the G-protein pathway and specific alterations in these genes likely lead to loss of conidiation and VCZ-R in A. flavus. Cross resistance to other triazoles including POS and ISZ need to be tested as well. Based on our data we propose to continue our studies on G-protein pathway genes involved in antifungal drug resistance in Aspergillus species. This pathway needs to be further explored not only for its possible contribution to VCZ-R but also to delineate its role in pathogenesis and also as a potential antifungal drug target

Open Access Original Research Article

Occurrence and Antibiogram of Shigella spp in Free Range and Intensively Reared Chickens in Nsukka, Enugu State, Nigeria

Obi, Okechukwu J., Ike, Anthony C.

Microbiology Research Journal International, Page 1-7
DOI: 10.9734/MRJI/2018/44934

Introduction: Shigellosis is considered a veterinary and public health problem of major importance. Shigella is implicated in food poisoning and bloody diarrhoea in humans and is an important cause of various diseases of livestock resulting in high morbidity and mortality. Shigella spp. is spread by direct contact with an infected host, or by eating contaminated food or drinking contaminated water. A cross-sectional survey was conducted to determine the occurrence of Shigella in free range and intensively reared chickens from markets and poultry farms in Nsukka, Enugu State, Nigeria, and to determine their antibiogram.

Materials and Methods: A total of 300 cloacal swabs from 150 free range and 150 intensively reared chickens, collected from 3 local markets and 3 farms respectively, were sampled. Shigella was isolated after passing the samples through pre-enrichment, selective enrichment and culture in a selective medium and identified using standard microbiological and biochemical methods. Antibiotic susceptibility test was performed by the disc diffusion method according to the CLSI method (Kirby-Bauer disk diffusion test) on Muller-Hinton agar.

Results: Out of the 300 samples, 10 (3.3%) were positive for shigellae. The occurrence in free-range chickens was 6.7%, while none was isolated in intensively reared chickens (0% occurrence). The Shigella spp. isolated were sensitive to ciprofloxacin (100%), moderately sensitive to ofloxacin (70%), gentamicin (70%), nalidixic acid (60%), cotrimoxazole (60%) and tetracycline (70%), and resistant to amoxicillin (100%) and augmentin (100%). The MIC ranges for cotrimoxazole, ciprofloxacin, gentamicin, and tetracycline, were 8-32, 0.015-0.25, 0.5-2.0, and 2.0-64.0 µg/ml, respectively. The MBC values obtained for ciprofloxacin, gentamicin, and tetracycline were 0.015-8, 2.0-8.0, and 128.0-512.0 µg/ml, were, respectively. The Shigella spp. isolates were classified as multidrug resistant. The difference in susceptibility patterns of the isolates from different sources was not significant (p > 0.05).

Conclusions: The findings of this study have shown that free-range chickens could serve as reservoirs/vehicles for the transmission of Shigella spp. in the study area.

Open Access Original Research Article

Multidrug Resistance Pattern of Salmonella Typhimurium Isolated from Rectal Swabs of Stray Dogs at Chittagong Metropolitan Area (CMA), Bangladesh

Tofazzal Md. Rakib, Md. Shafiqul Islam, Md. Nur-E-Azam, Shariful Islam, Abdullah Al Faruq, Tridip Das, Lipi Akter, Mohammad Mahmudul Hassan, Mohammad Alamgir Hossain

Microbiology Research Journal International, Page 1-11
DOI: 10.9734/MRJI/2018/43939

A cross-sectional study was conducted to investigate the prevalence and antimicrobial resistance pattern in Salmonella from 108 rectal swab of stray dogs of 9 randomly selected areas of Chittagong Metropolitan Area. Rectal swabs were collected for isolating Salmonella enterica serovar Typhimurium through bacteriological culture and InvA specific PCR assay followed by antimicrobial susceptibility testing. Out of the 108 samples, females showed higher prevalence (66.67%) than males (58.93%). Among the 67 bacterial culture positive isolates, 10.45% was Salmonella Typhimurium in InvA gene specific PCR. Isolated Salmonella was tested for resistance to twelve different antimicrobial agents, using disc diffusion method. In cultural sensitivity test, 100% resistance was found against Amoxicillin where higher resistance was found against Azithromycin, Cefixime, Ampicilin and Pefloxacin. Gentamycin and Colistin appeared to be sensitive. Multidrug resistance of Salmonella spp. has increased with a great deal in developing countries in the last decades. In this study, most of the Salmonella isolates were multidrug resistant. Rational use of antibiotics needs to be adopted in clinical practice to prevent the emergence of multi-drug resistance Salmonella and their zoonotic transmission.

Open Access Original Research Article

Frequency and Antibiotic Susceptibility Pattern of Pseudomonas aeruginosa Isolated from Patients Attending University of Maiduguri Teaching Hospital

Askira M. Umoru, Tijani Isa, Muhammad M. Ibrahim, T. M. Isyaka, I. Y. Ngoshe, A. Aliyu

Microbiology Research Journal International, Page 1-6
DOI: 10.9734/MRJI/2018/44610

Aim: This study was aimed at determining the frequency of occurrence of Pseudomonas aeruginosa and the susceptibility pattern of isolates to antibiotics.

Place of Study: Department of Medical Microbiology, University of Maiduguri Teaching Hospital (UMTH), Nigeria.

Methodology: One hundred and thirty one (131) clinical specimens (comprising of urine, wound swab, ear swab, high vaginal swab and catheter swab) were collected from patients (female=80, male=51) attending UMTH and were screened for P. aeruginosa using standard microbiological and biochemical methods. Antimicrobial susceptibility of the isolates was determined by the disc diffusion assay.

Results: Our results showed that thirty six (36) patients were positive for P. aeruginosa with an occurrence rate of 27.5% with male patients having the highest occurrence rate of 55.6% compared to female patients with 44.4%. The result also showed that the occurrence rate was higher among patients within the age group of 31-40 years (25.0%) and the least was observed among those in age group of 41-50 years and 71-80 years (5.6% respectively). The distribution of P. aeruginosa in relation to sample types examined indicate that wound swab had the highest isolation rate of 38.9% followed by urine 27.8%, while the least were catheter tips (2.8%). The distribution of P. aeruginosa based on clinics and wards of the hospital showed that patients from general out patients departments (GOPD) had the highest occurrence rate of 27.8%, while the least was observed among those from female medical ward (2.8%). The antimicrobial susceptibility test revealed that Tetracycline and Cefuraxime had high activity against 42.0% of isolates while Ofloxacin recorded the highest resistance of 92.0%.

Conclusion: This study reveals an increased distribution rate for P. aeruginosa in the hospital environment, hence appropriate measures and proper identification techniques are required for surveillance and control.

Open Access Original Research Article

Effect of Processing on Microbial Load, Physicochemical Properties and Nutritional Composition of Plukenetia conophora (Africa Walnut)

A. O. Ileola, T. R. Omodara, O. S. Fatoba

Microbiology Research Journal International, Page 1-9
DOI: 10.9734/MRJI/2018/41024

This research was carried out to determine the effect(s) of different processing methods on the nutritional composition of Plukenetia conophora (Africa walnut) seeds. The dried walnut seeds were sorted, cleaned, cracked and dehulled by abrasion to get the cotyledons. The raw sample and processed (boiled and fermented) seeds were analyzed for microbial load, physicochemical properties (pH, total titratable acidity and moisture contents), proximate composition, vitamin contents and antioxidant level. The boiled sample had the least microbial load (7.55 Cfu/ml) followed by the raw sample 8.50 (Cfu/ml). There was a progressive increase in the microbial load with an increase in fermentation time from 8.18 Cfu/ml to 8.40 Cfu/g in FW24 and FW120, respectively. The raw sample had least pH and moisture content of 5.78 and 9.50%, respectively. Boiling and increase in fermentation time led to significant increase in pH and moisture content of the samples. The raw sample had the highest TTA (2.88N) while there was a significant decrease in (Total Titerable Acidity) TTA with an increase in fermentation time. The raw sample had the least protein (26.78%), fat (30.11%) and ash (4.43%) contents while the fermented sample had the highest percentage of protein (29.01%), fat (32.67%) and ash (6.23%). The antioxidant properties of the fermented samples, i.e. total phenolics (17.67 mg/g) and DPPH (24.57 mg/g) were significantly higher than the boiled and raw samples. The fermented sample had highest vitamin A (33.71 mg/g), vitamin B1 (0.16 mg/g) and B2 (01.2 mg/g) vitamin C (22.67 mg/g). The vitamin B2 (0.02 mg/g) and vitamin E (23.91 mg/g) of the boiled sample were significantly higher than the fermented and raw sample. From the study, it was observed that walnut is better consumed fermented for its important roles in health and nutrition than boiling and raw consumption.