Burkholderia pseudomallei is the causative agent of melioidosis. The complete genome sequences of this pathogen have been revealed, which explain some pathogenic mechanisms. In various hostile conditions, for example, during nitrogen and amino acid starvation, bacteria can utilize alternative sigma factors such as RpoS and RpoN to modulate genes expression for their adaptation and survival. In this study, we demonstrate that mutagenesis of rpoN2, which lies on chromosome 2 of B. pseudomallei and encodes a homologue of the sigma factor RpoN, did not alter nitrogen and amino acid utilization of the bacterium. However, introduction of B. pseudomallei rpoN2 into E. coli strain deficient for rpoN restored the ability to utilize amino acids. Moreover, comparative partial proteomic analysis of the B. pseudomallei wild type and its rpoN2 isogenic mutant was performed to elucidate its amino acids utilization property which was comparable to its function found in the complementation assay. By contrast, the rpoN2 mutant exhibited decreased katE expression at the transcriptional and translational levels. Our finding indicates that B. pseudomallei RpoN2 is involved in a specific function in the regulation of catalase E expression.

Duong Thi Hong Diep

Nguyen Thi Thanh Phuong

Mya Myintzu Hlaing

Potjanee Srimanote

Sumalee Tungpradabkul

Role of Burkholderia pseudomallei Sigma N2 in Amino Acids Utilization and in Regulation of Catalase E Expression at the Transcriptional Level

Antibiotic resistance has increased sharply, while the pace for the development of new antimicrobials has slowed down. Plants provide an alternative source for new drugs. This study aimed to screen extracts from Cissus welwitschii and Triumfetta welwitschii for antibacterial activity against Escherichia coli and Bacillus cereus. The tests conducted included a susceptibility determination test, analysis of the effect of T. welwitschii on cell wall integrity, and transport across the membrane. It was found that the T. welwitschii methanol extracts were more effective than the water extracts and had the lowest minimum inhibitory concentration and minimum bactericidal concentration at 0.125&#x2009;mg/mL and 0.5&#x2009;mg/mL, respectively, against E. coli and B. cereus. The C. welwitschii extract caused the most drug accumulation in E. coli. In B. cereus, no significant drug accumulation was observed. Nucleic acid leakage in B. cereus and E. coli and protein leakage in E. coli were observed after exposure to the T. welwitschii extract. The extracts from T. welwitschii had greater antibacterial activity than the extracts from C. welwitschii. T. welwitschii may be a potential source of lead compounds for that could be developed into antibacterial agents.

Batanai Moyo

Stanley Mukanganyama

Antibacterial Effects of Cissus welwitschii and Triumfetta welwitschii Extracts against Escherichia coli and Bacillus cereus

Background. Microbial transmission from patient to patient has been linked to transient colonization of health care workers attires. Contamination of health care workers&#x2019; clothing including white coats may play a big role in transmission of microbes. Study Objective. This study was conducted to determine the type of bacterial contamination on the white coats of medical doctors and students and associated factors. Methods. A cross-sectional study with purposive sampling of the bacterial contamination of white coats was undertaken. Demographic variables and white coats usage details were captured: when the coat was last washed, frequency of washing, washing agents used, and storage of the white coats. Swabs were collected from the mouth of left and right lower pockets, sleeves, and lapels of white coat in sterile techniques. Results. Out of 180 participants involved in the current study, 65.6&#x25; were males. Most of the coats were contaminated by staphylococci species and other bacteria such as Gram negative rods. Conclusion and Recommendations. White coats are potential source of cross infection which harbour bacterial agents and may play a big role in the transmission of nosocomial infection in health care settings. Effort should be made to discourage usage of white coats outside clinical areas.

Josephat Qaday

Margaretha Sariko

Adam Mwakyoma

Emmanuel Kifaro

Dominick Mosha

Richard Tarimo

Balthazar Nyombi

Elichilia Shao

Bacterial Contamination of Medical Doctors and Students White Coats at Kilimanjaro Christian Medical Centre, Moshi, Tanzania

Objectives. We sought to describe the prevalence of a hyaluronidase gene and hyaluronidase production in 197 clinical isolates of P. acnes; we assessed kinetics of hyaluronidase production in a subset of three isolates. Methods. The hyaluronidase gene was detected using polymerase chain reaction. Hyaluronidase production was detected by growing isolates on BHI agar containing 400&#x2009;&#x3bc;g/mL hyaluronic acid and 1&#x25; albumin and flooding plates with 2&#x2009;N glacial acetic acid to precipitate unbound hyaluronic acid, with a zone of clearing representing a positive phenotype. Hyaluronidase production kinetics were measured as a function of hyaluronic acid digestion over time in a liquid medium. Results. A hyaluronidase gene and hyaluronidase production were detected in 100 and 97&#x25; of P. acnes isolates, respectively. Hyaluronidase production in liquid medium was detectable after 96 hours of growth. Conclusions. Hyaluronidase production is nearly universal among P. acnes isolates. Three days appear to be required for significant hyaluronidase production in a liquid medium. Detection of hyaluronidase in tissue specimens may be a strategy to differentiate P. acnes infection from colonization when P. acnes is isolated from a clinical specimen.

Harmony Tyner

Robin Patel

Hyaluronidase in Clinical Isolates of Propionibacterium acnes

Microbiological content specifically bacterial and fungal etiologies from tracheal aspirates in a tertiary hospital in Bacolod City was reviewed for baseline information. A total of 130 tracheal aspirates were subjected for culture to isolate and identify the pathogen and determine their susceptibilities to various antibiotics. Productions of certain enzymes responsible for antibiotic resistance like ESBL (Extended Spectrum Beta-Lactamase), metallo-&#x3b2;-lactamase, and carbapenemase were also studied. Out of 130 specimens, 69.23&#x25; were found to be positive for the presence of microorganisms. Most infections were from male patients aging 60 years and above, confined at the Intensive Care Units (ICU). Pseudomonas aeruginosa and Klebsiella pneumoniae were found to be the most frequent bacterial isolates and non-Candida albicans for fungal isolates, respectively. Among the various antibiotics tested, most isolates were found to be resistant to third generation cephalosporins and penicillins, but susceptible to aminoglycoside Amikacin. On the other hand, production of ESBL and carbapenemase was found to be common among members of Enterobacteriaceae especially K. pneumoniae.

Alain C. Juayang

Dominador G. Maestral

Gemma B. de los Reyes

Michael Angelo D. Acosido

Christine T. Gallega

Review on the Antimicrobial Resistance of Pathogens from Tracheal and Endotracheal Aspirates of Patients with Clinical Manifestations of Pneumonia in Bacolod City in 2013

Leptospirosis is a worldwide zoonosis caused by an infection with the pathogenic species of Leptospira. We have developed a loop-mediated isothermal amplification (LAMP) assay to detect the DNA of Leptospira spp. Six sets of primers targeting the gene of the subsurface protein, lipL32, were evaluated for their detection sensitivity. The best primer set detected less than 25 copies of lipL32 per reaction of both plasmid DNA template and purified leptospiral genomic DNA. By combining primers targeting lipL32 with the previously published primer set targeting lipL41, the sensitivity of the assay was improved to 12 copies of L. interrogans. The specificity of the LAMP assay was evaluated by using the genomic DNA from other clinically encountered bacterial species such as different strains of Orientia tsutsugamushi, Rickettsia typhi, Rickettsia conorii, Rickettsia rickettsii, Coxiella burnetii, and Bartonella bacilliformis. These genomic DNA samples were all negative in our LAMP assay. The sensitivity of the LAMP assay was very similar to that of quantitative real time PCR. Several detection methods for the amplified product of LAMP assay were performed to demonstrate the simplicity of the assay. In summary, our results have suggested that this assay is rapid, robust, and easy to perform and has the potential to be used in endemic locations.

Hua-Wei Chen

Giulia Weissenberger

Erin Atkins

Chien-Chung Chao

Yupin Suputtamongkol

Wei-Mei Ching

Highly Sensitive Loop-Mediated Isothermal Amplification for the Detection of Leptospira

Quorum sensing (QS) is a key regulator of virulence factors and biofilm formation in Gram-negative bacteria such as Pseudomonas aeruginosa. Microorganisms that inhabit soil are of strategic importance in the discovery of compounds with anti-QS properties. The objective of the study was to test the culture extract of a taxonomically novel species of Paenibacillus strain 139SI for its inhibitory effects on the QS-controlled virulence factors and biofilm formation of Pseudomonas aeruginosa both in vitro and in vivo. The Paenibacillus sp. culture extract was used to test its anti-QS effects on the LasA protease, LasB elastase, pyoverdin production, and biofilm formation of P. aeruginosa as well as evaluate its therapeutic effects on lung bacteriology, pathology, hematological profile, and serum antibody responses of experimental animals in a rat model of chronic lung infection. Results showed significant decrease in the activities of QS-controlled LasA protease, LasB elastase pyoverdin, and biofilm formation of P. aeruginosa caused by the culture extract. Moreover, the extract significantly prolonged the survival times of rats and facilitated the clearance of biofilm infections from infected lungs. In conclusion, the antiquorum sensing effects of culture extract from a novel species of Paenibacillus provide new insights to combat biofilm-associated infections.

Saad Musbah Alasil

Rahmat Omar

Salmah Ismail

Mohd Yasim Yusof

Inhibition of Quorum Sensing-Controlled Virulence Factors and Biofilm Formation in Pseudomonas aeruginosa by Culture Extract from Novel Bacterial Species of Paenibacillus Using a Rat Model of Chronic Lung Infection

We report a novel approach utilising a real-time PCR screening assay targeting a 53&#x2009;bp tandemly repeated element present at various loci within the Mycobacterium tuberculosis (Mtb) genome. Positive samples were identified within a discriminatory melting curve range of 90&#x2013;94&#xb0;C, with results obtained in under one hour directly from decontaminated sputum samples without extraction. A panel of 89 smear-positive sputa were used for analytical validation of the assay with 100&#x25; concordance, with sensitivity matching that of culture. Cross reactivity was detected within a narrow range of mycobacteria other than tuberculosis (MOTT) (five sputa, three in silico), with the highest sensitivity within M. avium complex (MAC). A year-long head to head evaluation of the test with the GeneXpert platform was carried out with 104 consecutive samples at the Royal Free Hospital, UK. Receiver operating characteristics (ROC) analysis of the data revealed that the two tests are approximately equivalent in sensitivity, with the area under the curve being 0.85 and 0.80 for the GeneXpert and our assay, respectively, indicating that the test would be a cost effective screen prior to GeneXpert testing.

Lisa Jane Cross

Catherine Anscombe

Timothy D. McHugh

Ibrahim Abubakar

Robert John Shorten

Nicola Thorne

Cath Arnold

A Rapid and Sensitive Diagnostic Screening Assay for Detection of Mycobacteria Including Mycobacterium tuberculosis Directly from Sputum without Extraction

About this journal

Journal profile

Meet the editorial board

Editor spotlight

Find out more

This journal's articles appear in a wide range of abstracting and indexing databases, and are covered by numerous other services that aid discovery and access. Find out more about where and how the content of this journal is available.

International Journal of Bacteriology