The accurate and rapid identification of bacteria in the enteric tract is necessary for early treatment. In this study, we describeD a novel system which consists of a multiplex polymerase chain reaction (PCR) to simultaneously identify a group of six Enterobacteriaceae members including Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Citrobacter spp., Enterobacter cloacae and Salmonella typhi. Genus and species specific primers were designed for this group of pathogens and conventional multiplex PCR and SYBR green based real time PCR assays were performed to detect these pathogens. All the samples were analysed with a eubacterial real-time PCR assay that enables detection of bacterial DNA and then detection of the organisms was determined using genus and species specific PCR assays. This assay was evaluated using clinical specimens and was found to be quite sensitive and specific. Their PCR results matched with the conventional culture identifications. The conventional and SYBR green real time multiplex PCR assays takes only 3 h to be performed and has the potential to replace the conventional culture technique and thus can speed up the treatment process. This technique has the potential to be a valuable diagnostic tool for simultaneous identification of E. coli, K. pneumoniae, P. mirabilis, Citrobacter spp., E. cloacae and S. typhi.
Although Streptococcus pneumoniae is a leading cause of childhood disease in South East Asia, little has previously been reported regarding the epidemiology of invasive pneumococcal disease in Malaysia and very few studies have explored pneumococcal epidemiology using multilocus sequence typing (MLST). Here we describe serotype, multilocus sequence type (ST), and penicillin susceptibility of thirty pneumococcal invasive disease isolates received by the University of Malaya Medical Centre between February 2000 and January 2007 and relate this to the serotypes included in current pneumococcal conjugate vaccines. A high level of diversity was observed; fourteen serotypes and 26 sequence types (ST), (11 of which were not previously described) were detected from 30 isolates. Penicillin non-susceptible pneumococci accounted for 33% of isolates. The extent of molecular heterogeneity within carried and disease-causing Malaysian pneumococci remains unknown. Larger surveillance and epidemiological studies are now required in this region to provide robust evidence on which to base future vaccine policy.
The genetic diversity and antimicrobial resistance rates of clinical Salmonella isolates (2007–2008) at the University of Malaya Medical Centre, Kuala Lumpur, were investigated and the genetic diversity of the isolates was determined by pulsed-field gel electrophoresis (PFGE) and repetitive extragenic palindromic (REP)-PCR. XbaI-PFGE analysis generated 57 profiles (Dice coefficient, F=0.08–1.00), whereas REP-PCR using the REP primer generated only 35 (F=0.34–1.00). PFGE was therefore the more discriminative and reproducible method for assessing the genetic diversity of salmonellae. The antibiograms of 78 Salmonella isolates were assessed against 19 antimicrobials using the disk diffusion method. Twenty serotypes were identified, with the most common being S. Enteritidis (18%) followed by S. Typhimurium (14%), S. Paratyphi B var Java (9%), S. Weltevreden (9%), and S. Corvallis (9%). A total of 38 resistant profiles were defined, with 53.8% of the isolates being resistant to three or more antimicrobials. The highest resistance rates were observed for cephalothin (55.1%), tetracycline (47.4%), and nalidixic acid (35.9%). The presence of multidrug-resistant Salmonella strains is a cause for concern as it may limit the treatment of severe salmonellosis. One multidrug-resistant S. Enteritidis strain was a putative extended-spectrum beta-lactamase producer, based on a double disk diffusion analysis, and was resistant to ceftriaxone (MIC>32 µg/mL). The data generated by this study will contribute towards epidemiological monitoring and investigations of Salmonella infections in Malaysia.
The effectiveness of many antimicrobial agents is currently decreasing; therefore, it is important to search for alternative therapeutics. Our study was carried out to assess the in vitro antibiofilm activity using microtiter plate assay, to characterize the bioactive compounds using Ultra Performance Liquid Chromatography-Diode Array Detection and Liquid Chromatography-Mass Spectrometry and to test the oral acute toxicity on Sprague Dawley rats of extract derived from a novel bacterial species of Paenibacillus strain 139SI. Our results indicate that the crude extract and its three identified compounds exhibit strong antibiofilm activity against a broad range of clinically important pathogens. Three potential compounds were identified including an amino acid antibiotic C 8 H 20 N 3 O 4 P (MW 253.237), phospholipase A2 inhibitor C 21 H 36 O 5 (MW 368.512), and an antibacterial agent C 14 H 11 N 3 O 2 (MW 253.260). The acute toxicity test indicates that the mortality rate among all rats was low and that the biochemical parameters, hematological profile, and histopathology examination of liver and kidneys showed no significant differences between experimental groupsP>0.05. Overall, our findings suggest that the extract and its purified compounds derived from novel Paenibacillus sp. are nontoxic exhibiting strong antibiofilm activity against Gram-positive and Gram-negative pathogens that can be useful towards new therapeutic management of biofilm-associated infections.
Asia is one of the continents in the world heavily impacted by pneumococcal diseases but yet the information on disease burden and serotype distribution remained largely unclear.The data is essentially needed to inform the burden of pneumococcal diseases as a priority public health concern among the Asian countries.The formulations of pneumococcal conjugate vaccines (PCV) included a number of prevailing serotypes in the Western world but geographical and temporal variations of vaccination effectiveness could be expected in Asia.This review focuses specifically on the most recent five years trend in serotype distributions from both invasive and non-invasive pneumococcal diseases in Asia.Other important features such as antimicrobial resistance and associated clones were also noted.All latest studies reported that complied with the scopes of this review were included and the serotyping data were extracted for comparison analysis between countries, regions, and to represent Asia as the whole.The most common serotypes detected in highest to lowest frequencies order are 19F, 14, 23F, 6B, 19A, 3, and 6A, accounted for approximate two third of the incidences.Heptavalent PCV (PCV7) is expected to cover half of the incidences with significant increment in efficacy with PCV13.East Asia, Southeast Asia, and West Asia have relatively similar serotype distributions though slight variations were observed.The more unique pattern is noted in South Asia region.Initiation of surveillance study in countries with no reporting data is needed.Continued surveillance involving nationwide or multinational collaborative networks need to be set up to enhance and standardize the reporting incidences.
Background Streptococcus pneumoniae is a major causative agent of severe infections, including sepsis, pneumonia, meningitis, and otitis media, that has since become a major public health concern. In this study, the serotypes distribution of pneumococcal isolates was investigated to predict the efficacy of the 7-valent pneumococcal conjugate vaccine (PCV7) among the Malaysian populations. Methodology/Principal Findings A total of 151 clinical isolates were serotyped using multiplex PCR assays. Out of them, there were 21.2% penicillin-resistant, 29.1% penicillin-intermediate, and 49.7% penicillin-susceptible S.pneumoniae strains. Serotypes detected among the Malaysian isolates were 1, 3, 10A, 11A/11D, 12F/12A, 14, 15A, 15B/15C, 16F, 18C/18B/18A/18F, 19A, 19F, 23F, 35B, 35F/47F, 6A/6B, 7C/7B/40, 7F/7A, 9V/9A, and 34. Serotype 19F and 23F were the two most prevalent serotypes detected. Serotypes are highly associated with invasiveness of isolates (p = 0.001) and penicillin susceptibility (p<0.001). Serotype 19F was observed to have increased resistance against penicillin while serotype 19A has high invasive tendency. Age of patients was an important factor underlying the pneumococcal serotypes (p = 0.03) and clinical sites of infections (p<0.001). High prevalence of pneumococcal isolates were detected among children <5 years old at nasopharyngeal sites while elderly adults ≥60 years old were at increased risk for pneumococcal bacteremia. Conclusion/Significance Current study revealed that a number of serotypes, especially those associated with high penicillin resistance, have been formulated in the PCV7. Therefore, the protections expected from the routine use of PCV7 would be encouraging for the Malaysian. However, it is not possible to predict serotypes that might become predominant in the future and hence continued surveillance of circulating serotypes will be needed.
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.
It has been reported that there are structural differences in the muropeptides of the cell wall in penicillin-resistant Streptococcus pneumoniae. The cell wall composition and variation of the murMN operon sequence of S. pneumoniae strains with different penicillin susceptibilities were investigated. PCR amplification and sequencing of the murM and murN genes were carried out on three selected strains of S. pneumoniae. The cell wall was then extracted and elucidated using Fourier Transfer InfraRed (FTIR) Spectroscopy, followed by proton Nuclear Magnetic Resonance (NMR) Spectroscopy. The sequences of the murM and murN genes were shown to be highly conserved while FTIR and NMR analysis suggested a branching structure of the cell wall and also the presence of ethanolamine in the resistant strain. The variations in murM and murN genes may have caused modifications in the cell wall structure leading to decreased binding capacity of penicillins and other β-lactam drugs. (J Infect Dis Antimicrob Agents 2009;26:97-108.)
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