Rapid detection and E-test antimicrobial susceptibility testing of Vibrio parahaemolyticus isolated from seafood and environmental sources in Malaysia.

Objectives: To find out the prevalence and antimicrobial susceptibility of Vibrio parahaemolyticus in seafoods and environmental sources. Methods: The study was carried out at the Center of Excellence for Food Safety Research, University Putra Malaysia; Universiti Kebangsaan Malaysia; Medical Molecular Biology Institute; and University Kebansaan Malaysia Hospital, Malaysia between January 2006 and August 2008. One hundred and forty-four isolates from 400 samples of seafood (122 isolates) and seawater sources (22 isolates) were investigated for the presence of thermostable direct hemolysin (tdh+) and TDH-related hemolysin (trh+) genes using the standard methods. The E-test method was used to test the antimicrobial susceptibility. Results: The study indicates low occurrence of tdh+ (0.69%) and trh+ isolates (8.3%). None of the isolates tested posses both virulence genes. High sensitivity was observed against tetracycline (98%). The mean minimum inhibitory concentration (MIC) of the isolates toward ampicillin increased from 4 ug/ml in 2004 to 24 ug/ml in 2007. Conclusions: The current study demonstrates a low occurrence of pathogenic Vibrio parahaemolyticus in the marine environment and seafood. Nonetheless, the potential risk of vibrio infection due to consumption of Vibrio parahaemolyticus contaminated seafood in Malaysia should not be neglected

Characterizing edge-wear in ceramic-on-ceramic acetabular cups

The use of fourth generation ceramic as an orthopaedic biomaterial has proved to be a very efficient and has gained popularity for primary hip surgery in the last 8-10 years. Cumulative percentage probability of revision after 7 years for uncemented CoC is 3.09% and for hybrid CoC is 2.00%, this compares favourably with traditional metal-on-UHMWPE uncemented at 3.05% and hybrid at 2.35% (12th Annual Report - NJR, 2015). Such ceramic-on-ceramic hip prostheses are being implanted in ever younger, more active patients, and yet very few long-term large cohort retrieval studies are yet to be carried out due to the survivorship of the implants. It has been seen in previous studies that levels of wear in ceramic-on-ceramic bearing surface can be of the order of 0.2 mm3/million cycles (Al-Hajjar, Fisher, Tipper, Williams, & Jennings, 2013). This is incredibly low when compared to studies that characterize wear in other bearing surface combinations. It has also been reported that an unusual stripe pattern of wear can occur in some in-vivo retrieved cups (Macdonald & Bankes, 2014) and it has further been postulated that this is caused by cup edge loading (Walter, Insley, Walter, & Tuke, 2004). The combined measurement challenge of stripe wear occurring at the edge of a low-wear ceramic-on-ceramic device is considerable, a solution to which is presented here. Current literature on wear measurement of such cases has been confined to in-vitro simulator studies and use of gravimetric measurement which by definition has limitations due to the lack of spacial characterisation. This paper details a novel method for measuring edge-wear in CoC acetabular liners. The method has been employed in an in-vitro study where it has been benchmarked against gravimetric measurements. These liners were measured on a CMM to determine the volume of material loss. The measurements were conducted as a blinded post-wear study akin to measurement of retrieved components. The most challenging part of this novel method was to create a reference geometry that replicates the free form edge surface of the ‘unworn’ cup using the residual post-wear surface. This was especially challenging due to the uncontrolled geometry at the cup edge and intersection of geometric features at this point. To achieve this, the geometry surrounding the wear patch was used to create a localized reference feature that minimised the effect of global form errors caused by hand polishing in the edge area. Furthermore, the reference geometry is compared with the measured surface to determine the linear penetration and volumetric wear loss. Result of this novel method can be seen in Fig 1 and Fig 2. The findings have been compared to gravimetric results and a bar graph comparing two results can be seen in Fig 3. Overall the accuracy of the method for this cohort was 0.03-0.2 mm3 when compared to gravimetric reference measurements. This compares very favourably with previously published wear measurement methods and gives confidence in the ability to measure such small measurement volumes over complex geometry

Ultrastructural Observation of Nasal and Pulmonary Intracellular Pasteurella multocida A:3 in Rabbits

Sixteen 8- to 9-week-old Pasteurella multocida-free rabbits were divided into two equal groups. Eight rabbits in one group were inoculated intranasally with P. multocida type A:3. The other eight were inoculated intranasally with phosphate-bu¡ered saline and used as controls. Nasal swabs taken before and after inoculation were cultured for bacterial isolation. Post-mortem nasal swabs and lung samples were cultured for bacteriological isolation. Nasal mucosa and lung samples were collected and processed for transmission electron microscopy. Pasteurella multocida was isolated from the nasal cavity of all infected rabbits and from the lungs of four infected rabbits. Degenerative ultrastructural changes in epithelial cells and endothelial cells were seen in the infected rabbits. Deciliation of the cilated epithelium and hyperplasia of the goblet cells in the nasal mucosa were noted. Thickening of the alveolar septa due to hyperplasia of type II pneumocytes, swelling of the endothelial lining of capillaries and in¢ltration of in£ammatory cells were also observed. Intracellular invasion of the nasal epithelial cells and of type II pneumocytes by the organism was observed. Coccobacilli were observed in membrane-bound vacuoles in the cytoplasm of these cells. The vacuoles were adjacent to the host-cell mitochondria and some of these vacuoles appeared to be fused to the mitochondrial membrane. Some type I pneumocytes with intracellular membrane-bound vacuoles containing bacterial cells showed protrusions, which appeared to detach into the alveolar lumina. These results indicated that P. multocida serotype A:3 in rabbits can invade the epithelial cell and cause structural changes in the interstitium, epithelium and endothelium. Heterophils and macrophages appear to play important roles in tissue injury

Antibiotic resistance of vibrio parahaemolyticus isolated from cockles and shrimp sea food marketed in Selangor, Malaysia

Introduction: The main aim of this study is to determine the antibiotic profile of V. parahaemolyticus gastroenteritis associated with the consumption of contaminated shrimp and cockles marketed in Selangor Malaysia. V. parahaemolyticus is the leading cause of seafood-associated gastroenteritis in Asian Countries typically is associated with the consumption of raw shellfish and oysters specially shrimp and cockles. Rapid, sensitive and specific detection methods are needed to control V. parahaemolyticus infections. We describe a recognized the pathogenic V. parahaemolyticus in shrimp and cockles that will be the risk of gastroenteritis associated with the consumption of seafood marketed in Malaysia. Methods: This study was carried out between July 2011 and August 2013 at the Center of Excellence for Food Safety Research, Faculty of Food Science and Technology, Faculty of Medicine and Health Sciences, Department of Biomedical Sciences, and Faculty of Biotechnology, Dep. of Cell and Molecular Biology, University Putra Malaysia and other centers as collaboration. The seafood samples were collected from different markets and more than 400 samples from shrimp and cockles were investigated for detection and isolation of V. parahaemolyticus. CHROMagar Vibrio and TCBS agar media were used for fast detection and isolation of V. parahaemolyticus isolates. PCR based methods targeted to toxR regulatory gene, tlh the species and family gene, tdh and trh the virulence genes were extensively used. The antibiotic susceptibility testing of 65 V. parahaemolyticus isolates recovered from retail shrimp and cockles seafood were determined with four types of E-test antibiotic strips. Results: All the 65 isolates were positive to toxR and tlh genes. Out of 65 isolates, only eight isolates (12.31%) were positive for tdh virulence gene isolated form cockles and shrimp (3 isolates from shrimp and 5 isolates from cockles), whereas twenty six (40%) isolates were positive for trh virulence gene isolated from shrimp and cockles (9 from shrimp and 17 from cockles). This result indicates high occurrence of tdh+ and trh+ isolates in shrimp and cockles marketed in Malaysia. None of the isolates tested possess both virulence genes. For the antibiotic E-test susceptibility test, overall, V. parahaemolyticus is remained susceptible to tetracycline (97%). A slight increase in the susceptibility of tetracycline is observed from 2011 to 2013. While reduced susceptibility was detected only in V. parahaemolyticus for ampicillin. The mean of MIC of the isolates toward ampicillin is increased from 64 μg/ml in 2011 to 128 μg/ml in year 2013. The current study demonstrates a high risk of pathogenic V. parahaemolyticus in the shrimp and cockles marketed in Selangor Malaysia. Conclusions: The potential risk of V. parahaemolyticus infection due to the consumption of contaminated seafood in Malaysia should not be neglected. The increased resistance of ampicilin from our studies in Malaysia since 2004 to 2013 could be in indication of antibiotic abuse in clinical and agricultural used of ampicilin in Malaysia

Multiplex PCR assays for the detection of clinically relevant antibiotic resistance genes in Staphylococcus aureus isolated from Malaysian hospitals.

Multiple drug resistant Staphylococcus aureus is one the most common nosocomial pathogen worldwide. The timely identification of this hospital acquired pathogen and detection of the various antibiotic resistant genes harbored is one of the most important function of the microbiology laboratory. In this study, we report the development of a multiplex PCR system for the diagnosis of S. aureus and the detection of clinically relevant antibiotic resistance genes harbored by some isolates. This system was designed to identify S. aureus at species level and to detect methicillin, gentamycin, erythromycin, vancomycin and mupirocin resistant genes, respectively from a single colony in a single tube reaction. All isolates amplified a 108 bp fragment (conserved in S. aureus) confirming the identity of S. aureus, 23 isolates produced a band at the position of 533 bp, 28 isolates at 139 bp and 30 isolates at 174 bp evidencing the presence of mecA (methicillin or oxacillin resistance), ermA (erythromycin resistance), aac (6`)-aph (2``) (gentamycin resistance) genes. None of the isolates amplified van A (vancomycin resistance) and ileS-2 (mupirocin resistance) genes showing the absence of their resistance in the isolates studied. These genotypic results when compared with classical antibiotic susceptibility tests showed less correlation. Overall, we found a correlation between phenotypic and genotypic methods of 60% for methicillin, 36.7% for gentamycin, 43.3% for erythromycin, 100% for vancomycin and mupirocin. This suggests that classical antibiotic sensitivity test is not accurate, but need to be supplemented with other methods to be applied in a clinical laboratory. The system developed in this study offers a rapid, simple specific and accurate detection of multiple antibiotic resistant genes in clinical S. aureus isolates and thus could be systematically applied as a diagnostic test in clinical microbiology laboratories, facilitating the design and use of antibiotic therapy

Molecular characterization of Pasteurella multocida isolates from rabbits

Forty isolates of Pasteurella multocida from healthy (17 isolates) and diseased (23 isolates) rabbits were assayed for the presence of plasmids in seeking to determine whether any correlation exists between the presence of plasmids and health status, sensitivity to antimicrobial agents, capsular and somatic type, and the anatomic site of isolation. Six isolates were found harboring plasmids. A similar ladder pattern ranging from 18 to 3 megadalton (Mda) were found in three isolates recovered from diseased rabbits. One band of molecular weight 6.6 Mda was shared by four of five (4/5) isolates from the diseased rabbits. No correlation was found between the presence of the common plasmids and serotype, resistance to antimicrobial agents, and anatomic sites from which the bacteria were cultured. Random amplification polymorphic DNA was applied to subtype all the isolates of P. multocida. Two single primers were tested for their abilities to generate individual fingerprints by using PCR. Primer 1 grouped the isolates into 7 profiles, and primer 2 grouped them into 15. Random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) results show the presence of a wide heterogeneity within P. multocida isolates. Therefore RAPD-PCR is an efficient technique to detect the DNA polymorphism and could be used to discriminate P. multocida of rabbit isolates together with serologic typing

Method for volumetric assessment of edge-wear in ceramic-on-ceramic acetabular liners

This paper details a novel method to characterize and quantify edge wear patterns in ceramic-on-ceramic acetabular liners using a roundness measurement machine to measure the post-wear surface. A 3D surface map is produced which encompasses the measured surface covering the wear patch, the uncontrolled edge geometry and form of the bearing surface. The data is analysed to quantify linear penetration and volume. The developed method was applied in a blind study to a set of six 36 mm ceramic- on-ceramic acetabular cup liners that were measured and analysed to characterise the edge wear. The in-vitro linear wear penetration ranged from 10 μm to 30 μm. The computed volumetric wear results obtained from the blind roundness measurement study were compared against the measured gravimetric results indicating a strong correlation between the results (0.9846). This study has also highlighted that measured liners exhibited an area of localised edge wear locates above the bearing surface as well as a smearing effect on the bearing surface caused by debris from edge wear. A study was carried out to test the repeatability of the measurement method and the inter-operator variability of the analysis. The results of the study show a standard deviation for the entire measurement and analysis process of 0.009 mm3 for first user and 0.003 mm3 for second user over twenty datasets. Hence the method displays high repeatability of the measurement and analysis process between users. This method allows for the delineation of form and wear through the determination of local geometry changes on what is essentially a freeform surface. The edge geometry is only partially controlled from a GD&T perspective and its geometry relative to the bearing surface varies from part-to-part. This method whilst being subjective allows for the determination of wear in this area with a high level of repeatability. However the limitation of this method is that it can only measure 5mm wide band of the liner due to the limited gauge travel range of 2mm