Role of extra-cellular fatty acids in vancomycin induced biofilm formation by vancomycin resistant Staphylococcus aureus

In the present study a vancomycin resistant Staphylococcus aureus [S. aureus] [VRSA] [Labeled as CP2] was isolated from the blood of a post-operative cardiac patient is described. It harbors a plasmid which carry vanA gene and exhibited low-level vancomycin resistance [MIC 16 micro g/ml], was sensitive to teicoplanin. It has been observed that sublethal dose of vancomycin induced biofilm formation by CP2 on nylon and silicon indwelling. The results divulge new insights into associations between vancomycin induced biofilms and extra-cellular fatty acids. Gas chromatography coupled with Mass spectrometry [GC-MS] revealed that biofilm matrix of CP2 contains a variety of saturated and unsaturated fatty acids, especially, diverse species of octadecanoic [C18:0] and octadecenoic acids [C18:1]. A large difference in fatty acids composition was noticed in biofilms, isolated from hydrophobic and hydrophilic surfaces. CP2 produced thicker layer of biofilms on hydrophobic silicon and nylon surfaces which contains variety of saturated, unsaturated and cyclic fatty acids. Contrary to this on hydrophilic glass surfaces it produced thinner layer of biofilm which contains only straight chain saturated fatty acids. These fatty acid components seem to play a crucial role in cell-cell communication and in the establishment of biofilms, consequently, advantageous for pathogens to survive in hospital environment under enormous antibiotics pressure

Genomic organization of a vancomycin-resistant staphylococcus aureus

To study the genomic organization of vancomycin resistance in a local isolate of vancomycin resistant Staphylococcus aureus [VRSA]. Experimental study. Department of Microbiology, University of Karachi, January 2008 through December 2010. A vancomycin-resistant Staphylococcus aureus [VRSA-CP2] isolate [MIC 16 microg/ml] was isolated from a local hospital of Karachi. Species identification was confirmed by Gram staining, standard biochemical tests and PCR amplification of the nuc gene. The vancomycin MIC was re-confirmed by E-test. For the genetic determination of vancomycin resistance, in-vitro amplification of vanA cassette was performed by using plasmid DMA of CP2, CP2's transformant as template on MWG Thermo-Cycler. Amplified products of vanR, vanS, vanH, vanA, vanY, or/2, orfID, orf2E, orf-Rev and IS element genes were subjected to Sanger's electrophoresis based sequence determination using specific primers. The Basic Local Alignment Search Tool [BLAST] algorithm was used to identify sequences in GenBank with similarities to the vanA cassette genes. The vancomycin-resistant isolate CP2 was found to be resistant to oxacillin, chloramphenicol, erythromycin, rifampicin, gentamicin, tetracycline and ciprofloxacin, as well. The isolate CP2 revealed four bands: one of large molecular size -56.4 kb and three of small size -6.5 kb, -6.1 kb and -1.5 kb by agarose gel electrophoresis indicating the presence of 3 plasmids. The plasmid DNA of isolate CP2 was analyzed by PCR for the presence of the van cassettes with each of the vanA, vanB and vanC specific primers. It carried vanA cassette, which comprises of vanR, vanS, vanH, vanA, vanY, and or/2. The vanA cassette of isolate CP2 also carried an insertion element [IS]. However, it did not show the PCR product for orfl. Vancomycin resistance was successfully transferred from the donor CP2 to a vancomycin-sensitive recipient S. aureus. The MIC of vancomycin for the transformant was 16 microg/ml, similar to the parent isolate CP2. Nucleotide sequencing of the PCR product showed similarity with van genes of enterococci and other VRSA reported from different parts of the world. Sequence of vanA cassette of CP2 showed partial homology with vancomycin resistant enterococci, VRSA vanA cassette element recorded in gene bank NCBI

Congenital malformations in newborns of consanguineous and non-consanguineous parents

To find out the pattern of different congenital malformation [CM] and to compare the proportion of congenital malformations between consanguineous and non-consanguineous parents. This observational study was done in Countess of Dufferin Fund Hospital, [CDF] Hyderabad from July 2006 to June 2008. All newborns with congenital anomaly at birth were included. Complete examination of the newborn after birth and relevant investigations were done. Babies with malformations whose parents were consanguineous were compared with babies having CM whose parents were non-consanguineous. Maternal age, parity, singletons, multiple births, still births and neonatal death were also recorded. Overall prevalence of congenital malformations was 15.7 / 1000 births. Central nervous system anomalies were the commonest [51%]. Congenital malformations in the newborns of consanguineous parents were significantly higher than in the newborns of non-consanguineous parents. Still births and neonatal deaths were commoner in the newborns of consanguineous parents. The results of this study show that parental consanguinity is associated with increased congenital malformations; neural tube defect is the most common anomaly seen

Characterization of a vancomycin intermediate-resistant staphylococcus aureus isolated from a hospital

A Vancomycin intermediate resistant strain of Staphylococcus aureus [S. aureus] labeled as CP2 [MIC 16 micro g/ml] was isolated from an in-patient of local Cardiac Hospital of Karachi. CP2 showed typical characters of Vancomycin intermediate resistant S. aureus [VISA] i.e. high level of oxacillin resistance, thickened cell wall with rough surface and reduced autolytic activities associated with murein hydrolase [MH] enzyme. This strain may have acquired vancomycin resistance due to long term exposure to antibiotic during the treatment of the patient. Therefore, it implicates the importance of monitoring the usage and also to control of the abuse of antibiotics for prevention of any further proliferation of this type of notorious bugs

Outbreak of gastroenteritis in Gadap, Karachi during summer of 2003

Outbreaks of gastroenteritis are common in Karachi during the monsoon season. Usually Vibrio cholerae is the suspected agent but etiological identification is rarely attempted because of lack of adequate diagnostic facilities. In July 2003, large outbreak of acute gastroenteritis with several deaths was reported from Gadap, an industrial suburb of Karachi. We investigated the cause of this outbreak