ABSTRACT
Objective: To determine the role of icaAD and agr genes in biofilm formation and evaluate the consistency of two phenotypic methods for biofilm measurement
Methods: A total of 81 clinical S. aureus strains were included and analyzed for biofilm formation by two methods. The microtitration plate method was optimized using computational fluid dynamics and compared with the Congo red assay. The genes for icaAD and agr were detected using PCR
Results: Of 81 isolates, biofilm production was detected in 43% isolates using Congo red method while microtiter plate assay showed biofilm production in 92% isolates. Both methods showed correlation in 30% isolates. PCR detection showed icaAD gene in 42 [52%] isolates. Out of 81 S. aureus isolates 65 strains [80%] contained agr while 16 [20%] strains were non-typeable
Conclusions: In conclusion, biofilm production was observed for both agr positive and agr negative isolates. Furthermore, the presence of icaAD genes was not associated with all biofilm producing strains as some strains negative for icaAD genes displayed biofilm production
ABSTRACT
The accessory gene regulator [agr] locus in Staphylococcus aureus [S. aureus] is a global regulator of quorum sensing and controls the production of virulence factors. This study was carried out to investigate the agr specific groups both in methicillin resistant and sensitive Staphylococcus aureus [MRSA and MSSA] and their relation with antibiotic resistance. A total of 90 clinical S. aureus isolates were studied from two tertiary care hospitals. The isolates were identified by standard biochemical tests. Methicillin resistance was confirmed by oxacillin and cefoxitin resistance. Multiplex PCR was used to determine the agr groups. MRSA prevalence was found to be 53.3%.The agr groups' distribution in MRSA was as follows: 22 [45.8%] belonged to group I, 14 [29.1%] belonged to group III and 2 [4.1%] belonged to group II. agrIV was not detected in MRSA. For 17 isolates, the agr group was not detected.agr III isolates showed higher antibiotic resistance than agrI isolates except in case of oxacillin and linezolid. Strict infection control policy and antibiotic guidelines should be adopted to control the problem of MRSA. Higher prevalence of agr I and agr III shows that they are dominant agr groups of our area
ABSTRACT
The acquisition of blaNDM-1 gene by Gram negative bacteria has emerged as critical threat to human health as these organisms display high resistance to available antibiotics. The presence of this gene has been observed in both clinical as well as environmental settings. The present study was carried out to evaluate the prevalence of blaNDM-1 containing microorganisms in water sources. A total of 241 water samples were collected from different sites in Islamabad, Rawalpindi and areas of Khyber Pakhtunkhwa. Meropenem resistant organisms were isolated and PCR was used for the detection of the blaNDM-1 gene among the resistant isolates of all the water samples, 43 meropenem resistant bacteria were isolated among which 12 isolates were found to carry blaNDM-1 gene. The blaNDM-1 isolates were resistant to most of the antibiotics but sensitive to colistin and polymyxin B. The presence of blaNDM-1 gene harboring organisms in aquatic environment is concerning and poses public health threat
ABSTRACT
The rapid spread of metallo- Beta-lactamase producing clinical pathogens is a matter of great concern and with the addition of NDM-1 it poses more threat for public health as NDM-1 positive isolates show resistance to most of the antibiotics. The current study was carried out to determine the prevalence of extended-spectrum Beta-lactamases [ESBLs] and metallo- Beta-lactamases [MBLs], particularly NDM-1 in clinical multi-drug resistant isolates from two tertiary care hospitals in Pakistan. A total of 356 clinical isolates were included in the study where 301 isolates were collected from the Pakistan Institute of Medical Sciences [PIMS], Islamabad and 55 were collected from the Mayo Hospital Lahore. The isolates were screened for ESBLs and MBLs production by phenotypic method and PCR was performed to detect the presence of blaVIM, blaIMP and blaNDM-1 genes. Out of 356 clinical isolates, 160 showed carbapenem resistance. Of these 160 isolates, 131 displayed MBLs production as accessed by combined disk method. In MBLs producing organisms, PCR amplification confirmed 31 [23.6%] isolates harboring blaNDM-1 gene, 33 [25.1%] isolates having blaVIM gene and 2 [1.5%] isolates displaying blaIMP gene. Plasmid profile analysis of NDM-1 positive organisms showed variable number of plasmids which were stable during serial passages in antibiotic free media. The prevalence of ESBL producing organisms was recorded to be 87.5%. The results show a high level of NDM-1 positive organisms from variety of samples at both hospitals, implicating the spread of MBL genes in clinical isolates