Genotyping and antibiotic susceptibility patterns of pseudomonas aeruginosa isolated from burn ward of sina hospital in Tabriz

Background and Objectives: Pseudomonas aeruginosa is one of the important nosocomial Gram-negative bacilli which are resistant to most of antimicrobial agents and antibiotics. This opportunistic bacterium is capable of causing life threatening infections in patients, especially in those with immunodeficiency such as those in ICUs and burn wards. This study was conducted to detect antibiotic susceptibility and also molecular typing of P. aeruginosa isolates from burn infections by using RAPD [Random amplified polymorphic DNA]

Materials and Methods: Totally 124 P. aeruginosa isolates collected from bum patients consisting of burn infection discharge and blood specimens by application of conventional microscopic, culture and biochemical identification tests. The collected isolates were studied for their antibiotic susceptibility patterns using routine antibiotics ceftazidim [30 microg], aztreonam [30 microg], carbenicillin [100 microg], polymixin B [300 u], colistin [100 microg], gentamicin [10 microg] and ciprofloxacin [5 microg] by disc agar diffusion method and detection of genotypes by two short primers namely 272[5-AGCGGCCAA-3] and 208[5-ACGGCCGACG3] according to RAPD-PCRmethod

Results: Results of antibiotic susceptibility tests showed high resistance to aztreonam [70.1%], ceftazidime [66.1%], colistin [61.2%] and gentamicin [47.5%] but less resistance to ciprofloxacin[18.5%] and polymixin B[13.7%]. Based on antibiotic susceptibility 41 patterns were detected. RAPD-PCR created 32 genotypic profiles with base pair length ranging from 250 to 10000. Each genotype showed between 1 and 8 different weight DNA bands. Genotype 3 was the most prevalent, identified in 42 isolates [33.8%] and accommodated isolates with similar antibiotic susceptibility patterns, while in other genotypes no similar susceptibility patterns were encountered

Conclusion: Our P. aeniginosa isolates collected from burn infections were most resistant to aztreonam [70.1%], but least resistant to polymixin B [13.7%]. The test isolates showed 41 antibiotic susceptibility patterns and 32 RAPD genotypes. Genotype 3 was the most prevalent and accommodated isolates with similar antibiotic susceptibility patterns, but in other genotypes, isolates with similar antibiotic susceptibility patterns was not detected. Some isolates with similar antibiotic patterns underline possibility of their transfer among burn patients and suggest need for restricted conditions and microbiplogic surveillance in the bum wards

[Cassette chromosome mec typing of methicillin-resistant staphylococcus aureus isolates collected from Sina and Imam Reza Hospitals of Tabriz]

Backgrounds and Objectives: Methicillin-resistant Staphylococcus aureus is a cause of nosocomial infections leading to high mortality. Since these strains have become prevalent in the world, it is necessary to identify and type them

Materials and Methods: This cross-sectional study was conducted to study a total of 1475 specimens collected from patients of Imam Reza and Sina hospitals of Tabriz in 2012-2013. Using phenotypic tests such as Gram stain, catalase, coagulase, DNase and mannitol fermentation 169 isolates of Staphylococcus aureus and by utilizing methicillin-resistance test 100 MRSA isolates were identified. SCCmec typing was performed by multiplex PCR method and the results were analyzed using chi-square tests using SPSS-18 software

Results: Disc agar diffusion test using cefoxitin disc [30 microg] showed methicillin resistance in 59% of our isolates. mecA and femB genes were identified in all of the MRSA isolates using PCR method. Frequency of SCCmec types and sub-types were as follow: SCCmecIII [77%], SCCmecI [5%], SCCmecIVa [1%], SCCmecIVc [1%], mixed isolates SCCmecIVc-III [1%] and Non typeable isolates [15%]. Non typeable isolates recovered in two groups [10% without any band and 5% of multi-bands III-I]. In this study, 82% of isolates were HA-MRSA, 3% were CA-MRSA and 15% were Non-typeable

Conclusion: In our S. aureus isolates, the prevalence of methicillin resistance was 59%. The most frequent SCCmec type was SCCmecIII [77%]. Our results demonstrated the spread of HA-MRSA isolates in the community and propagating CA-MRSA isolates in the studied hospitals

PER-1-type extended-spectrum beta-lactamase producing acinetobacter baumannii isolated from clinical specimens in Tabriz, Iran

To determine the prevalence of PER-1 gene type ESBLs producing isolates of A. baumannii in clinical specimens. During March 2008 to June 2009, a total of 100 A. baumannii isolates were recovered from clinical specimens of hospitalized patients in Imam Reza hospital in Tabriz. These isolates were subjected to susceptibility tests using five selected cephalosporins according to CLSI guidelines. Screening for ESBL production was carried out by confirmatory tests including DDST and CDM. The prevalence of PER-1 gene in these isolates was also determined by using PCR. All of A. baumannii isolates in this study were resistant at least to one of the selected cephalosporins. Sixty four percent of isolates exhibited a>5 mm zone size enhancement in the CDM test, whereas 53% of them gave positive results by DDST as ESBL producer. Collectively CD method and DDST showed 70% of A. baumannii as ESBLs producer, of which 51% had PER-1 gene. This research shows high prevalence of PER-1 gene type ESBLs producing A. baumannii isolates in Tabriz which is strong evidence for their resistance to cephalosporins