ABSTRACT
Background: Campylobacter infections may lead to serious conditions, including septicemia or other invasive forms of the disease, which require rapid and accurate laboratory diagnosis and subsequently appropriate antimicrobial therapy. The aim of this study was to compare the species distribution and antimicrobial susceptibility pattern of Campylobacter spp. strains isolated from patients and food samples
Methods: Biochemical identification was performed on 15 clinical and 30 food isolates of Campylobacter recovered onto Brucella agar containing 5% sheep blood. PCR was carried out to confirm the identity of Campylobacter spp. using primers for cadF, hipO, and asp genes of Campylobacter. To determine antibiotic sensitivity of isolates, Kirby- Bauer assay was carried out using 16 different antibiotic discs
Results: PCR assay and biochemical tests confirmed all 45 isolates as Campylobacter: 20 [44.44%] as C. jujeni, 10 [22.22%] as C. coli, and 15 [33.34%] as other Campylobacter strains. The maximum resistance was observed to cefotaxime and imipenem [each 86.49%] and the maximum sensitivity to erythromycin [48.65%]
Conclusion: C. jujeni is dominant among isolates from clinical and food samples. In addition, tetracycline remains the first-line therapeutic agent against Campylobacter infections in Iran
ABSTRACT
Background: The aim of this study was to compare the biofilm formation and the prevalence of biofilm-associated genes between the isolates of methicillin-resistant [MRSA] and methicillin-susceptible [MSSA] Staphylococcus aureus
Methods: In total, 209 S. aureus isolates were collected. The antibiotic susceptibility test was conducted using nine antibiotics according to the guidelines of Clinical and Laboratory Standards Institute. Phenotypic biofilm formation was performed with microtiter plate assay. The polymerase chain reaction was employed to detect icaA, icaD, icaB, icaC, clfA, clfB, fnbA, fnbB, fib, cna, eno, ebps, bbp, mecA, and SCCmec types as well as agr group genes with specific primers
Results: Sixty-four [30.62%] isolates were resistant to methicillin, and 54 [83%] MRSA harbored SCCmec III. Furthermore, 122 [58.3%] isolates belonged to agr group I. Twenty-six [36.1%] MRSA and 42 [28.9%] MSSA isolates were strong biofilm producers [no significant difference]. The prevalence of icaA, icaD, icaB, and icaC genes in MSSA isolates was 71, 41, 76, and 72%, respectively. The frequency of clfA, clfB, fnbA, fnbB, fib, cna, eno, ebps, and bbp in MSSA was 100, 100, 56, 46, 74, 54, 78%, 11, and 1%, respectively. However, in MRSA isolates, the frequency was 97, 97, 64, 51, 76, 56, 79, and 12% with no track of bbp, respectively
Conclusion: Statistical difference between MSSA and MRSA regarding biofilm formation and the frequency of all biofilm-encoding genes was not significant. The majority of the S. aureus isolates harbored clfA, clfB, eno, fib, icaA, and icaD genes
ABSTRACT
Cholera toxin B subunit [CTB] has been extensively considered as an immunogenic and adjuvant protein, but its yield of expression is not satisfactory in many studies. The aim of this study was to compare the expression of native and mutant recombinant CTB [rCTB] in pQE vector. ctxB fragment from Vibrio cholerae O1 ATCC14035 containing the substitution of mutant ctxB for amino acid S128T was amplified by PCR and cloned in pGETM-T easy vector. It was then transformed to E. coli Top 10F' and cultured on LB agar plate containing ampicillin. Sequence analysis confirmed the mature ctxB gene sequence and the mutant one in both constructs which were further subcloned to pQE-30 vector. Both constructs were subsequently transformed to E. coli M15 [pREP4] for expression of mature and mutant rCTB. SDS-PAGE analysis showed the maximum expression of rCTB in both systems at 5 hours after induction and Western-blot analysis confirmed the presence of rCTB in blotting membranes. The expression of mutant rCTB was much higher than mature rCTB, which may be the result of serine-to-threonine substitution at position 128 of mature rCTB amino acid sequence created by PCR mutagenesis. The mutant rCTB retained pentameric stability and its ability to bind to anti- cholera toxin IgG antibodies. Point mutation in ctxB sequence resulted in over-expression of rCTB, probably due to the increase of solubility of produced rCTB. Consequently, this expression system can be used to produce rCTB in high yield
ABSTRACT
The aim of this study was to determine the prevalence of virulence-associated genes and enterobacterial repetitive intergenic consensus PCR [ERIC-PCR] analysis of Campylobacter spp. isolated from children with diarrhea in Iran. A total of 200 stool specimens were obtained from children under 5 years during July 2012 to July 2013. Detection of C. jejuni and C. coli was performed by standard biochemical and molecular methods. The presence of virulence-associated genes and genetic diversity of isolates was examined using PCR and ERIC-PCR analyses. A total of 12 [6%] Campylobacter spp. were isolated from patients including 10 [4.5%] C. jejuni and 2 [1.5%] C.coli. The flaA, cadF and ciaB genes were present in 100% of isolates, while no plasmid of virB11 gene was present in their genome. The prevalence of invasion-associated marker was 100% among C. coli and was not detected in C. jejuni isolates. The distribution of both pldA and the genes associated with cytolethal distending toxin [CDT] was 58.3% in C. jejuni isolates. Seven distinct ERIC-PCR profiles were distinguished in three clusters using ERIC-PCR analysis. Genotyping analysis showed a relative correlation with geographic location of patients and virulence gene content of isolates. To our knowledge, this is the first molecular survey of Campylobacter spp. in Iran concerning genotyping and virulence gene content of both C. jejuni and C. coli. ERIC-PCR revealed appropriate discriminatory power for clustering C. jejuni isolates with identical virulence gene content. However, more studies are needed to clearly understand the pathogenesis properties of specific genotypes
ABSTRACT
Cholera is a diarrheal disease caused by different serotypes of Vibrio cholerae. More than 200 O-antigen serotypes have been identified. Interestingly, only the O[1] and O[139] serotypes are known to cause epidemic disease. Different cases of Ogawa and Inaba serogroups have been found during last years in Iran. In this study, seroepidemiology of cholera in Iran between 2004 and 2008 was studied. In this descriptive study, fecal specimens [stool or rectal swabs] were cultured in a selective plating media like TCBS. Overnight growth of V. cholerae colony on TCBS was cultured on BHI. Colonies grown on BHI, used for biochemical and biotyping and serotyping tests. Among 93 clinical strains isolated during 5 consecutive years [2004-2008], different serogroups of V. cholerae O[1] [Ogawa, Inaba and Hikojima] biotype El Tor were identified. This study showed significantly decreasing number of Ogawa strains compared with Inaba strains in recent years in Iran. However, some rare cases of Hikojima strains have been detected in Iran in 2007 and 2008