Background Nosocomial infections and persistence of multidrug resistant biofilm forming Acinetobacter baumannii in hospitals has made it as a serious problem in healthcare settings worldwide. Methods A total of 100 A. baumannii clinical isolates from immunocompromised patients hospitalized in ICU were investigated for biofilm formation, the presence of biofilm related genes ( bap, ompA, csuE, fimH, epsA, bla PER-1 , bfmS, ptk, pgaB, csgA, kpsMII ), integron characterization and molecular typing based on REP-PCR. Results All isolates were resistant to three or more categories of antibiotics and considered as multidrug resistant (MDR). A total of 32 isolates were resistant to all tested antibiotics and 91% were extensively drug-resistance (XDR). All isolates were able to produce biofilm and 58% of isolates showed strong ability to biofilm formation. All strong biofilm forming A. baumannii isolates were XDR. All A. baumannii isolates carried at least one biofilm related gene. The most prevalent gene was csuE (100%), followed by pgaB (98%), epsA and ptk (95%), bfmS (92%) and ompA (81%). 98% of isolates carried more than 4 biofilm related genes, simultaneously. Class I integron (67%) was more frequent in comparison with class II (10%) ( P < 0.05). The REP-PCR patterns were classified as 8 types (A-H) and 21 subtypes. The A1 (23%) and C1 (15%) clusters were the most prevalent among A. baumannii isolates ( P < 0.05). According to the REP-PCR patterns, 23% of all isolates had a clonal relatedness. Conclusion Our study revealed the high frequency of biofilm forming XDR A. baumannii in ICU patients, with a high prevalence of biofilm related genes of csuE and pgaB. It seems that the appropriate surveillance and control measures are essential to prevent the emergence and transmission of XDR A. baumannii in our country.

Background: Enterotoxigenic Bacteroides fragilis (ETBF) is an enterotoxin-producing bacterium that possibily has a role in the occurrence and progression of colorectal cancer (CRC) by modulating the mucosal immune response and inducing epithelial cell changes. The aim of this study was to investigate the frequency of ETBF in stool samples of CRC patients and healthy volunteers. Methods: A total of 60 stool samples from confirmed CRC patients and 60 stool samples from healthy volunteers with no personal or familial history or diagnosis of colorectal disease were collected. Stool samples were screened for direct detection of B. fragilis using PCR targeting the marker genes of neu and bft. Enterotoxin isotypes bft-1, bft-2 and bft-3 were also detected in B. fragilis positive samples. Results: The frequency of B. fragilis among CRC and control cases was 58.3 and 26.6%, respectively (P < 0.05). The rate of bft gene in CRC cases was significantly higher than in controls (P < 0.05). Also, the presence of bft gene in CRC patients stage III was significantly higher than stages I and II (P < 0.05). Enterotoxin isotype bft-2 was detected with higher frequency among CRC patients than healthy control (P < 0.05). Conclusion: Our results show the association between fecal ETBF and CRC, and we suggest that detection of ETBF may be a potential marker for colorectal cancer diagnosis. However, additional investigations on tumor and paired normal tissue samples are required to substantiate this possible correlation.

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Quorum sensing (QS) system in Pseudomonas aeruginosa may be an important target for pharmacological intervention. The present study aimed to investigate the synergetic activity of sub-MIC concentrations of curcumin (C) with ceftazidime (CAZ) and ciprofloxacin (CIP) against P. aeroginusa QS system. We determined the MIC and synergistic activity of C, CAZ and CIP against P. aeroginusa PAO1 using broth microdilution and checkerboard titration methods. The activity of sub-MIC (1/4 and 1/16 MIC) concentrations of C on the QS signal molecules was assessed using a reporter strain assay. The influence of sub-MIC of C, CAZ and CIP alone and in combination on motility and biofilm formation was also determined and confirmed by RT-PCR to test the expression of QS regulatory genes lasI, lasR, rhlI and rhlR. The addition of C decreased the MIC of CAZ and CIP. Curcumin showed synergistic effects with CAZ and additive activity with CIP. Treated PAO1 cultures in the presence of C showed significant reduction of signals C12-HSL and C4-HSL (P < 0.05). Sub-MIC concentrations (1/4 and 1/16 MIC) of C, CAZ and CIP alone and in combination significantly reduced swarming and twitching motilities and biofilm formation. Expression of QS regulatory genes lasI, lasR, rhlI, and rhlR using 1/4 MIC of C, CAZ and CIP alone and in combination was repressed significantly relative to untreated PAO1. Our results indicate that a combination of the sub-MIC concentration of C and CAZ exhibited synergism against P. aeroginusa QS system. This combination could lead to the development of a new combined therapy against P. aeruginosa.

Our study revealed the high frequency of multidrug- and carbapenem-resistant isolates of A. baumannii in ICU patients, with a high prevalence of the genes blaOXA-23 and blaOXA-51. However, no apparent biocide resistance was seen in A. baumannii isolates. It appears that appropriate surveillance and control measures are essential to prevent the emergence and transmission of MDR A. baumannii in Iran.

Diarrhoea continues to be one of the most common causes of morbidity and mortality among infants and children in developing countries. Diarrhoeagenic Escherichia coli (DEC) is an emerging agent among pathogens that cause diarrhoea. Between March 2011 and January 2012, a total of 600 stool specimens from children younger than 5 years of age (450 with and 150 without diarrhoea) were investigated for enteroaggregative E. coli (EAEC), enterohaemorrhagic E. coli (EHEC), enteropathogenic E. coli (EPEC) and enterotoxigenic E. coli (ETEC) using PCR. Antimicrobial susceptibility testing was performed following Clinical and Laboratory Standards Institute guidelines. The prevalence of DEC pathotypes was 30.4 % (137 patients) and 12 % (18 patients) in the diarrhoea group and the control group, respectively. The most frequently isolated pathotype in diarrhoeal children was ETEC. This pathotype was detected significantly more often in children with diarrhoea (14.4 %) than in children without diarrhoea (5.3 %). EAEC and EPEC were detected with slightly higher frequencies in children with (8 and 4.2 %, respectively) than in children without (4.6 and 2 %, respectively) (P.0.05) diarrhoea. EHEC was only detected in children with diarrhoea (3.8 %). Of the children from the diarrhoea group, 10 % were colonized with more than one DEC pathotype. The DEC isolates exhibited high-level resistance to erythromycin (100 %), azteronam (80.7 %), amoxicillin (74.4 %) and tetracycline (69.3 %), and 86.4 % of isolates were multidrug resistant. In conclusion, ETEC continues to be an important agent associated with diarrhoea in children from Tabriz, Iran.

Background Multidrug resistant (MDR) enterococci are important nosocomial pathogens causing serious problem in hospitalized patients. The aim of present study was to investigate the frequency of high-level aminoglycoside-resistant and vancomycin-resistant enterococci (VRE) and virulence encoding genes in enterococci isolated from hospitalized patients. Methods A total of 100 enterococci isolated from urine samples of hospitalized patients with symptomatic urinary tract infections were investigated for antimicrobial susceptibility, the frequency of aminoglycoside and vancomycin resistance genes (including aac (6′)-Ie-aph (2“)-Ia, aph (3’)-IIIa, ant (4’)-Ia, aph (2”)-Ic, aph (2“)-Ib, aph (2”)-Id, ant (3″)-III, ant (6′)-Ia, vanA, vanB and vanC ) and virulence encoding genes (including gelE, PAI, esp, ace, cyl, hyl and sprE ). Results Enterococcus faecalis species was identified as predominant enterococci (69%), followed by “other” Enterococcus species (21%) and E. faecium (10%). Ninety three percent of isolates were resistant to one or more antimicrobial agents, with the most frequent resistance found against tetracycline (86%), ciprofloxacin (73%) and quinupristin-dalfopristin (53%). Gentamicin and streptomycin resistance were detected in 50 and 34% of isolates, respectively. The most prevalent aminoglycoside resistance genes were ant (3″)-III (78%) and aph (3′)-IIIa (67%). Vancomycin resistance was detected in 21% of isolates. All E. faecium isolates carried vanA gene, whereas, the vanB gene was not detected in Enterococcus species. The most frequent virulence gene was ace (88.6%), followed by esp (67.1%), PAI (45.5%) and sprE (41.7%). Conclusion Our study revealed the high frequency of gentamycin resistance and VRE in E. faecium isolates, with a high prevalence and heterogeneity of virulence and resistance genes. Due to high frequency of MDR enterococci, it seems that the appropriate surveillance and control measures are essential to prevent the emergence and transmission of these isolates in hospitals.

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