Multiplex detection of five common respiratory pathogens from bronchoalveolar lavages using high resolution melting curve analysis.

BACKGROUND: The study describes the application of the multiplex high-resolution melting curve (MHRM) assay for the simultaneous detection of five common bacterial pathogens (Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii and Escherichia coli) directly from bronchoalveolar lavage samples. RESULTS: Our MHRM assay successfully identified all five respiratory pathogens in less than 5 h, with five separate melting curves with specific melt peak temperatures (Tm). The different Tm were characterized by peaks of 78.1 ± 0.4 °C for S. aureus, 83.3 ± 0.1 °C for A. baumannii, 86.7 ± 0.2 °C for E. coli, 90.5 ± 0.1 °C for K. pneumoniae, 94.5 ± 0.2 °C for P. aeruginosa. The overall sensitivity and specificity of MHRM were 100% and 88.8-100%, respectively. CONCLUSIONS: Our MHRM assay offers a simple and fast alternative to culture approach for simultaneous detection of five major bacterial lower respiratory tract infection pathogens. Utilization of this assay can help clinicians initiate prompt and appropriate antimicrobial treatment, towards reducing the morbidity and mortality of severe respiratory infections.

Frequency of Salmonella serotypes among children in Iran: antimicrobial susceptibility, biofilm formation, and virulence genes.

BACKGROUND/SIGNIFICANCE: Salmonella gastroenteritis causes significant morbidity among pediatric patients, mainly in developing world, such as the Middle East and North Africa (MENA) region. Concurrently, data from MENA countries like Iran, regarding prevalence of Salmonella serotypes, antimicrobial susceptibility, and biofilm production is scarce. MATERIAL & METHODS: Slide agglutination was used to determine the serogroup of 140 Salmonella isolates recovered from 4477 stool specimens collected from children with gastroenteritis, and isolates were serotyped by PCR assay. The antimicrobial susceptibility of isolates to five first line drugs was assessed by disk diffusion assay using CLSI guidelines. Semi-quantitative evaluation of biofilm production was done by microtiter plate assay followed by PCR detection of biofilm-associated virulence genes csgD, pefA, and bcsA for each isolate. RESULTS: Nearly 94% of Salmonella isolates were recovered from ≤ 5-year-old patients, and 99% of isolates were non-typhoidal. While we found extensive diversity among Salmonella isolates, serogroup D (46%) predominated, and Salmonella Enteritidis (41%) was the most common serotype that showed the highest antimicrobial susceptibility rate (> 96%). For the first time in Iran, S. Newport serotype from human specimens was isolated. Most isolates were sensitive to all test antimicrobials, but 35% of isolates were not-typed (NT) that showed the highest resistance with 48% being resistant to ≥ 1 test antimicrobial. Majority of isolates made weak (or no) biofilm, and we found a weak association between antimicrobial susceptibility, biofilm production, or virulence genes csgD, pefA, and bcsA. CONCLUSIONS: The most effective measure that may control pediatric salmonellosis outbreaks is raising awareness of parents of preschoolers about food safety. Isolation of highly diverse Salmonella serotypes, including many commonly isolated from animals, indicates widespread contamination of the food chain. Majority of serotypes were sensitive to first-line antimicrobials, thus presently, pediatric Salmonella infections in this region may be controlled by conventional antimicrobials. However, despite the current trend, an imminent emergence of resistant Salmonella strains is foreseen, since various serotypes resistant to > 1 antimicrobial agent are typically associated with animals. Our results warrant further investigation that includes correlation analysis of clinical data regarding treatment outcomes, and serotype attributes like virulence genes.

A trivalent vaccine consisting of "flagellin A+B and pilin" protects against Pseudomonas aeruginosa infection in a murine burn model.

Pseudomonas aeruginosa is a common nosocomial pathogen in burn patients, and rapidly achieves antibiotic resistance, and thus, developing an effective vaccine is critically important for combating P. aeruginosa infection. Flagella and pili play important roles in colonization of P. aeruginosa at the burn wound site and its subsequent dissemination to deeper tissue and organs. In the present study, we evaluated protective efficacy of a trivalent vaccine containing flagellins A and B (FlaA + FlaB) + pilin (PilA) in a murine burn model of infection. "FlaA + FlaB + PilA" induced greater protection in P. aeruginosa murine burn model than the single components alone, and it showed broad immune protection against P. aeruginosa strains. Immunization with "FlaA + FlaB + PilA" induced strong opsonophagocytic antibodies and resulted in reduced bacterial loads, systemic IL-12/IL-10 cytokine expression, and increased survival after challenge with three times lethal dose fifty (LD50) of P. eruginosa strains. Moreover, the protective efficacy of "FlaA + FlaB + PilA" vaccination was largely attributed to specific antibodies. Taken together, these data further confirm that the protective effects of "FlaA + FlaB + PilA" vaccine significantly enhance efficacy compared with antibodies against either mono or divalent antigen, and that the former broadens the coverage against P. eruginosa strains that express two of the three antigens.

Strategies to eradicate HIV from infected patients: elimination of latent provirus reservoirs.

35 years since identification of HIV as the causative agent of AIDS, and 35 million deaths associated with this disease, significant effort is now directed towards the development of potential cures. Current anti-retroviral (ART) therapies for HIV/AIDS can suppress virus replication to undetectable levels, and infected individuals can live symptom free so long as treatment is maintained. However, removal of therapy allows rapid re-emergence of virus from a highly stable reservoir of latently infected cells that exist as a barrier to elimination of the infection with current ART. Prospects of a cure for HIV infection are significantly encouraged by two serendipitous cases where individuals have entered remission following stem cell transplantation from compatible HIV-resistant donors. However, development of a routine cure that could become available to millions of infected individuals will require a means of specifically purging cells harboring latent HIV, preventing replication of latent provirus, or destruction of provirus genomes by gene editing. Elimination of latently infected cells will require a means of exposing this population, which may involve identification of a natural specific biomarker or therapeutic intervention to force their exposure by reactivation of virus expression. Accordingly, the proposed "Shock and Kill" strategy involves treatment with latency-reversing agents (LRA) to induce HIV provirus expression thus exposing these cells to killing by cellular immunity or apoptosis. Current efforts to enable this strategy are directed at developing improved combinations of LRA to produce broad and robust induction of HIV provirus and enhancing the elimination of cells where replication has been reactivated by targeted immune modulation. Alternative strategies may involve preventing re-emergence virus from latently infected cells by "Lock and Block" intervention, where transcription of provirus is inhibited to prevent virus spread or disruption of the HIV provirus genome by genome editing.

Association of virulence gene expression with colistin-resistance in Acinetobacter baumannii: analysis of genotype, antimicrobial susceptibility, and biofilm formation.

BACKGROUND: Acinetobacter baumannii causes difficult-to-treat nosocomial infections, which often lead to morbidity due to the development of antimicrobial drug resistance and expression of virulence genes. Data regarding the association of resistance to colistin, a last treatment option, and the virulence gene expression of A. baumannii is scarce. METHODS: We evaluated the MLVA genotype, antimicrobial resistance, and biofilm formation of 100 A. baumannii isolates from burn patients, and further compared the in vitro and in vivo expression of four virulence genes among five colistin-resistant A. baumannii (Cst-R-AB) isolates. Five Cst-R-AB isolates were tested; one from the present study, and four isolated previously. RESULTS: Our results showed that reduced expression of recA, along with increased in vivo expression of lpsB, dnaK, and blsA; are associated with colistin resistance among Cst-R-AB isolates. Differences in virulence gene expressions among Cst-R-AB isolates, may in part explain common discrepant in vitro vs. in vivo susceptibility data during treatment of infections caused by Cst-R-AB. CONCLUSIONS: Our findings highlight the intricate relationship between colistin-resistance and virulence among A. baumannii isolates, and underscore the importance of examining the interactions between virulence and antimicrobial resistance toward efforts to control the spread of multidrug-resistant A. baumannii (MDR-AB) isolates, and also to reduce disease severity in burn patients with MDR-AB infection.

HIV Provirus Stably Reproduces Parental Latent and Induced Transcription Phenotypes Regardless of the Chromosomal Integration Site.

UNLABELLED: Understanding the mechanisms of HIV proviral latency is essential for development of a means to eradicate infection and achieve a cure. We have previously described an in vitro latency model that reliably identifies HIV expression phenotypes of infected cells using a dual-fluorescence reporter virus. Our results have demonstrated that ∼50% of infected cells establish latency immediately upon integration of provirus, a phenomenon termed early latency, which appears to occur by mechanisms that are distinct from epigenetic silencing observed with HIV provirus that establishes productive infections. In this study, we have used a mini-dual HIV reporter virus (mdHIV) to compare the long-term stability of provirus produced as early latent or productive infections using Jurkat-Tat T cell clones. Cloned lines bearing mdHIV provirus integrated at different chromosomal locations display unique differences in responsiveness to signaling agonists and chromatin-modifying compounds, and they also produce characteristic expression patterns from the 5' long terminal repeat (LTR) dsRed and internal EIF1α-enhanced green fluorescent protein (EIF1α-eGFP) reporters. Furthermore, reporter expression profiles of single cell sorted subcultures faithfully reproduce expression profiles identical to that of their original parental population, following prolonged growth in culture, without shifting toward expression patterns resembling that of cell subclones at the time of sorting. Comparison of population dispersion coefficient (CV) and mean fluorescence intensity (MFI) of the subcloned lines showed that both untreated and phorbol myristate acetate (PMA)-ionomycin-stimulated cultures produce expression patterns identical to those of their parental lines. These results indicate that HIV provirus expression characteristics are strongly influenced by the epigenetic landscape at the site of chromosomal integration. IMPORTANCE: There is currently considerable interest in development of therapies to eliminate latently infected cells from HIV-infected patients on antiretroviral therapy. One proposed strategy, known as "shock and kill," would involve treatment with therapies capable of inducing expression of latent provirus, with the expectation that the latently infected cells could be killed by a host immune response or virus-induced apoptosis. In clinical trials, histone deacetylase (HDAC) inhibitors were shown to cause reactivation of latent provirus but did not produce a significant effect toward eliminating the latently infected population. Results shown here indicate that integration of HIV provirus at different chromosomal locations produces significant effects on the responsiveness of virus expression to T cell signaling agonists and chromatin-modifying compounds. Given the variety of phenotypes produced by integrated provirus, it is unlikely that any single potential shock-and-kill therapy will be effective toward purging the latently infected population.

Protective effect of pilin protein with alum+naloxone adjuvant against acute pulmonary Pseudomonas aeruginosa infection.

Pseudomonas aeruginosa is an important opportunistic human pathogen that causes a wide variety of severe nosocomial infections. Type IV pili of P. aeruginosa are made up of polymerized pilin that aids in bacterial adhesion, biofilm formation and twitching motility. The aim of this study was to evaluate the efficacy of alum and naloxone (alum+NLX) as an adjuvant for P. aeruginosa recombinant PilA (r-PilA) as a vaccine candidate in the improvement of humoral and cellular immunity. Primary immunization with r-PilA in combination with alum+NLX followed by two booster shots was sufficient to generate robust cellular and humoral responses, which were Th1 and Th2 type responses consisting of IgG1 and IgG2a subtypes. Analysis of the cytokine response among immunized mice showed an increased production of IL-4, INF-γ and IL-17 by splenocytes upon stimulation by r-PilA. These sera were also able to reduce bacterial load in the lung tissue of challenged mice. The reduction of systemic bacterial spread resulted in increased survival rates in challenged immunized mice. In conclusion, immunization with r-PilA combined with alum+NLX evokes cellular and humoral immune responses, which play an important role in providing protection against acute P. aeruginosa lung infection among immunized mice.

Frequency of Chlamydia trachomatis in women with cervicitis in Tehran, Iran.

Chlamydia trachomatis (CT) is the most common cause of bacterial sexually transmitted infection (STI) worldwide, but current data concerning the prevalence of CT among women in Iran is scarce. Data regarding the frequency of CT infection among Iranian women can help to justify the implementation of a national CT screening program that can reduce the high morbidity associated with sequelae of CT infections by treating infected women. Endocervical secretions from 123 married women (20-55 years) with cervicitis were tested by a PCR-EIA method using primers to amplify a CT-specific plasmid. The digoxigenin-labeled amplicon was measured by hybridization to a biotin-labeled probe and a strepavidin-coated plate, followed by an enzyme-linked colorimetric analysis. Overall frequency of CT infection among women was 17% (21/123). The range of CT frequency among various age groups was 12-25%. The 31-40-year-age group comprised the majority (49%) of CT positive samples, followed by 20-30 year group (33%). Although the 20-to-30-year-old women reported the highest frequency of STI history, they had the lowest relative frequency of CT infection (12%). There is a high frequency of CT infection among women with cervicitis in Tehran, Iran, thus indicating a necessity to implement a routine CT screening program in the major cities of Iran and possibly nationwide. Identification of CT-infected women may prevent its spread, and thereby reduce the high morbidity associated with CT infections among women in Iran.

Molecular characterization of the glycoprotein and fusion protein in human respiratory syncytial virus subgroup A: Emergence of ON-1 genotype in Iran.

HRSV is a principle cause of infant hospitalization, childhood wheezing and a common pathogen in the elderly. Limited information exists regarding HRSV genotypes in Iran. In order to better understand HRSV strain diversity, we performed an in-depth evaluation of the genetic variability of the HRSV F protein detected in children under two years of age that, presented with acute respiratory symptoms during 2015-2016 in Tehran. A total of 180 nasopharyngeal swabs were evaluated. The HRSV positive samples were genotyped for G and F gene sequences using RT-PCR and sequencing methods. Phylogenetic analysis was performed using the neighbor-joining and maximum likelihood methods. Genetic and antigenic characteristics of the F gene, nucleotide and amino acids in significant positions and immune system binding regions, as well as the p-distance, positive/negative selection site, linear epitopes and glycosylation sites were investigated in all selected sequences. Among the 83 HRSV positive samples, the Fifty-five cases were successfully sequenced. All of them were classified as subgroup A and belonged to the ON-1 genotype, which possessed 72-nt duplication in the G gene. This study is the first report on the emergence of ON-1 in Iran. ON-1 Iranian sequences clustered in three lineages according to virus fusion (F) gene variations. F gene sequence analysis showed that all genetic changes in the isolates from Iran were base substitutions and no deletion/insertions were identified. The low dN/dS ratio and lack of positively selected sites showed that the fusion genes found in the strains from Iran are not under host selective pressure. Continuing and long-term molecular epidemiological surveys for early detection of circulating and newly emerging genotypes are necessary to gain a better understanding of their epidemic potential.

Immunization with Bivalent Flagellin Protects Mice against Fatal Pseudomonas aeruginosa Pneumonia.

Pseudomonas aeruginosa lung infections present a major challenge to healthcare systems worldwide because they are commonly associated with high morbidity and mortality. Here, we demonstrate the protective efficacy of type a and b flagellins (bivalent flagellin) against acute fatal pneumonia in mice. Mice immunized intranasally with a bivalent flagellin vaccine were challenged by different flagellated strains of P. aeruginosa in an acute pneumonia model. Besides the protective effect of the vaccine, we further measured the host innate and cellular immunity responses. The immunized mice in our study were protected against both strains. Remarkably, active immunization with type a or b flagellin significantly improved survival of mice against heterologous strain compared to flagellin a or b antisera. We also showed that after an intranasal challenge by P. aeruginosa strain, neutrophils are recruited to the airways of vaccinated mice, and that the bivalent flagellin vaccine was proved to be protective by the generated CD4+IL-17+ Th17 cells. In conclusion, bivalent flagellin vaccine can confer protection against different strains of P. aeruginosa in an acute pneumonia mouse model by eliciting effective cellular and humoral immune responses, including increased IL-17 production and improved opsonophagocytic killing.

Antimicrobial Resistance of Acinetobacter baumannii to Imipenem in Iran: A Systematic Review and Meta-Analysis.

Imipenem-resistant multi-drug resistant (IR-MDR) Acinetobacter baumannii has been emerged as a morbidity successful nosocomial pathogen throughout the world.To address imipenem being yet the most effective antimicrobial agent against A. baumannii to control outbreaks and treat patients, a systematic review and meta-analysis was performed to evaluate the prevalence of IR-MDR A. baumannii. We systematically searched Web of Science, PubMed, MEDLINE, Science Direct, EMBASE, Scopus, Cochrane Library, Google Scholar, and Iranian databases to identify studies addressing the antibiotic resistance of A. baumannii to imipenem and the frequency of MDR strains in Iran. Out of 58 articles and after a secondary screening using inclusion and exclusion criteria and on the basis of title and abstract evaluation, 51 studies were selected for analysis. The meta-analysis revealed that 55% [95% confidence interval (CI), 53.0-56.5] of A. baumannii were resistant to imipenem and 74% (95% CI, 61.3-83.9) were MDR. The MDR A. baumannii population in Iran is rapidly changing toward a growing resistance to imipenem. Our findings highlight the critical need for a comprehensive monitoring and infection control policy as well as a national susceptibility review program that evaluates IR-MDR A. baumannii isolates from various parts of Iran.

Immunogenicity of Pseudomonas aeruginosa recombinant b-type fagellin as a vaccine candidate: Protective efficacy in a murine burn wound sepsis model.

Pseudomonas aeruginosa (PA) is a formidable opportunistic pathogen among patients with burn wound infections. Antimicrobial therapy is often unsuccessful because PA can develop multi-drug resistance; thus, immunotherapy can be a rational alternative. The goal of this study was to evaluate the immunogenicity recombinant type b flagellin (r-b-flagellin) as a potential vaccine against P. aeruginosa in a mouse model for burn wound sepsis. Primary immunization with r-b-flagellin (10µg) followed by two booster shots was sufficient to generate a robust humoral response, which was predominantly a T helper 2 (Th2) type response consisting mainly of subtype IgG1 and low levels of IgG2a. Analysis of the Th1-Th2 response among immunized mice showed an increased production of IL-4, INF-γ and IL-17 by splenocytes upon stimulation by r-b-flagellin. Opsono-phagocytosis assays confirmed the enhanced killing of bacteria by anti r-b-flagellin immune sera. These antibodies were also able to inhibit motility of P. aeruginosa and afforded protection to immunized mice by reducing bacterial load in the site of original infection into the liver of challenged mice. The reduction of systemic bacterial spread resulted in an increase in the survival rate of challenged immunized mice. In conclusion, immunization of mice with r-b-flagellin protein increased the level of humoral and cellular immune response and led to an efficacious protection against P. aeruginosa infection in the burn mouse model.

Flagellin and pilin immunization against multi-drug resistant Pseudomonas aeruginosa protects mice in the burn wound sepsis model.

Pseudomonas aeruginosa is a formidable pathogen and a major threat to burn patients. Antimicrobial therapy is often unsuccessful because P. aeruginosa can develop multi-drug resistance; thus, immunotherapy and vaccine can be a rational alternative. Flagella and type IV pili have been identified as important virulence factors in the colonization and pathogenesis of P. aeruginosa in burn wound infections. Immunogenicity and efficacy of mixed recombinant full-length type b flagellin (r-b-flagellin) and recombinant PilA (r-PilA) as candidate vaccines were assessed by measuring humoral and cellular responses, using an experimental burned mouse model. Primary immunization with "r-b-flagellin+r-PilA" followed by two booster shots was sufficient to generate a robust humoral response, which was predominantly a Th2 response consisting mainly of subtype IgG1 and low levels of IgG2a. Analysis of the cytokine response among immunized mice showed an increased production of IL-4, INF-γ and IL-17 by splenocytes upon stimulation by "r-b-flagellin+r-PilA". Opsonophagocytosis assays confirmed the enhanced killing of bacteria by anti "r-b-flagellin+r-PilA" immune sera. These antibodies were also able to reduce bacterial load in the site of original infection into the liver and spleen of challenged mice. The reduction of systemic bacterial spread resulted in an increased survival rate of challenged immunized mice. In conclusion, immunization with "r-b-flagellin+r-PilA" proteins provides a better protective response against P. aeruginosa infection in the burn mouse model.

Immunogenicity and protective efficacy of Pseudomonas aeruginosa type a and b flagellin vaccines in a burned mouse model.

Immunogenicity and efficacy of Pseudomonas aeruginosa type a and b flagellins (hereafter, flagellins) as candidate vaccines were evaluated using an experimental burned mouse model. The protection afforded and the reduction in bacterial burden achieved by these vaccine candidates were determined. Primary immunization with flagellins followed by two booster shots generated a robust immune response. Cytokine analysis demonstrated the secretion of interleukin-4 more than interferon-γ from immunized T-cells in response to in vitro antigen stimulation. IgG response was of Th2 type, predominantly with IgG1 and lower IgG2a levels before and after challenge. In vitro opsonophagocytosis assays confirmed protective potential of immune sera via enhanced bacterial cell killing. Immune sera also inhibited P. aeruginosa motility. Serum cytokine analysis demonstrated high IL-12 and low IL-10 levels in flagellin-immunized mouse sera. Reduced systemic bacterial spread from original infection site into liver and spleen was associated with increased survival. Immunization of mice with flagellins increased the humoral immune response and protection against P. aeruginosa infection in our mouse model.

Frequency of isolation and antimicrobial susceptibility of bacteria isolated from bloodstream infections at Children's Medical Center, Tehran, Iran, 1996-2000.

Antimicrobial susceptibility patterns of major bloodstream pathogens from Iran provide essential information regarding the selection of antibiotic therapy for patients with bloodstream infections (BSIs) living in Iran. Unfortunately, data regarding the isolation frequency and antimicrobial susceptibility patterns of endemic BSI pathogens are scarce in Iran. To shed some light on the susceptibility patterns of BSI pathogens endemic to Tehran, Iran, we investigated the antimicrobial susceptibility patterns of 2248 bloodstream isolates from patients in Children's Medical Center (CMC) Hospital in Tehran between January 1996 and December 2000. Microbiology reports of 24600 blood specimens collected from inpatients in CMC Hospital were retrospectively reviewed. Specimen culture, bacterial identification and disk diffusion susceptibility testing were performed according to National Committee for Clinical Laboratory Standards guidelines. Overall, Gram-positive bacteria comprised 72% (1627/2248) of recovered isolates and Gram-negative bacteria comprised 28% (621/2248). Coagulase-negative staphylococci (CoNS) comprised 48.4% of all isolates, followed by Staphylococcus aureus (16.7%) and Klebsiella spp. (8.5%). Among the 621 Gram-negative organisms, Klebsiella spp. (31%) were the most frequently isolated, followed by Escherichia coli (21%) and Pseudomonas aeruginosa (17%). The rates of oxacillin resistance for S. aureus and CoNS isolates were similar (60% versus 61%); however, the rate of S. aureus vancomycin resistance was almost twice that of CoNS resistance (21% versus 11%). Over 55% of S. pneumoniae were resistant to penicillin and co-trimoxazole. Although all isolates of enterococci were susceptible to vancomycin, only 21% were susceptible to gentamicin. Among Gram-negative isolates, amikacin was shown to be very effective, with susceptibility rates of 84%. The susceptibility of Klebsiella spp. to ampicillin and co-trimoxazole was 1% and 39%, respectively. The susceptibility of Klebsiella spp., E. coli and Enterobacter spp. to ceftriaxone was 47%, 86% and 67%, respectively. There were notable differences in the order of the five most common organisms isolated from blood cultures, which can help set priorities for focused control efforts. Our findings highlight the importance of a nationwide surveillance programme to monitor the trends in isolation frequency of bacteria and their antimicrobial resistance patterns throughout Iran.

Antibiotic Resistance of Acinetobacter baumannii in Iran: A Systemic Review of the Published Literature.

OBJECTIVES: Acinetobacter baumannii is a bacterium responsible for health care-associated infections, and it frequently develops multiple drug resistance (MDR). The prevalence of antibiotic-resistant A. baumannii in Iran has increased, and this may cause significant clinical problems. Therefore, in order to elucidate the development of antibiotic resistance, we performed a systematic review of the literature published on antibiotic-resistant A. baumannii reported in Iran. METHODS: Thirty-six publications that met the criteria for inclusion were reviewed from an initial 87 papers. Selected papers published between 2008 and September 2014, were categorized on the basis of the sample collecting year been between 2001 and 2013. RESULTS: Analysis of data revealed that, in general, there was an increase in antimicrobial resistance. During the initial time point of these studies (2001-2007) there was a high rate of resistance to all antibiotics, with the exception of carbapenems, lipopeptides, and aminoglycosides that had a low resistance rate in comparison with the others. Also, the resistance rate was increased in one group of these three antimicrobial groups from 2010 to 2013. In particular, there was an increase in resistance to carbapenems (imipenem and meropenem) from 2010-2011 and 2012-2013, whereas no significant change in the resistance rate of the other two antimicrobial groups (lipopeptides and aminoglycosides) during the study time was observed, although we did observe certain trends in amikacin (aminoglycoside group antibiotic) between 2011-2012 and 2012-2013. CONCLUSION: These findings indicate that antimicrobial resistance of A. baumannii in Iran has increased, which may very well affect the antimicrobial resistance of this organism worldwide. Based on these results, novel prevention and treatment strategies against A. baumannii infections are warranted. Furthermore, these data may assist in revising treatment guidelines and regional policies in care units to slow the emergence of antimicrobial resistance.

In vitro evaluation of the antimicrobial activity of nanosilver-mineral trioxide aggregate against frequent anaerobic oral pathogens by a membrane-enclosed immersion test.

BACKGROUND: Nanoparticles of silver (NanoAg) have been shown to control the growth of bacteria, but application of NanoAg in endodontics has not been evaluated. This in vitro study evaluates the antimicrobial activity of NanoAg to enhance the inhibitory effects of mineral trioxide aggregate (MTA). METHODS: The antibacterial activities of NanoAg and NanoAg-MTA against four types of anaerobic pathogens were tested in vitro using (1) agar diffusion test (ADT) and (2) a newly devised membrane-enclosed immersion test (MEIT). RESULTS: Both NanoAg and NanoAg-MTA inhibited the growth of all four test bacteria at 25 ppm concentration. MEIT analysis consistently showed that NanoAg enhanced the antimicrobial activity of MTA significantly, and the bacterial susceptibility to lower concentrations of NanoAg varied depending on the type of bacteria. Overall, NanoAg-MTA showed significant inhibitory effect which was time and dose dependent. CONCLUSIONS: Our data support that NanoAg can serve as an excellent MTA additive against anaerobic endodontic-periodontal pathogens with clinical applications for infection control in endodontics.

Genotypic and Antimicrobial Susceptibility of Carbapenem-resistant Acinetobacter baumannii: Analysis of is Aba Elements and bla OXA-23-like Genes Including a New Variant.

Carbapenem-resistant Acinetobacter baumannii (CR-AB) causes serious nosocomial infections, especially in ICU wards of hospitals, worldwide. Expression of bla OXA genes is the chief mechanism of conferring carbapenem resistance among CR-AB. Although some bla OXA genes have been studied among CR-AB isolates from Iran, their bla OXA-23-like genes have not been investigated. We used a multiplex-PCR to detect Ambler class A, B, and D carbapenemases of 85 isolates, and determined that 34 harbored bla OXA-23-like genes. Amplified fragment length polymorphism (AFLP) genotyping, followed by DNA sequencing of bla OXA-23-like amplicons of CR-AB from each AFLP group was used to characterize their bla OXA-23-like genes. We also assessed the antimicrobial susceptibility pattern of CR-AB isolates, and tested whether they harbored insertion sequences ISAba1 and ISAba4. Sequence comparison with reference strain A. baumannii (NCTC12156) revealed five types of mutations in bla OXA-23-like genes; including one novel variant and four mutants that were already reported from China and the USA. All of the bla OXA-23-like genes mutations were associated with increased minimum inhibitory concentrations (MICs) against imipenem. ISAba1 and ISAba4 sequences were detected upstream of bla OXA-23 genes in 19 and 7% of isolates, respectively. The isolation of CR-AB with new bla OXA-23 mutations including some that have been reported from the USA and China highlights CR-AB pervasive distribution, which underscores the importance of concerted national and global efforts to control the spread of CR-AB isolates worldwide.

Wide distribution of carbapenem resistant Acinetobacter baumannii in burns patients in Iran.

Antimicrobial resistance in carbapenem non-susceptible Acinetobacter baumannii (CNSAb) is a major public health concern globally. This study determined the antibiotic resistance and molecular epidemiology of CNSAb isolates from a referral burn center in Tehran, Iran. Sixty-nine CNSAb isolates were tested for susceptibility to antimicrobial agents using the E test methodology. Multiple locus variable number tandem repeat analysis (MLVA), Multilocus sequence typing (MLST) and multiplex PCR were performed. PCR assays tested for ambler classes A, B, and D ß-lactamases. Detection of ISAba1, characterization of integrons, and biofilm formation were investigated. Fifty-three (77%) isolates revealed XDR phenotypes. High prevalence of bla OXA-23-like (88%) and bla PER-1 (54%) were detected. ISAba1 was detected upstream of bla ADC, bla OXA-23-like and bla OXA51-like genes in, 97, 42, and 26% of isolates, respectively. Thirty-one (45%) isolates were assigned to international clone (IC) variants. MLVA identified 56 distinct types with six clusters and 53 singleton genotypes. Forty previously known MLST sequence types forming 5 clonal complexes were identified. The Class 1 integron (class 1 integrons) gene was identified in 84% of the isolates. The most prevalent (33%) cassette combination was aacA4-catB8-aadA1. The IC variants were predominant in the A. baumannii lineage with the ability to form strong biofilms. The XDR-CNSAb from burned patients in Iran is resistant to various antimicrobials, including tigecycline. This study shows wide genetic diversity in CNSAb. Integrating the new Iranian A. baumannii IC variants into the epidemiologic clonal and susceptibility profile databases can help effective global control measures against the XDR-CNSAb pandemic.

Multidrug resistance among Acinetobacter baumannii isolates from Iran: changes in antimicrobial susceptibility patterns and genotypic profile.

BACKGROUND AND AIM: Widespread multidrug-resistant Acinetobacter baumannii (MDR-AB) strains have limited therapeutic options for treating intensive care unit (ICU) patients with MDR-AB infection in Iran. We aimed to evaluate MDR-AB diversity and antimicrobial susceptibility in Tehran (Iran) to address the need for feasible and effective control approaches against severe MDR-AB infections. METHODS: We used amplified fragment length polymorphism (AFLP) and minimum inhibitory concentration (MIC) determinations to compare genotypic diversity and susceptibility patterns of 100 MDR-AB isolates from ICU patients in two medical centers in Tehran (Iran), from 2006 to 2011. RESULTS: Within 5 years, drastic genotypic changes occurred among MDR-AB isolates, and resistance to antimicrobials increased 0-30%. In 2011, 6-100% of isolates were resistant to every agent tested. All isolates remained susceptible to either minocycline or tobramycin, however, MIC50 concentrations against these agents increased. Novel international clone (IC) variants (not IC I-III types) comprised 36% MDR-AB isolates in 2011. CONCLUSIONS: The MDR-AB population in Tehran is rapidly changing toward growing resistance to various antimicrobials, including colistin and tigecycline. Although increasing resistance to last-resort antimicrobials is alarming, simultaneous susceptibility of all MDR-AB isolates to some conventional antibiotics highlights the merits of investigating their synergistic activity against extended-spectrum and pandrug resistant A. baumannii. Integrating the novel Iranian MDR-AB IC variants into epidemiologic clonal and susceptibility profile databases can help global efforts toward the control of MDR-AB pandemic.