Etiology and Antimicrobial Susceptibility Pattern of Urinary Tract Infection in the First Year after Pediatric Renal Transplantation: A Preliminary Study.

Background: Urinary tract infection (UTI) is common after pediatric renal transplantation, and the emergence of multidrug-resistant (MDR) bacteria causing UTI is a therapeutic challenge in this regard. The main purpose of this study was to determine the UTI frequency, its etiologic agents, and the antibiotic susceptibility pattern in the first year following renal transplantation in Iranian pediatric recipients. Methods: In a retrospective cohort study, all of the 81 children who had undergone renal transplantation in Hazrat Rasoul Akram Hospital between 2012 and 2017 were enrolled. Confirmed episodes of UTI during the first year following renal transplantation were analyzed. The pattern of antibiotic resistance was determined for the causative agents of UTI. The data were analyzed using the IBM SPSS Statistics software (version 20). and the P < 0.05 was considered significant. Results: Totally, from 81 enrolled cases, 37(44.7%) cases were in the age group of 11-15 years. Overall, 19, 10, and 3 UTI episodes had occurred in the first month, from the first to sixth month, and between the sixth month and one year after transplantation, respectively. The four most common isolated bacteria were Escherichia coli (E. coli; 31.2%), Pseudomonas aeruginosa (P. aeruginosa; 25%), Enterococci (21.9%) and Klebsiella pneumoniae (K. pneumoniae; 12.5%). The highest rate of resistance was reported to trimethoprim/sulfamethoxazole (TMP/SMX), cephalosporins, and fluoroquinolones among gram-negative bacteria. However, none of the Enterococci isolates were resistant to linezolid and nitrofurantoin. Conclusion: Resistance to antibiotics is increasing among the pathogens causing UTI in pediatric renal transplanted cases. It is suggested to stop the administration of TMP/SMX and third-generation cephalosporins for empiric treatment of UTI in Iranian pediatric renal transplant recipients. Ciprofloxacin might be administered cautiously secondary to the increasing rate of antibiotic resistance in this group.

Passive immunization with anti- chimeric protein PilQ/PilA -DSL region IgY does not protect against mortality associated with Pseudomonas aeruginosa sepsis in a rabbit model.

BACKGROUND: Pseudomonas aeruginosa sepsis is associated with unacceptably high mortality and, for many of those who survive, long-term morbidity. The aims of this study were to production of IgY against chimeric protein pilQ-pilA-DSL region and killed- whole cell Pseudomonas aeruginosa O1 (PAO1) strain and their efficacy for immunoprophylaxis of sepsis caused by P. aeruginosa in a rabbit model. METHODS: Specific IgY was obtained by immunization of hens. The purity of IgY was determined by SDS-PAGE analysis. The effect of IgY on growth and hydrophobicity of P. aeruginosa were performed through time-kill assay and microbial adhesion to hydrocarbons test (MATH), respectively. The efficacy of specific IgYs was examined against P. aeruginosa sepsis in a rabbit model. The rabbits were monitored for 72 h to record physiological characters and survival. Hematologic factors, C-reactive protein, pro-inflammatory cytokines, and bacterial count from blood and solid organs were measured, periodically. RESULTS: We found that the growth inhibitory effect of the anti- killed whole cell IgY was higher than anti-pilQ-pilA IgY (P < 0.001). The hydrophobicity effect of PAO1 increased when bacteria were opsonized by anti- killed whole cell IgY while the hydrophobicity activity was decreased following incubation of PAO1 with anti-pilQ-pilA IgY in a broth medium (P < 0.001). Following intravenous (IV) administration of produced IgYs, no significant difference was observed in the survival, decrease in inflammatory mediators and clinical symptoms between the groups 48h post infection (P > 0.05). Moreover, no considerable decrease was observed in the bacterial load of blood, lungs and kidneys in rabbits treated with specific IgYs and control groups (P > 0.05). No bacteria were found in the spleen and liver samples from infected rabbits. CONCLUSION: Although produced IgYs had a good immunoreactivity, IV immunization of IgYs was not protective against P. aeruginosa sepsis in the rabbit model. Further studies are needed to assess the immune response and decreasing mortality rate using the rabbit sepsis model.

A decade of trends in the distribution and antimicrobial susceptibility of prevalent uropathogens among pediatric patients from Tehran, Iran during 2005-2016.

OBJECTIVES: To determine changes in the distribution of uropathogens and their antimicrobial resistance in pediatric patients in a children's hospital from 2005 to 2016. METHODS: A cross-sectional analysis of uropathogens and their antimicrobial resistance within inpatient children was performed over the 11-year period, 2005 to 2016, in Ali Asghar children's hospital. The rate of antibiotic resistance among patients was evaluated according to demographic data including age, sex, urinary tract abnormities and history of antibiotic consumption. RESULTS: In total, 958 female and 349 male positive cultures were analyzed. Escherichia coli (E. coli) (77.6%) was the most common causative agent of urinary tract infection (UTI) in children and Klebsiella pneumoniae (10.4%), Pseudomonas aeruginosa (2.4%), and Enterococcus spp (2.4%) were less frequent isolated bacteria. The resistance rates of E. coli isolates were increased against amikacin, ceftriaxone, ceftazidime, ciprofloxacin, cotrimoxazole and imipenem from 2005 to 2010. However, we observed a decreasing trend for some of antibiotics including amikacin, gentamicin, imipenem, ceftazidime and cotrimoxazole during 2014-2016. The rate of antibiotic resistance was greater in boys than in girls against many antibiotics. The rate of resistance to amikacin, gentamicin, nitrofurantoin and cotrimoxazole in patients aged <1 year was higher than other age groups (p<0.001). A higher antibiotic resistance rate was observed in patients with anatomical abnormality and those who have had a history of antibiotic consumption. CONCLUSION: The study indicated the significant decrease in E. coli antibiotic resistance in the last 3 years. An effective empirical treatment regime should be based on local epidemiology and antimicrobial susceptibility testing.

Immunogenic and protective antigens of Brucella as vaccine candidates.

Brucella is an intracellular pathogen that causes abortion in domestic animals and undulant fever in humans. Due to the lack of a human vaccine against brucellosis, animal vaccines play an important role in the management of animal and human brucellosis for decades. Strain 19, RB51 and Rev1 are the approved Brucella spp. vaccine strains that are most commonly used to protect livestock against infection and abortion. However, due to some disadvantages of these vaccines, numerous studies have been conducted for the development of effective vaccines that could also be used in other susceptible animals. In this review, we compare different aspects of immunogenic antigens that have been a candidate for the brucellosis vaccine.

Phenotypic and molecular characterization of CTX-M extended-spectrum beta-lactamase-producing Escherichia coli isolates in Shiraz, Iran.

INTRODUCTION: The aim of this study was to detect the prevalence of the extended-spectrum beta-lactamase (ESBL)-encoding CTX-M gene in Escherichia coliisolates. METHODS: Phenotypic screening of 376 E. coli isolates for ESBL was conducted using disk diffusion. ESBL-producing isolates were tested using PCR and specific primers. The bla(CTX-M) cluster was identified using the RFLP method, and its genotype was sequenced. RESULTS: From 202 ESBL-producing E. coli , 185 (91.5%) possessed CTX-M genes. CTX-M-1 subtypes were found in 98% of the isolates. The bla(CTX-M) gene was identical to CTX-M-15. CONCLUSIONS: A high prevalence of CTX-M-1-producing E. coli apparently exists in Shiraz, Iran.

Synthesis of some new 2,5-disubstituted 1,3,4-thiadiazoles containing isomeric pyridyl as potent antimicrobial agents.

Several new 2,5-disubstituted derivatives of 1,3,4-thiadiazoles containing isomeric pyridyl were obtained from cyclization of corresponding thiosemicarbazides under acidic conditions. The newly synthesized compounds were characterized using different methods of spectroscopy such as IR, 1H-NMR, 13C-NMR, MS and elemental analysis. The minimal inhibitory concentration (MIC) results of screening of some of the synthesized compounds were also reported. Most of the synthesized compounds have been found to be active against both Gram-positive and Gram-negative bacteria at less than 3.6 mg/ml. The compound (10b) is most active against all seventeen used gram-positive and gram-negative bacteria.