Molecular characteristics and antibiotic resistance profiles of Escherichia coli strains isolated from urinary tract infections in children admitted to children's referral hospital of Qom, Iran.

BACKGROUND: Urinary tract infections (UTIs) are a highly prevalent infection among children and Escherichia coli is one of the most important pathogens causing pediatric UTIs. Production of extended spectrum b-lactamase (ESBL) enzymes is an important factor in the emergence of antibiotic resistance among these bacteria. This study aimed to determine the resistance patterns, the frequency of ESBL-encoding genes and the genetic diversity of E. coli strains isolated from children with UTIs who were admitted to children's referral hospital of Hazrat Masoumeh, Qom, Iran. METHODS: A total of 102 consecutive non-duplicative strains of E.coli that were isolated from children with UTIs were included into the study. Antibiotic susceptibility of the isolates was determined by disk diffusion method according to the CLSI guidelines. The ability of the isolates to produce ESBLs was phenotypically determined by both combined disk test and double disk synergy test. The ESBL encoding genes (bla CTX-M, bla SHV, and bla TEM) in phenotypically confirmed ESBL-positive isolates was detected by PCR method. The genetic relatedness of the isolates was designated by enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR). RESULTS: Eighty-three percent (n=85) of the children were female. Most of the infected boys (88%, n=15) were less than 1 year of age and most of the infected girls (48%, n=41) aged 1 to 6 years old. The highest sensitivity was observed to nitrofurantoin (8%, n=8), followed by amikacin (12%, n=12) and piperacillin-tazobactam (17%, n=17). In contrast, the highest resistance rate was seen to ampicillin (94%, n=96) and cefazolin (93%, n=95). Eighty-eight percent (90 out of 102) of the strains were multidrug-resistant (MDR). Fifty-eight percent (n=59) of the strains were ESBL-positive and results of the combined disk test was in concordance with PCR. The blaCTX-M was the most frequent ESBL encoding gene (88%, n=52), followed by blaTEM (54%, n=32), and blaSHV (15%, n=9). Based on the ERIC-PCR technique, isolates were clustered in 13 different types. There was no relationship between different ERIC types and origin of the isolates (i.e. hospitalized or outpatients), ESBL-producing ability, and antibiotic resistance patterns. CONCLUSIONS: High prevalence of ESBL-positive isolates of E. coli (58%) was found in our study and all of them were MDR. In addition, there were statistically significant differences in the resistance rates of ESBL-producers, and non-producers to some antibiotics, which result in limiting their therapeutic options. Continuous surveillance of the emergence of ESBL-producing isolates and their antibiotic resistance profiles as well as using appropriate typing methods is needed for reducing their spread, selecting appropriate treatment regimens and finding hospital outbreaks.

High frequency of vancomycin resistant Enterococcus faecalis in children: an alarming concern.

INTRODUCTION: Enterococcus spp. is considered as important etiological agents of nosocomial infections. However, a little is known about the epidemiology of vancomycin resistant Enterococcus faecalis (VREF). The aim of this study was to investigate the frequency of VREF and detecting of two prevalent resistance genes (vanA, vanB) at Children Medical Center Hospital, an Iranian referral pediatric Hospital. MATERIALS AND METHODS: During January 2013 to December 2013, 180 E. faecalis were isolated from clinical samples of hospitalized children. Antimicrobial testing was performed by Kirby-Bauer disk diffusion to gentamicin, amikacin, ceftriaxone, cefotaxime, ceftazidim, cefixime, piperacillin/tazobactam, cefepime, trimethoprim/sulfamethoxazole, erythromycin, clindamycin, linezolide and E-test method vancomycin and teicoplanin according to Clinical Laboratories Standards Institute (CLSI). Two prevalent resistance genes (vanA, vanB) were investigated in VREF isolates. RESULTS: Seventy-five (42%) of patients were male and 105 (58%) were female. Mean age of patients was 34.74 months. Cephalosporin resistance was found in majority of E. faecalis isolates (98.7 to ceftazidim, 95% to cefixime, 93.3% to ceftriaxone, and 89.4% to cefotaxime). Most of the isolated were susceptible to cefepime (91.7%). In addition, high level of erythromycin and clindamycin resistance was reported (93.4% and 91.2%). There were no linezolid-resistant E. faecalis among all isolates. Teicoplanin resistance was observed in 13.8% of E. faecalis (n = 25). Minimum Inhibitory concentration (MIC) ≥ 32 µg/ml for vancomycin was found in 29 isolates (16%) and vanA gene was detected in 21 (72%) VREF strains, while vanB gene was not detected in any of these isolates. The mortality rate of all cases was 3.4%. CONCLUSIONS: This study revealed high rate of vancomycin resistance in E. faecalis strains. Therefore, periodic surveillance of antibacterial susceptibilities is highly recommended to detect emerging resistance.

Emergence of community-acquired methicillin-resistant Staphylococcus aureus in an Iranian referral paediatric hospital.

The epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in hospitals has been changed in recent years due to the arrival of community-associated MRSA (CA-MRSA) strains into healthcare settings. The aim of this study is to investigate the distribution of staphylococcal cassette chromosome mec (SCCmec) type V as well as SCCmec IV subtypes, which have been associated with community-acquired infection among healthcare-associated MRSA (HA-MRSA) isolates. Antimicrobial susceptibility, SCCmec type, spa type and the presence of Panton-Valentine leukocidin (PVL) genes were determined for all HA-MRSA isolates in an Iranian referral hospital. In this study of 48 HA-MRSA isolates, 13 (27%), three (6.2%), five (10.4%) and one (2%) belonged to SCCmec subtypes IVa, IVb, IVc and IVd, respectively. Only two isolates (4.2%) belonged to SCCmec types V Notably, one isolate was found to harbour concurrent SCCmec subtypes IVb and IVd. MRSA containing SCCmec subtype IVb, IVc and IVd as well as type V isolates were all susceptible to chloramphenicol, clindamycin and rifampicin, while the sensitivity to these antibiotics was lower among MRSA containing SCCmec subtype IVa. The most frequently observed spa ttype was t037, accounting for 88% (22/25). Three other spa type was t002, t1816 and t4478. Large reservoirs of MRSA containing type IV subtypes and type V now exist in patients in this Iranian hospital. Therefore, effective infection control management in order to control the spread of CA-MRSA is highly recommended.

Investigation of thermal reversibility and stability of glycated human serum albumin.

Protein glycation, the process by which carbohydrates attach to proteins upon covalent binding, can alter protein thermal reversibility and stability. Protein stability and reversibility have important role in protein behavior and function. Also they are benefit properties for drug produce and protein industrial applications. In this research the thermal reversibility and stability changes in human serum albumin (HSA) were studied upon incubation with glucose (GHSA) under physiological conditions for 21 and 35 days. The thermal reversibility and stability changes in GHSA were evaluated using circular dichroism (CD), UV-vis spectroscopy, fluorescence spectroscopy and differential scanning calorimetry (DSC). Our results showed that the glycation of HSA increased its thermal reversibility and stability, but decreased its conformational entropy compared to fresh native HSA and untreated HSA. Free lysine content assay (TNBSA test) indicated glucose can bind to protein covalently. These alterations were mainly attributed to the formation of crosslink between the lysine residues of HSA upon incubation with glucose.

Pseudomonas aeruginosa infection among cystic fibrosis and ICU patients in the referral children medical hospital in Tehran, Iran.

INTRODUCTION: Pseudomonas aeruginosa is one of the important causes of hospital-acquired infections in Intensive Care Unit (ICU) and considered as a major determinant of morbidity and mortality in patients affected by cystic fibrosis (CF). The aim of this study was to investigate clonal diversity among randomly picked P. aeruginosa isolates of CF and the other hospitalized patients in ICU. METHODS: Cultivation, identification, and antimicrobial susceptibility testing of P. aeruginosa isolates were performed using standard techniques. The genetic similarity of the strains was investigated by amplification of the Enterobacterial Repetitive Intergenic Consensus-polymerase chain reaction (ERIC-PCR) sequence. RESULTS AND DISCUSSION: Among 49 isolates, sixteen were isolated from 11 patients affected by CF and 33 came from an epidemiological investigation of 25 P. aeruginosa infected patients of ICU. Five clusters were generated for all isolates analyzed through ERIC-PCR genotyping. Two major clusters (B and C) were discovered in P. aeruginosa isolates of ICU and CF patients during the whole period of this study. Fifteen unique antibiogram patterns obtained from all isolates and multi-resistant P. aeruginosa (MRPA) were identified in 23 isolates (47%). MRPA isolates were detected in all clusters (except A) while pan-resistant isolates were recovered only in cluster C. The high prevalence of related or identical isolates in CF and non-CF patients can be due to transmission of particular dominant clones in ICU ward. Therefore, enhanced infection-control may become necessary to prevent further spread of clonal strains.

Staphylococcus aureus infections in children in an Iranian referral pediatric hospital.

INTRODUCTION: Staphylococcus aureus is associated with various infections ranging from skin and soft tissues such as surgical site infections and abscesses to lower respiratory tracts and bloodstream. The aim of this study was to evaluate underlying condition of patients with S. aureus infections in an Iranian referral pediatric Hospital. MATERIAL AND METHODS: Information was extracted retrospectively from the medical records of patients who were diagnosed with S. aureus infections. Data obtained about the study subjects included basic demographics, reason for admission, culture site, length of hospital stay, and methicillin susceptibility. RESULTS: The underlyning condition of of patients with S. aureus infection during November 2011 and March 2013 were included in the study. The most frequent diagnosis in patients with S. aureus infection was jaundice (12%), abscess (10%), cellulitis (10%), wound infection (8%), septic arthritis (7%) and sezeire (5%). Wound was the most common infection sites among all subjects 34/98 (35%) following by blood (20/98, 20%) as well as skin and soft tissue (19/98, 19%). The proportion of MRSA infections among all S. aureus isolates was 79% (77/98) during the study period. In addition, 58/74 (78%) met the definition of Hospital-Associated Methicillin-Resistant S. aureus (HA-MRSA) infections and the rest; 20/24 patients (83%), were classified as Community-Associated Methicillin-Resistant S. aureus (CA- MRSA). CONCLUSION: In our study, the high frequency of MRSA was found not only in HA S. aureus but also in CA S. aureus isolates; therefore, the strategic goals to optimize antimicrobial use including

Genotypic characteristics of Pseudomonas aeruginosa strains circulating in the tertiary referral Children's Medical Hospital in Tehran, Iran.

Pseudomonas aeruginosa is an important pathogen with the ability to cause infection in all departments of the hospital, especially in intensive care units (ICUs). The aim of this study is to analyse the epidemiological relationships among clinical P. aeruginosa strains isolated from different wards of the Children's Medical Center Hospital (Tehran, Iran). These isolates were identified by standard laboratory procedures and tested for antimicrobial resistance to several antibiotic agents. The genetic similarity of the strains was investigated by amplification of the enterobacterial repetitive intergenic consensus sequence (ERIC-PCR). During the study period, 87 non-duplicate patients were colonised or infected with P. aeruginosa. Among the isolates, resistance to piperacillin/tazobactam was low (27%), followed by amikacin (31%), gentamicin (33%), imipenem (33%), ciprofloxacin (36%) and meropenem (39%). Thirty-five patients (40.2%) were either colonised or infected with a multidrug-resistant P. aeruginosa strain (MDRP) over a one-year period, and 17 isolates were non-susceptible to all the tested antibiotics. One predominant profile (D) was identified in 59 strains. This profile first appeared in the paediatric intensive care unit (PICU) and infection ward in June 2010, and circulated around all wards up to the end of the study period. Of the 35 MDRP, 22 (62.8%) were found to be profile D. Molecular typing of the isolates suggests considerable cross-transmission of P. aeruginosa not only between patients in one ward but also between patients from different wards. This can be explained partly by the high number of patients transferred between different wards of the hospital.

Genotyping of Staphylococcus aureus strains among healthcare workers and patients in the tertiary referral Children's Medical Hospital in Tehran, Iran.

Nasal carriage among hospital personnel is an important source of nosocomial staphylococcal infection. Therefore, this study aims to evaluate Staphylococcus aureus nasal colonisation among healthcare workers (HCWs) and its association with infection in children through analysis of antibiotic susceptibility profiles and genetic similarity. Nasal swabs were taken from the anterior nares of HCWs and also a total of 130 strains that had been isolated from various clinical samples were examined. Antibiotic susceptibility profiles of the strains were determined using the disc-diffusion technique and genotyping was performed by amplification of the enterobacterial repetitive intergenic consensus sequences (ERIC-PCR). Approximately 48% of clinical strains obtained were methicillin-resistant S. aureus (MRSA), whereas only 24.7% of strains from HCWs were MRSA. Among isolates from HCWs, cephalothin, cefazolin, chloramphenicol, rifampicin and vancomycin were most effective, with susceptibility rates of 100%. In this study, the ERIC-PCR profiles did not reveal any genetic similarity among the S. aureus strains from HCWs and the clinical samples. In contrast, MRSA strains showed clonal dissemination, with clones D and A2 predominant among patients and HCWs, respectively. No association was observed between the MRSA nasal carriers and infections in patients. These findings suggest that MRSA nasal carriage among HCWs may not be the source of related infections in the group studied.

Calorimetric and binding dissections of HSA upon interaction with bilirubin.

The interactions between bilirubin and human serum albumin (HSA) were studied by isothermal titration calorimetry (ITC) and UV-vis spectrophotometry at 27 degrees C in 100 mM phosphate buffer pH 7.4 containing 1 mM EDTA. The biphasic shape of the HSA-bilirubin binding curve depicted the existence of two bilirubin binding sets on the HSA structure which had distinct binding interactions. Each binding set contained one or more bilirubin binding site. The first binding set at subdomain IIA included one binding site and had a more hydrophobic microenvironment than the other two binding sites in the second bilirubin binding set (subdomain IIIA). With our method of analysis, the calculated dissociation constant of the first binding site is 1.28 x 10(-6) M and 4.80 x 10(-4) M for the second and third binding sites. Here, the typical Boltzmann's equation was used with a new approach to calculate the dissociation constants as well as the standard free energy changes for the HSA-bilirubin interactions. Interestingly, our calculations obtained using the Wyman binding potential theory confirmed that our analysis method had been correct (especially for the second binding phase). The molar extinction coefficient determined for the first bound bilirubin molecule depicted that the bilirubin molecules (in low concentrations) should interact with the nonpolar microenvironment of the first high affinity binding site. Binding of the bilirubin molecules to the first binding site was endothermic (deltaH > 0) and occurred through the large increase in the binding entropy established when the hydrophobic bilirubin molecules escaped from their surrounding polar water molecules and into the hydrophobic medium of the first binding site. On the other hand, the calculated molar extinction coefficient illustrated that the microenvironment of the second binding set (especially for the third binding site) was less hydrophobic than the first one but still more hydrophobic than the buffer medium. The binding of the third bilirubin molecule to the HSA molecule was established more through exothermic (electrostatic) interactions.