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 metronidazole and clarithromycin-resistant Helicobacter pylori in formalin-fixed, paraffin-embedded gastric biopsies.

BACKGROUND: Clarithromycin and metronidazole resistance of Helicobacter pylori is increasing worldwide and has resulted in a loss in the effectiveness of therapeutic regimens. We aimed to evaluate common mutations of resistance genes to clarithromycin (A2143G, A2142G and A2142C) and metronidazole (rdxA and frxA) in H. pylori strains in formalin-fixed, paraffin-embedded gastric biopsies. METHODS: A total of 110 tissue blocks from children suspected of H. pylori infection were included. After DNA extraction, UreC PCR was performed. Specific primers and restriction enzymes by PCR-RFLP were used for analysis of A2143G and A2142G mutations. To detect A2142C and assess frequent mutations of metronidazole resistance, specific primers and PCR method were used. RESULTS: One hundred cases of H. pylori (91%) were by PCR. Of 34 (34%) clarithromycin-resistant isolates 17 (50%), 10 (29%) and 7 (21%) had A2143G, A2142G, A2142C, respectively. Resistance rate to metronidazole was 60% (N = 60). In sequencing rdxA and frxA in the mutated strains, missense mutations were most frequent (60 and 57%, respectively), and there were differences in frameshift and non-sense mutations (p < 0.001). CONCLUSION: Resistance rate to clarithromycin was high and the highest percentage of mutation was of A2143G. PCR-RFLP was used directly with formalin-fixed gastric biopsies, thus, avoiding the requirement for time-consuming culture-based methods. The isolates that developed resistance were mainly associated with mutations of both rdxA and frxA genes.

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 ERG11 gene expression among fluconazole-resistant Candida albicans: first report from an Iranian referral paediatric hospital.

The multiplicity of mechanisms of resistance to azole antifungal agents has been described. As fluconazole-resistant clinical Candida albicans isolates that constitutively over-express ERG11 have been identified in previous studies, the aim of this study is to investigate this molecular mechanism involved in fluconazole resistance of C. albicans clinical isolates. Fluconazole susceptibility testing was carried out on clinical isolates of Candida spp. obtained from hospitalised children in an Iranian referral children's hospital. A polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) technique was used to differentiate Candida spp. The resistant C. albicans isolates were subjected to RT-qPCR using primers that identify ERG11 gene expression. Of the 142 Candida spp. isolates studied, C. albicans was the most predominant isolate, occurring in 68.3% (97/142) of the patients. According to the CLSI method, the majority of the C. albicans isolates (91.7%, 89/97), categorised as susceptible (minimum inhibitory concentration [MIC] ≤8 µg/mL), five isolates were considered resistant (MIC ≤64 µg/mL) and three had dose-dependent susceptibility (MIC = 8.16-32 µg/mL). The ERG11 gene in the five fluconazole-resistant C. albicans isolates was upregulated 4.15-5.84-fold relative to the ATCC 10231 control strain. In this study, the expression of ERG11 was upregulated in all the fluconazole-resistant C. albicans isolates. There are limited data on the antifungal susceptibility of Candida spp. as well as the molecular mechanism of azole resistance in Iran, especially for isolates causing infections in children. Therefore, the surveillance of antifungal resistance patterns and investigation of other mechanisms of azole resistance in all Candida spp. isolates is recommended.

Human herpesvirus 6 infection in febrile children: frequency in an Iranian referral hospital.

Polymerase chain reaction (PCR) tests for virus in blood and saliva are frequently positive in persons with past infection, re-infection with new strains or latency with or without repeated reactivation of human herpesvirus 6 (HHV6). The aim of this study is to determine the frequency of HHV6 infections in children aged two years or under with an initial diagnosis of fever during an evaluation in the paediatric emergency department of the Children's Medical Center, an Iranian referral hospital, using PCR methodology. In all children, the clinical characteristics noted at the initial evaluation as well as demographic and laboratory findings were obtained. Among 150 patients (91 male, 59 female) admitted to the paediatric emergency department, HHV6 was found in 49 (33%; 14 female [29%] and 35 male [71%]). Rash was seen in 14/49 (29%) of HHV6-positive cases, while 35 cases without rash had a positive PCR test (71%). Seizures were found in 78/150 (52%) patients. There was no significant association between seizures and positive HHV6 results (43% in patients without seizure; 57% in cases that developed seizure). Although standard PCR on samples including blood cannot discriminate between latent and active HHV6 infection, nearly a third of patients (mainly children less than one year old) had HHV6 infection.

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.