Phenotypic and genotypic determinants of mupirocin resistance among Staphylococcus aureus isolates recovered from clinical samples of children: an Iranian hospital-based study.

BACKGROUNDS: The aim of this study was to evaluate both phenotypic and genotypic determinants of mupirocin resistance among methicillin-resistant Staphylococcus aureus (MRSA) and methicillin susceptible S. aureus (MSSA) strains recovered from different clinical samples of children who were admitted to the Children's Medical Center (CMC) Hospital, Tehran, Iran. MATERIALS AND METHODS: A total of 120 clinical isolates of S. aureus were collected from the microbiology laboratory of CMC Hospital. Antimicrobial susceptibility of the isolates to different antimicrobial agents was determined by disk diffusion method. The methicillin resistance phenotype (MRSA) was identified using a 30 µg cefoxitin disk. The minimum inhibitory concentration (MIC) of mupirocin was determined by broth microdilution method. Strains with mupirocin MIC between 8 and 256 µg/mL were considered as low-level mupirocin resistant (LLMR), and strains with an MIC≥512 µg/mL were considered as high-level mupirocin resistant (HLMR). The presence of genes encoding HLMR (ie, mupA and mupB genes) was evaluated by PCR method. RESULTS: Four out of 120 isolates (3%) had mupirocin MIC≥512 µg/mL and were HLMR; however, no LLMR isolate was detected. Fifty-two isolates (43%) were MRSA, and there were no differences in the distribution of mupirocin resistance among MRSA and MSSA isolates (P>0.05). The PCR method identified mupA gene in two out of four HLMR isolates, and mupB gene was not detected in any HLMR isolates. CONCLUSION: Because of discrepancies between the phenotypic and genotypic patterns of mupirocin resistance and due to the avoidance of false-negative results, it is better to determine the mupirocin resistance by both antibiotic susceptibility tests and PCR method. Considering the increasing need of mupirocin for the control of S. aureus infections, continuous checking of its susceptibility status is necessary.

Antimicrobial Resistance Patterns of the Gram-positive Bacteria Isolated from Children with Bloodstream Infection in an Iranian Referral Hospital: A 6-year Study.

BACKGROUND: Bloodstream infections (BSI) are considered as a serious cause of morbidity and mortality in children. The aim of this study was to report the common Gram-positive bacteria (GPB) responsible for bloodstream infections in children and determine their antimicrobial resistance patterns in Children Medical Center (CMC) Hospital, Tehran, Iran. METHODS: This retrospective study was conducted within a six-year period (March 2011 to September 2016) for pediatric patients with BSI. Standard bacteriological methods were performed for identification of the bacteria. Antimicrobial susceptibility tests were evaluated by using the disk diffusion method according to the CLSI recommendations. RESULTS: Among 68233 blood cultures, 2349 isolates were obtained which 59% of them (N=1393) were GPB and 41% (n=956) were Gram-negative. The most common GPB isolates were Coagulase negative Staphylococcus (CoNS) (N= 609, 44%), followed by Staphylococcus aureus (N=319, 23%), Enterococcus spp. (N=139, 10%), Streptococcus pneumonia (N= 106, 8%), Streptococci viridans (N= 180, 13%) Micrococcus spp. (N=24, 1.7%) and Streptococcus group B (N= 16, 1%). The rate of methicillin resistance in S. aureus and CoNS was 47% (N=116/246) and 91% (N=557/609), respectively. Isolates of S. pneumoniae showed high-level of resistance to trimethoprim/sulfamethoxazole (N=28/33, 85%) and erythromycin (N=59/91, 65%). S. viridans isolates and Micrococcus spp. were highly sensitive to linezolid (100%). All of the tested isolates of Streptococcus group B were sensitive to all the antibiotics used in this study. Among Enterococcus spp., 52% (N=69/133) of the m were resistant to vancomycin. CONCLUSIONS: Our results emphasize the importance of a valuable guide in identifying resistance trends and selecting appropriate antibiotic.

Antimicrobial resistance patterns of Gram-negative bacteria isolated from bloodstream infections in an Iranian referral paediatric hospital: A 5.5-year study.

OBJECTIVES: Bloodstream infections (BSIs) are a major cause of paediatric morbidity and mortality worldwide. This study describes the epidemiology and antimicrobial resistance of Gram-negative bacteria (GNB) from BSIs in children admitted to an Iranian paediatric hospital. METHODS: Clinical and microbiological data of patients with positive blood cultures were collected from March 2011 to September 2016. Standard laboratory methods were used for blood culture and bacterial identification. Antimicrobial sensitivity was evaluated by the Kirby-Bauer disk diffusion and broth microdilution methods. RESULTS: Of 2325 bacterial pathogens isolated from blood cultures, 41.1% (n=956) were GNB. Most clinical isolates (n=208; 21.8%) were identified in the cardiac intensive care unit. Predominant bacterial isolates were Klebsiella pneumoniae subsp. pneumoniae (n=263; 27.5%), Escherichia coli (n=192; 20.1%), Serratia marcescens (n=151; 15.8%), Pseudomonas aeruginosa (n=111; 11.6%) and Enterobacter spp. (n=100; 10.5%). Enterobacter isolates showed a high level of ampicillin resistance. Escherichia coli were highly resistant to chloramphenicol (100%), cefixime (100%), ceftriaxone (100%) and ampicillin (96%). Cefixime had the least efficacy against Haemophilus spp. (100% resistant). All K. pneumoniae (100%) were ampicillin-resistant. All S. marcescens were ceftazidime-resistant. No Acinetobacter baumannii were resistant to colistin. All P. aeruginosa were resistant to cefotaxime and trimethoprim/sulfamethoxazole. CONCLUSIONS: These results demonstrate the increasing trend in antibiotic resistance among GNB associated with BSI in children, emphasising the importance of continuous screening and surveillance programmes for detection of antibiotic resistance in BSI pathogens for selection of appropriate treatment regimens.

Zinc status in febrile seizure: a case-control study.

OBJECTIVE: Febrile seizure is the most common type of seizure in children. Their incidence is 2-5%. There are different hypotheses about relationship between neurotransmitters and trace elements (such as zinc) and febrile seizure. Zinc, as a major element of some enzymes, plays an important role in the central nervous system (CNS) and can affect some inhibitory mechanisms of CNS. The aim of the present study was to determine whether there were any changes in serum zinc level in children with febrile seizure in comparison with febrile children without seizure. MATERIALS & METHODS: This case-control study was performed on 100 patients aged 6 months to 6 years. This study was conducted between January and August 2012, on 50 children with febrile seizures (case) and 50 febrile children without seizures (control), that were referred to Amirkola Children Hospital (a referral hospital in the north of Iran). Two groups were matched for age and sex. The serum zinc levels in the both groups were determined by atomic absorption spectrophotometry method. RESULTS: The mean serum zinc level was 0.585±0.166 mg/L and 0.704±0.179 mg/L in the case group and the control group, respectively (p=0.001). The mean serum zinc level was significantly lower in the febrile seizure group compared to the control groups. CONCLUSION: Our findings revealed that serum zinc level was significantly lower in children with simple febrile seizure in comparison with febrile children without seizure. It can emphasize the hypothesis that there is a relation between serum zinc level and febrile seizure in children.