Comparison of ertapenem non-susceptibility with 2-mercaptopropionic acid phenotypic tests in predicting NDM-1 and IMP-1 production in clinical isolates of Escherichia coli.

BACKGROUND: A routine phenotypic test has not been recommended for the detection of metallo-ß-lactamases (MBLs) producing Enterobacteriaceae species such as Escherichia coli. The current study was conducted to compare the 2-mercaptopropionic acid (2-MPA) phenotypic method and ertapenem non-susceptibility test with polymerase chain reaction in predicting the production of MBLs in clinical isolates of E. coli. METHODS: Antimicrobial susceptibility test for beta-lactam antibiotics were performed by disk diffusion method. All isolates which showed inhibition zones of ≤ 22 mm for CAZ and ≤ 27 mm for CTX were considered potential MBLs producing isolates. The production of MBLs was confirmed using 2-MPA compound. Also, susceptibility to ertapenem was evaluated in all isolates. Conventional PCR was performed to detect blaIMP-1 and/or blaNDM-1 genes in all potential MBLs producing E. coli isolates. RESULTS: Of 259, 138 (53.3%) isolates were potential MBLs producing bacteria. One hundred and fifteen out of 138 (83.3%) isolates were susceptible to ertapenem. MBLs production was confirmed in 75/138 (54.4%) isolates by 2-MPA phenotypic method. The blaNDM-1 or/and blaIMP-1 genes were found in 30/75(40%) and 39/115(33.9%) isolates which were confirmed by 2-MPA and were susceptible to ertapenem, respectively. The sensitivity of 2-MPA method and ertapenem non-susceptibility test compared with PCR were 65.2% and 15.2%, and the specificity was 52.1% versus 82.6%, respectively. CONCLUSION: This study demonstrated that the 2-MPA phenotypic method does not have acceptable sensitivity and specificity in comparison with PCR, but its results are more reliable for the detection of MBL producing E. coli isolates compared with non-susceptibility to ertapenem.

Antibacterial activity of high-molecular-weight and low-molecular-weight chitosan upon oral pathogens.

CONTEXT: One of the common oral bacterial infectious diseases is dental caries. Control of dental plaque formed by Streptococcus mutans and Streptococcus sobrinus leads to prevention and treatment of caries. Chitosan (1-4, 2-amino-2-deoxy-b-D-glucan), a deacetylated derivative from chitin, is an antimicrobial polysaccharide that exerts broad-spectrum activity against pathogenic bacteria and has been suggested as a preventive and therapeutic material for dental caries. AIM: The aim of this investigation is whether chitosan has effective antimicrobial and antibiofilm properties against common cariogenic microorganisms. MATERIALS AND METHODS: The effect of 0.019-5 mg/ml of high-molecular-weight (HMW) and low-molecular-weight (LMW) chitosan on S. mutans and S. sobrinus was evaluated, and minimal inhibitory concentration (MIC) and minimal bactericide concentration (MBC) were determined. In addition, the effects of HMW and LMW of chitosan on bacterial adhesion to surfaces and biofilm formation were assayed by tube method. RESULTS: The results showed that chitosan is capable of inhibiting S. mutans and S. sobrinus growth (P = 0.001). MIC of HMW chitosan for S. mutans and S. sobrinus was 0.62 mg/mL and MIC of LMW chitosan for S. mutans and S. sobrinus was 0.62 mg/mL, 1.25 mg/mL, respectively. MBC of HMW chitosan for S. mutans and S. sobrinus was 1.25 mg/mL, respectively, and MBC of LMW chitosan for S. mutans and S. sobrinus was 1.25 and 2.5 mg/ml, respectively. On the other hand, HMW chitosan was more effective than LMW chitosan. In addition, S. mutans showed equal MIC and MBC values for both MWs chitosan, but S. sobrinus was more resistant to LMW chitosan. Regarding biofilm growth, chitosan inhibited S. mutans and S. sobrinus adhesion and biofilm formation. The results of tube test showed weak adherence and biofilm formation in concentration of 0.312 and 0.625 mg/ml, but 1.25 and 2.5 mg/ml concentrations of both MWs could completely inhibit biofilm formation. CONCLUSION: These results display the potential of chitosan to be used as an effective antibacterial and antibiofilm agent for oral hygiene and health care.

Association of staphylococcus cohnii subspecies urealyticum infection with recurrence of renal staghorn stone.

BACKGROUND: Stphylococcus cohnii is an organism of coagulase negative species which is considered as normal flora. However, it has been isolated from urinary tract infections and surgical prostheses but its relation with staghorn stones has not been reported, yet. CASE PRESENTATION: A 50-years-old woman presented with left renal staghorn stone in June 2014. She had bilateral staghorn stones 7 years ago. Staphylococcus cohnii subspecies urealyticum were detected from a removed stone. After 7 years, recurrence staghorn stone in her left kidney was diagnosed and patient underwent another surgery. The patient had several attacks of cystitis during these 7 years. The results of stone and urine cultures revealed staphylococcus cohnii subspecies urealyticum. CONCLUSION: This case report emphasizes a possible association between staphylococcus cohnii subspecies urealyticum infection and recurrence renal staghhorn stone.

Efficacy of daily versus intermittent administration of iron supplementation in anemia or blood indices during pregnancy.

BACKGROUND: Pregnant women take iron supplements in order to prevent iron deficiency anemia which may have undesirable effects for both the mother and fetus. This study aimed to compare the daily and intermittent dose of iron supplementation in blood and iron indices in healthy pregnant women. METHODS: In this clinical trial study, 145 healthy pregnant women were selected with Hb≥11g%. The participants were randomly divided into two groups. Group 1 received daily iron supplement at 50 mg/day and group 2 received an intermittent dose of 3 times per week. Blood samples were assessed for complete blood count (Hb, Hct, RBC), iron, ferritin and zinc at baseline in the first trimester in all participants and the two groups were compared in regard to mean changes from baseline to the end of the study period in the third trimester. This clinical trial was registered in the Iranian Registry of Clinical Trials (www.irct.ir) with registration number ID: 2012082810682N1. RESULTS: The incidence of iron deficiency anemia was 2.7% in both groups. The mean levels of Hb, Hct and RBC in the first trimester were 13.3 g/dl, 39.4% and 4.5 mil/ml(3), respectively. At the end of the study, Hb, Hct, and RBC reduced significantly in both groups compared with baseline values (p<0.05). The difference from baseline in Hb and other blood indices did not differ significantly across the two groups. CONCLUSION: These findings indicate that daily or intermittent administration of iron supplement to pregnant women has the same outcome. Regarding the side effects of iron in pregnancy, intermittent method seems preferable to daily intake.