Antibiotic Susceptibility and Biofilm Formation of Bacterial Isolates Derived from Pediatric Patients with Cystic Fibrosis from Tehran, Iran.

Cystic fibrosis (CF) is a genetic disease with a high rate of morbidity and mortality. Children with CF commonly suffer from recurrent and persistent pulmonary tract infections caused by diverse bacterial pathogens. This study aimed to investigate the prevalence, antimicrobial susceptibility, and biofilm formation of bacterial isolates in pediatric patients with CF. The study population of this cross-sectional study included 8,908 children suspected to have CF by clinical manifestations from March 2015 to August 2017 who were referred to the Tehran Pediatric Central Hospital, Iran. The tests carried out for each participant included screening sweat test, sputum culture, antibiotic susceptibility test using Kirby-Bauer disk diffusion method, and biofilm formation in microtiter plates method. Based onclinical examination and screening sweat test, 183 (2.05 %( out of 8,908 children, were positive for CF. The mean age of children was estimated at 2.93 years, and the majority of them were male (n=103, 56.2%). No gender-specific difference was observed in CF disease in this study (P>0.05). In addition, the results of sputum culture showed that 153 (83.6%) microorganisms (bacteria and fungi) were collected from CF patients. Normal flora was isolated in 30 (16.4%) patients and more than one bacterial species were isolated in 7.2% of patients. The obtained results indicated that Pseudomonas aeruginosa was the most prevalent isolated bacteria followed by Staphylococcus aureus, and Klebsiella pneumoniae. Based on the antibiotic susceptibility test results, P. aeruginosa and piperacillin/tazobactam had the highest (11.7%) and the lowest (2.3%) resistance rate against gentamicin, respectively. However, all K. pneumoniae isolates were resistant to Cefotaxime. Among S. aureus isolates, 83.4% and 16.6% were methicillin-susceptible Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus respectively. Concerning biofilm formation, 76%, 67%, and 72.5% of P. aeruginosa, S. aureus, and K. pneumoniae isolates were biofilm producers, respectively. Based on the study results, P. aeruginosa was the dominant pathogen in pediatric patients with CF from Tehran, Iran, and most of the pathogens were biofilm producers. No severe antibiotic resistance was observed in the isolates; however, the anti-microbial resistance profile should be carefully checked in CF patients on a regular basis.

Clonal relatedness and resistance characteristics of OXA-24 and -58 producing carbapenem-resistant Acinetobacter baumannii isolates in Tehran, Iran.

AIMS: The present study was conducted to investigate the mechanism of carbapenem resistance and the molecular epidemiology of carbapenem-resistant Acinetobacter baumannii (CRAB) isolates collected from two nearby hospitals in Tehran, Iran. METHODS AND RESULTS: A total of 180 CRAB isolates were studied. Antimicrobial susceptibility testing was performed using disk diffusion and Epsilometer tests. The detection of OXA-23, -24 and -58 was implemented for all isolates using polymerase chain reaction. Subsequently, isolates harbouring OXA-24 and -58 were investigated for the presence of resistance determinants of Ambler class A, metallo-ß-lactamases (MBLs), and carbapenem-hydrolysing class D ß-lactamases, ISAba1, and the genetic relatedness between them was analysed using pulsed-field gel electrophoresis (PFGE). All isolates were found to be resistant to imipenem with a MIC of ≥8 µg ml-1 and were susceptible to colistin with a MIC of ≤1·5 µg ml-1 . Sixty percent of the isolates had OXA-23. OXA-24 and -58 were detected in 31 of 180 CRAB isolates. These chosen isolates were devoid of MBLs and blaSHV , blaC TX-M , blaVEB ESBL genes. The PER determinant was detected in 38% of isolates as the most common extended spectrum ß-lactamases (ESBLs). Of these isolates, 51·6% had OXA-23, and ISAba1 was found to be upstream of OXA-23 and OXA-51 in 16 and 8 isolates, respectively. The band patterns produced by PFGE showed nine clonal pulsotypes distributed between the two hospitals. CONCLUSION: The findings showed that the refractory CRAB isolates were transmitted intra- and inter-hospital, particularly in the ICU due to shortcomings in infection control surveillance. SIGNIFICANCE AND IMPACT OF THE STUDY: Carbapenem resistance is a substantial threat in the treatment of infections caused by A. baumannii due to limitations in the therapeutic options.

Comparative in vitro activity of carbapenems against clinical isolates of Acinetobacter baumannii.

AIMS: The aim of this multi-hospital study was to assess the in vitro activity of doripenem and its comparators, imipenem and meropenem, using the new CLSI breakpoints against a large population of a frequently isolated nosocomial pathogen, Acinetobacter baumannii. METHODS AND RESULTS: During a 2-year period, four referral or tertiary hospitals submitted 400 isolates of Ac. baumannii for susceptibility testing using imipenem, meropenem and doripenem via disc diffusion and E-test methods. A subset of 390 isolates was resistant to all three tested carbapenems. Doripenem and meropenem (MIC50 , 32 µg ml(-1) ) had comparable activity, albeit doripenem's activity was greater than imipenem (MIC50 , >32 µg ml(-1) ). A significantly higher proportion of the isolates were inhibited by doripenem than by imipenem at MIC values of 12, 16, 24 and 32 µg ml(-1) (P < 0·05). The cumulative percentage of imipenem MICs was lower compared to its comparators. The comparison of resistance rate to imipenem and meropenem based on old and new breakpoints showed <1% difference. The overall agreement between the two susceptibility testing methods was ≥95%. CONCLUSION: Doripenem has a slightly greater in vitro activity than imipenem in terms of zone breakpoints and MIC values, but its activity is comparable to meropenem. SIGNIFICANCE AND IMPACT OF THE STUDY: Doripenem should be considered as a therapeutic option for monotherapy or combination therapy, particularly when the therapeutic options are limited.

Isospora belli associated recurrent diarrhea in a child with AIDS.

Persistent diarrhea is a major manifestation of Acquired Immunodeficiency Syndrome (AIDS) which might be more complicated in Human Immunodeficiency Virus (HIV) infected children especially those from developing countries. There are numerous reports showing the emergence of intestinal opportunistic coccidian parasites, mostly Cryptosporidium parvum and Isospora belli in HIV-infected individuals. The prevalence of isosporiasis is probably underestimated in developing countries because routinely not all HIV-infected patients are examined for the presence of this protozoan infection. Here we report a case of HIV-infected isosporiasis presenting with failure to thrive and persistent diarrhea. Since I. belli infection in children responds well to therapy with trimethoprim-sulfamethoxazole, isosporiasis should be considered as a treatable infection in AIDS, if it is detected at proper time.