Molecular testing of Klebsiella pneumoniae contaminating tissue allografts recovered from deceased donors.

Microbiological screening of tissue allografts is crucial to prevent the transmission of bacterial and fungal infections to transplant recipients. Klebsiella was the most prevalent and resistant contaminating microorganism observed in our setting in the Iranian Tissue Bank. This study was conducted to determine the presence of extended-spectrum ß-lactamase (ESBL) genes, antimicrobial resistance patterns of Klebsiella pneumoniae isolates, and their clonal relationships in allograft materials. K. pneumoniae contaminating bone and other tissue allografts recovered from deceased donors were identified and ESBL isolates were detected using a phenotypic confirmatory method. Antimicrobial susceptibility testing was carried out using the disk diffusion method. Distribution of ESBL genes and molecular typing were performed using polymerase chain reaction (PCR) and Repetitive-element (rep-PCR) methods. Of 3828 donated tissues, 51 (1.3%) were found contaminated by K. pneumoniae isolates. Compared to tissue allografts from brain-dead, heart-beating tissue donors, allografts from donors with circulatory cessation were associated with a higher risk of K. pneumoniae contamination [odds ratio (OR), 1.2 (CI 95% 0.9-2.3) (P value < 0.001)]. Half of the isolates produced ESBL, and the rate of susceptibility to cephalosporins was 51%. Among isolates, 22 (43.1%) harbored CTX-M, 31 (60.8%) SHV, and 9 (17.6%) harbored TEM types. The rep-dendrogram indicated that clones having identical or related strains with a similar antibiotype were isolated in the same period. This study provides evidence that a single clone of K. pneumoniae contaminated tissue allografts recovered from many different donors. A single clone found on tissues from several donors suggests contamination of tissues from a single source such as the tissue recovery process and environment. Genomic DNA testing and clonality of contaminating bacteria using molecular methods can focus the epidemiologic investigation on the tissue allograft recovery process including a search for contamination of the tissue recovery room environment, recovery staff, recovery equipment, reagents, solutions and supplies.

The prevalence of exotoxins, adhesion, and biofilm-related genes in Staphylococcus aureus isolates from the main burn center of Tehran, Iran.

OBJECTIVES: The present study investigated the prevalence of genes encoding for exotoxins, adhesion and biofilm factors in Staphylococcus aureus isolates obtained from samples in a referral burn hospital in Tehran, Iran. MATERIALS AND METHODS: S. aureus isolates obtained from patients, personnel and surfaces in the wards of a burn hospital were identified and confirmed by biochemical and molecular tests, respectively. The susceptibility of isolates was determined using the disk diffusion method. Virulence factors were detected by multiplex PCR. RESULTS: The frequency of hla, hlb, hld, hlg, tst and pvl genes was 92.8%, 34.7%, 89.8%, 11.9%, 10.7%, and 0.5% respectively. The results revealed that the hla gene had the highest frequency among isolates (94.4% for methicillin-resistant S. aureus (MRSA) and 89.8% for methicillin-susceptible S. aureus (MSSA)). The most prevalent adhesion and biofilm-related gene was eno (85.6%). The prevalence of the remaining genes was as follows: fib (71.8%), clfB (70%), cna (59.2 %), fnbB (17.9%), icaA (72.4%), and icaD (85.6%). The incidence of fib, hlb, hlg, and tst genes was significantly higher in MRSA isolates compare to the MSSA isolates. Moreover, the resistance rates for all antibiotics were higher is MRSA isolates except for nitrofurantoin and chloramphenicol antibiotics. CONCLUSION: Data indicate the high prevalence rates of virulence factors among S. aureus isolates, especially MRSA strains in the burn hospital. This should to be taken into account in the development of an effective infection control policy and continuous monitoring of drug resistance in hospitals.

Toxin production and drug resistance profiles of pediatric methicillin-resistant Staphylococcus aureus isolates in Tehran.

INTRODUCTION: Staphylococcus aureus is known to be a major cause of skin and soft tissue infections, pneumonia and invasive diseases. In this study, attempts were made to examine the prevalence of tsst-1, eta, etb, and luk-PV genes among methicillin-resistant S. aureus (MRSA) isolated from children in Tehran. METHODOLOGY: In the present cross-sectional study, a total of 100 MRSA were isolated from children who were referred to a pediatric hospital during 11-month period of September 2014 to August 2015. Isolates were identified using biochemical tests and then, using PCR, the isolates were tested for the presence of mecA, tsst-1, eta, etb, and luk-PV genes. Susceptibility of isolates to cefoxitin, penicillin, erythromycin, clindamycin, gentamicin, rifampin, minocycline, co-trimoxazole, linezolid, and vancomycin were evaluated using standard methods. RESULTS: It was found that the MRSA isolates had the greatest resistance to clindamycin (72%) and erythromycin (59%), while the lowest rates of resistance were observed to be related to minocycline (6%) and rifampin (12%). All of isolates were sensitive to vancomycin and linezolid. The mecA gene was detected in all the isolates. Moreover, luk-PV and tsst-1 were detected in 18% and 17% of the isolates, respectively. None of the isolates harbored eta and etb genes. CONCLUSIONS: Our data provide specifications about the toxin production status of S. aureus isolates from pediatric children. The current study showed increased resistance to different antibiotics in S. aureus isolates. Therefore, to prevent multi-resistance to other antibiotic classes, it is essential to withhold prescriptions and stop unessential use of available antibiotics.

Variable number of tandem repeat profiles and antimicrobial resistance patterns of Staphylococcus haemolyticus strains isolated from blood cultures in children.

Staphylococcus haemolyticus is a healthcare-associated pathogen and can cause a variety of lifethreatening infections. Additionally, multi-drug resistance (MDR), in particular methicillin-resistant S. haemolyticus (MRSH) isolates, have emerged. Dissemination of such strains can be of great concern in the hospital environment. A total number of 20S. haemolyticus isolates from blood cultures obtained from children were included in this study. A high prevalence of MDR-MRSH isolates with high MIC values to vancomycin was found and 35% of the isolates were intermediate resistant to vancomycin. Multilocus variable number of tandem repeats analysis (MLVF) revealed 5 MLVF types among 20 isolates of S. haemolyticus. Twelve isolates shared the same MLVF type and were isolated from different wards in a pediatric hospital in Iran. This is a serious alarm for infection control; i.e. in the absence of adequate infection diagnostics and infection control guidelines, these resistant strains can spread to other sectors of a hospital and possibly among the community.