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J Glob Infect Dis. 2019 Jul-Sep;11(3):112-117. doi: 10.4103/jgid.jgid_118_18.

Biofilm Formation of Methicillin-resistant Coagulase-Negative Staphylococci Isolated from Clinical Samples in Northern Thailand.

Author information

1
Department of Microbiology and Parasitology, Faculty of Oriental Medicine, Chiang Rai College, Bangkok, Thailand.
2
Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
3
Department of Microbiology and Parasitology, Faculty of Medical Sciences, Naresuan University, Chiang Rai, Thailand.
4
Department Clinical Microbiology, Chiangrai Prachanukroh Hospital, Chiang Rai, Thailand.
5
Division of Clinical Pathology, Faculty of Medicine, Naresuan University, Phitsanulok, Thailand.
6
Centre of Excellence in Medical Biotechnology, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand.

Abstract

Background:

Methicillin-resistant coagulase-negative staphylococci (MR-CoNS) are multidrug-resistant bacteria that are difficult to treat because of their ability to form biofilms.

Objectives:

In the present study, we evaluated the antibiotic-resistant phenotypes, biofilm-forming ability, and biofilm associated genes of 55 clinical MR-CoNS isolates obtained from two hospitals in Thailand.

Materials and Methods:

MALDI-TOF-MS and tuf gene sequencing were performed to determine the species of all isolates. Biofilm production was determined using Congo red agar (CRA) and the microtiter plate (MTP) assay. Biofilm-associated genes were characterized using polymerase chain reaction (PCR).

Results:

Among the 55 MR-CoNS isolates, five species were identified as Staphylococcus haemolyticus (34.5%), Staphylococcus epidermidis (32.7%), Staphylococcus capitis (18.2%), Staphylococcus cohnii (9.1%), and Staphylococcus hominis (5.5%). The antimicrobial susceptibility pattern of MR-CoNS isolates indicated high resistance to cefoxitin (100%), penicillin (98.2%), erythromycin (96.4%), ciprofloxacin (67.3%), sulfamethoxazole/trimethoprim (67.3%), gentamicin (67.3%), and clindamycin (63.6%). All the isolates were susceptible to vancomycin and linezolid. The biofilm production was detected in 87.3% isolates through the CRA method and in 38.1% isolates through the MTP assay. The prevalence rates of icaAD, bap, fnbA, and cna were 18.2%, 12.7%, 47.3%, and 27.3%, respectively. There were significant differences in the presence of these biofilm-associated genes among the MR-CoNS isolates. Moreover, quantitative biofilm formation was significantly different among MR-CoNS species.

Conclusion:

The present study revealed that biofilm-associated genes are important for biofilm biomass in MR-CoNS isolates, and the findings of this study are essential for finding new strategies to control biofilm formation and prevent the spread of MR-CoNS infectious diseases.

KEYWORDS:

Biofilm; biofilm-associated protein; intracellular adhesion AD; methicillin-resistant coagulase-negative staphylococcus

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