Molecular epidemiology and spatiotemporal analysis of hospital-acquired Acinetobacter baumannii infection in a tertiary care hospital in southern Thailand.

BACKGROUND: Acinetobacter baumannii is a major hospital-acquired pathogen in Thailand that has a negative effect on patient survival. The nature of its transmission is poorly understood. AIM: To investigate the genotypic and spatiotemporal pattern of A. baumannii infection at a hospital in Thailand. METHODS: The medical records of patients infected with A. baumannii at an 800-bed tertiary care hospital in southern Thailand between January 2010 and December 2011 were reviewed retrospectively. A. baumannii was identified at the genomospecies level. Carbapenemase genes were identified among carbapenem-resistant isolates associated with A. baumannii infection. A spatiotemporal analysis was performed by admission ward, time of infection and pulsed-field gel electrophoresis (PFGE) groups of A. baumannii. RESULTS: Nine PFGE groups were identified among the 197 A. baumannii infections. All A. baumannii isolates were assigned to International Clonal Lineage II. blaOXA-23 was the most prevalent carbapenemase gene. Outbreaks were observed mainly in respiratory and intensive care units. The association between PFGE group and hospital unit was significant. Spatiotemporal analysis identified 20 clusters of single PFGE group infections. Approximately half of the clusters involved multiple hospital units simultaneously. CONCLUSIONS: A. baumannii transmitted both within and between hospital wards. Better understanding and control of the transmission of A. baumannii are needed.

Detection of Leishmania martiniquensis DNA in various clinical samples by quantitative PCR.

Leishmaniasis is a neglected tropical parasitic disease affecting a large number of countries in the world. Early diagnosis of Leishmania infections is essential for therapeutic reasons, as it can decrease morbidity and mortality. L. siamensis and L. martiniquensis are novel Leishmania species recently described in Thailand and Myanmar. The disease is usually found in immunocompromised patients, especially those who have AIDS. Currently, the diagnosis of Leishmania infection in Thailand relies on microscopy, microbial culture, and polymerase chain reaction (PCR). In this study, we established a quantitative PCR (qPCR) method for detection of L. martiniquensis DNA in various types of clinical specimens, including whole blood, buffy coat, saliva, and urine of L. martiniquensis infected patients. The results of the qPCR assay were positive in all saliva samples. The assay is therefore effective to detect L. martiniquensis DNA even in noninvasive specimens, and it could be used for the diagnosis, follow up, and survey of L. martiniquensis infections.

Inhibition of Staphylococcus epidermidis Biofilm Formation by Traditional Thai Herbal Recipes Used for Wound Treatment.

Development of biofilm is a key mechanism involved in Staphylococcus epidermidis virulence during device-associated infections. We aimed to investigate antibiofilm formation and mature biofilm eradication ability of ethanol and water extracts of Thai traditional herbal recipes including THR-SK004, THR-SK010, and THR-SK011 against S. epidermidis. A biofilm forming reference strain, S. epidermidis ATCC 35984 was employed as a model for searching anti-biofilm agents by MTT reduction assay. The results revealed that the ethanol extract of THR-SK004 (THR-SK004E) could inhibit the formation of S. epidermidis biofilm on polystyrene surfaces. Furthermore, treatments with the extract efficiently inhibit the biofilm formation of the pathogen on glass surfaces determined by scanning electron microscopy and crystal violet staining. In addition, THR-SK010 ethanol extract (THR-SK010E; 0.63-5 µg/mL) could decrease 30 to 40% of the biofilm development. Almost 90% of a 7-day-old staphylococcal biofilm was destroyed after treatment with THR-SK004E (250 and 500 µg/mL) and THR-SK010E (10 and 20 µg/mL) for 24 h. Therefore, our results clearly demonstrated THR-SK004E could prevent the staphylococcal biofilm development, whereas both THR-SK004E and THR-SK010E possessed remarkable eradication ability on the mature staphylococcal biofilm.

Anti-biofilm activity of Quercus infectoria G. Olivier against methicillin-resistant Staphylococcus aureus.

AIMS: To establish the effect of Quercus infectoria G. Olivier extract and its main constituent, tannic acid, on staphylococcal biofilm and their anti-biofilm mechanisms. METHODS AND RESULTS: Anti-biofilm activity of the plant materials on clinical isolated of methicillin-resistant Staphylococcus aureus and methicillin-susceptible Staph. aureus was employed using a crystal violet-stained microtiter plate method. The extract at minimum inhibitory concentration (MIC; 0.25 mg ml(-1)) was significantly reduced the biofilm formation of the isolates (P < 0.05). The effect on staphylococcal cell surface hydrophobicity (CSH) of the test compounds was investigated as a possible mode of action of the anti-biofilm activity. The hydrophobicity index of all the bacterial isolates increased following treatment with supra-MIC, MIC and sub-MIC of the extract and tannic acid. Observation of the treated bacterial cells by electron microscopy revealed that the test compounds caused clumps of partly divided cocci with thickened and slightly rough cell wall. CONCLUSIONS: The results indicated that Q. infectoria extract and tannic acid affected staphylococcal biofilm formation and their effect on bacterial CSH and cell wall may involve in the anti-biofilm activity. SIGNIFICANCE AND IMPACT OF THE STUDY: This evidence highlighted the anti-biofilm potency of the natural products and clarified their anti-biofilm mechanisms.

Damage of staphylococcal cytoplasmic membrane by Quercus infectoria G. Olivier and its components.

AIMS: In traditional Thai medicine, nutgall of Quercus infectoria G. Olivier is well-documented as an effective agent for wound and skin infections. The present study was aimed to establish modes of action of the ethanol extract of the plant as well as its main constituents to induce anti-methicillin-resistant Staphylococcus aureus (MRSA) activity. METHODS AND RESULTS: The minimal inhibitory concentration (MIC)/minimal bactericidal concentration (MBC) values of ethyl acetate I, ethyl acetate II, 95% ethanol and 30% ethanol fractions against MRSA were 0.06/0.25, 0.13/0.25, 0.25/0.5 and 0.5/1.00 mg ml(-1), respectively. Ellagic acid, gallic acid, syringic acid and tannic acid as major components of Q. infectoria nutgall extract were included in this study. Among these, gallic acid and tannic acid demonstrated good MIC/MBC values at 0.06/0.06 and 0.13/0.25 mg ml(-1), respectively. A lysis experiment demonstrated that the ethanol extract, ethyl acetate fraction I and all of the main components failed to lyse MRSA cells. In contrast, both MRSA and Staph. aureus ATCC 25923 treated with the ethanol extract, ethyl acetate fraction I, gallic acid and tannic acid displayed significant loss of tolerance to low osmotic pressure and high salt concentration. CONCLUSIONS: The results documented the effect of different fractions of Q. infectoria and purified compounds on MRSA and Staph. aureus. In addition, the study demonstrated that treatment with Q. infectoria extract and the purified compounds results in hypersensitivity to low and high osmotic pressure. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides scientific information to support the traditional uses of the nutgall extract and suggesting its anti-MRSA mechanisms.

Detailed studies on Quercus infectoria Olivier (nutgalls) as an alternative treatment for methicillin-resistant Staphylococcus aureus infections.

AIMS: To investigate the antimethicillin-resistant Staphylococcus aureus (MRSA) mechanism of Quercus infectoria (nutgalls) extract and its components. METHODS AND RESULTS: Ethanol extract, an ethyl acetate fraction I, gallic acid and tannic acid could inhibit the growth of clinically isolated MRSA strains with minimum inhibitory concentration values between 63 and 250 microg ml(-1). Clumps of partly divided cocci with thickened cell wall were observed by transmission electron microscopy in the cultures of MRSA incubated in the presence of the ethanol extract, the ethyl acetate fraction I and tannic acid. Because cell wall structure of the organism structures seemed to be a possible site for antibacterial mechanisms, their effect with representative beta-lactam antibiotics were determined. Synergistic effects with fractional inhibitory concentration index ranged from 0.24 to 0.37 were observed with 76% and 53% of the tested strains for the combination of the ethanol extract with amoxicillin and penicillin G, respectively. CONCLUSIONS: The appearance of pseudomulticellular bacteria in the treated cells and the synergistic effect of the plant extract with beta-lactamase-susceptible penicillins suggest that the extract may interfere with staphylococcal enzymes including autolysins and beta-lactamase. SIGNIFICANCE AND IMPACT OF THE STUDY: Our results provide scientific data on the use of the nutgalls, which contain mainly tannin contents up to 70% for the treatment of staphylococcal infections.

Quercus infectoria: a candidate for the control of methicillin-resistant Staphylococcus aureus infections.

Acetone, ethyl acetate, 95% ethanol and aqueous extracts of Quercus infectoria (Q. infectoria) demonstrated significant antibacterial activities against all strains of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible Staphylococcus aureus (MSSA). Inhibition zones were in the range 11.75-16.82 mm. Both MRSA and MSSA strains exhibited minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values at 0.13 and 0.13-1.00 mg/mL, respectively. At 2 MIC, the growth of two representative MRSA strains was continually inhibited for at least 20 h. Surviving MRSA cells were not detected within 12-14 h after treatment with the extract at 4 MIC concentration. Staphylococcus aureus ATCC 25923 demonstrated similar results.