1.The emergence of Acinetobacter baumannii ST-6 multidrug resistant: A resilient biofilm producer, Malaysia
Jayakayatri Jeevajothi Nathan ; Mohd Nasir Mohd Desa ; Voon Chen Yong ; Parasakthi Navaratnam ; Navindra Kumari Palanisamy ; Eng Hwa Wong
Malaysian Journal of Microbiology 2016;12(4):265-269
Aims: The aim of this research is to explore the presence of multidrug-resistance (MDR) Acinetobacter baumannii
strains isolated from hospitalized patients in a tertiary-care center, Subang Jaya, Selangor, Malaysia and to compare
their genotypic and phenotypic characteristics.
Methodology and results: Clonal relationships were determined by multilocus sequence typing (MLST) and biofilm
forming ability was evaluated by using 2, 3 - bis (2 - methoxy - 4 - nitro - 5-sulfophenyl) - 5 - [(phenylamino) carbonyl] -
2H-tetrazolium hydroxide (XTT) reduction assay in microplates and Congo red agar method (CRA). Four virulence
genes coding for A. baumannii pilus usher-chaperone assembly protein, csuE gene; outer membrane protein, ompA
gene; biofilm poly-β-1, 6-Nacetylglucosamine (PNAG) synthesis protein, pgaA gene; and acinetobactin-mediated iron
acquisition protein, bauA gene were searched for in a collection of strains. Antimicrobial resistance against 11 antibiotics
were studied by broth microdilution method. Seventeen A. baumannii clinical strains were isolated and MLST showed
that the strains belonged to 5 distinct sequence types (STs), namely, ST-6, ST-265, ST-324, ST-325 and ST-432. Fiftythree
percent of the strains were resistant to 4 or more antibiotics. Twelve strains produced biofilm and out of them, 4
were strong biofilm producer, besides, these strong biofilm producers were MDR strains and belongs to ST-6. In
addition, all strains were ompA positive, biofilm producing strains were csuE and pgaA positive and only strong biofilm
producing strains were bauA positive.
Conclusion, significance and impact study: Our study demonstrates that the ST-6 strains in Malaysia could represent
MDR, capable of forming strong biofilm and possess csuE, ompA, pgaA and bauA genes, virulence characteristics that
probably help the bacteria to persist and cause infection.
Acinetobacter baumannii
2.Prevalence of macrolide resistance and in vitro activities of six antimicrobial agents against clinical isolates of Streptococcus pneumoniae from a multi-center surveillance in Malaysia
Jayakayatri Jeevajothi Nathan ; Niazlin Mohd Taib ; Mohd Nasir Mohd Desa ; Siti Norbaya Masri ; Rohani Md Yasin ; Farida Jamal ; Sreenivasa Rao Sagineedu ; Arunkumar Karunanidhi
The Medical Journal of Malaysia 2013;68(2):119-124
The in vitro activities of 6 antimicrobial agents against
clinical isolates of Streptococcus pneumoniae
(pneumococci) were investigated and the erythromycin
minimum inhibitory concentrations (MICs) were correlated
with the two major macrolide resistance determinants,
mef(A) and erm(B). MICs of commonly used antibiotics as
well as the presence of macrolide resistance determinant
genes in all isolates were tested. Seventy one
pneumococcal isolates collected at Institute for Medical
Research (IMR) were included in this study. Phenotypic
characterization, MIC determination using E-test strips and
polymerase chain reactions for antibiotic resistance
determination were included. Among the isolates, 25 (35.2%)
isolates were erythromycin susceptible, 3 (4.2%) were
intermediate and 42 (60.6%) were resistant. Fifty three
isolates (74.7%) were found with mef(A) alone, 15 (21.1%)
isolates with erm(B) + mef(A) combination and 3 (4.2%)
isolates with none of the two genes. The in vitro activity of penicillin, amoxicillin clavulanic acid, ceftriaxone and
cefotaxime is superior to trimethoprim-sulfamethoxazole
and erythromycin. In conclusion, pneumococcal isolates in
this study were highly susceptible to penicillin with very low MICs. However, a very high prevalence rate of erythromycin resistance was observed. Erythromycin resistant S.pneumoniae isolates with both mef(A) and erm(B) showed very high MICs ≥256 μg/mL.
3.Antifungal and antibiofilm activity of Persian shallot (Allium stipitatum Regel.) against clinically significant Candida spp.
Arunkumar Karunanidhi ; Ehsanollah Ghaznavi-Rad ; Jayakayatri Jeevajothi Nathan ; Fazlin Mohd Fauzi ; Leslie Thian Lung Than ; Mallikarjuna Rao Pichika ; Rukman Awang Hamat ; Vasanthakumari Neela
Tropical Biomedicine 2018;35(3):815-825
Candida species are the most common cause of fungal infections that range from
non-life-threatening mucocutaneous illness to life-threatening invasive processes that may
involve virtually any organ. Such a broad range of infections requires an equally broad range
of therapeutic approach. Persian shallot (Allium stipitatum Regel.) is a medicinal plant that
has been widely used in tradition Persian medicine for various ailments. Allium stipitatum is
also used in modern medicine and has been reported to have a range of health benefits
including antibiotic (antifungal) properties. The present study assessed the in vitro
anticandidal and antibiofilm potential of hexane (ASHE) and dichloromethane (ASDE) extracts
of Allium stipitatum (Persian shallot) against planktonic and biofilm forms of 5 medically
important Candida spp. Antifungal activity was assessed by disk diffusion, minimum inhibitory
concentration (MIC), minimum fungicidal concentration (MFC) and time-kill assay. The
antibiofilm activity of ASHE and ASDE against reference strain C. albicans ATCC 14053 was
determined by XTT [2,3-bis(2-methoxy-4-nitro-5-sulfo-phenyl)-2H-tetrazolium-5-carboxanilide]
reduction assay. The zone of inhibition ranged from 22 to 40 mm, while the MICs ranged from
8 to 32 μg mL-1. The MFCs of ASHE and ASDE were in the range of 16 to 32 μg mL-1 each
respectively. Time-kill kinetics showed that both extracts were strongly fungicidal against
planktonic cultures of C. albicans with ~ 1.45 log reduction in CFU at 4 h post-treatment
(hpt). In addition, both ASHE and ASDE were shown to inhibit preformed C. albicans biofilms
in a concentration-dependent manner. The results demonstrated that ASHE and ASDE were
broad-spectrum in action, and could be developed as a promising alternative to synthetic
antifungals in controlling infections due to Candida spp. of clinical significance.