Table 3.

Virulence and virulence associated factors in S. maltophilia and its potential application in diagnosis/therapy.

Virulence and virulence associated factors	Unique composition/structure/attributes	Virulence mechanisms	Potential application of the factor in diagnosis/therapy	Reference
Biofilm	*Coded for, by biosynthetic genes rmlA, rmlC, and xanB *Produced as the bacteria spread and intimately attach to surfaces	*Protects the bacteria against host immune factors *Promotes antibiotic resistance	Iron-restrictive regulation to slow done biofilm formation and reduce spread	Di Bonaventura et al., 2004; Huang et al., 2006
Quorum sensing	“Diffusible Signal Factor (DSF) quorum sensing (QS) system to”	“Mediate intra- and inter-specific signaling and regulate virulence-related processes”	Quorum quenching therapeutic approach by incorporating the structural analogs of DSF and other factors	Tay and Yew, 2013; Thomas et al., 2014; Huedo et al., 2015
Extracellular enzymes	“DNase, RNase, arbutinase, protease (StmPr1 serine protease) acetase, esterases, lipases, mucinase, acid and alkaline phosphatases, hyaluronidase, phosphoamidase, elactase, leucine arylamidase, and β-glucosidase”	*Utilizes varieties of enzymes to digest tissue proteins and serum making leading to the collapse of immune architechture, lesion, and hemorrhage	Synthesis of a Structural analogs of DSF to block extracellular enzymes production & other virulence factors	Crossman et al., 2008; Thomas et al., 2014; DuMont and Cianciotto, 2017
Flagella	Sequence identity to the flagellin of Proteus mirabilis, Serratia mercenscens, Escherichia coli, etc.	*Facilitates evasion via motility from lysin, agglutinin, precipitin etc in humoral responses *Adhesins factor	Anti-Flagella antibodies	Zgair and Chhibber, 2011; Haiko and Westerlund-Wikström, 2013
Pili/fimbriae	“Fimbrillar structures (5–7 μm in width) just like pili interconnecting bacteria and mediating adhesion of the bacteria to the abiotic surface”	*The aid in adherence, autoaggregration, colonization of surfaces, and *Antibiotic resistance	“Specific antibodies against SMF-1 fimbriae inhibited the agglutination of animal erythrocytes, adherence to HEp-2 cells and biofilm formation by S. maltophilia”	de Oliveira-Garcia et al., 2002, 2003
Small colony variant	Down-regulation of the bacterial electron transport and/or dihydrofolate reductase (DHFR) pathway sulfamethoxazole resistance, bringing about small colonial form	Switch to the SCV phenotype is a response to antibiotic pressure due to down-regulation of the bacterial electron transport and/or dihydrofolate reductase (DHFR) pathway	“SCV S. maltophilia from the sputum of CF patients has implications in laboratory testing”	Anderson et al., 2007

^*Indicates particular concern.