Stenotrophomonas maltophilia

OVERVIEW

Stenotrophomonas maltophilia is an environmental global emerging Gram-negative MDRO that is most commonly associated with respiratory infections in humans

• high fatality/case ratio
• transmitted by healthcare workers and by direct contact with source
• primarily a hospital acquired infection, though community acquire infections are increasing

MICROBIOLOGY

• Gram-negative obligate aerobic motile bacillus with a few polar flagella
• able to persist in nutrient-poor aqueous environments, including plant rhizospheres, animals, foods, water sources and in-hospital sites (e.g. tap water, sink drains, soap, medical devices and prostheses)
• adheres to plastics and forms biofilms
• low virulence, primarily affects the immunocompromised
• intrinsically resistant to antibiotics due to:
  — low membrane permeability
  — presence of chromosomally encoded multidrug resistance efflux pumps, β-lactamases and antibiotic-modifying enzymes

RISK FACTORS

For infection

• immunocompromise
• cystic fibrosis
• ECMO
• RRT
• prolonged ICU stay
• malignancy
• prior antibiotic use
• indwelling devices (e.g. IDCs, CVCs, ICCs)

For mortality

• LOS in ICU
• CVC present
• mechanical ventilation
• malignancy inappropriate antibiotics
• shock
• thrombocytopenia

CLINICAL FEATURES

• most commonly respiratory tract infection
• can cause infection of nearly any organ or tissue, e.g. endocarditis, osteomyelitis, meningitis, biliary sepsis, septicaemia, central line associated infection, eye infections, soft tissue and skin infections

INVESTIGATIONS

Difficult to distinguish between colonisation and infection in many instances

• swabs and tissue samples MCS
• PCR

MANAGEMENT

• infection control measures
• do not treat colonisation with antibiotics, only infection
• source control
• antibiotics
  — co-trimoxazole (first line)
  — other options: minocycline, moxifoxacin, colistin/polymyxin B, cefepime, tigecycline, combination therapy
  — resistant to: aminoglycosides, antipseudomonal penicillins, and antipseudomonal third-generation cephalosporins
• supportive care and monitoring
• consult infectious diseases specialist

References and Links

Journal articles

• Brooke JS. Stenotrophomonas maltophilia: an emerging global opportunistic pathogen. Clin Microbiol Rev. 2012 Jan;25(1):2-41. PMC3255966.
• Looney WJ, Narita M, Mühlemann K. Stenotrophomonas maltophilia: an emerging opportunist human pathogen. Lancet Infect Dis. 2009 May;9(5):312-23. PMID: 19393961.