MethylobacteriumSpecies: An Increasingly Important Opportunistic Pathogen

Methylobacterium hispanicum sp. nov. and Methylobacterium aquaticum sp. nov., isolated from drinking water

“…These bacteria also occur in man-made environments, including potable water supplies, air-conditioning systems and masonry bathrooms and washstands, where they sometimes produce pink ropy masses of growth (Hiraishi et al, 1995;Trotsenko et al, 2001;Ultee et al, 2004). Some species have been described as opportunistic human pathogens (Truant et al, 1998;Hornei et al, 1999). On the other hand, methylotrophic bacteria are frequently associated with terrestrial and aquatic plants, colonizing roots and leaf surfaces (Austin et al, 1978;Yoshimura, 1982;Corpe & Rheem, 1989;Trotsenko et al, 2001;Lidstrom & Chistoserdova, 2002).…”

Pink-pigmented Non-fermentative Gram-negative Rods Associated with Human Infections: a Clinical and Diagnostic Challenge

“…In 1998, Truant [22] stated that "It is debated whether Methylobacterium species are emerging pathogens or, as postulated by some, are simply an unusual microbiologic curiosity". The past 8 years have witnessed a logarithmic increase in the number of case reports of pink-pigmented bacteria reputedly associated with human illness, and molecular diagnostics have equally provided an expanded list of aerobic species and genera potentially involved in these processes.…”

“…The most frequent clinical presentation associated with methylobacteria is bacteremia, and the most common site of isolation of these bacteria in the clinical setting is from blood [22,23]. The median age of persons with positive blood cultures is approximately 38 years (range 14 months-77 years) and there is almost an equal distribution of reported cases of sepsis based upon gender.…”

The Family Methylobacteriaceae

“…Methylobacterium strains have been increasingly reported as infectious agents in humans (Borsali et al 2011;Holton et al 1990;Lambert et al 1983;Sanders et al 2000;Truant et al 1998), with 30 clinical cases reviewed by Sanders et al (2000). Clinically recovered Methylobacterium strains are typically regarded as opportunistic pathogens in immunocompromised patients, such as those on chemotherapy (Engler and Norton 2001;Sanders et al 2000), and with immunosuppression due to alcoholism, renal failure, diabetes, tuberculosis, or (uncommonly) from patients with no previous underlying clinical condition (Gilardi and Faur 1984;Lai et al 2011;Lambert et al 1983;Liu et al 1997;Strazzi et al 1992;Truant et al 1998). Symptoms due to Methylobacterium infections range from bacteremia, fever, sepsis, empyema, pneumonia, peritonitis, to eye or urinary tract infection (Borsali et al 2011;Brown et al 1996;Fernandez et al 1997;Furuhata et al 2006;Hiraishi et al 1995;Lee et al 2004;Sanders et al 2000).…”

“…A frequent isolate from infected patients has been Mtb mesophilicum (Engler and Norton 2001;Holton et al 1990;Kaye et al 1992;Sanders et al 2000), which has also been shown as the cause of a postoperative septicemia case (Barriere et al 2008). Other species (including Mtb radiotolerans, Mtb aminovorans, Mtb thiocyanatum, Mtb extorquens, Mtb zatmanii, Mtb fujisawaense, Mtb lusitanum, and Mtb podarium) have also been reported (Borsali et al 2011;Fanci et al 2010;Furuhata et al 2006;Hornei et al 1999;Lai et al 2011;Truant et al 1998), with Mtb extorquens earning the clinical nickname ''the red phantom'' (Holton et al 1990). It has been suggested that infection rates may be underestimated because of the difficulty of identifying Methylobacterium strains which grow only slowly on commonly used clinical media (Hornei et al 1999), and underreporting of infection by Methylobacterium species due to difficulties in identification using standard clinical practices (Blomqvist et al 1997; Lee et al 2004).…”