Alcaligenes, Bordetella (Non-pertussis), Comamonas, and Similar Organisms

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Alcaligenes, Bordetella (Non-pertussis), Comamonas, and Similar Organisms

Genera and Species to Be Considered

Current Name Previous Name
Achromobacter denitrificans Alcaligenes denitrificans, Achromobacter xylosoxidans subsp. denitrificans
Achromobacter piechaudii Alcaligenes piechaudii
Achromobacter xylosoxidans Achromobacter xylosoxidans subsp. xylosoxidans
Alcaligenes faecalis type species Pseudomonas or Alcaligenes odorans
A. faecalis subsp. faecalis  
A. faecalis subsp. parafaecalis  
A. faecalis subsp. phenolicus  
Bordetella bronchiseptica CDC group IVa
CDC Alcaligenes-like group 1  
CDC group IIg  
Comamonas spp.  
Cupriavidus pauculus CDC group IVc-2, Wautersia paucula, Ralstonia paucula
Delftia acidovorans Comamonas acidovorans, Pseudomonas acidovorans
Ignatzchineria spp. Ciliari rod group 1
Myroides spp. Flavobacterium odoratum
Oligella ureolytica CDC group IVe
Oligella urethralis Moraxella urethralis, CDC group M-4
Pseudomonas alcaligenes  
Pseudomonas pseudoalcaligenes  
Psychrobacter spp. (asaccharolytic strains) Moraxella phenylpyruvia
Psychrobacter phenylpyruvicus Moraxella phenylpyruvica
Roseomonas spp.  

General Characteristics

The genera discussed in this chapter are considered together because most of them are usually oxidase-positive, non–glucose utilizers capable of growth on MacConkey agar. They are a diverse group of organisms. The organism’s specific morphologic and physiologic features are presented later in this chapter in the discussion of laboratory diagnosis.

Achromobacter species are gram-negative, nonsporulating, motile rods with 1 to 20 peritrichous flagella. They are strictly aerobic and nonfermentative. However, some strains are capable of anaerobic growth. The genus Alcaligenes is limited to the pathogenic type species A. faecalis, with two subspecies that are limited to environmental isolates: A. faecalis subsp. parafaecalis and A. faecalis subsp. phenolicus. Alcaligenes species are gram-negative, strict aerobic rods or coccobacilli that are oxidase and catalase positive. They are motile and have 1 to 12 peritrichous flagella. Comamonas spp. are typically environmental species that may be problematic opportunistic nosocomial pathogens. Comamonas and Delftia spp. are aerobic, non–spore forming, straight or slightly curved, gram-negative rods with one or more polar flagella. The genus Oligella comprises two asaccharolytic coccobacilli species, O. ureolytica and O. urethralis. O. ureolytica are motile by peritrichous flagella, and O. urethralis are nonmotile. Roseomonas spp. are coccoid, plump rods in pairs or short chains. They are typically motile by one or two polar flagella.


The habitats of the species listed in Table 25-1 vary from soil and water environments to the upper respiratory tract of various mammals. Certain species have been exclusively found in humans, whereas the natural habitat for other organisms remains unknown.

TABLE 25-1


Species Habitat (Reservoir) Mode of Transmission
Achromobacter xylosoxidans Environment, including moist areas of hospital. Transient colonizer of human gastrointestinal or respiratory tract in patients with cystic fibrosis Not often known. Usually involves exposure to contaminated fluids (e.g., intravenous fluids, hemodialysis fluids, irrigation fluids), soaps, and disinfectants
Achromobacter piechaudii Environment Unknown. Rarely found in humans
Alcaligenes faecalis Environment; soil and water, including moist hospital environments. May transiently colonize the skin Exposure to contaminated medical devices and solutions
Bordetella bronchiseptica Normal respiratory flora of several mammals, including dogs, cats, and rabbits. Not part of human flora Probably by exposure to contaminated respiratory droplets during close contact with animals
Comamonas spp. Environment, soil and water; can be found in hospital environment. Not part of human flora Nosocomial opportunistic pathogens because of their ability to survive in aqueous environments
CDC group IVc-2 Uncertain. Probably water sources, including those in the hospital setting. Not part of human flora Usually involves contaminated dialysis systems or exposure of wounds to contaminated water
Delftia acidovorans Environment, soil and water; can be found in hospital environment. Not part of human flora Uncertain. Rarely found in humans. Probably involves exposure to contaminated solutions or devices
Ignatzchineria spp. Unknown. Probably environmental. Not part of human flora Unknown. Rarely found in humans
Oligella urethralis
Oligella ureolytica
Unknown. May colonize distal urethra Manipulation (e.g., catheterization) of urinary tract
Psychrobacter spp. Unknown Unknown
Roseomonas spp. Unknown Unknown. Rarely found in humans

The diversity of the organisms’ habitats is reflected in the various ways they are transmitted. For example, transmission of environmental isolates such as Achromobacter denitrificans frequently involves exposure of debilitated patients to contaminated fluids or medical solutions. In contrast, Bordetella bronchiseptica transmission primarily occurs by close contact with animals, whereas Bordetella holmesii has been detected only in human blood, and no niche or mode of transmission is known.

Pathogenesis and Spectrum of Disease

Identifiable virulence factors are not known for most of the organisms listed in Table 25-2. However, because infections usually involve exposure of compromised patients to contaminated materials, most of these species are probably of low virulence. Among the environmental organisms listed, Achromobacter spp. are most frequently associated with various infections, including bacteremia, meningitis, pneumonia, and peritonitis. They also have been implicated in outbreaks of nosocomial infections. Achromobacter piechaudii has been isolated from pharyngeal swabs, wounds, blood, and ear discharge. Achromobacter xylosoxidans increasingly has been recovered from patients with cystic fibrosis. However, it is unclear whether the organism is implicated in causing clinical disease in patients with cystic fibrosis or whether it simply colonizes the respiratory tract. A. denitrificans has been recovered from urine, prostrate secretions, the buccal cavity, pleural fluid, and eye secretions. A. faecalis has been isolated from a wide range of clinical specimens and has been identified in bacteremia, ocular infections, pancreatic abscesses, bone infections, urine, and ear discharge. Comamonas spp. have been identified in cases of endocarditis, meningitis, and catheter-associated bacteremia. They have also been recovered from sputum in patients with cystic fibrosis. Other organisms, such as O. urethralis and O. ureolytica have been isolated predominantly from the human urinary tract. Pseudomonas alcaligenes and Pseudomonas pseudoalcaligenes rarely have been identified in clinical samples.

TABLE 25-2

Pathogenesis and Spectrum of Disease

Species Virulence Factors Spectrum of Disease and Infections
Achromobacter dentrificans Unknown. Survival in hospital the result of inherent resistance to disinfectants and antimicrobial agents Infections usually involve compromised patients and include bacteremia, urinary tract infections, meningitis, wound infections, pneumonia, and peritonitis; occur in various body sites; can be involved in nosocomial outbreaks.
Achromobacter xylosoxidans Unknown. Survival in hospital the result of inherent resistance to disinfectants and antimicrobial agents Infections usually involve compromised patients and include meningitis, pneumonia, otitis media, urinary tract infections, surgical wound infections, and bacteremia.
Alcaligenes faecalis Unknown Infections usually involve compromised patients. Often a contaminant; clinical significance of isolates should be interpreted with caution. Has been isolated from blood, respiratory specimens, and urine.
Alcaligenes piechaudii Unknown Rare cause of human infection.
Bordetella bronchiseptica Unknown for humans. Has several factors similar to B. parapertussis Opportunistic infection in compromised patients with history of close animal contact. Infections are uncommon and include pneumonia, bacteremia, urinary tract infections, meningitis, and endocarditis.
CDC group IVc-2 Unknown Rare cause of human infection. Infections in compromised patients include bacteremia and peritonitis.
Comamonas testosteroni
Comamonas spp.
Unknown Isolated from respiratory tract, eye, and blood but rarely implicated as being clinically significant.
Cupriavidus spp. Unknown Recovered from cystic fibrosis patients. Additional infections include bacteremia, peritonitis and tenosynovitis.
Delftia acidovorans Unknown Isolated from respiratory tract, eye, and blood but rarely implicated as being clinically significant.
Ignatzchineria spp. Unknown Clinical significance uncertain, has been isolated from wounds, urine, and blood.
Oligella urethralis Unknown Urinary tract infections, particularly in females.
Oligella ureolytica Unknown Also isolated from kidney, joint, and peritoneal fluid.
P. alcaligenes
P. pseudoalcaligenes
Unknown; low virulence associated with administration of contaminated solutions and medicines Recovered from the respiratory secretions of patients with cystic fibrosis.
Psychrobacter spp. Unknown Rare cause of human infection
Roseomonas spp. Unknown; uncommon isolates from humans Clinical significance uncertain. Typically opportunistic infections. Most isolated from blood, wounds, exudates, abscesses, or genitourinary tract of immunocompromised or debilitated patients.

Laboratory Diagnosis

Specimen Collection and Transport

No special considerations are required for collection and transport of the organisms discussed in this chapter. Refer to Table 5-1 for general information on specimen collection and transport.

Direct Detection Methods

Other than Gram staining of patient specimens, there are no specific procedures for the direct detection of these organisms in clinical material. B. bronchiseptica is a medium-sized straight rod, whereas O. urethralis, Psychrobacter spp., Roseomonas spp., and Moraxella spp. are all coccobacilli, although Psychrobacter phenylpyruvicus may appear as a broad rod, and some Roseomonas spp. may appear as short, straight rods. O. ureolytica is a short, straight rod; Myroides spp. are pleomorphic rods and are either short or long and straight to slightly curved.

Alcaligenes and Achromobacter spp. are medium to long straight rods, as are CDC Alcaligenes-like group 1, Cupriavidus pauculus, Delftia acidovorans, P. alcaligenes, and P. pseudoalcaligenes. The Comamonas spp. are pleomorphic and may appear as long, paired, curved rods or filaments. The cells of CDC group IIg appear as small, coccoid-to-rod forms or occasionally as rods with long filaments.


Media of Choice

B. bronchiseptica grows on 5% sheep blood, chocolate, and MacConkey agars, usually within 1 to 2 days after inoculation. It should also grow in thioglycollate broth. Psychrobacter spp., Myroides spp., Oligella spp., Achromobacter spp., D. acidovorans, Alcaligenes spp., CDC Alcaligenes-like group 1, Comamonas spp., Roseomonas spp., P. alcaligenes, P. pseudoalcaligenes, C. pauculus, and CDC group IIg all grow well on 5% sheep blood, chocolate, and MacConkey agars. Most of these genera should also grow well in the broth of blood culture systems, as well as in common nutrient broths such as thioglycollate and brain-heart infusion.

Colonial Appearance

Table 25-3 describes the colonial appearance and other distinguishing characteristics (e.g., pigment and odor) of each genus on 5% sheep blood and MacConkey agars.

TABLE 25-3

Colonial Appearance and Characteristics

Organism Medium Appearance
Achromobacter denitrificans

Achromobacter xylosoxidans Achromobacter piechaudii Alcaligenes faecalis
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