Stenotrophomonas maltophilia
Encyclopedia
Stenotrophomonas maltophilia is an aerobic
, nonfermentative
, Gram-negative
bacterium. It is an uncommon bacterium and human
infection
is difficult to treat. Initially classified as Pseudomonas
maltophilia, S. maltophilia was also grouped in the genus
Xanthomonas
before eventually becoming the type species
of the genus Stenotrophomonas
in 1993.
S. maltophilia are slightly smaller (0.7–1.8 × 0.4–0.7 micrometers) than other members of the genus. They are motile due to polar
flagella and grow well on MacConkey agar
producing pigmented colonies. S. maltophilia are catalase
-positive, oxidase
-negative (which distinguishes them from most other members of the genus) and have a positive reaction for extracellular DNase.
S. maltophilia is ubiquitous in aqueous environments, soil and plants; it has also been used in biotechnology
applications. In immunocompromised patients, S. maltophilia can lead to nosocomial infections (see "pathogenesis" section below).
such as endotracheal or tracheostomy tubes, the respiratory tract and indwelling urinary catheters
. Infection is usually facilitated by the presence of prosthetic material (plastic or metal), and the most effective treatment is removal of the prosthetic material (usually a central venous catheter
or similar device). The growth of S. maltophilia in microbiological culture
s of respiratory or urinary specimens is therefore sometimes difficult to interpret and not a proof of infection. If, however, it is grown from sites which would be normally sterile (e.g., blood), then it usually represents true infection.
In immunocompetent individuals, S. maltophilia is a relatively unusual cause of pneumonia
, urinary tract infection
, or blood stream infection
; in immunocompromised patients, however, S. maltophilia is a growing source of latent pulmonary infections. S. maltophilia colonization rates in individuals with cystic fibrosis
have been increasing.
In the UK in 2006 there were about 1000 recorded cases with 300 fatalities (30%).
S. maltophilia is naturally resistant to many broad-spectrum antibiotic
s (including all carbapenem
s) and is thus often difficult to eradicate. Many strains of S. maltophilia are sensitive
to co-trimoxazole
and ticarcillin
, though resistance has been increasing. It is not usually sensitive to piperacillin
, and sensitivity to ceftazidime
is variable.
infection, malignancy, cystic fibrosis
, neutropenia
, mechanical ventilation
, central venous catheter
s, recent surgery
, trauma
, and broad-spectrum antibiotics.
Aerobic organism
An aerobic organism or aerobe is an organism that can survive and grow in an oxygenated environment.Faculitative anaerobes grow and survive in an oxygenated environment and so do aerotolerant anaerobes.-Glucose:...
, nonfermentative
Fermentation (biochemistry)
Fermentation is the process of extracting energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound. In contrast, respiration is where electrons are donated to an exogenous electron acceptor, such as oxygen,...
, Gram-negative
Gram-negative
Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...
bacterium. It is an uncommon bacterium and human
Human
Humans are the only living species in the Homo genus...
infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
is difficult to treat. Initially classified as Pseudomonas
Pseudomonas
Pseudomonas is a genus of gammaproteobacteria, belonging to the family Pseudomonadaceae containing 191 validly described species.Recently, 16S rRNA sequence analysis has redefined the taxonomy of many bacterial species. As a result, the genus Pseudomonas includes strains formerly classified in the...
maltophilia, S. maltophilia was also grouped in the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Xanthomonas
Xanthomonas
Xanthomonas is a genus of Proteobacteria, many of which cause plant diseases. Most varieties of Xanthomonas are available from the National Collection of Plant Pathogenic Bacteria in the United Kingdom and other international culture collections such as ICMP in New Zealand, CFBP in France, and...
before eventually becoming the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of the genus Stenotrophomonas
Stenotrophomonas
Stenotrophomonas is a genus of Gram-negative bacteria. With species ranging from common soil organisms to opportunistic human pathogens , the molecular taxonomy of the genus is still somewhat unclear....
in 1993.
S. maltophilia are slightly smaller (0.7–1.8 × 0.4–0.7 micrometers) than other members of the genus. They are motile due to polar
Chemical polarity
In chemistry, polarity refers to a separation of electric charge leading to a molecule or its chemical groups having an electric dipole or multipole moment. Polar molecules interact through dipole–dipole intermolecular forces and hydrogen bonds. Molecular polarity is dependent on the difference in...
flagella and grow well on MacConkey agar
MacConkey agar
MacConkey agar is a culture medium designed to grow Gram-negative bacteria and stain them for lactose fermentation.-Contents:It contains bile salts MacConkey agar is a culture medium designed to grow Gram-negative bacteria and stain them for lactose fermentation.-Contents:It contains bile salts...
producing pigmented colonies. S. maltophilia are catalase
Catalase
Catalase is a common enzyme found in nearly all living organisms that are exposed to oxygen, where it catalyzes the decomposition of hydrogen peroxide to water and oxygen...
-positive, oxidase
Oxidase
An oxidase is any enzyme that catalyzes an oxidation-reduction reaction involving molecular oxygen as the electron acceptor. In these reactions, oxygen is reduced to water or hydrogen peroxide ....
-negative (which distinguishes them from most other members of the genus) and have a positive reaction for extracellular DNase.
S. maltophilia is ubiquitous in aqueous environments, soil and plants; it has also been used in biotechnology
Biotechnology
Biotechnology is a field of applied biology that involves the use of living organisms and bioprocesses in engineering, technology, medicine and other fields requiring bioproducts. Biotechnology also utilizes these products for manufacturing purpose...
applications. In immunocompromised patients, S. maltophilia can lead to nosocomial infections (see "pathogenesis" section below).
Pathogenesis
S. maltophilia frequently colonizes breathing tubesVertebrate trachea
In tetrapod anatomy the trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air. It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus...
such as endotracheal or tracheostomy tubes, the respiratory tract and indwelling urinary catheters
Foley catheter
A Foley catheter is a flexible tube that is often passed through the urethra and into the bladder. The tube has two separated channels, or lumens, running down its length. One lumen is open at both ends, and allows urine to drain out into a collection bag...
. Infection is usually facilitated by the presence of prosthetic material (plastic or metal), and the most effective treatment is removal of the prosthetic material (usually a central venous catheter
Central venous catheter
In medicine, a central venous catheter is a catheter placed into a large vein in the neck , chest or groin...
or similar device). The growth of S. maltophilia in microbiological culture
Microbiological culture
A microbiological culture, or microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture media under controlled laboratory conditions. Microbial cultures are used to determine the type of organism, its abundance in the sample being tested,...
s of respiratory or urinary specimens is therefore sometimes difficult to interpret and not a proof of infection. If, however, it is grown from sites which would be normally sterile (e.g., blood), then it usually represents true infection.
In immunocompetent individuals, S. maltophilia is a relatively unusual cause of pneumonia
Pneumonia
Pneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...
, urinary tract infection
Urinary tract infection
A urinary tract infection is a bacterial infection that affects any part of the urinary tract. Symptoms include frequent feeling and/or need to urinate, pain during urination, and cloudy urine. The main causal agent is Escherichia coli...
, or blood stream infection
Bacteremia
Bacteremia is the presence of bacteria in the blood. The blood is normally a sterile environment, so the detection of bacteria in the blood is always abnormal....
; in immunocompromised patients, however, S. maltophilia is a growing source of latent pulmonary infections. S. maltophilia colonization rates in individuals with cystic fibrosis
Cystic fibrosis
Cystic fibrosis is a recessive genetic disease affecting most critically the lungs, and also the pancreas, liver, and intestine...
have been increasing.
In the UK in 2006 there were about 1000 recorded cases with 300 fatalities (30%).
S. maltophilia is naturally resistant to many broad-spectrum antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
s (including all carbapenem
Carbapenem
Carbapenems are a class of β-lactam antibiotics with a broad spectrum of antibacterial activity. They have a structure that renders them highly resistant to most β-lactamases...
s) and is thus often difficult to eradicate. Many strains of S. maltophilia are sensitive
Antibiotic sensitivity
Antibiotic sensitivity is a term used to describe the susceptibility of bacteria to antibiotics. Antibiotic susceptibility testing is usually carried out to determine which antibiotic will be most successful in treating a bacterial infection in vivo. Testing for antibiotic sensitivity is often...
to co-trimoxazole
Co-trimoxazole
Trimethoprim/sulfamethoxazole or co-trimoxazole is a sulfonamide antibiotic combination of trimethoprim and sulfamethoxazole, in the ratio of 1 to 5, used in the treatment of a variety of bacterial infections.The name co-trimoxazole is the British Approved Name, and has been marketed worldwide...
and ticarcillin
Ticarcillin
Ticarcillin is a carboxypenicillin. It is almost invariably sold and used in combination with clavulanate as Timentin. Because it is a penicillin, it also falls within the larger class of beta-lactam antibiotics. Its main clinical use is as an injectable antibiotic for the treatment of...
, though resistance has been increasing. It is not usually sensitive to piperacillin
Piperacillin
Piperacillin is an extended spectrum beta-lactam antibiotic of the ureidopenicillin class.It is normally used together with a beta-lactamase inhibitor such as tazobactam. The combination drug piperacillin/tazobactam is commercially available as e.g. Tazocin, Zosyn, Brodactam, Piptaz and as Trezora...
, and sensitivity to ceftazidime
Ceftazidime
Ceftazidime is a third-generation cephalosporin antibiotic. Like other third-generation cephalosporins, it has broad spectrum activity against Gram-positive and Gram-negative bacteria. Unlike most third-generation agents, it is active against Pseudomonas aeruginosa, however it has weaker activity...
is variable.
Epidemiology
Stenotrophomonas infections have been associated with high morbidity and mortality in severely immunocompromised and debilitated individuals. Risk factors associated with Stenotrophomonas infection include HIVHIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...
infection, malignancy, cystic fibrosis
Cystic fibrosis
Cystic fibrosis is a recessive genetic disease affecting most critically the lungs, and also the pancreas, liver, and intestine...
, neutropenia
Neutropenia
Neutropenia, from Latin prefix neutro- and Greek suffix -πενία , is a granulocyte disorder characterized by an abnormally low number of neutrophils, the most important type of white blood cell...
, mechanical ventilation
Mechanical ventilation
In medicine, mechanical ventilation is a method to mechanically assist or replace spontaneous breathing. This may involve a machine called a ventilator or the breathing may be assisted by a physician, respiratory therapist or other suitable person compressing a bag or set of bellows...
, central venous catheter
Central venous catheter
In medicine, a central venous catheter is a catheter placed into a large vein in the neck , chest or groin...
s, recent surgery
Surgery
Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...
, trauma
Trauma
Trauma can refer to:-In psychology and medicine:* Trauma , an often serious and body-altering physical injury, such as the removal of a limb...
, and broad-spectrum antibiotics.
External links
- Stenotrophomonas maltophilia article at eMedicine.
- The genus Stenotrophomonas
- Stenotrophomonas Genome Projects from Genomes OnLine Database
- http://www.cysticfibrosismedicine.com/htmldocs/CFText/stenotr.htm Relevance to Cystic Fibrosis
- Effect of different antibiotics eg minocycline, Tigecycline; JAC 2002 correspondence