Citrobacter koseri

Last updated

Citrobacter koseri
Scientific classification Red Pencil Icon.png
Domain: Bacteria
Phylum: Proteobacteria
Class: Gammaproteobacteria
Order: Enterobacteriales
Family: Enterobacteriaceae
Genus: Citrobacter
C. koseri
Binomial name
Citrobacter koseri
Frederiksen 1970 [1]
Citrobacter koseri
Specialty Infectious disease

Citrobacter koseri is a Gram-negative, non-spore-forming bacillus. It is a facultative anaerobe capable of aerobic respiration. It is motile via peritrichous flagella. [2] It is a member of the family of Enterobacteriaceae. The members of this family are the part of the normal flora of human and animal digestive tracts. C. koseri may act as an opportunistic pathogen in a variety of human infections.[ citation needed ]

<i>Bacillus</i> genus of bacteria

Bacillus is a genus of Gram-positive, rod-shaped bacteria, a member of the phylum Firmicutes, with 266 named species. The term is also used to describe the shape (rod) of certain bacteria; and the plural Bacilli is the name of the class of bacteria to which this genus belongs. Bacillus species can be either obligate aerobes: oxygen dependent; or facultative anaerobes: having the ability to be anaerobic in the absence of oxygen. Cultured Bacillus species test positive for the enzyme catalase if oxygen has been used or is present.

Enterobacteriaceae family of bacteria

The Enterobacteriaceae are a large family of Gram-negative bacteria. This family is the only representative in the order Enterobacteriales of the class Gammaproteobacteria in the phylum Proteobacteria.


Brain abscesses have a high rate of mortality and complications, therefore, neonates usually left with severe residual permanent damage. The transmission of C. koseri could be vertical from mother to fetus (local vaginal infection, rupture of the membranes, chorioamniotis may occur between the seventh and 11th day prior to delivery) and other sources can be horizontal nosocomial transmission by asymptomatic nursery staff. [3]

Signs and symptoms

The neonates become very sick and present sepsis, meningitis, and cerebritis, seizures, apnea, and a bulging fontanelle. No evidence of stiff neck or high-grade fever is present. [4]


Occasionally, it causes meningitis, but it can cause sepsis, ventriculitis, and cerebritis with 80% frequent multiple brain abscesses in low-birth-weight, immunocompromised neonates; rare cases have been reported in older children and adults, most of whom have underlying diseases. [4]


Ventriculitis is the inflammation of the ventricles in the brain. The ventricles are responsible for containing and circulating cerebrospinal fluid throughout the brain. Ventriculitis is caused by infection of the ventricles, leading to swelling and inflammation. This is especially prevalent in patients with external ventricular drains and intraventricular stents. Ventriculitis can cause a wide variety of short-term symptoms and long-term side effects ranging from headaches and dizziness to unconsciousness and death if not treated early. It is treated with some appropriate combination of antibiotics in order to rid the patient of the underlying infection. Much of the current research involving ventriculitis focuses specifically around defining the disease and what causes it. This will allow for much more advancement in the subject. There is also a lot of attention being paid to possible treatments and prevention methods to help make this disease even less prevalent and dangerous.

Arterial and venous infarctions are possible because of the bacterial infiltration along the main vessel; exudates within the ventricles and ventriculitis may obstruct the ventricular foramina and result in a multicystis hydrocephalus with consequent long-lasting shunting difficulties, and necrotizing meningeoencephalitis with pneumocephalus has been reported. [4]


The pathogenic mechanism is poorly understood. C.koseri may have a unique ability to penetrate, survive, and replicate into vascular endothelial cells and macrophages. Furthermore, it survives in phagolysozomal fusion and replicates within macrophages, which may contribute to the establishment of chronic abscesses. [4] [5]


Medical imaging

Early and massive tissue necrosis is a specific feature of C. koseri brain infection. The early stage of the disease predominates in the white matter, causing cerebritis; the later stage is marked with necrotic cavities in multiple locations. The cavities are initially square in shape and not tense, but when pus forms and collects in these cavities, they tend to become more rounded in shape; a persisting cavity leads to septated ventriculitis that may result in multicyctic hydrocephalus. [4]

Early, cerebritis is seen, and multiple large cavities can be seen in the late stage of the disease; abscesses formation, contraction of the cavities, and hydrocephalus due to ventriculitis are observed in the late follow up. [4] [5]


Macroscopic findings include purulent exudates, opaque leptomeninges (thinning of meninges), pus, and ventriculitis/ ependymitis.


In samples collected from cerebrospinal fluid, C. koseri grows well on an any ordinary medium; they produce unpigmented, colorless mucoid colonies. If incubated for 24 hours in other media such as indole, citrate, and adonitol, C.koseri will be positive, hydrogen sulfide negative in Kligers’ iron agar, negative results in lactose, salicin, and sucrose broth as well. . [4] [6]


C. koseri may be identified in the walls of congested vessels, presence of the cavities resulting from the infection do not develop well-formed fibrotic wall. [4]

Differential diagnosis

The differential diagnosis of C. koseri brain abscesses can be confused with other related diseases, so diagnostic imaging is important to confirm this bacterium. The significant feature of C. koseri is the necrotic cavity which cannot be misidentified as earlier ischemic or hemorrhagic insult or other mass lesions; congential/neonatal tumors are uncommon (choroid plexus papillomas, craniopharyngiomas, teratomas); even when they present, they are different from the inflammatory ring of a cerebral infection. Early cerebritis should not be mistaken for normal, immature white matter, nor for cicatricial leukomalacia. [4] [5]


A broad spectrum cephalosporin and meropenem are often used because of the good penetration into the central nervous system. If the response to the antibiotic is poor, the surgical aspiration of the collected pus reduces the mass effect and enhances the efficacy of the antibiotics. [4] [6] [7]


The prognosis of the C. koseri infection is 20 to 30% of neonates die, and 75% of survivors have significant neurologic damage such as complex hydrocephalus, neurologic deficits, mental delay, and epilepsy. [4]


The most effective way to reduce transmission of organisms is regular handwashing. [4]

Related Research Articles

Abscess localized collection of pus that has built up within the tissue of the body

An abscess is a collection of pus that has built up within the tissue of the body. Signs and symptoms of abscesses include redness, pain, warmth, and swelling. The swelling may feel fluid-filled when pressed. The area of redness often extends beyond the swelling. Carbuncles and boils are types of abscess that often involve hair follicles, with carbuncles being larger.

Brain abscess abscess caused by inflammation and collection of infected material in the brain

Brain abscess is an abscess caused by inflammation and collection of infected material, coming from local or remote infectious sources, within the brain tissue. The infection may also be introduced through a skull fracture following a head trauma or surgical procedures. Brain abscess is usually associated with congenital heart disease in young children. It may occur at any age but is most frequent in the third decade of life.

Encephalitis Brain disease that is characterized as an acute inflammation of the brain with flu-like symptoms

Encephalitis is inflammation of the brain. Severity is variable. Symptoms may include headache, fever, confusion, a stiff neck, and vomiting. Complications may include seizures, hallucinations, trouble speaking, memory problems, and problems with hearing.

Lemierre's syndrome refers to infectious thrombophlebitis of the internal jugular vein. It most often develops as a complication of a bacterial sore throat infection in young, otherwise healthy adults. The thrombophlebitis is a serious condition and may lead to further systemic complications such as bacteria in the blood or septic emboli.


An exudate is a fluid emitted by an organism through pores or a wound, a process known as exuding or exudation. Exudate is derived from exude, "to ooze," from the Latin exsūdāre, "to sweat".

Boil deep folliculitis, infection of the hair follicle

A boil, also called a furuncle, is a deep folliculitis, infection of the hair follicle. It is most commonly caused by infection by the bacterium Staphylococcus aureus, resulting in a painful swollen area on the skin caused by an accumulation of pus and dead tissue. Boils which are expanded are basically pus-filled nodules. Individual boils clustered together are called carbuncles. Most human infections are caused by coagulase-positive S. aureus strains, notable for the bacteria's ability to produce coagulase, an enzyme that can clot blood. Almost any organ system can be infected by S. aureus.

Liquefactive necrosis is a type of necrosis which results in a transformation of the tissue into a liquid viscous mass. Often it is associated with focal bacterial or fungal infections, and can also manifest as one of the symptoms of an internal chemical burn. In liquefactive necrosis, the affected cell is completely digested by hydrolytic enzymes, resulting in a soft, circumscribed lesion consisting of pus and the fluid remains of necrotic tissue. Dead leukocytes will remain as a creamy yellow pus. After the removal of cell debris by white blood cells, a fluid filled space is left. It is generally associated with abscess formation and is commonly found in the central nervous system.

Lung abscess lung disease characterized by microbial infection which causes a type of liquefactive necrosis of the pulmonary tissue and formation of cavities containing necrotic debris or fluid

Lung abscess is a type of liquefactive necrosis of the lung tissue and formation of cavities containing necrotic debris or fluid caused by microbial infection.

Cefotaxime chemical compound

Cefotaxime is an antibiotic used to treat a number of bacterial infections. Specifically it is used to treat joint infections, pelvic inflammatory disease, meningitis, pneumonia, urinary tract infections, sepsis, gonorrhea, and cellulitis. It is given either by injection into a vein or muscle.

Meningococcal disease Human disease

Meningococcal disease describes infections caused by the bacterium Neisseria meningitidis. It has a high mortality rate if untreated but is vaccine-preventable. While best known as a cause of meningitis, it can also result in sepsis, which is an even more damaging and dangerous condition. Meningitis and meningococcemia are major causes of illness, death, and disability in both developed and under-developed countries.

<i>Citrobacter</i> genus of bacteria

Citrobacter is a genus of Gram-negative coliform bacteria in the Enterobacteriaceae family.

Cavernous sinus thrombosis Human disease

Cavernous sinus thrombosis (CST) is the formation of a blood clot within the cavernous sinus, a cavity at the base of the brain which drains deoxygenated blood from the brain back to the heart. This is a rare disorder and can be of two types–septic cavernous thrombosis and aseptic cavernous thrombosis. Most commonly the form is of septic cavernous sinus thrombosis. The cause is usually from a spreading infection in the nose, sinuses, ears, or teeth. Staphylococcus aureus and Streptococcus are often the associated bacteria.

Dental abscess tooth disease characterized by a localized collection of pus associated with a tooth

A dental abscess is a localized collection of pus associated with a tooth. The most common type of dental abscess is a periapical abscess, and the second most common is a periodontal abscess. In a periapical abscess, usually the origin is a bacterial infection that has accumulated in the soft, often dead, pulp of the tooth. This can be caused by tooth decay, broken teeth or extensive periodontal disease. A failed root canal treatment may also create a similar abscess.

Cerebral shunt Surgical implant

Cerebral shunts are commonly used to treat hydrocephalus, the swelling of the brain due to excess buildup of cerebrospinal fluid (CSF). If left unchecked, the cerebrospinal fluid can build up leading to an increase in intracranial pressure (ICP) which can lead to intracranial hematoma, cerebral edema, crushed brain tissue or herniation. The cerebral shunt can be used to alleviate or prevent these problems in patients who suffer from hydrocephalus or other related diseases. Shunts can come in a variety of forms but most of them consist of a valve housing connected to a catheter, the end of which is usually placed in the peritoneal cavity. The main differences between shunts are usually in the materials used to construct them, the types of valve used, and whether the valve is programmable or not.

A pneumococcal infection is an infection caused by the bacterium Streptococcus pneumoniae, which is also called the pneumococcus. S. pneumoniae is a common member of the bacterial flora colonizing the nose and throat of 5–10% of healthy adults and 20–40% of healthy children. However, it is also a cause of significant disease, being a leading cause of pneumonia, bacterial meningitis, and sepsis. The World Health Organization estimate that in 2005 pneumococcal infections were responsible for the death of 1.6 million children worldwide.

Meningitis inflammation of membranes around the brain and spinal cord

Meningitis is an acute inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The most common symptoms are fever, headache, and neck stiffness. Other symptoms include confusion or altered consciousness, vomiting, and an inability to tolerate light or loud noises. Young children often exhibit only nonspecific symptoms, such as irritability, drowsiness, or poor feeding. If a rash is present, it may indicate a particular cause of meningitis; for instance, meningitis caused by meningococcal bacteria may be accompanied by a characteristic rash.

Neonatal sepsis is a type of neonatal infection and specifically refers to the presence in a newborn baby of a bacterial blood stream infection (BSI) in the setting of fever. Older textbooks may refer to neonatal sepsis as "sepsis neonatorum". Criteria with regards to hemodynamic compromise or respiratory failure are not useful clinically because these symptoms often do not arise in neonates until death is imminent and unpreventable. Neonatal sepsis is divided into two categories: early-onset sepsis (EOS) and late-onset sepsis (LOS). EOS refers to sepsis presenting in the first 7 days of life, with LOS referring to presentation of sepsis after 7 days. Neonatal sepsis is the single most common cause of neonatal death in hospital as well as community in developing country.

Neonatal meningitis

Neonatal meningitis is a serious medical condition in infants. Meningitis is an inflammation of the meninges and is more common in the neonatal period than any other time in life and is an important cause of morbidity and mortality globally. Mortality is roughly half in developing countries and ranges from 8%-12.5% in developed countries.

Neonatal infection human disease

Neonatal infections are infections of the neonate (newborn) acquired during prenatal development or in the first four weeks of life. Neonatal infections may be contracted by mother to child transmission, in the birth canal during childbirth, or contracted after birth. Some neonatal infections are apparent soon after delivery, while others may develop in the postnatal period. Some neonatal infections such as HIV, hepatitis B, and malaria do not become apparent until much later.


  1. "Citrobacter". Retrieved 1 March 2019.
  2. Ong CL, Beatson SA, Totsika M, Forestier C, McEwan AG, Schembri MA (2010). "Molecular analysis of type 3 fimbrial genes from Escherichia coli, Klebsiella and Citrobacter species". BMC Microbiol. 10: 183. doi:10.1186/1471-2180-10-183. PMC   2900259 . PMID   20576143.
  3. Greenwood, David; Slack, Richard C. B.; Peutherer, John F.; Barer, Michael R. (2007). Medical Microbiology: A Guide to Microbial Infections: Pathogenesis, Immunity, Laboratory Diagnosis and Control (17th ed.). Elsevier. pp. 1264–6. ISBN   978-0-7020-4009-2.
  4. 1 2 3 4 5 6 7 8 9 10 11 12 Babyn, Paul S. (2011). "Section I: Neuroradiology: Case 3". Teaching Atlas of Pediatric Imaging. Thieme. pp. 44–7. ISBN   978-1-60406-494-0.
  5. 1 2 3 Doran TI (1999). "The role of Citrobacter in clinical disease of children: review". Clin. Infect. Dis. 28 (2): 384–94. doi:10.1086/515106. PMID   10064257.
  6. 1 2 Feferbaum R, Diniz EM, Valente M, Giolo CR, Vieira RA, Galvani AL, Ceccon ME, Araujo MC, Krebs VL, Vaz FA (2000). "Brain abscess by Citrobacter diversus in infancy: case report". Arq Neuropsiquiatr. 58 (3A): 736–40. doi:10.1590/s0004-282x2000000400023. PMID   10973119.
  7. McPherson C, Gal P, Ransom JL (2008). "Treatment of Citrobacter koseri infection with ciprofloxacin and cefotaxime in a preterm infant". Ann Pharmacother. 42 (7): 1134–8. doi:10.1345/aph.1L008. PMID   18577764.