Citrobacter is a genus of gram-negative bacteria in the family of the Enterobacteriaceae. (coliform)
The administrator of this site has first hand knowledge that Citrobacter is a very bad hospital acquired bug that causes
urinary tact infections.
Citrobacter (a coliform & fecal colifom) is a genus of gram-negative bacteria in the family of the
Enterobacteriaceae and a part of the normal intestinal flora of humans and animals and can be isolated
from many environmental sources including food, soil, water, sewage, and sludge/biosolids. Infections
include, aneurysms, endocarditis, urinary tract and infant meningitis, necrotizing meningo-encephalitis.
It is multiple antibiotic resistant and now produces poisonous Hydrogen Sulfide (H2S) gas.
In the 1980 study, “Citrobacter Infections in Humans: Experience at the Seattle Veterans
Administration Medical Center and a Review of the Literature,” Benjamin A. Lipsky, et al., Veterans
Administration Medical Center at Seattle, reported, “The genus Citrobacter is a distinct group of human
pathogens comprising three species: Citrobacter freundii (biotypes a and b), Citrobacter amalonaticus,
and Citrobacter diversus. In this review the clinical and microbiologic experience during 1972–1978 at
the Seattle Veterans Administration Medical Center (Seattle, Wash.) with 298 isolates of Citrobacter is
analyzed in relation to a survey of the literature. The most common sources of citrobacter isolates were
urine, sputum, and soft tissue exudates. Members of this genus can cause neonatal meningitis and,
perhaps, gastroenteritis in both children and adults. Although deep tissue infections due to Citrobacter
have been reported only occasionally, in this study a large number of cultures of peritoneal fluid and
bone contained Citrobacter. Most isolates of Citrobacter were from elderly, debilitated patients and
either represented secondary infections or were of indeterminate clinical significance.”
According to the 1996 “Medical Microbiology. 4th edition, Chapter 26,” “The role of Citrobacter
species in human disease is not as great as that of the other coliforms and Proteus. Citrobacter freundii
and C diversus (C koseri) have been isolated predominantly as superinfecting agents from urinary and
respiratory tract infections. Citrobacter septicemia may occur in patients with multiple predisposing
factors; Citrobacter species also cause meningitis, septicemia, and pulmonary infections in neonates
and young children. Neonatal meningitis produced by C diversus, while uncommon, is associated with
a very high frequency of brain abscesses, death, and mental retardation in survivors.”
In the 1999 study, “Citrobacter freundii Invades and Replicates in Human Brain Microvascular
Endothelial Cells ,” Julie L. Badger, et al., Childrens Hospital Los Angeles, reported, “Neonatal
bacterial meningitis remains a disease with unacceptable rates of morbidity and mortality despite the
availability of effective antimicrobial therapy. Citrobacter spp. cause neonatal meningitis but are unique
in their frequent association with brain abscess formation. – The fatality rate associated with neonatal
meningitis is 25 to 50%; moreover, serious neurological sequelae result in 75% of survivors. Although
the implication Citrobacter spp. in neonatal meningitis and brain abscess is clear, the mechanisms by
which these organisms cause disease have been poorly investigated.”
In a 2004 study, “Pneumocephalus in neonatal meningitis: diffuse, necrotizing meningo-encephalitis in
Citrobacter meningitis presenting with pneumatosis oculi and pneumocephalus,” S.K. Pooboni, et al.,
Glenfield Hospital at Leicester, said, “We report a case of a 19-day-old baby who presented with a
rapid onset of septic shock complicated by progressively increasing gas accumulation within the brain
and anterior chamber of the eye. – Despite effective antibiotic therapy and supportive management, the
patient died with worsening accumulation of gas within the brain, resulting in brainstem death. –
Citrobacter koseri was identified from the blood and cerebrospinal fluid cultures. – This case reemphasises
the importance of C. koseri as both a community-acquired and nosocomial neonatal
In a 2008 study, “Resuscitation of eleven-year VBNC Citrobacter,” Amel Dhiaf, et al, reported,
“Citrobacter freundii strain WA1 was stressed by incubation in seawater microcosms for eleven
years. After two years of starvation, no culturable strain was observed. Incubation of samples
in nutrient-rich broth medium not supplemented with growth factors, however, allowed
resuscitation of VBNC cells so that subsequent plating yielded observable colonies
for significantly extended periods of time. Recovery of VBNC Citrobacter freundii was obtained
by incubation in nutrient broth even after eleven years of starvation. To see whether the samples
contained the same strain of Citrobacter freundii inoculated 11 years ago. The complete 16S
rRNA gene was PCR amplified and sequenced from initial, stressed and revived strains
of Citrobacter freundii strain WA1.The 16S rRNA gene sequences from eleven-year stressed
strains were homologous with a high degree of similarity to the GenBank reference strain and
were identical to each other.”
In the 2009 study, “Endogenous endophthalmitis caused by Citrobacter koseri,” C.H. Chiu, et al., Tri-
Service General Hospital, National Defense Medical Center at Taipei, reported, “Endogenous
endophthalmitis occurs when organisms are hematogenously disseminated in to the eye from a distant
focus of infection. The most common isolated organisms that cause endogenous endophthalmitis are
Klebsiella pneumoniae and Escherichia coli. Previous reports on endophthalmitis caused by Citrobacter
species are limited. We present the first case of endogenous endophthalmitis caused by Citrobacter
koseri bacteremia and renal abscesses.” http://www.ncbi.nlm.nih.gov/pubmed/19834321
In a 2011 study, “Citrobacter freundii infection after acute necrotizing pancreatitis in a patient with a
pancreatic pseudocyst: a case report,” Antonio Lozano-Leon, et al., said, “We describe a Citrobacter
freundii isolation by endoscopy ultrasound fine needle aspiration in a 80-year-old Caucasian man with
pancreatic pseudocyst after acute necrotizing pancreatitis. – Conclusion:
Our case report confirms that this organism can be recovered in patients with a pancreatic pseudocyst.
On-site cytology feedback was crucial to the successful outcome of this case as immediate
interpretation of the fine needle aspiration sample directed the appropriate cultures and, ultimately, the
curative therapy. To the best of our knowledge, this is the first reported case of isolated pancreatic C.
freundii diagnosed by endoscopy ultrasound fine needle aspiration.”
Am J Med Sci. 2009 Dec;338(6):509-10.
Endogenous endophthalmitis caused by Citrobacter koseri.
Chiu CH, Peng MY, Wang YC, Chang FY.
SourceDivision of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General
Hospital, National Defense Medical Center, Taipei, Taiwan.
Endogenous endophthalmitis occurs when organisms are hematogenously disseminated in to the eye from a distant
focus of infection. The most common isolated organisms that cause endogenous endophthalmitis are Klebsiella
pneumoniae and Escherichia coli. Previous reports on endophthalmitis caused by Citrobacter species are limited. We
present the first case of endogenous endophthalmitis caused by Citrobacter koseri bacteremia and renal abscesses
The species C. amalonaticus, C. koseri, and C. freundii use solely citrate as a carbon source. These bacteria can be
found almost everywhere in soil, water, wastewater, etc. It can also be found in the human intestine. They are rarely the
source of illnesses, except for infections of the urinary tract and infant meningitis.
Citrobacter: C. freundii is suspected to cause diarrhea and possibly extraintestinal infections. C. diversus has been
linked to a few cases of meningitis in newborns.
Citrobacter shows the ability to accumulate uranium by building phosphate complexes.
From 1974 to 1982, 38 patients developed Citrobacter bacteremia at two adult community-teaching hospitals in the
Detroit Medical Center (incidence, 1.2 cases per 10,000 discharges). Citrobacter accounted for 0.7% of all bacteremias
during the study period. Of 31 cases reviewed, Citrobacter bacteremia frequently developed in elderly patients (65%)
and was hospital acquired (77%). Initial sites of infection included the urinary tract (39%), gastrointestinal tract (27%),
wound (10%), and unknown (13%). More bacteremias caused by Citrobacter diversus [C. koseri] tended to arise from
the urinary tract, while patients with Citrobacter freundii bacteremia had significantly more gallbladder disease. Patients
with Citrobacter bacteremia were more likely than patients with Escherichia coli bacteremia to have had additional
pathogens in the bloodstream, to develop bacteremia in the hospital, and to have undergone invasive procedures
contributing to infection. Significant differences were not observed in demographic, host, or other epidemiologic or
clinical factors examined. Of patients with Citrobacter bacteremia, 48% died.
Pediatr Crit Care Med. 2004 Jul;5(4):393-5. Links
Pneumocephalus in neonatal meningitis: diffuse, necrotizing meningo-encephalitis in Citrobacter meningitis presenting
with pneumatosis oculi and pneumocephalus.Pooboni SK, Mathur SK, Dux A, Hewertson J, Nichani S.
Paediatric Critical Care Unit, Glenfield Hospital, Leicester, UK.
OBJECTIVE/PATIENT: Gas-containing encephalitis is rarely associated with neonatal meningitis. We report a case of a
19-day-old baby who presented with a rapid onset of septic shock complicated by progressively increasing gas
accumulation within the brain and anterior chamber of the eye. We describe the evolution of the clinical picture and the
management. INTERVENTIONS: Ventilatory support, fluid resuscitation, and continuous venovenous hemofiltration were
provided in view of multiple system failure. Despite effective antibiotic therapy and supportive management, the patient
died with worsening accumulation of gas within the brain, resulting in brainstem death. RESULTS: Computed
tomographic images were characteristic of diffuse necrotizing meningo-encephalitis. Postmortem examination showed
friable brain tissue with venous infarction and extensive gas accumulation. Citrobacter koseri was identified from the
blood and cerebrospinal fluid cultures. CONCLUSION: This case re-emphasises the importance of C. koseri as both a
community-acquired and nosocomial neonatal pathogen. Radiologic evidence suggestive of diffuse necrotizing meningo-
encephalitis in combination with pneumocephalus and pneumatosis oculi in Citrobacter infections has never been
described before. Diagnostic imaging with computed tomographic scanning of the brain and initiation of broad-spectrum
antibiotics with good penetration into cerebrospinal fluid are indicated as soon as infection with Citrobacter species is
suspected clinically, with appearance of pneumatosis oculi as a rare, late finding. http://www.ncbi.nlm.nih.