Musculoskeletal infections associated with Citrobacter koseri

A Novel Case of Citrobacter koseri Septic Arthritis in a Native Knee Joint

Citrobacter koseri is a rare cause of septic arthritis in a native knee joint. We present the first recorded case of C. koseri septic arthritis in the native knee from a hematogenous spread resulting from a gastrointestinal illness, along with a review of the literature. A search of PubMed, Embase, OVID, and Google Scholar was conducted. Fifteen cases of musculoskeletal infection were identified, and of these, only six cases involved a septic joint and one case involved a septic knee. None of the recorded adult cases presented hematogenously without prior trauma. All of the cases achieved resolution after either antibiotic treatment alone or in conjunction with surgical treatment. Citrobacter koseri is not a rare cause of infection in general. However, it is not a common cause of septic arthritis, and this may complicate the treatment course as it can be overlooked as a cause of infection. It is essential to obtain a thorough history and a broad differential diagnosis when evaluating septic arthritis as although it may be difficult to identify the infection, C. koseri septic arthritis can be effectively treated with surgery as well as newer generation beta-lactams and cephalosporin antibiotic therapy.

Osteomyelitis Caused by Citrobacter koseri in a Young Immunocompetent Man

Citrobacter koseri is a non-sporulating, motile, gram-negative, facultative anaerobic bacteria found in various environmental sources, including the human intestine. It is considered an opportunistic infection as it typically causes infection in newborns, elderly, and immunocompromised patients. Common sites of infection are the urinary tract, gastrointestinal system, and respiratory tract in immunocompromised adults, as well as the bloodstream and meninges in newborns. However, osteomyelitis secondary to C. koseri is very rare. We present an unusual case of Citrobacter osteomyelitis in a healthy young man with no identifiable risk factors.

Multiple Retroperitoneal Abscesses Caused by Citrobacter koseri Are Associated with a Poor Prognosis

Citrobacter koseri causes opportunistic infections in various organs. We herein report an 84-year-old man with diabetes mellitus who presented to our hospital with left hip pain and walking difficulty. Computed tomography showed an extensive abscess with gas production, mainly in the left retroperitoneal space, caused by C. koseri infection. Despite daily cleaning of the wound and antimicrobial therapy (with surgical drainage), the patient developed repeated pneumonia and small bowel hemorrhaging caused by disseminated intravascular coagulation and died on day 65 of hospitalization. Overall, retroperitoneal abscesses caused by C. koseri are rare, and multiple abscesses may show a poor prognosis.

Microbial Community Characterization and Molecular Resistance Monitoring in Geriatric Intensive Care Units in China Using mNGS

Background

Surface pathogens in the ICU pose a global public health threat, especially to elderly patients who are immunocompromised. To detect these pathogens, unbiased methods such as metagenomic next-generation sequencing (mNGS) are increasingly utilized for environmental microbiological surveillance.

Methods

In a six-month study from January to July 2022, we investigated microbial communities in Chinese geriatric ICUs by regularly monitoring multiple surfaces at three-month intervals. Using mNGS sequencing, we analyzed microorganisms present at eight specific locations within the ICU. Additionally, we compared pathogen profiles and drug resistance genes between patient cultures and environmental samples collected during the same period.

Results

The microbial composition remained relatively stable over time, but significant differences in alpha diversities were observed among various surfaces such as floors, hands, pumps, trolleys, and ventilator inlets/outlets. Surfaces with high contact frequency for healthcare workers, including workstations, ventilator panels, trolleys, pumps, and beds, harbored pathogenic microorganisms such as Acinetobacter baumannii, Cutibacterium acnes, Staphylococcus haemolyticus, Pseudomonas aeruginosa, and Enterococcus faecium. Acinetobacter baumannii, particularly the carbapenem-resistant strain (CRAB), was the most frequently identified pathogen in geriatric ICU patients regardless of testing method used. The mNGS approach enabled detection of viruses, fungi, and parasites that are challenging to culture. Additionally, an abundance of drug resistance genes was found in almost all environmental samples.

Conclusion

The microbial composition and abundance in the ICU remained relatively constant over time. The floor exhibited the highest microbial diversity and abundance in the ICU environment. Drug-resistant genes in the ICU environment may migrate between patients. Overall, mNGS is an emerging and powerful tool for microbiological monitoring of the hospital environment.

Genotypic Detection of qnrA and qnrC Genes in Citrobacter koseri Isolated from Patients with Urinary Tract Infection

The urinary tract infection (UTI) is a prevalent infection that affects people of all ages. Bacterial agents are the most common causes of UTIs. Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, and other staphylococcal species, Citrobacter freundii and Citrobacter koseri (C. koseri) account for a smaller number of infections. These pathogens are transported into the urinary tract from the colonic biotope into dysbacteriosis. Urine samples were randomly collected from 249 outpatients who were suspected of having UTIs. After genital cleaning, 10 mL of urine specimens were collected in a sterilized bowel. Then, the specimens were centrifuged at 2,000 rpm for 5 min and the residue was aerobically incubated with the broth infusion of brain flasks at 37°C for 24 h and then applied with a sterile ring onto blood agar plates and MacConkey agar (OxoidTM). Out of 249 urine samples, the results proved that there were 176 (70.7%) and 51(20.5%) gram-negative and gram-positive bacteria isolates, respectively. However, the results demonstrated that there were 22 (8.8%) urine samples with no growth. In addition, the results showed that eight various antimicrobials are used to treat C. koseri. In the current study, C. koseri was treated with eight different antimicrobial agents. The antimicrobial resistance rate for 7 isolates against Cefotaxime, Ceftriaxone, Ciprofloxacin, and Levofloxacin was high for 6 (85.71%) isolates. The results indicated that 6 and 5 isolates had 85.71% and 71.42% antimicrobial resistance against Ceftazidime and Levofloxacin, respectively. Whereas Gentamicin showed a moderate rate of resistance (4 isolates, 57.14%), and Amikacin resistance was found in 5 isolates, accounting for 28.57%. The bacterial isolates had a high susceptibility rate to Imipenem. The qnrA gene was found in 6 (85.71%) isolates. However, the recorded data demonstrated that there is no isolate carrying the qnrC gene. Among all pathogenic bacteria, C. koseri was the lowest causative agent of UTI in this study and was highly resistant to most antimicrobials except Imipenem, which was a good antibiotic with 100% sensitivity.

Citrobacter koseri causing osteomyelitis in a diabetic foot with concomitant acute gouty arthritis successfully treated with ertapenem

We present an elderly diabetic man with left hallux pain and drainage who was initially diagnosed with acute gouty arthritis using the diagnostic rule for acute gout and monosodium urate crystals presented on synovial fluid analysis. Further investigation with surgical debridement, plain X-ray, MRI and wound culture revealed concomitant Citrobacter koseri septic arthritis with osteomyelitis. C. koseri is considered an opportunistic infection that rarely causes musculoskeletal infections. Acute gouty arthritis and septic arthritis are rarely seen occurring concomitantly in the same joint and are often difficult to differentiate due to similar findings on exam and imaging. The present case illustrates that osteomyelitis with an opportunistic organism can present concomitantly with acute gouty arthritis, and the diagnosis of one should not exclude the other.