Treatment of Citrobacter kosen Infection with Ciprofloxacin and Cefotaxime in a Preterm Infant

Emergence of carbapenem-resistant Citrobacter spp. across human, animal, and water environments in China

OBJECTIVE

With the rise of carbapenem-resistant Citrobacter spp. (CRC), it is essential to investigate their distribution and resistance characteristics across diverse ecological niches. This study aims to collect CRCs from humans, animals, and water environments to analyze their epidemiology, genetic characteristics, and resistance mechanisms, providing insights into transmission dynamics.

METHODS

CRCs were isolated from different samples using methods including filtration, enrichment, screening, and purification. Antimicrobial susceptibility tests were conducted using the broth microdilution method. Transconjugation experiments were performed through filter mating. Whole genome sequencing and bioinformatics analysis were carried out to analyze genomic features of CRCs.

RESULTS

Total of 171 CRCs were isolated from diverse Chinese provinces between 2016 and 2023. All strains are classified into seven Citrobacter species. Citrobacter freundii is the most common (76.02%), with ST116 and ST22 being the predominant strains. Among all strains, 63.16% carried blaNDM-1, and 41.52% carried blaKPC-2. Hospital wastewater was the primary source of CRCs harbouring two carbapenemase genes, with the most prevalent combination being blaNDM-1 and blaKPC-2 (85.71%, 24/28). All strains showed multi-drug resistance, with over 95% resistant to various carbapenems. Transconjugation experiments showed that carbapenemase genes in the majority of CRCs were located on the plasmids and can be transferred to the recipient strains. Phylogenetic analysis displayed that clonal transmission was observed among a few CRCs.

CONCLUSIONS

Multiple mobile genetic elements mediate the spread and prevalence of carbapenem resistance in Citrobacter spp. Monitoring carbapenemase genes and CRCs across ecological niches is needed to controlling carbapenem resistance, particularly in high-risk sources like hospital wastewater.

Genomic analysis of Citrobacter from Australian wastewater and silver gulls reveals novel sequence types carrying critically important antibiotic resistance genes

Antimicrobial resistance (AMR) is a major public health concern, and environmental bacteria have been recognized as important reservoirs of antimicrobial resistance genes (ARGs). Citrobacter, a common environmental bacterium and opportunistic pathogen in humans and other animals, has been largely understudied in terms of its diversity and AMR potential. Whole-genome (short-read) sequencing on a total of 77 Citrobacter isolates obtained from Australian silver gull (Chroicocephalus novaehollandiae) (n = 17) and influent wastewater samples (n = 60) was performed, revealing a diverse Citrobacter population, with seven different species and 33 sequence types, 17 of which were novel. From silver gull using non-selective media we isolated a broader range of species with little to no mobilised ARG carriage. Wastewater isolates (selected using Carbapenem- Resistant Enterobacterales (CRE) selective media) carried a heavy burden of ARGs (up to 21 ARGs, conferring resistance to nine classes of antibiotics), with several novel multidrug-resistant (MDR) lineages identified, including C. braakii ST1110, which carried ARGs conferring resistance to eight to nine classes of antibiotics, and C. freundii ST1105, which carried two carbapenemase genes, blaIMP-4 in class 1 integron structure, and blaKPC-2. Additionally, we identified an MDR C. portucalensis isolate carrying blaNDM-1, blaSHV-12, and mcr-9. We identified IncC, IncM2, and IncP6 plasmids as the likely vectors for many of the critically important mobilised ARGs. Phylogenetic analyses were performed to assess any epidemiological linkages between isolation sources, demonstrating low relatedness across sources beyond the ST level. However, these analyses did reveal some closer relationships between strains from disparate wastewater sources despite their collection some 13,000 km apart. These findings support the need for future surveillance of Citrobacter populations in wastewater and wildlife populations to monitor for potential opportunistic human pathogens.

A brief insight into Citrobacter species - a growing threat to public health

Citrobacter spp. are Gram-negative, non-spore forming, rod-shaped, facultative anaerobic bacteria from the Enterobacteriaceae family often found in soil, sewage, sludge, water, food, and the intestinal tracts of animals and humans. Several members of Citrobacter spp. especially C. freundii, C. koseri, C. braakii are frequently detected in newborn illnesses, urinary tract infections, and patients with severe underlying conditions, including hypertension, diabetes, cancer, and respiratory infections, or those who are immunocompromised. Strains of Citrobacter spp. can spread vertically or horizontally from carriers or other hospital sources and thus cause nosocomial infections in hospital settings. A total of 19 Citrobacter genomospecies have been recognized based on genomics. It has been noted that the Citrobacter genus acquired antimicrobial resistance and virulence, including invasion, colonization, biofilm formation, and toxin production. The recent emergence and spread of antimicrobial resistance to β-lactams, carbapenems, fluoroquinolones, aminoglycosides, and colistin in Citrobacter spp. through chromosomal and plasmid-mediated resistance limits the empiric treatment options. Therefore, combination therapy involving costly and potentially hazardous antibiotics poses significant challenges in treating Citrobacter infections. Here we summarized the nomenclature of Citrobacter spp., clinical manifestations, epidemiology, pathogenesis, antibiotic resistance mechanisms, and treatments from various clinical samples. This review will expand our knowledge of the genomics and epidemiology of Citrobacter spp., enabling improved control of infections and the spread of these organisms.

Citrobacter freundii induces sepsis with new-onset status seizure in an adult: A case report and literature review

RATIONALE

Sepsis with brain abscess induced by Citrobacter freundii in adults has rarely been reported and is extremely pathogenic with a high mortality rate. Early diagnosis of the infection still remains challenging.

PATIENT CONCERNS

A 27-year-old woman was transferred to our emergency department for fever, status seizure and refractory hypotension. Administration of midazolam, propofol and sodium valproate could not attenuate the seizure except for the addition of vecuronium. The blood white blood cell count was 42.91 (109/L) with 80% neutrophils, and procalcitonin was 22.46ng/mL.

DIAGNOSES

Both deoxyribonucleic acid and ribonucleic acid of C freundii were detected in blood by metagenomic next-generation sequencing of pathogens,the diagnosis of septic shock and brain abscess caused by C freundii was highly suspected.

INTERVENTIONS

On day 1, antibiotics of cefoperazone sodium and sulbactam sodium 6g/day, immunoglobulin, and hydrocortisone were used with suspected septic shock. Continuous renal replacement therapy was used to eliminate excessive lactate, ammonia, myohemoglobin and creatinine. On day 2, a brain computed tomography scan revealed multiple patchy slightly low densities in the brain, antibiotics were adjusted to meropenem intravenously 3g/day.

OUTCOMES

On day 2, a brain computed tomography scan revealed multiple patchy slightly low densities in the brain, she died on day 3.

LESSONS

Clinicians should consider the possibility of brain abscess when evaluating a patient with new-onset dizziness, fever, seizure, or other neurologic symptoms or signs, especially for patients whose mental status changes. metagenomic next generation sequencing and resistance genes could be considered when cerebrospinal fluid or blood results are negative and clinical manifestations are highly suspected of infection or when the treatment time is limited.

New insights into Citrobacter freundii sepsis in neonates

BACKGROUND

The aim of this study was to investigate the clinical features of neonatal sepsis caused by Citrobacter freundii as well as the current status and treatment strategy for multi-drug resistance of infection with this bacterium.

METHODS

Nine newborns were diagnosed with C. freundii sepsis between January 2014 and December 2017. We collated and analyzed a range of data for these nine patients, including general information, laboratory tests during infection, blood culture and treatment.

RESULTS

One of the patients died after only 7 h of infection. In the remaining eight cases, three patients developed meningitis, although none had brain abscess. A reduction of white blood cells (WBC) was detected <24 h after the start of infection, compared with at 48-72 h, when WBC count had increased and platelets progressively decreased. In all nine cases the infection was susceptible to tigecycline and was resistant to cephalosporins, carbapenems, and quinolones. In eight cases the infection was susceptible to co-trimoxazole and in the other case it was susceptible to amikacin. Of the eight patients who were cured, three received meropenem, two received ceftriaxone, one received amikacin, and two received tigecycline.

CONCLUSION

Reduction in WBC could take place in the early stages of C. freundii infection in newborns. The incidence of brain abscess was not high, but multi-drug resistance was common. Some non-sensitive drugs can also treat C. freundii sepsis effectively.

Musculoskeletal infections associated with Citrobacter koseri

Introduction Citrobacter koseri is a well known cause of central nervous system infections in the paediatric setting. Musculoskeletal infections caused by C koseri are rare, with only 14 previously reported cases. We present the first recorded case of C koseri induced septic arthritis of the knee along with a review of the literature. Methods A search of the PubMed, Embase(®) and Google Scholar™ databases was undertaken. Only complete or near complete cases were reviewed. Findings Fourteen musculoskeletal infections were identified. Of these, five were associated with an operative procedure and five involved a septic joint. Surgical treatment was required in the majority of cases and cure was achieved in all cases following prolonged antibiotic use. Conclusions C koseri associated musculoskeletal infections may complicate primary orthopaedic procedures. The organism can present aggressively and can be difficult to identify microbiologically. It is sensitive to newer generation beta-lactams, cephalosporin-based antibiotics and timely surgery.

Favorable outcome in cerebral abscesses caused by Citrobacter koseri in a newborn infant

The treatment of brain abscesses in newborn infants is controversial. We report on a 6-week-old infant with multiple brain abscesses caused by Citrobacter koseri that resolved after treatment with combined surgical drainage and intravenous therapy with meropenem and fosfomycin.

Characterization of a virulent bacteriophage LK1 specific for Citrobacter freundii isolated from sewage water

Citrobacter freundii is a worldwide emerging nosocomial pathogen with escalating incidence of multidrug resistance. Citrobacter freundii exists in natural environment, especially in health care settings and is difficult to eradicate. Phage therapy is considered as an alternative way of controlling bacterial infections and contaminations. In this study, we have described isolation and characterization of a virulent bacteriophage LK1 capable of specifically infecting Citrobacter freundii. A virulent bacteriophage LK1, specific for Citrobacter freundii was isolated from sewage water sample. TEM showed that phage Lk1 has an icosahedral head 70 nm in diameter and short tail of 17 nm, and can be classified as a member of the Podoviridae family. Restriction analysis indicated that phage LK1 was a dsDNA virus with an approximate genome size of 20-23 kb. Proteomic pattern generated by SDS PAGE using purified LK1 phage particles, revealed three major and six minor protein bands with molecular weight ranging from 25 to 80 kDa. Adsorption rate of LK1 relative to the host bacterium was also determined which showed significant improvement in adsorption with the addition of CaCl2 . In a single step growth experiment, LK1 exhibited a latent period of 24 min and burst size of 801 particle/cell. Moreover, pH and thermal stability of phage LK1 demonstrated a pH range of 5.0-6.0 and phage viability decreased to 0% at 65 °C. When LK1 was used to infect six other clinically isolated pathogenic strains, it showed relatively narrow host range. LK1 was capable of eliciting efficient lysis of Citrobacter freundii, revealing its potential as a non-toxic sanitizer for controlling Citrobacter freundii infection and contamination in both hospital and other public environments.

[Clinical outcome and prognosis of neonatal bacterial meningitis]

OBJECTIVES

To study the epidemiological, clinical, and bacteriological aspects as well as the outcome of neonatal bacterial meningitis and analyze the factors of poor prognosis of this condition.

PATIENTS AND METHODS

We report a retrospective analysis of 44 cases of neonatal bacterial meningitis hospitalized in the pediatric unit of Tahar Sfar Hospital in Mahdia, Tunisia, between January 1996 and December 2010. Inclusion criteria were infants less than 29 days of age who were hospitalized for bacterial meningitis diagnosed on either the presence of bacteria in cerebrospinal fluid or with more than 50 cells/mm(3), predominance of neutrophils, and the protein level greater than 1.2g/l. Clinical data were obtained through the analysis of patient files. Statistical analysis was based on the Chi(2) test, and P-values less than 0.05 were considered statistically significant.

RESULTS

The incidence of neonatal bacterial meningitis was 0.49 per 1000 live births. The patients were premature in 20.4 % and low birth weight in 13.6 % of cases. The clinical presentation was not specific for most cases. The main signs at admission were hyperthermia (43.2 %), refusal to nurse (20.4 %), seizures (18.2 %), and respiratory distress (13.6 %). The cerebrospinal fluid culture was positive in 36.4 % of cases. The group B streptococcus was the most frequently isolated (62.5 %) followed by Escherichia coli (12.5 %). The association of cefotaxime-ampicillin-gentamicin was used as the first treatment in all cases. Ofloxacin was associated with initial antibiotic therapy during the first 5 days in 20.4 % of cases. The mortality rate was 15.9 % and the rate of neurological sequelae in survivors was 21.6 %. Prematurity, low birth weight, shock, respiratory distress, and pleocytosis of less than 500 cells/mm(3) were the main factors of a poor prognosis. The addition of ofloxacin to the initial antibiotic therapy was associated with a decreased rate of neurological sequelae in survivors (11 % vs. 25 %, P=0.042).

CONCLUSION

This study emphasizes the severity of neonatal bacterial meningitis with high rates of mortality and neurological sequelae, especially in premature and low birth weight infants. An early diagnosis and effective antibiotic therapy is needed to improve the prognosis.

Citrobacter freundii brain abscess in a preterm infant: a case report and literature review

Intracranial abscesses are serious conditions but uncommon in preterm neonates. Citrobacter species are an uncommon cause of bacterial meningitis in neonates, but are associated with brain abscesses in a majority of cases. We report a preterm infant who developed Citrobacter freundii meningitis with brain abscess, who was successfully treated with antibiotics and surgical drainage. The infant had normal neurological outcome at follow-up. We report this case to highlight the importance of serial neuroimaging in the diagnosis of cerebral abscess in infants with Citrobacter meningitis.

Sepsis, meningitis and cerebral abscesses caused by Citrobacter koseri

After a 36-week diamniotic dichorionic gestation, an infant was delivered by elective caesarean section due to growth restriction and altered diastolic flow in the umbilical artery. Birth weight was 2140 g. The patient was admitted for exclusive parenteral nutrition, with umbilical venous catheter placement. Sinus tachycardia and temperature instability with positive inflammatory markers occurred at 51 h. Penicillin and gentamicin were started, but 6 h later septic shock with disseminated intravascular coagulation was noted. Vancomycin and meropenem were started and penicillin suspended. Citrobacter koseri was isolated from blood culture. Generalised clonic convulsions occurred on day 4, and an electroencephalogram revealed severe encephalic dysfunction. Cerebrospinal fluid cytochemical analysis was suggestive of meningitis, although culture was negative. Cefotaxime was added to the drug regimen. Cranioencephalic MR showed a temporal abscess and diffuse hemispheric destruction, with no indications for neurosurgery. After 6 weeks of therapy, neuroimaging follow-up showed multiloculated cystic encephalomalacia. Currently, the patient is 14 months old with axial hypotonia and decreased movements. The source of infection has not been determined. Nosocomial infection cannot be excluded and vertical transmission is unlikely.

Ciprofloxacin use in neonates: a systematic review of the literature

BACKGROUND

ciprofloxacin has no marketing authorization for use in neonates worldwide but it is prescribed for the treatment of neonatal life-threatening infections, mainly in developing countries and in Europe. Given the concerns about its toxicity in this population and the necessity for its use in specific clinical situations, we conducted a systematic review of the use of ciprofloxacin in neonates.

METHODS

we performed a systematic search of PubMed, Embase, and the Cochrane Database of Systematic Reviews and bibliographies of relevant articles. We included all studies, regardless of design, that reported efficacy, safety, and pharmacokinetics of ciprofloxacin for the treatment of any neonatal infectious condition. We excluded letters, editorials, preliminary reports, and abstracts.

RESULTS

observational cohort studies, case reports, and descriptions of patient series account for all literature reviewed. Ciprofloxacin was administrated in neonates as a salvage therapy for sepsis due to multidrug-resistant strains or with signs of clinical deterioration under first-line antibiotic treatment. Initial administration was always intravenous with variable dosing schedule. Clinical response to treatment was estimated at 64% and 91% in 2 cohort studies, with a median of 83% in case series. Of the 14 case reports, 12 yielded positive clinical outcomes. No serious adverse events, particularly joint toxicity, were observed, although evaluation was predominantly clinical and follow-up limited to few months after the end of treatment.

CONCLUSIONS

the current literature provides some information to support the use of ciprofloxacin in neonates. Additional high quality studies should be undertaken to provide reliable data on pharmacokinetics, efficacy, and long-term safety.

Clinical features of neonatal sepsis caused by resistant Gram-negative bacteria

BACKGROUND

Clinical features and outcomes of neonatal sepsis caused by resistant Gram-negative bacteria are not well described in Jordan. The aim of the present study was therefore to describe microbiology and clinical features, laboratory findings and outcomes of early- and late-onset Gram-negative neonatal sepsis.

METHODS

All patients with Gram-negative bacteremia between July 2003 and June 2005 were retrospectively included. Resistance profiles, clinical features and outcomes of early and late-onset neonatal sepsis were compared.

RESULTS

A total of 79 patients (after excluding all nine cases of Gram-positive bloodstream infection (BSI) were identified as having Gram-negative BSI (25 had early-onset and 54 had late-onset neonatal sepsis). Respiratory distress, metabolic acidosis and requirement of ventilation were found in 74.7%, 40.5%, and 58.2%, respectively. Hypotension was found in 22.9% of patients. Klebsiella pneumoniae was responsible for 43 cases (54.4.2%). Klebsiella pneumoniae resistance rates to ampicillin and ceftazidime were 100% and 50%, respectively. Mortality rate was 30.9%. Forty-eight percent of deaths occurred within 3 days of sepsis. Meningitis was diagnosed in five cases. Elevated C-reactive protein (CRP) and thrombocytopenia were seen in 28% and 24% of infants with early-onset sepsis, respectively, and in 79.6%, 59.3% of infants with late-onset sepsis respectively.

CONCLUSION

Both early- and late-onset neonatal sepsis are caused by highly resistant Gram-negative bacteria. Mortality of sepsis is high. Elevated CRP and thrombocytopenia is seen more commonly in late-onset neonatal sepsis.