Citrobacter braakii CLABSI in a hematopoietic stem cell transplant patient

INTRODUCTION

Citrobacter bacteria are gram-negative anaerobic bacilli commonly found in water, soil, food, and the intestinal tracts of animals and humans. Patients at highest risk of these nosocomial infections include neonates and adults who are ≥65 years of age, debilitated, or immunocompromised. Citrobacter braakii (C. braakii), specifically, has been reported to cause sepsis in immunocompromised patients. Herein, we describe a case of an allogeneic stem cell transplant (SCT) adult patient with C. braakii bloodstream infection.

CASE REPORT

We report our experience managing a central line-associated bloodstream infection (CLABSI) due to C. braakii in an allogeneic SCT patient.Management and Outcomes: Our patient was initially managed with cefepime. The central venous catheter (CVC) was removed. Blood cultures cleared 24 hours after antibiotic initiation. Therapy was transitioned to oral levofloxacin once susceptibilities resulted.

DISCUSSION

The course of this patient highlights the important relationship between an unusual pathogen, C. braakii, in an immunocompromised allogeneic SCT patient. In our case, the source of the bacteremia was most likely a CLABSI given the positive catheter tip cultures. Although this report describes the successful utilization of cefepime and levofloxacin in the treatment of C. braakii infection, caution should be exercised when choosing empiric antimicrobial therapy as AmpC resistance. This clinical scenario can aid health care providers in making informed treatment decisions when faced with patients diagnosed with this relatively uncommon pathogen. Further reports should be published to determine C. braakii bacteremia management in hematopoietic stem cell transplant patients.

Novel IncR/IncP6 Hybrid Plasmid pCRE3-KPC Recovered from a Clinical KPC-2-Producing Citrobacter braakii Isolate

Reports of human-pathogenic C. braakii strains, especially of strains showing resistance to carbapenems, are rare. To the best of our knowledge, our results represent the first detection of carbapenemase gene bla_KPC-2 in C. braakii strains. In addition, we have studied detailed genetic characteristics of the novel IncR/IncP6 hybrid plasmid pCRE3-KPC, which was isolated from a clinical multidrug-resistant Citrobacter braakii CRE3 strain. Our results may provide further insight into the horizontal transfer of multidrug resistance genes in bacteria and into the genomic diversity and molecular evolution of plasmids.

Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae have become widespread in hospitals and the environment. Here, we describe a bla_KPC-2-carrying plasmid called pCRE3-KPC, which was recovered from a clinical multidrug-resistant Citrobacter braakii CRE3 strain in China. The complete nucleotide sequence of pCRE3-KPC was determined by combining MiSeq and MinION sequencing and then compared with those of three related plasmids. Plasmid conjugal transfer and electroporation tests, modified carbapenem inactivation method, and bacterial antimicrobial susceptibility test were carried out. We compared this plasmid with three related plasmids to verify that the backbone of pCRE3-KPC was composed of the backbones of the IncR plasmid and IncP6 plasmid. Further bioinformatics analysis showed that pCRE3-KPC carried two resistance-related regions (the bla_KPC-2 gene cluster and the aacC2-tmrB-related region). The aacC2-tmrB-related region included two novel insertion sequences (ISCfr28 and ISCfr16).

IMPORTANCE Reports of human-pathogenic C. braakii strains, especially of strains showing resistance to carbapenems, are rare. To the best of our knowledge, our results represent the first detection of carbapenemase gene bla_KPC-2 in C. braakii strains. In addition, we have studied detailed genetic characteristics of the novel IncR/IncP6 hybrid plasmid pCRE3-KPC, which was isolated from a clinical multidrug-resistant Citrobacter braakii CRE3 strain. Our results may provide further insight into the horizontal transfer of multidrug resistance genes in bacteria and into the genomic diversity and molecular evolution of plasmids.

Microbiological survey of sugar gliders (Petaurus breviceps) kept as pets in Italy

The sugar glider (Petaurus breviceps) is a small, arboreal, nocturnal, gliding mammalian possum belonging to the marsupial infraclass. Exotic marsupials, including sugar gliders, are becoming popular companion pets and, consequently, the risk of potential infections that can be transmitted to humans should be investigated. Data on the role of the sugar glider as a possible carrier of pathogenic and zoonotic bacteria are scarce and fragmentary. Therefore, this study is aimed at evaluating the prevalence of potentially zoonotic bacteria (Salmonella spp., Escherichia coli, Campylobacter spp., Pseudomonas spp., Klebsiella spp., Listeria monocytogenes and Yersinia enterocolitica) in 64 sugar gliders kept as pets in Italy. The highest prevalence of infection pertained to members of the family Enterobacteriaceae, in particular Citrobacter spp. (50%), Enterobacter spp. (28·1%) and Klebsiella pneumoniae (15·6%); Pseudomonas aeruginosa was isolated from 10 out of 64 samples (15·6%). All strains of Klebsiella pneumoniae exhibited some level of resistance to multiple antimicrobials (ampicillin, amoxicillin-clavulanic acid and doxycycline). SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study show that sugar gliders may act as carriers of potentially pathogenic agents for humans and other animal species, therefore caution should be exercised in the handling and contact with these animals.

Citrobacter braakii bacteremia-induced septic shock after colonoscopy preparation with polyethylene glycol in a critically ill patient: a case report

Background

Polyethylene glycol (PEG) is widely used for bowel cleaning in preparation for colonoscopy because of its safety. Septic shock after PEG preparation is an extremely rare complication. Herein, we describe a case of septic shock that occurred immediately after colonoscopy preparation with PEG.

Case presentation

A 75-year-old Japanese male who had previously developed diabetes after total pancreatectomy received PEG in preparation for colonoscopy. He had been admitted to the emergency intensive care unit 4 days earlier due to hematochezia presenting with shock. He ingested PEG to prepare for a colonoscopy examination, which was performed to identify the source of his bleeding over a 5-h period, but suddenly exhibited septic shock and markedly elevated procalcitonin levels. A blood culture subsequently revealed Citrobacter braakii. Immediate resuscitation and intensive care with appropriate antibiotics improved his condition.

Conclusions

Clinicians should be aware of the possibility of deteriorating conditions after bowel preparation with PEG among severely ill patients with recent episodes of hemorrhagic shock.

Bacteremia due to Citrobacter braakii: A case report and literature review

Among the Citrobacter genus, the most commonly isolated bacteria from human specimens are Citrobacter freundii and Citrobacter koseri, and previous cases of infection due to Citrobacter braakii have been rarely reported. We present a case of bacteremia due to C. braakii in a 38-year-old woman with cervical cancer. She was admitted to our hospital with complaints of a fever, chills, and nausea. Blood culture results showed gram-negative bacilli identified as C. braakii via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis, although biochemical testing findings were suggestive of C. freundii. Since a rare pathogen was detected in the present case and the results of additional biochemical studies were suggestive of both C. braakii and Citrobacter farmeri, genetic analysis was conducted. Finally, the gram-negative bacilli were confirmed as C. braakii, a member of the C. freundii complex since 1993, by 16S ribosomal RNA gene sequencing analysis. The gastrointestinal tract was considered the portal of entry, because the patient had a rectal fistula and other cultures such as urine and vaginal discharge incubated species other than C. braakii. The patient recovered after receiving treatment with ciprofloxacin for 14 days. The epidemiology and clinical characteristics of C. braakii infection are still unknown because of the limitations in accurate identification by using currently available commercial biochemical testing and previously, only 6 cases of C. braakii infection have been reported. Physicians should focus on this species, because it causes community-acquired infections, although further studies are needed to clarify the clinical characteristics of C. braakii infections.

Citrobacter peritonitis: two cases and review of the literature

One of the uncommon gram negative organisms causing peritonitis in peritoneal dialysis patients is Citrobacter. Because of this organism's resistant nature, treatment for Citrobacter peritonitis may be difficult, and removal of the catheter may be necessary in refractory cases. Here we present 2 cases of peritonitis caused by this organism and fully treated with antibiotics. The literature contains only a limited number of reports on Citrobacter peritonitis, mostly case reports or portions of general papers about the microbiological spectrum of peritonitis in the relevant units. Until enough data about this micro-organism have been accumulated to map out an approach, it is wise to individualize treatment by watching the response of the patient during the wait for the antibiogram result and not to hesitate to remove the catheter if the clinical situation deteriorates.

Bacteraemia caused by non-freundii, non-koseri Citrobacter species in Taiwan

This study analysed the clinical characteristics of bacteraemia due to unusual Citrobacter species. All non-freundii and non-koseri Citrobacter isolates were identified to species level by two commercial identification methods and 16S rRNA gene sequence analysis. A total of 306 patients with Citrobacter spp. bacteraemia were identified from January 2000 through December 2009. Four patients (1.3%) had C. braakii bacteraemia, and one had C. amalonaticus and C. sedlakii sepsis, respectively. Misidentification as non-freundii and non-koseri Citrobacter spp., which occurred in eight isolates with the Phoenix automated system PMIC/ID-30 and three with the Vitek II system, occurred in five of six infection episodes. Among the six patients with bacteraemia caused by non-freundii and non-koseri Citrobacter spp., five (83.3%) had healthcare-associated infection and five (83.3%) infections were secondary to intra-abdominal infection. Cancer and liver cirrhosis were the commonest underlying diseases. An attributable mortality was 33.3%. Antimicrobial susceptibility testing showed that the resistance patterns varied among different Citrobacter species. Non-freundii and non-koseri Citrobacter species are difficult to identify and are a rare cause of intra-abdominal infections with secondary healthcare-associated bacteraemia in immunocompromised patients.

Antibiotic susceptibility profiles of uncommon bacterial species causing severe infections in Italy

This study presents the results of the italian "Severe infections project" involving bacteria that can be considered rare causes of disease. we isolated 30 uncommon human pathogens from a total of 60 strains (1.2% of all the isolates). The most frequent sources of uncommon human pathogens were primary bloodstream infections (48.3%) and pneumonia (20%). Species such as Comamonas testosteroni, Enterococcus hirae, Kluyvera ascorbata, Kluyvera cryocrescens, Leclercia adecarboxylata and Ochrobactrum anthropi were recovered from bacteremia patients. Clinically useful antimicrobial agents were tested against each isolate. Resistance to 4 or more antibiotics tested was found in Achromobacter xylosoxidans, O. anthropi, Pseudomonas stutzeri, Citrobacter braakii, Enterobacter sakazakii, K. ascorbata, Proteus penneri and Serratia plymuthica. About 16% of the Gram-negative species were resistant to third-generation cephalosporins and 28.6% of the staphylococci were oxacillin-resistant. the results from this study offer indications for empirical therapy for severe infections from uncommon human pathogens.