Leclercia adecarboxylata

While authorising the urine result – I found that a urine sample from the community has grown Leclercia adecarboxylata. The patient is a young female complaining of increased frequency. The number of organisms in the urine was >100,000 organisms/ml.
What is the significance?

The bacteria

 Previously known as Escherichia adecarboxylata, it now belongs to a new genus Leclercia (family Enterobacteriaceae).
First described by Leclerc in 1962 as ubiquitous in nature (Food, water etc., animals – snails).
It is also a member of the gut flora (commensal).

Identification

A motile, aerobic, Gram-negative bacillus

Positive for	Negative for
Indole production, methyl red, growth in the presence of KCN, malonate utilization, esculin hydrolysis, gas and acid production from D-glucose and D-lactose	Voges-Proskauer, citrate (Simmons), H2S (Kligler), amino acid decarboxylases, phenylalanine deaminase, gelatinase and DNase

Modern identification methods like MALDI-TOF  and 16 s rRNA gene sequencing can distinguish it from phenotypically similar organisms.

Pathogenesis & pathology

Leclercia is an environmental organism but also a member of human bowel flora.
It is considered an opportunistic pathogen, and most cases are reported from immunocompromised patients [Hess, 2008].
It is often associated with polymicrobial infection, especially in immunocompetent hosts.
It is a possibility that the organism is often misidentified as E coli as they share many biochemical features.

The reported cases are –

• Pharyngeal and peri-tonsillar abscess [Bali et al., 2013], 
• Endocarditis with embolic complication [Bora el al, 2009]
• Polymicrobial wound infection and pneumonia [Temesgen et al., 1997] [Greco et al., 2001]
• Cholecystitis (polymicrobial) [de Baere 2001]
• UTI With Ent faecalis in case of bladder tumour [Sawamura et al., 2005]
• Bacterial peritonitis in a peritoneal dialysis patient [Rodriguez et al. 2001]
• Bacteraemia in the presence of
  – preexisting diseases like cancer, leukaemia, renal failure, haematopoietic stem cell transplant and cirrhosis or
  – conditions associated with skin barrier dysfunction, including trauma, burn wounds, peritoneal dialysis and cellulitis [Anuradha 2014] [Matsuura 2018] [Temesgen et al., 1997]

In some cases, the bacteremia associated with Leclercia has been reported to be polymicrobial.

So, in summary, Leclercia can cause various infections, usually associated with an immunocompromised state; however, infections have been reported in immunocompetent people. Infections are often polymicrobial.

Treatment

Leclercia adecarboxylata is susceptible to most common antibiotics; however, resistance to various antibiotic classes has been reported.
Stock et al. analysed the natural susceptibility of 101 strains by broth microdilution. The pattern is not unexpected from Enterobacteriaceae except for natural resistance to fosfomycin.
Note – the only azithromycin amongst all macrolides has been listed as susceptible. Dicationic azithromycin penetrates Enterobacteriaceae hydrophilic outer membrane and acidic lipopolysaccharide more efficiently than other hydrophobic macrolides.

Naturally sensitive to	Naturally resistant to
Tetracyclines, Aminoglycosides*, All but two beta-lactams, Quinolones*, Trimethoprim, Cotrimoxazole, Chloramphenicol, Nitrofurantoin and Azithromycin.	Penicillin G, oxacillin, Erythromycin, roxithromycin, clarithromycin, ketolides, Lincosamides, Streptogramins, Linezolid, Glycopeptides, Rifampicin, fusidic acid and fosfomycin.

ESBL production and resistance to aminoglycosides, quinolones, and aztreonam have been reported by various authors [Hurley 2015]

Cristina Riazzo (2017) reported a case of NDM from Spain, which was resistant to all beta-lactams, fluoroquinolones, trimethoprim-sulfamethoxazole, gentamicin and tobramycin, and only remained sensitive to tigecycline, amikacin and colistin. This patient was successfully treated with Imipenem/ cilastatin and amikacin. Another case of NDM-1-producing Leclercia was reported from China in 2015.