|LETTER TO EDITOR
|Year : 2016 | Volume
| Issue : 2 | Page : 128-129
A case of community-acquired multi-drug resistant Acinetobacter lwoffii bacteremia
Rudrajit Paul1, Jayanti Ray1, Sagnik Mondal1, Jayati Mondal2
1 Department of Medicine, Medical College, Kolkata, West Bengal, India
2 Department of Gynecology and Obstetrics, Matri Bhavan Hospital, Kolkata, West Bengal, India
|Date of Web Publication||24-May-2016|
Department of Medicine, Medical College, 88, College Street, Kolkata - 700 073, West Bengal
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Paul R, Ray J, Mondal S, Mondal J. A case of community-acquired multi-drug resistant Acinetobacter lwoffii bacteremia. J Med Soc 2016;30:128-9
|How to cite this URL:|
Paul R, Ray J, Mondal S, Mondal J. A case of community-acquired multi-drug resistant Acinetobacter lwoffii bacteremia. J Med Soc [serial online] 2016 [cited 2021 Apr 12];30:128-9. Available from: https://www.jmedsoc.org/text.asp?2016/30/2/128/182926
Acinetobacter lwoffii has only recently been reported as a cause of bacteremia and sepsis.  The organism (formerly Acinetobacter calcoaceticus var. lwoffii) has long been known as a commensal flora of human skin and oropharynx.  But now, it has been found to invade into internal organs, especially in patients with another predisposing condition such as malignancy. 
We here report a case of a 21-year-old female who presented with acute onset fever and abdominal pain. She had no significant medical history and was not on any drugs. There was no recent history of trauma or surgical intervention. Initial blood reports revealed hemoglobin of 8.3 g/dl with total leukocyte count (TLC) of 56,000/cmm (neutrophil 82%). Platelet count was 120,000/cmm. Malaria antigen test, salmonella typhi IgM antibody test, and urine routine examination were all negative. Although there was no arthritis, we still did antinuclear antibody profile, which came to be negative. Blood C-reactive protein was raised at 35 mg/L (N<6). Chest X-ray and computed tomography scan of abdomen were normal with no likely focus of infection.
Finally, blood culture under aerobic conditions grew Acinetobacter spp. The biochemical reactions for identification of the organism, as depicted below, were done independently by two qualified microbiologists. The organism was a Gram-negative nonmotile Coccobacillus with catalase positive reaction. Oxidation test on Hugh Leifson medium showed the isolate to be a nonoxidizer. It grew well on MacConkey agar and did not produce acid from glucose, maltose, xylose, mannitol, or lactose. There was no fermentation in triple sugar iron agar and no production of hydrogen sulfide. Nitrate reduction was negative and finally, Simmons's citrate agar also showed no reaction. Thus, the organism was provisionally identified as A. lwoffii. Genetic sequencing and other nucleic acid tests are the gold standard for identification. However, we could not attempt it due to financial reasons.
Drug sensitivity testing was done by disc diffusion (DD) method. Earlier, the Clinical and Laboratory Standards Institute guidelines had common DD interpretive criteria for Pseudomonas and Acinetobacter. The standards were formulated primarily by studies on Enterobacteriaceae and Pseudomonas.  But recently, separate guidelines have been given for Acinetobacter sp. in 2014.  Thus, we used this standard. It revealed the organism to be resistant to all common drugs except meropenem and amikacin. It was even resistant to colistin and tigecycline. Tigecycline is a new drug and hence, its DD breakpoints are not well-defined. Hence, for this particular drug, the microbiology laboratory used the cut-off for DD suggested by a multicentric study on Acinetobacter, published in 2004. 
The patient was promptly started on a combination of meropenem and amikacin (intravenous) and by the 3 rd day, her fever came down. The TLC also came down to 18,000/cmm on the 4 th day and 5600/cmm on the 6 th day. No source of this infection could be identified.
Acinetobacter infection other than in lungs is said to be vascular catheter-related. But often, no source of the infection is identified. Earlier, A. baumannii was the main infecting organism of this group, but now, nonbaumannii Acinetobacters are also increasing in incidence. A. lwoffii is important in this group because of its propensity to multi-drug resistance.  In one study from Italy, 40% of the isolated strains were multi-drug resistant with even higher percentage of cephalosporin resistance. 
The organism in our patient was also resistant to most drugs except meropenem and aminoglycosides. It was even resistant to colistin and tigecycline. This ominous trend of colistin resistance in Acinetobacter has recently emerged as a new threat all over the world, especially in Asia.  Colistin resistance was first reported in the genus in 1999. But by 2009, some studies reported a colistin resistance rate as high as 40%.  Tigecycline resistance has also been reported. Other authors have also used DD, like us, to document tigecycline sensitivity in Acinetobacter.  This drug resistance pattern is really worrisome because these two are almost the last line antibiotics in use now. Furthermore, the resistance can spread to other species by plasmids. Hence, Acinetobacter treatment should always be with more than one drug to prevent the development of resistance. Usually, carbapenem resistance in Acinetobacter is more common than colistin resistance.  However, the organism isolated in our patient was colistin resistant, but meropenem sensitive. Although no conclusion can be drawn from a single case, still this is a novel finding and needs further studies.
A. lwoffii is also implicated in other infections such as cellulitis. However, since the reported number of cases is very small, the exact extent of this bacterial infection is still unknown. The organism is difficult to identify in clinical laboratories and often specialized tests are needed. However, sometimes, other bacteria are also misdiagnosed as A. lwoffii.
A. lwoffii has very rarely been reported from India. In one study from South India, A. lwoffii was isolated in 10.2% of clinical Acinetobacter specimens. There was significant antibiotic resistance and mortality was 33%.  Respiratory tract was the most common source of bacteremia. However, in our patient, we could not identify any source. Furthermore, in most other series, the organism is hospital-acquired, although in our case, it was community-acquired.
Thus, our case is unique in being a community acquired multi-drug resistant A. lwoffii infection in an immunocompetent person, with bacterial resistance to colistin, but sensitivity to meropenem. We present this case to sensitize clinicians to the threat of this emerging multi-drug resistant organism.
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Conflicts of interest
There are no conflicts of interest.
| References|| |
Ku SC, Hsueh PR, Yang PC, Luh KT. Clinical and microbiological characteristics of bacteremia caused by Acinetobacter lwoffii
. Eur J Clin Microbiol Infect Dis 2000;19:501-5.
Swenson JM, Killgore GE, Tenover FC. Antimicrobial susceptibility testing of Acinetobacter
spp. by NCCLS broth microdilution and disk diffusion methods. J Clin Microbiol 2004;42:5102-8.
Patel JB, Cockerill FR, Alder J, Bradford PA, Eliopoulos GM, Hardy DJ, et al
. M100-S24: Performance Standards for Antimicrobial Susceptibility Testing; Twenty-Fourth Informational Supplement. Philadelphia: Clinical and Laboratory Standards Institute; 2014.
Jones RN, Ferraro MJ, Reller LB, Schreckenberger PC, Swenson JM, Sader HS. Multicenter studies of tigecycline disk diffusion susceptibility results for Acinetobacter
spp. J Clin Microbiol 2007;45:227-30.
Tega L, Raieta K, Ottaviani D, Russo GL, Blanco G, Carraturo A. Catheter-related bacteremia and multidrug-resistant Acinetobacter lwoffii
. Emerg Infect Dis 2007;13:355-6.
Cai Y, Chai D, Wang R, Liang B, Bai N. Colistin resistance of Acinetobacter baumannii
: clinical reports, mechanisms and antimicrobial strategies. J Antimicrob Chemother 2012;67:1607-15.
Navon-Venezia S, Leavitt A, Carmeli Y. High tigecycline resistance in multidrug-resistant Acinetobacter baumannii
. J Antimicrob Chemother 2007;59:772-4.
Miyakis S, Pefanis A, Tsakris A. The challenges of antimicrobial drug resistance in Greece. Clin Infect Dis 2011;53:177-84.
Prashanth K, Badrinath S. Nosocomial infections due to Acinetobacter
species: Clinical findings, risk and prognostic factors. Indian J Med Microbiol 2006;24:39-44.