|Year : 2014 | Volume
| Issue : 3 | Page : 327-330
Myroides odoratus and Chryseobacterium indologenes: Two rare isolates in the immunocompromised
R Deepa1, KG Venkatesh1, J Durdana Parveen2, S Thasneem Banu3, G Jayalakshmi4
1 Assistant Professor Institute of Microbiology, Madras Medical College and Rajiv Gandhi Government General Hospital, Chennai, Tamil Nadu, India
2 Postgraduate, Institute of Microbiology, Madras Medical College, Chennai, Tamil Nadu, India
3 Professor, Institute of Microbiology, Madras Medical College, Chennai, Tamil Nadu, India
4 Director and Professor, Institute of Microbiology, Madras Medical College, Chennai, Tamil Nadu, India
|Date of Submission||23-Jun-2013|
|Date of Acceptance||24-Oct-2013|
|Date of Web Publication||10-Jul-2014|
Assistant Professor Institute of Microbiology, Madras Medical College and Rajiv Gandhi Government General Hospital, Chennai, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Myroides spp and Chryseobacterium spp are uncommon clinical isolates, though more frequently reported to cause infections than other pigmented non-fermentors. Two cases of Myroides odoratus and Chryseobacterium indologenes infection in a diabetic with pulmonary tuberculosis and a patient with de-compensated alcoholic liver disease, respectively, are reported here. Anti-microbial susceptibility testing of the isolates was performed by determining the minimum inhibitory concentration. The clinical picture, characteristic features of the isolates and the antibiotic susceptibility pattern are discussed briefly.
Keywords: Chryseobacterium indologenes, myroides odoratus, minimum inhibitory concentration
|How to cite this article:|
Deepa R, Venkatesh K G, Parveen J D, Banu S T, Jayalakshmi G. Myroides odoratus and Chryseobacterium indologenes: Two rare isolates in the immunocompromised. Indian J Med Microbiol 2014;32:327-30
|How to cite this URL:|
Deepa R, Venkatesh K G, Parveen J D, Banu S T, Jayalakshmi G. Myroides odoratus and Chryseobacterium indologenes: Two rare isolates in the immunocompromised. Indian J Med Microbiol [serial online] 2014 [cited 2020 Oct 25];32:327-30. Available from: https://www.ijmm.org/text.asp?2014/32/3/327/136592
| ~ Introduction|| |
Genera Myroides and Chryseobacterium are members of the family Flavobacteriaceae and comprise of a heterogeneous group of non-motile, oxidase positive non-fermentative Gram-negative bacilli. The species belonging to these genera were earlier included in the genus Flavobacterium and later re-classified based on genotypic, chemotaxonomic and phenotypic data. 
Myroides and Chryseobacterium spp are not part of human flora and are commonly found in soil and water. They behave as low grade pathogens occurring in immunocompromised patients and are resistant to many anti-microbial agents. ,
We report two cases of infections caused by Myroides odoratus and Chryseobacterium indologenes in immunocompromised patients. These cases are presented to highlight the increasing incidence of infections due to these seemingly rare isolates. A brief review of literature and the anti-microbial susceptibility patterns are discussed.
| ~ Case Report|| |
A 45-year-old female was admitted with high grade intermittent fever with chills and rigor for 10 days and cough with breathlessness on exertion for 4 days. She was a known diabetic on oral hypoglycaemic agents since one year. On examination patient was febrile, with tachycardia. Respiratory examination revealed crepitations in the right supraclavicular region. Chest X-ray showed small cavity in upper zone and hilar opacity with cavitation in midzone of right lung. Computed tomography (CT) chest revealed right lobar consolidation with cavity. Sputum smear examination by Ziehl-Neelsen staining showed acid fast bacilli (RNTCP grade 2). Gram stain of sputum showed more than 25 pus cells/LPF with many Gram-negative bacilli and normal flora. The patient was started on anti-tuberculous treatment (ATT) and empiric therapy with parenteral Cefotaxime.
Laboratory investigations revealed neutrophilic leucocytosis, elevated ESR, elevated fasting and post-prandial blood sugar levels (130 and 220 mg/L, respectively). Liver and renal function tests were normal. Antibodies to HIV 1 and 2 were non-reactive. Sputum culture yielded heavy growth of 2-3 mm domed translucent pale yellow pigmented colonies with fruity odour on nutrient agar after 24 h of incubation at 37°C with no haemolysis on sheep blood agar [Figure 1]. There was no growth on MacConkey agar. Colonies consisted of non-motile, short Gram-negative bacilli, which were catalase and oxidase positive, indole negative, Triple sugar iron (TSI)-non-fermentor reaction, urease positive, starch hydrolysis negative, oxidative fermentative test (OF) for glucose not utilised, nitrate reduction test negative, gelatin liquefaction test positive, resistance to polymyxin B 300 units and penicillin. The organism was presumptively identified as Myroides spp. Repeat culture of sputum on the third day yielded the same organism. Correlating the culture reports, persistence of fever, diabetic status and underlying pulmonary tuberculosis, a secondary bacterial pulmonary infection was suspected. Blood culture did not yield growth.
|Figure 1: Non-haemolytic pale yellow pigmented colonies of Myroides odoratus on sheep blood agar|
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The minimum inhibitory concentration (MIC) of the isolate was determined by broth microdilution (Neg BP Combo Panel Type 34, Microscan, Siemens Health Care Diagnostic Inc., West Sacramento, CA959691, USA) using Clinical Laboratory Standards Institute (CLSI) interpretative standards for other non-Enterobacteriaceae and ATCC Pseudomonas aeruginosa 27853 as control.  The isolate was susceptible to Ciprofloxacin (<1 μg/ml), Levofloxacin (<2 μg/ml), Trimethoprim-sulphamethoxazole (<2/38 μg/ml), Amikacin (<16 (μg/ml), Tobramicin (<4 μg/ml), Imipenem (<4 μg/ml), Meropenem (<4 μg/ml) and Piperacillin-Tazobactam (<16/4 μg/ml) and resistant to Gentamicin (>8 μg/ml) Tetracycline (32 μg/ml) Aztreonam (>16 μg/ml), Cefipime (>16 μg/ml), Ceftazidime (>16 μg/ml) Cefotaxime (>32 μg/ml), Ceftriaxone (>32 μg/ml).
Antibiotics were changed to parenteral Amikacin based on susceptibility report. The patient was afebrile after 4 days and showed clinical improvement. Antibiotic was continued for 7 days, she was discharged with advice to continue ATT.
A 45-year-old male presented with abdominal distension and swelling in both legs for 1 month, fever and oliguria for 1 week. He was a known alcoholic for past 20 years. On examination, patient was drowsy, responding to painful stimuli, anaemic and icteric. Abdomen was distended, with hepatosplenomegaly and moderate ascites. He was hospitalised elsewhere 2 weeks ago and ascitic tap done, details of which were not available. The patient was clinically diagnosed with alcohol-induced decompensated liver disease with ascites and hepatic encephalopathy.
Investigations revealed Hb - 6.2 g%, total WBC count of 12600/cumm, neutrophilia (83%), ESR - 70 mm, total bilirubin - 8.1 g/dl, direct bilirubin - 4.7 g/dl, elevated liver enzymes and reversal of albumin globulin ratio. HBsAg and anti-HCV antibodies were negative. Gram stain of the ascitic fluid showed few pus cells with Gram-negative bacilli. Patient was treated with parenteral Cefotaxime, Lactulose, Sspironolactone, vitamin K and fresh frozen plasma. Culture revealed 2-3 mm translucent deep yellow pigmented colonies on nutrient agar [Figure 2] with beta haemolysis on sheep blood agar after 24 h of incubation at 37°C aerobically. There was no growth on MacConkey agar. The colonies consisted of non-motile, Gram-negative bacilli, which were catalase and oxidase positive, indole and urease positive, TSI - not fermented, OF glucose oxidatively utilised, nitrate reduction test negative, starch and gelatin liquefaction test positive, resistant to polymyxin B 300 units and penicillin 10 IU. The organism was presumptively reported as Chryseobacterium spp.
|Figure 2: Translucent deep yellow pigmented colonies on nutrient agar of Chryseobacterium indologenes|
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The MIC of the isolate was determined by broth microdilution (Neg BP Combo Panel Type 34, Microscan, Siemens Health Care Diagnostic Inc., West Sacramento, CA 959691, USA) as per the CLSI guidelines for non-Enterobacteriaceae and ATCC Pseudomonas aeruginosa 27853 as the control. . The isolate was susceptible to Ciprofloxacin (<1 μg/ml), Levofloxacin (<2 μg/ml) Trimethoprim-Sulphamethoxazole (2/38 μg/ml), Cefipime (4 μg/ml), Ceftazidime (<8 μg/ml), Cefotaxime (8 μg/ml), Ceftriaxone (<8 μg/ml), Tetracycline (<4 μg/ml), Imipenem (<4 μg/ml), Meropenem (<4 μg/ml), Piperacillin-Tazobactam (<16/4 μg/ml) and resistant to Gentamicin (>8 μg/ml), Aztreonam (>16 μg/ml), Amikacin (>32 μg/ml), Tobramycin (>8 μg/ml). There was no growth in blood culture. The general condition of the patient deteriorated due to hepatic failure and he died on the third day. The sample could not be repeated.
Both the isolates were speciated and confirmed as Myroides odoratus (Case 1) and Chryseobacterium indologenes (Case 2) by the Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu.
| ~ Discussion|| |
Most of the clinically significant members of the family Flavobacteriaceae produce yellow pigmented colonies on blood agar, do not reduce nitrate, fail to grow on MacConkey agar and polymyxin resistant. Genus Myroides (Myron - perfume, oides - resembling) can be further recognised by the characteristic fruity odour, positive gelatin hydrolysis and urease tests and inability to produce acid in OF glucose. Two species produce infections namely Myroides odoratus and M. odoratimimus, which cannot be differentiated phenotypically. 
The earliest recorded isolation of M. odoratus in 1929 by Stutzer et al., was followed by reports of isolation from urinary tract infections, cellulitis, bacteraemia, necrotising fasciitis, septic shock and pneumonia. , Despite their low virulence, Myroides spp are multi-drug resistant. The organism is usually susceptible to Trimethoprim-Sulphamethoxazole and Ciprofloxacin, though a study by Fraser et al., reported susceptibility to ciprofloxacin in only one-quarter of the isolates tested.  Our isolate was susceptible to these agents, Piperacillin-Tazobactam, Amikacin and penems. Resistance to betalactam agents, Gentamicin and Tetracycline was observed.
Among the six species of the genus Chryseobacterium defined in 1994, C. indologenes is the most frequent human isolate, which is recognised by the ability to produce indole. As they exist in water systems and on wet surfaces in the hospital environment, their recovery may represent colonisation in the absence of clinical disease. They are reported to cause bacteraemia, ventilator-associated pneumonia, surgical wound infections, community-acquired pyonephrosis and nosocomial infections linked to the use of catheter-related devices, but the mortality is relatively low. , Chryseobacterium indologenes bacteraemia in a pre-term baby and urinary tract infection in a girl operated for renal calculi have been reported from India. ,
Community-acquired peritonitis with secondary bacteraemia due to Chryseobacterium indologenes has been reported by Hsueh et al., in a 44-year-old male with diverticulitis.  Our patient had a recent history of hospitalisation and the peritonitis may have been nosocomially acquired. The significance of the isolate was ascertained by the presence of pus cells and Gram-negative bacteria in the direct gram stain.
Chryseobacterium spp are intrinsically resistant to most betalactams including carbapenems due to the production of chromosomally mediated metallobetalactamase.  The most active agents against Chryseobacterium spp are the quinolones and trimethoprim-sulphamethoxazole, while aminoglycosides, tetracyclines, carbapenems and glycopeptides are the least active.  Our isolate was resistant to aminoglycosides and aztreonam.
In vitro susceptibility testing of M. odoratus and C. indologenes is done by various methods as there are no established interpretative criteria by the CLSI.  Broth microdilution, agar dilution and disc diffusion have been used to guide therapy for these infections. ,,,, Our isolates were tested against a panel of anti-microbial agents with activity against Gram-negative bacteria by broth microdilution (automated) using CLSI interpretative standards for non-Enterobacteriaceae.
| ~ Conclusion|| |
Myroides odoratus and Chryseobacterium indologenes are increasingly playing a role in infections especially in the immunocompromised. The typical growth characteristics make them easily identifiable in the microbiology laboratory. As determination of MIC for guiding therapy is laborious and impractical in routine diagnostic laboratory, disc diffusion method criteria need to be standardised for anti-microbial susceptibility testing of these isolates.
| ~ Acknowledgement|| |
We sincerely thank Dr. V. Balaji, Professor of Microbiology, Christian Medical College and Hospital, Vellore for speciation and confirmation of the isolates.
| ~ References|| |
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