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 Table of Contents  
Year : 2013  |  Volume : 15  |  Issue : 1  |  Page : 25-27

Moraxella osloensis causing left subclavian artery thrombus infection

1 Department of Microbiology, Sree Chitra Thirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India
2 Department of CardioVascular and Thoracic Surgery, Sree Chitra Thirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India

Date of Web Publication3-Aug-2013

Correspondence Address:
Kavita Raja
Department of Microbiology, Sree Chitra Thirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0972-1282.116099

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A case of left subclavian artery aneurysm with thrombus from which Moraxella group was recovered on culture is described. Patient had presented with life threatening hemoptysis, which on computed tomography (CT) scan evaluation of the chest, revealed a fistulous communication between aneurysm from the origin of left subclavian artery and segmental left upper lobe bronchus. Biochemically on the Vitek system and by growth characteristics organism present was identified as Moraxella osloensis. It was highly sensitive to all antibiotics tested. Cocci with exactly the same morphology could be seen in the Gram stain of a sputum sample from the patient. Postoperative antibiotics eradicated the bacteria and so no growth occurred on culture of the sputum. To our knowledge, this is the first ever time Moraxella species has been isolated from an arterial thrombus, particularly so from a person with normal heart valves.

Keywords: Aneurysm with thrombus, Moraxella osloensis, bronchus, sputum

How to cite this article:
Raja K, Antony M, Shashidhar K P, Unnikrishnan M. Moraxella osloensis causing left subclavian artery thrombus infection. J Acad Clin Microbiol 2013;15:25-7

How to cite this URL:
Raja K, Antony M, Shashidhar K P, Unnikrishnan M. Moraxella osloensis causing left subclavian artery thrombus infection. J Acad Clin Microbiol [serial online] 2013 [cited 2023 Jun 3];15:25-7. Available from: https://www.jacmjournal.org/text.asp?2013/15/1/25/116099

  Introduction Top

Bacteria of the genus  Moraxella More Details are Gram-negative coccobacilli initially included under  Neisseria More Details, then under Branhamella, and finally under Moraxella. They are normal commensals of the human upper respiratory tract and very uncommonly recovered from the skin and urogenital tract. Moraxella catarrhalis is the human pathogen that causes otitis media, lower respiratory tract infections in people with chronic obstructive pulmonary disease (COPD), sinusitis, nosocomial respiratory infections, and even bacteremia. [1]

Moraxella species other than M. catarrhalis are unusual pathogens in humans. Case reports have established Moraxella species as unusual causes of invasive infections in humans, including endocarditis, bacteremia, septic arthritis, purulent pericarditis, cellulitis, and meningitis. Antimicrobial susceptibility should be performed on isolates recovered from normally sterile sites, but Moraxella species are generally susceptible to penicillins and cephalosporins. [1] In this case report we describe a very rare and unusual case of Moraxella species recovered from a thrombus evacuated from the left subclavian artery aneurysm during surgery.

  Case Report Top

A 66-year-old male was referred to the Cardiovascular and Thoracic Surgery service complaining of cough with purulent sputum for the past 2 weeks. For the past 10 days he was having large amount of hemoptysis, last episode around 500-ml blood, leading to referral to our institute. On examination, he was afebrile and comfortable at rest with normal hemodynamic parameters. Pulses in left upper limb were feeble and chest auscultation revealed normal air entry with a few scattered rhonchi.

An emergency computed tomography (CT) angiogram showed intrathoracic left subclavian artery aneurysm with bronchial fistula to left upper lobe. He was taken up for surgery on semiemergent basis. Peroperatively, a 4 × 4 cm size aneurysm of the left subclavian artery with thrombus was found infringing on to superior segment of left upper lobe bronchus. Surgery entailed posterolateral thoracotomy to gain access to the arch of aorta and disconnection of origin of left subclavian artery aneurysm from aortic arch without the aid of circulatory support followed by resection of left upper lobe segment.

The thrombus was removed and sent for culture. In the Microbiology laboratory, the tissue was ground, Gram-stained smear was prepared and tissue inoculated on blood agar and MacConkey agar (MA). The Gram stain showed pus cells with plenty of Gram-negative diplococci, which had the plane sides facing each other [Figure 1]. Colonies that grew on blood agar resembled Acinetobacter colonies and were pale pink on MA [Figure 2]. Smear showed the same Gram-negative cocci seen on the Gram stain of the thrombus, which was Oxidase positive and catalase positive. Using Vitek 2 Systems Version:05.02, it was identified as Moraxella group sensitive to Ampicillin, all cephalosporins, all aminoglycosides, and quinolones.
Figure 1: Gram stain showing Gram-negative Diplococci in thrombus

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Figure 2: Moraxella colony on MacConkey Agar

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Following the growth of this oral commensal in the thrombus, a sputum sample was requested. Since patient was still complaining of cough, a sputum sample was sent for culture. Postoperatively, patient was on Ciprofloxacin for 2 days followed by Cefoperazone and Amikacin for 5 days.

The sputum Gram stain revealed plenty of pus cells and Gram negative diplococci resembling the organism isolated from the thrombus, along with Gram-negative bacilli [Figure 3]. There was no normal flora. On culture, the Moraxella seen in plenty on Gram stain did not grow and were overgrown by Klebsiella pneumoniae sensitive only to Cefoperazone-sulbactum and Amikacin. Treatment was given according to the sensitivity report. After that the patient made an uneventful recovery, hence was discharged on the 10 th postoperative day.
Figure 3: Gram stain of Sputum showing similar Gram-negative Diplococci and Gram negative bacilli (Klebsiella)

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On review 3 months later, the patient developed pleural effusion requiring thoracocentisis. Pleural aspirate was sterile on culture and sputum repeated had only normal flora.

  Discussion Top

This report pertains to Moraxella spp infecting thrombus evacuated from left subclavian artery aneurysm along with the same organism isolated from the patient's sputum. Isolation of Moraxella spp simultaneously from thrombus and sputum was possible only in the event of bacteremia or else in a clinical setting such as in this report where vascular and bronchial trees are in direct communication.

Blood culture, done at admission, only could have shown any bacteremia, but patient was taken up for emergency surgery due to the intractable hemoptysis and only minimum essential investigations were done at that time. The antibiotics given at surgery and postoperatively eradicated the Moraxella, which could only be seen in the sputum smear, but did not grow. The organism was well protected inside the thrombus and was proliferating there as evidenced by the prompt growth from the tissue specimen.

Strain identification

Morphologically, characteristic Gram-negative diplococci that were oxidase positive, catalase positive and grew well on blood agar and MA agar. Currently, almost all strains of M. catarrhalis produce β-lactamase. This isolate was sensitive to all antibiotics, both by disc diffusion and by automated system analysis. Hence possibility of M. catarrhalis was ruled out. The organism was identified as Moraxella group by Vitek 2 Systems Version:05.02. Additional tests were suggested by the system to differentiate between M. lacunata, M. nonliquefaciens, and M. osloensis, which were the only three species suggested by the system. The former two species do not grow on MA, while this grew well on MA [Table 1]. Hence biochemically and by growth characteristics this organism was identified as Moraxella osloensis. To obtain a definitive identification of the organism, 16S rRNA gene sequencing has to be performed.
Table 1: Laboratory procedures useful for identification of moraxella, oligella, moraxella-like organisms, and kingella[1]

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M. osloensis was originally grouped with M. nonliquefaciens but was reclassified into its own distinct species in 1967. The authors described it as Gram-negative, predominantly diplococci, nonmotile, and unencapsulated. Colonies were described as having circular periphery and even, glistening surface. It was nonhemolytic on blood agar (BA) and had a soft or coherent consistency. [2] A universal characteristic described for this organism is sensitivity to almost all antibiotics. [3] These characteristics hold true for this isolate.

M. osloensis, M. catarrhalis, M. nonliquefaciens, and M. lincolnii are part of the normal flora of the human respiratory tract. In a study performed by the Centers for Disease Control and Prevention, 933 isolates of Moraxella species and other closely related organisms were collected from 1953 to 1980. Of the 933 isolates, 199 isolates were identified as M. osloensis, making it the second most common species isolated; 44 of the M. osloensis strains were derived from blood cultures. [4] However, this is the first instance when a perfectly viable form of this species was isolated from a thrombus and morphologically similar bacteria were observed in plenty in the sputum sample of the same patient, showing very conclusively the source of the isolate.

This case also shows the importance of Gram smear in processing of any specimen, especially sputum. Respiratory specimens are generally difficult to interpret due to the presence of normal oral flora. Here the Gram stain established the source of the bacteria as the sputum of the patient. Due to its exquisite sensitivity to all antibiotics it could not be recovered from the sputum, postoperatively. To our knowledge, this is the first time Moraxella species has been isolated from an arterial thrombus, particularly so from a person with normal heart valves.

  References Top

1.Murphy TF. Moraxella catarrhalis, Kingella, and Other Gram-Negative Cocci. In: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 7 th Edition Philadelphia Churchill Livingstone. Chap 213. 7 th edn, Vol. 2. 2010.  Back to cited text no. 1
2.Biivre K, Henriksen SD. A new Moraxella species, Moraxella osloensis, and a revised description of Moraxella nonliquefaciens. International Journal of Systematic Bacteriology 1967;17:127-35.   Back to cited text no. 2
3.Bard JD, Lewinski M, Summanen PH, Deville JG. Sepsis with prolonged hypotension due to Moraxella osloensis in a non-immunocompromised child. J Med Microbiol 2011;60:138-41.  Back to cited text no. 3
4.Graham DR, Band JD, Thornsberry C, Hollis DG, Weaver RE. Infections caused by Moraxella, Moraxella urethralis, Moraxella-like groups M-5 and M-6, and Kingella kingae in the United States, 1953-1980. Rev Infect Dis 1990;12:423-31.  Back to cited text no. 4


  [Figure 1], [Figure 2], [Figure 3]

  [Table 1]


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