Indian Journal of Medical Microbiology Medknow Publications on behalf of Indian Association of Medical Microbiology ISSN: 0255-0857 EISSN: 1998-3646 Vol. 26, Num. 2, 2008, pp. 192-195

Indian Journal of Medical Microbiology, Vol. 26, No. 2, April-June, 2008, pp. 192-195

Case Report

Soft tissue infections with arcanobacterium haemolyticum: Report of three cases

Malini A, Deepa EK, Manohar PV, Borappa K, Prasad SR

Department of Microbiology, Sri Devaraj Urs Medical College, Tamaka, Kolar, Karnataka - 563 101
Correspondence Address:Department of Microbiology, Sri Devaraj Urs Medical College, Tamaka, Kolar, Karnataka - 563 101
panyamsr@rediffmail.com

Date of Submission: 13-Jun-2007
Date of Acceptance: 06-Jul-2007

Code Number: mb08056

Abstract

Keywords: Arcanobacterium haemolyticum, mixed infections, soft tissue infections

Arcanobacteria are gram positive bacilli which are characteristically catalase negative. As they morphologically resemble Corynebacterium diphtheriae they have been grouped under coryneform bacteria. ^[1],[2] To date, three species belonging to Arcanobacterium genus: Arcanobacterium haemolyticum (A.haemolyticum) , Arcanobacterium pyogenes and Arcanobacterium bernardiae are thought to be medically relevant. ^[1]

Arcanobacterium haemolyticum occurs as a commensal on human skin and the mucous membrane of the upper respiratory tract. ^[2] It is incriminated in causing pharyngitis and soft tissue infections like chronic ulcers and cellulitis. Deep seated infections like sinusitis, endocarditis, meningitis and septicemia due to A. haemolyticum have also been reported. ^[1] The deep seated infections by Arcanobacterium spp. are usually monomicrobial whereas the soft tissue infections are polymicrobial, associated with other bacteria. ^[3] Arcanobacterium spp. are also found on the mucous membrane of animals, as in man and cause infections in them. ^[2]

As arcanobacterial infections have been rarely reported, we report here three polymicrobial wound infections from which A. haemolyticum was isolated along with another co-pathogen.

Case Reports

Case 1
A woman of 64 years, from a village in Bangalore district was admitted to RL Jalappa hospital, Kolar, Karnataka, in June 2004 with the complaints of pain and swelling near lateral malleolus of right foot since two days. There was no history of trauma and the patient was not a diabetic. There was an ulcer over the lateral malleolus from which pus was oozing out. The right leg was swollen and erythematous up to the knee. There was tenderness and local rise of temperature. A provisional diagnosis of cellulitis of right foot was made.

X-ray of the right foot showed diffuse osteoporosis of the fifth metatarsal bone. Haematological study showed leucocytosis and neutrophilia (TC-16,000/cmm,DC-N 87%,L-10%,E-2% and M-1%).

The Gram stained smear of the pus sample from the ulcer showed pus cells along with short filamentous gram positive bacilli with rudimentary branching and gram positive cocci in pairs and chains [Figure - 1]a. Culture of the pus sample on sheep blood agar yielded two types of colonies: tiny colonies with wide zones of beta haemolysis and tiny colonies with narrow zones of beta haemolysis. The colonies with wide zone of beta haemolysis were identified as Group G β haemolytic streptococci (GGS) by grouping using latex agglutination and coagglutination tests. The colonies with narrow zone of haemolysis showed wider zones on incubation for 48 hours [Figure - 1]b. Gram stained smears of these colonies showed gram positive bacilli with rudimentary branching similar to those seen in the direct smear [Figure - 1]b inset. The organism grew on Mueller Hinton agar and brain heart infusion (BHI) agar. It fermented glucose and maltose with the production of acid but no gas and gave a positive reverse CAMP test [Figure - 1]c. It did not ferment xylose, sucrose, lactose and mannitol. It was negative for the catalase, urease, gelatin liquefaction and nitrate reduction tests. Based on the above morphological, cultural and biochemical characteristics, the gram positive bacilli were identified as Arcanobacterium haemolyticum . ^[2] A repeat sample yielded the same organisms from the lesion.

Both GGS and A. haemolyticum , were sensitive to penicillin, erythromycin, clindamycin, ciprofloxacin and gentamicin. A. haemolyticum was resistant to cotrimoxazole and GGS was resistant to tetracycline.

Initially, the patient received cefotaxime intramuscularly 1 g bd for four days with no clinical improvement. After the culture report was available, a below knee POP cast was applied and the patient was administered erythromycin 500 mg tid orally for 10 days, after which she made an uneventful recovery.

Case 2
A man aged 65 years from a village in Kolar district, Karnataka, came to the hospital in December 2004. He was a diabetic under treatment since five years. He had sustained an injury on the right great toe and developed an ulcer on its medial aspect. This was followed by swelling, pain and purulent discharge. When he came to the hospital, there was generalised swelling of distal one third of the right leg and foot. There were two sinuses with foul smelling discharge on the medial and lateral aspects of the right great toe [Figure - 2]a. A clinical diagnosis of chronic osteomyelitis of the right great toe was made. X-ray of the right foot showed osteomyelitis of the proximal and distal phalanges of the right great toe [Figure - 2]b.

The pus sample collected from the sinus on Gram stain showed many polymorphonuclear cells, gram positive bacilli similar to those seen in case 1 and gram negative bacilli. The pus sample did not show any acid fast bacilli on ZN staining. Culture yielded A.haemolyticum , identified as in case 1 and Proteus vulgaris . A repeat sample taken from the lesion also yielded both the organisms.

The A.haemolyticum from this case had a similar sensitivity pattern as in case 1. P.vulgaris was sensitive to ceftriaxone, gentamicin and amikacin. It was resistant to ampicillin, cefazolin, cefuroxime, cotrimoxazole, tetracycline and ciprofloxacin.

The patient was treated with procaine penicillin 4 lakh units intramuscularly and erythromycin 500 mg orally tid, which was started before the culture and sensitivity report was available and continued for six days. Local dressing of the wound was also done with betadine. He improved and there was no discharge from the sinus after eight days. The patient was discharged on request and lost to follow-up.

Case 3
A man aged 60 years from a village near Kolar district, came to our hospital in May 2005 with gangrene of second, third and fourth toes of the right foot. He had sustained an injury 25 days back. On examination lower one third of the right leg was swollen and tender. The gangrenous changes of the skin were evident up to the ankle. He was neither a diabetic nor hypertensive. The haemogram of the patient showed that he was anaemic and there was neutrophilia (Hb-6.8 gm%, TC-23,300 cells/cmm, DC- N 95%,L 5%).

An above knee amputation of the right leg was done. Three days after surgery, the wound showed purulent discharge. The Gram stained smear of the discharge showed few pus cells and gram positive bacilli with rudimentary branching and gram positive cocci in pairs. The pus sample on culture yielded A. haemolyticum and Group C Streptococci (GCS). A repeat sample from the patient yielded both A.haemolyticum and GCS.

The antibiogram of A.haemolyticum isolated from this patient was similar to the isolates obtained from the earlier two cases. Group C Streptococci was sensitive to penicillin, vancomycin and levofloxacin. It was resistant to bacitracin, erythromycin, cotrimoxazole, chloramphenicol, tetracycline and gentamicin. The patient was administered crystalline penicillin 20 lakh units eighth hourly intravenously and ciprofloxacin 500 mg bd for eleven days. The wound healed satisfactorily.

Discussion

We report here three cases of mixed wound infections caused by A.haemolyticum along with a co-pathogen. In the patients reported here, A.haemolyticum was associated with β-haemolytic streptococci (BHS) group G and C in cases 1 and 3, respectively and with P.vulgaris in case 2. In all the three cases, we could demonstrate the organisms in the direct smear along with pus cells and also repeatedly isolate them from the patients′ samples.

Usually the soft tissue infections of A.haemolyticum are known to be associated with BHS (Lancefield′s groups A, C or G) as in our patients, Staphylococcus aureus or Corynebacterium diphtheriae . ^[3] A.haemolyticum liberates extracellular enzymes such as phospholipase D, neuraminidase, hemolysin and DNAases which are responsible for the pathogenesis. ^[1] The co-pathogens are thought to play a synergistic role in causing tissue damage in arcanobacterial mixed infections. ^[4] A.haemolyticum and other potentially pathogenic organisms can exist on skin as bacterial flora. They may invade deeper tissues under favourable local conditions like tissue injury and devitalisation. Systemic conditions like diabetes, chronic alcoholism, immunodeficiency and old age may also predispose to such invasion. ^[4] Osteomyelitis seen in our second patient exemplifies such invasion and further pathogenesis.

A. haemolyticum strains show in vitro sensitivity to β-lactams, vancomycin, macrolides, clindamycin, tetracycline and fluoroquinolones. They are uniformly resistant to cotrimoxazole. ^[2] Macrolides like erythromycin and azithromycin are considered as the drugs of choice to treat arcanobacterial infections. ^[1] However, the antibiotic susceptibility pattern of the co-pathogens influence the choice of the antibiotic therapy. In our series, erythromycin was used in the first two cases and penicillin with ciprofloxacin in the third case with good results. Though Arcanobacterium species show in vitro susceptibility to penicillin, one should bear in mind the possibility of treatment failures reported, probably due to poor penetration of the antibiotic into the bacterial cell. ^[1]

The review of literature showed that there are very few reports of arcanobacterial infections from India, to date. This could be because A. haemolyticum is prone to be missed; it may be wrongly identified as diphtheroids based on microscopic morphology or may be passed over as BHS based on colony character on blood agar. Reports from India have documented the following arcanobacterial infections for the first time in literature: arcanobacterial urinary tract infection, ^[5] association of A.haemolyticum with pulmonary tuberculosis ^[6] and granulomatous inflammation involving A.haemolyticum in osteomyelitis. ^[7] Our report (case 3) substantiates an earlier report from India ^[8] that postoperative wound infection following amputation of limb can also occur due to A.haemolyticum .

The arcanobacterial infections reported here bring home the point that careful smear examination followed by culture and speciation are important to identify rarer pathogens.

Acknowledgement

References

Copyright 2008 - Indian Journal of Medical Microbiology

The following images related to this document are available:

Photo images