Abstract: The aim of the present research was to study infections caused by Bipolaris species which is usually recognized as a saprophyte and plant pathogen. Three species of Bipolaris viz., B. australiensis, B. hawaiiensis and B. spicifera were isolated causing infection at different sites of human body at Riyadh Military Hospital. Eight cases of infection from nasal site while four case each from wound and burn sites, three cases of post-operation and two case each from lung and skin of Bipolaris infections were recorded during the study period between April 2004 and April 2008. We conclude that Bipolaris species are now emerging as a potential human pathogen involving various parts. Although, immune-deficient patients are at high risk of infection but these species could also cause infections in immune-competent patients.
INTRODUCTION
The presence of pale to dark brown melanin-like pigment in the cell walls of mycelium are the characteristic features of dematiaceous fungi. Clinical infections caused by dematiaceous fungi are classified as chromomycoses, mycetomas, or phaeohyphomycoses.
Chromomycoses are chronic, localized, subcutaneous or cutaneous infections characterized by sclerotic bodies in tissue called muriform cells (Fleming et al., 2002; Brandt and Warnok, 2003; Robb et al., 2003; Espinel-Ingroff, 2001). In contrast, mycetomas are chronic infections of the skin and subcutaneous tissue with the potential to invade adjacent bone. This condition is characterized by anatomic distortion, draining sinus tracts and distinctive granules composed. Phaeohyphomycosis are superficial, cutaneous, subcutaneous, corneal, or systemic infections characterized by dematiaceous mycelial elements, which include hyphae, pseudohyphae-like structures and yeast-like cells in tissue with variable pigmentation of the fungus. (Fleming et al., 2002; Brandt and Warnok, 2003; Robb et al., 2003; Espinel-Ingroff, 2001). Bipolaris separated from genus Drechslera mainly because of bipolar conidial germination as compared to Drechslera where conidia could germinate from side too. Bipolaris is a dematiaceous, filamentous fungus, cosmopolitan in nature and usually grown on plant debris and in soil (Ellis, 1994) and well known to cause plant diseases (Fang et al., 2007; Koo et al., 2003). Among Bipolaris species, B. australiensis, B. hawaiiensis and B. spicifera are the major species causing infections in human and animals (Ellis, 1994). Earlier researches indicated that these species could cause infection in both immune-competent and immune-deficient patients (Flanagan and Brycesan, 1997; Fleming et al., 2002; Brandt and Warnok, 2003) allergic fungal sinusitis, mycotic keratitis, corneal ulcers, orbital cellulitis and cyst of conjunctiva (Koshy and Daniel, 2002; Eghtedari and Pakshir, 2006; q; Hamilton et al., 2006; Bashir et al., 2009). Allergic bronchopulmonary disease caused by Aspergillus and Bipolaris shown almost similar symptoms (Lake et al., 1991). Besides these Bipolaris species can colonise prosthetic heart valve (Drought et al., 1992) cutaneous and subcutaneous infections (Shafii et al., 2006), brain infection (Filizzola et al., 2003), osteoarthritis (Ziza et al., 1985) and fungemia (Walsh et al., 1995). Bipolaris causing lung infection has been reported from Saudi Arabia. The aim of the present research was to study the infections caused by Bipolaris species at Riyadh Military Hospital, Riyadh, Saudi Arabia.
MATERIALS AND METHODS
Collection of Samples
The site of collection and type of sample collected for study are given
below:
These samples were collected from inpatient and outpatient clinics of Riyadh Military Hospital.
Microscopic Examination
Microscopic examination was done by KOH Method. Slides were also prepared
for Silver and PAS (Period Acid Schiff) Stain (Evans and Richardson,
1989).
Medium for Isolation
Sabouraud dextrose agar (Oxoid Ltd., London) and Sabouraud dextrose agar
added with 5% horse blood were used for isolation of fungi from samples. These
media also contain three antibiotics, ciprofloxacin, vancomycin and penicillin
or gentamycin sulphate (0.03 g L-1 each) to check the growth of bacteria
(Parvez, 2010; Internal SOP of Riyadh Military Hospital)
(Evans and Richardson, 1989; Ellis,
2005).
Isolation and Identification of Fungi from the Samples
Isolation of fungi carried out according to Standard Operating Procedures
(SOP) for Medical Mycology (Parvez, 2010; Internal SOP
of Riyadh Military Hospital) (Evans and Richardson, 1989;
Ellis, 2005). Inoculated plates were incubated at 30°C
for 2 weeks. Isolated fungi were sub-cultured and maintained on Sabouraud dextrose
agar slants in tissue culture bottles. Identification of Bipolaris species
was carried out according to colony and microscopic morphological characteristics
as described and well documented earlier (Ellis, 1994;
http://www.mycology.adelaide.edu).
RESULTS AND DISCUSSION
A total number of 23 cases of Bipolaris infection were recorded from different types of samples during the study period.Bipolaris species were B. australiensis, B. hawaiiensis and B. spicifera.
| Table 1: | Number of cases of Bipolaris infections according to age group |
| Table 2: | Bipolaris species causing infections at different sites |
| Table 3: | Clinical details of patients having Bipolaris infection |
There were eight cases of nasal infection, two cases each of lung and skin infection, four cases each of wound and burn infection and three cases of post operation of Bipolaris were recorded. In the age group of 0-10 years only two cases of Bipolaris infection were recorded from burn cases. Age group of 11-20 yielded 5 cases, 4 of nasal infection and one wound infection. Age group of 21-30 yielded 8 cases, 4 nasal and one each of lung, skin, wound and post operation. Age group of 31-40 yielded 5 cases, one each lung, skin, wound, post operation and burn samples. Age 41 and above yielded only 3 cases, one each of wound, post operation and burned infection. Eight cases of allergic sinusitis were recorded and all from age group between 11-30 and these were immune-competent patients (Table 1).
Bipolaris spicifera was the leading species with 12 cases followed by B. australiensis and B. hawaiiensis. Bipolaris spicifera isolated from all types of samples. All these species were isolated from nasal, wound and burn sites although most number of cases were from nasal sites (B. spicifera 4 cases and 2 cases each of B. australiensis and B. hawaiiensis). All three Bipolaris species also isolated from nasal, wound and burn samples (Table 2).
All patients were immune-competent in the case of allergic fungal sinusitis caused by Bipolaris species. Also in the cases of burn and skin infection patients had no immune-deficiencies. In all other cases patients having some sort of immune-deficiencies including diabetic, renal transplant, post operations and other types of immune-deficiencies (Table 3).
Distinguishing features of Bipolaris australiensis conidia and conidiophores are shown in Fig. 1and 2.
As far as researcher knowledge are concerned this is the first report of Bipolaris human infection from Saudi Arabia. All the three species of Bipolaris recorded here, have been known to cause human and animal infections (Ellis, 1994). Bipolaris species have caused infections both in immune-compromised and immune-competent patients as it was reported earlier (Flanagan and Brycesan, 1997; Fleming et al., 2002).
| Fig. 1: | Bipolaris australiensis conidia and conidiophores (x400) |
| Fig. 2: | Bipolaris australiensis conidia and conidiophores (x1000) |
Lung infection caused by Bipolaris species also reported earlier (Lake et al., 1991). Infections of the skin, wound, post operation infection and burn infection caused by Bipolaris recorded earlier. In Saudi Arabia, only one case of lung infection was reported from a renal transplant patient.
Bipolaris species emerging as a potential pathogen of human and can infect almost every site of human body (Koshy and Daniel, 2002; Hamilton et al., 2006; Bashir et al., 2009; Ellis, 1994; Filizzola et al., 2003). Mainly Bipolaris cases were encountered in areas where a hot climate is predominant (Texas, South Carolina, Arizona and Georgia in the United States; Brisbane, Australia; Pakistan and India). Schubert made the same observations and actually reported Bipolaris spicifera to be the most common cause of allergic fungal sinusitis in the Southwestern United States . The climate of Saudi Arabia also has very hot and dry Summers with mild Winter, which indicate a suitable environment for the survival of Bipolaris.
Appropriate treatment consists of amphotericin B or itraconazole with surgical excision if necessary (Fleming et al., 2002). We conclude that Bipolaris species are now emerging as a potential human pathogen involving various parts. Although, immune-deficient patients are at high risk of infection but these species could also cause infections in immune-competent patients.