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Shivani Tyagi ¹, Aroma Oberoi ²

Affiliations
1 Department of Microbiology, Dr. Baba Saheb Ambedkar Medical College & Hospital, New Delhi − 110085, IN
2 Department of Microbiology, Christian Medical College & Hospital, Ludhiana, Punjab − 141008, IN

Abstract

Background: Staphylococcus aureus (S. aureus) is a well recognized nosocomial and community acquired pathogen which is implicated in causing a wide spectrum of superficial, deep pyogenic infections and toxin mediated illnesses. Localized infections sometimes progress to systemic infections, while ‘spontaneous’ bacteraemia also occur without an evident septic focus, particularly in chronic debilitated immunocompromised patients. Emergence of drug resistance to penicillins and penicillinase-resistant penicillins (i.e., oxacillin and methicillin) is a globally recognized problem. Methicillin Resistant Staphylococcus aureus isolates are also important with respect to the range of nosocomial infections it causes, leading to an increase in the hospital expenditure and mortality or morbidity rate. The increased prevalence of such resistant strains has narrowed down the list of available therapeutic options. Therefore, information regarding the prevalence of S. aureus infections in a health care setting and determining its current antibiotic resistance profile becomes crucial in selecting appropriate treatment regime. Therefore, the current study was done in the department of Microbiology to determine the prevalence of S. aureus infections and the antibiotic resistance pattern of S. aureus isolates from various clinical specimens at our tertiary care hospital in North India. Materials and Methods: A one year prospective study was carried out in the Department of Microbiology, at a tertiary care hospital in North India where non-duplicate strains of S. aureus isolated from various clinical specimens received in the Microbiology laboratory were studied. All S. aureus isolates were subjected to Antibiotic Susceptibility Testing using Kirby Bauer’s disk diffusion method on Mueller Hinton Agar plates in accordance to CLSI guidelines. The antibiotics tested included Penicillin (10U), Amoxicillin-clavulanic acid (20/10μg), Sulphamethoxazole-trimethoprim (1.25/23.75μg), Ciprofloxacin (5μg), Erythromycin (15μg), Clindamycin (2μg), Vancomycin (30μg), Teicoplanin (30μg) and Linezolid (30μg). Results: A total of 23,699 clinical specimens were processed in the laboratory while conducting this study, from which 1233 clinical isolates of S. aureus were identified and processed further. Among all clinical specimens, pyogenic samples (63.1%) yielded maximum number of S. aureus strains followed by blood samples (29.9%) and urine samples (4.8%). S. aureus infection was more evident in hospitalized 71.2% patients than in OPD patients 28.8%. Seasonal variation was also seen in isolation of S. aureus, with a higher percentage of isolates obtained during summer season than during winter season. On antibiotic susceptibility testing, 49.6% strains were Methicillin Resistant. Majority of the isolates were found resistant to Penicillin (92.1%), followed by Erythromycin (59%). Almost half of the total isolates were resistant to Sulphamethoxazole-Trimethoprim (49.3%) followed by Amoxicillin- Clavulanic acid (47.8%), Ciprofloxacin (43.4%) and Clindamycin (18.4%). Antibiotics to which all isolates showed 100% susceptibility included Vancomycin, Teicoplanin, Linezolid. Conclusion: Given the high prevalence of resistance to antibiotics seen in this study, effective treatment of infections caused by multidrug resistant Staphylococcal strains may become challenging. Drugs like Vancomycin, Teicoplanin and Linezolid promise to work as miracle drugs against the multidrug resistant MRSA strains but we need to warrant judicious use of these wonder drugs to conserve them for future use.

Keywords

Antibiotic Susceptibility Testing, Antimicrobial Resistance, Methicillin Resistant Staphylococcus aureus (MRSA), Staphylococoous aureus.

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Shivani Tyagi ¹, Ravinder Kaur ², Deepti Rawat ³

Affiliations
1 Department of Microbiology, Dr. Baba Saheb Ambedkar Medical College and Hospital, New Delhi–110085, IN
2 Director Professor & Head, Department of Microbiology, Lady Hardinge Medical College and Associated Hospitals, Connaught Place, New Delhi–110001, IN
3 Department of Microbiology, Lady Hardinge Medical College & Associated Hospitals, Connaught Place, New Delhi–110001, IN

Abstract

Background: Superficial fungal infections are one of the commonest human infections. Causative agents of such infections may vary from yeasts like Candida species, Trichosporon species to dermatophytes and non-dermatophyte moulds. Fungal culture therefore, holds importance in identification and characterization of a fungal isolate, so that proper diagnosis can be made and correct treatment is instituted. Our objective was to study the etiology of the superficial fungal infections in patients presenting to the dermatology department in a tertiary care hospital in New Delhi. Materials and Methods: A total of 340 skin and hair samples from patients clinically suspected to have superficial fungal infection of skin and hair were microscopically examined and cultured over a period of 2 years. The percentage and frequency distribution of etiological fungal agents was studied. Also the performance of the culture and microscopy as methods of detecting fungal agents was statistically compared using Kappa and proportions of positive and negative agreement as well as McNemar’s Chi-squared value. Corresponding p-values were also calculated for both kappa and Chi-squared values. The analysis has been done using Epitools. Results: Of these, 57.6% were positive for fungal elements by microscopic examination and the overall positivity of fungal infection was 70%. Out of 238 culture positive samples, 72.7% grew dermatophytes and 27.3% grew non-dermatophytes (including 16.8% yeasts and 10.9% non-dermatophyte moulds. Trichophyton mentagrophytes was the commonest (60.7%) dermatophyte isolated, followed by T. rubrum (17.3%), T. violaceum (7.5%), T. tonsurans (7.5%), T. verucosum (2.9%), Microsporum gypseum (1.2%) and M. canis (0.6%). Among the isolated non-dermatophytes, Candida species was the commonest (50.8%) majority of which were C. albicans, other non-dermatophytes included moulds like Fusarium spp. (6.1%), Aspergillus fumigatus (4.6%), A. flavus (3.1%), Alternaria spp. (3.1%), Acremonium spp. (3.1%), A. niger (3.1%) etc. and yeasts like Trichosporon spp. (10.8%). Conclusion: Dermatophytosis still remains the most common type of fungal infection involving skin and its appendages but non-dermatophytes are also slowly emerging as the causative agents for these infections.

Keywords

Dermatophytes, Hair, Skin, Superficial Mycoses, Yeast.

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