Renu Goyal

Changing trends in bacteriology of burns in the burns unit, Delhi, India

A retrospective study of bacterial isolates from the wounds of patients admitted to burns unit, was undertaken at Guru Tegh Bahadur Hospital, University College of Medical Sciences, Delhi, India, over a period of 5 years between July 1997 and April 2002. The study compared the results obtained with the previous 5 years data (June 1993-June 1997) from the same unit to determine the changing patterns and emerging trends of bacterial isolates and their antimicrobial susceptibilities. Pseudomonas species (31%) and Staphylococcus aureus (22%) were the most common pathogens followed by Klebsiella species (19%). Multi-drug resistant (MDR) Acinetobacter species (9%) have emerged as an important nosocomial pathogen in our burn unit. Most of the gram-negative isolates obtained were found to be multi-drug resistant and 61% of the tested isolates were extended spectrum beta-lactamase (ESBL) producers. Concomitant resistance to penicillin and aminoglycosides was observed in 61% of Enterococcus fecalis isolates. When compared with the results of previous 5 years (June 1993-June 1997) Pseudomonas spp. was still the commonest pathogen in the burns unit. However, isolation of this organism and other gram-negative organisms has decreased in comparison to previous years. The incidence of antimicrobial resistance has markedly increased over the past years resulting in limitation of therapeutic options.

EDIBLE VACCINES: CURRENT STATUS AND FUTURE

Edible vaccines hold great promise as a cost-effective, easy-to-administer, easy-to-store, fail-safe and socioculturally readily acceptable vaccine delivery system, especially for the poor developing countries. It involves introduction of selected desired genes into plants and then inducing these altered plants to manufacture the encoded proteins. Introduced as a concept about a decade ago, it has become a reality today. A variety of delivery systems have been developed. Initially thought to be useful only for preventing infectious diseases, it has also found application in prevention of autoimmune diseases, birth control, cancer therapy, etc. Edible vaccines are currently being developed for a number of human and animal diseases. There is growing acceptance of transgenic crops in both industrial and developing countries. Resistance to genetically modified foods may affect the future of edible vaccines. They have passed the major hurdles in the path of an emerging vaccine technology. Various technical obstacles, regulatory and non-scientific challenges, though all seem surmountable, need to be overcome. This review attempts to discuss the current status and future of this new preventive modality.

Laboratory-based epidemiological study of superficial fungal infections

Dermatophytosis continues to be a worldwide problem, constituting a large bulk of cases attending the dermatology outpatients department in tropical countries. Variable climatic conditions and multiple etiological agents, whose individual prevalence varies with time, prompted an attempt to define the current pattern and etiologic prevalence in our locality, and compare them with earlier studies from different centers. Of consenting patients clinically diagnosed to have superficial fungal infections, 1975 were investigated in the laboratory. All the specimens collected from patient skin, hair or nails were subjected to direct microscopy examination in 10% potassium hydroxide (KOH) and fungal culture. Confirmed diagnosis was made only if specimen was KOH and/or culture positive. Male : female ratio was 1.65 : 1. Tinea corporis (21.4%), onychomycoses (14.7%) and tinea capitis (6.2%) were the most common laboratory‐confirmed infections. Only 909 patients (47%) out of 1035 clinically suspected patients had evidence of fungal infection by either microscopy and/or culture. Of these 909 patients, 787 (86.5%) were both KOH and culture positive, 25 (2.7%) were KOH negative and culture positive, while 97 (10.6%) were KOH positive but culture negative. In 1051 patients (53%), no evidence of fungal infection was seen. Trichophyton rubrum was the most commonly isolated dermatophyte (55.2%) followed by Trichophyton mentagrophytes (19.6%) and Trichophyton tonsurans (2.9%). Candida sp. accounted for 16% of all isolates. Non‐dermatophyte moulds (NDM) were isolated only in patients with onychomycoses. Our study revealed a male preponderance, tinea corporis as the commonest clinical type, and dermatophytes as the commonest mycological isolates, which is in agreement with earlier studies. Relying on clinical diagnosis alone without laboratory confirmation may result in overestimation of the problem as evidenced in other studies as compared to our study. Rarely reported NDM appear to be important etiological agents of onychomycoses.

Antimicrobial resistance in invasive and colonising Streptococcus pneumoniae in North India

The present study was done to detect the antibiotic resistance in S. pneumoniae. One hundred twenty S. pneumoniae isolates from clinical specimens and 50 from nasopharyngeal sites were subjected to antimicrobial susceptibility testing by Kirby Bauer disk diffusion method and minimum inhibitory concentration (MIC) determination for penicillin and cefotaxime non-susceptible isolates. A total of 22 isolates (18.3%) from clinical sites and eight (16%) from nasopharyngeal sites showed decreased susceptibility to penicillin by oxacillin disk diffusion test. MICs of 26 of these resistant strains ranged from 0.12-1 microg/mL (intermediate resistance) by broth dilution and E test. Only four isolates, two from sputum and two from nasopharyngeal swabs, showed MIC of 2 microg/mL (complete resistance). However, MIC of two cefotaxime resistant isolates (by disk diffusion) was in the susceptible range (0.5 microg/mL). Highest antimicrobial resistance was seen to cotrimoxazole (55.2%) and tetracycline (61.2%). Antimicrobial resistance to cotrimoxazole and tetracycline was much more in clinical isolates than colonizing isolates. Multi-drug resistant phenotype was detected in 76.9% (20 of 26) of isolates that were intermediately sensitive to penicillin and 50% (2 of 4) of penicillin resistant isolates (co-resistant to tetracycline and cotrimoxazole). Routine screening for antibiotic susceptibility is recommended for clinical isolates of pneumococci. Strains with reduced susceptibility to penicillin should be subjected to MIC determination to detect relative resistance or true resistance as such strains are associated with increased virulence. The choice of antibiotics should be guided by the prevalence of local resistance patterns of pneumococci.

Disseminated nocardiosis in an immunocompetent child

Abstract We report a 2-month-old child with a disseminated Nocardia farcinica infection that presented with suppurative lymphatic abscess. The child did not have any predisposing factors and responded to treatment with co-trimoxazole and amikacin. This is first case report of disseminated nocardiosis caused by Nocardia farcinica in an immunocompetent child.

Fluoroquinolone resistance in Vibrio cholerae O1: emergence of El Tor Inaba.

The dynamics of Vibrio cholerae transmission are complex. Two serotypes of V. cholerae O1, Ogawa and Inaba, have been demonstrated to interconvert owing to an antigenic shift in the O antigen lipopolysaccharide. V. cholerae O1 El Tor, Ogawa and O139 are endemic in east Delhi, India with higher attack rates and mortality in children. Ciprofloxacin has been promoted as the first-line drug for treating V. cholerae infections in developing countries because of increasing reports of multi-drug resistance. A recent increase in reports of treatment failure with ciprofloxacin in children with cholera prompted us to undertake the following study on drug resistance.

Group B Streptococcus colonisation in obstetric cases in a tertiary care hospital in Delhi, India.

Group B Streptococcus (GBS, Streptococcus agalactiae) is considered to be an important cause of neonatal septicaemia. Studies have shown that newborns with early-onset GBS infection (i.e. within 7 days) acquire the organism intra-partum from mothers whose genital tracts are colonised with GBS, and that the use of systemic intra-partum antimicrobial prophylaxis in high-risk cases can reduce early-onset GBS infection. Lateonset infection occurs between 7 days and 3 months of life and can be acquired by vertical or horizontal transmission; obstetric intervention is not successful in these cases. Vaginal carriage rates of 2–25% have been reported from developed countries but analyses of reports from India with adequate methodologies have shown carriage rates of 8–12%. A study was undertaken to investigate the colonisation rate of GBS among pregnant women in Guru Teg Bahadur Hospital (GTBH) in east Delhi. A total of 304 pregnant women of 35–37 weeks gestation who had been referred to GTBH for prenatal and obstetric care were included. Women who had taken antibiotics in the last 2 weeks were excluded. Vaginal specimens were collected on sterile cotton swabs prior to the first pelvic examination and were then transported immediately to the laboratory in Todd Hewitt broth containing nalidixic acid (15 μg/ml) and gentamicin (8 μg/ml). They were incubated at 37 ß C with 5% CO2 for 24 hrs and subcultured on 5% sheep blood agar. For presumptive GBS identification, all gram-positive, catalase-negative, b-haemolytic or nonhaemolytic colonies were examined for positive CAMP (Christie Atkins & Munch Peterson) reaction, resistance to bacitracin, ability to hydrolyse sodium hippurate and negative bile esculin reaction. These bacteria were confirmed as GBS by latex agglutination (Streptococcus grouping kit, The Binding Site, Birmingham, UK). GBS was isolated from only four women (1.3%), similar to Kishore et al. who isolated GBS from only one woman (0.47%). Ross & Needham also failed to isolate GBS from Asian mothers. Some studies have shown rectal colonisation to be a major determinant of GBS carriage during pregnancy but we did not attempt to isolate GBS from the rectum as transmission from mother to baby is determined mainly by vaginal carriage. These few reports suggest that GBS infection is not a problem in our population and that there is no need to consider mass screening for GBS in pregnancy. Occasional monitoring for bacterial ecology, however, is necessary.