Slime production a virulence marker in Pseudomonas aeruginosa strains isolated from clinical and environmental specimens: a comparative study of two methods.

Detection of slime in Pseudomonas aeruginosa can be useful in understanding the virulence of this organism. Here, comparative studies of two phenotypic methods using the tube method and the spectrophotometric method for slime production from 100 clinically and 21 environmentally significant isolates of P. aeruginosa were performed. A total of 68 isolates were positive by either of the tests whereas only 34 were positive by both the tests. The tube method detected slime significantly in more number of isolates than the spectrophotometric method. The tube test was found to be superior to the spectrophotometric method in ease of performance, interpretation and sensitivity. Among the clinical isolates, systemic isolates produce less slime compared to wound, respiratory and urinary isolates. Isolates from the hospital environment produced more slime indicating that this virulence marker helps the organism to survive for longer periods and cause nosocomial infections.

Phenotypic switching and its influence on expression of virulence factors by Candida albicans causing candidiasis in human immunodeficiency virus-infected patients.

PURPOSE: The purpose of the present study was to determine the degree of expression of virulence factors such as adherence, cell surface hydrophobicity (CSH) and production of proteinase by different morphological forms of Candida albicans causing oral candidiasis in human immunodeficiency virus (HIV)-infected individuals. METHODS: C. albicans 3153A and two strains isolated from oral thrush in HIV infected individuals were induced to undergo phenotypic switching by exposure to UV light and the degree of expression of virulence factors by the different morphological forms was studied. RESULTS: Three different morphological forms of C. albicans were obtained namely, star (S), wrinkled (W) and ring (R) types from the original smooth (O) variety. It was found that proteinase production was greatest with the W type followed by the R type and O type. The S type produced the least proteinase. Expression of cell surface hydrophobicity and adherence was greatest in the O type followed by the R and then the W type and finally the S type. CONCLUSIONS: The differential expression of virulence factors occurs with different phenotypic forms of C. albicans and this may provide a particular morphological type with a distinct advantage over other types in causing candidiasis.

Paraffin baiting system for demonstration of growth and biofilm production in Pseudomonas aeruginosa.

Pseudomonas aeruginosa is one of the commonest pathogens among the pseudomonads. This organism can grow in minimal nutritional requirements. Because of the ability of pseudomonads to grow on paraffin is not commonly found among other human pathogens and the primary human pathogen being P. aeruginosa, we studied the adaptation of this organism to paraffin baiting system for growth and biofilm formation. Strains were tested for the capacity to use paraffin as the sole source of carbon using Czapek's minimal salt medium. Of the 53 clinical isolates of P. aeruginosa, 20 strains exhibited growth by 24 hrs and 42 strains by 48 hrs. The remaining strains did not show any growth in the paraffin baiting system. The oxidase test with the paraffin baiting system was also performed. This simple and inexpensive method can be used to isolate and demonstrate the biochemical and biofilm forming capacity of the organism.

Intestinal protozoal infestation profile in persistent diarrhea in children below age 5 years in western Nepal.

Unlike acute diarrhea, the role of pathogens in persistent diarrhea in children in Nepal is unclear. Protozoal parasites are suspected to be a major cause. The study was carried out to find the association between protozoal agents and persistent diarrhea in children below age 5 years from western Nepal. Stool samples were collected from 253 children with persistent diarrhea, from 155 children with acute diarrhea (disease controls) and from 100 healthy children from the community (normal controls). Of 253 children with persistent diarrhea, 90 (35.5%) had protozoal infections, 63 (24.9%) helminthic infections, 32 (12.6%) had bacterial infections and 16 had mixed infections. Giardia lamblia was the most prevalent (67.7%), followed by Entamaeba histolytica (27.7%). HIV infection and severe malnutrition were associated with Cyclospora cayetanensis and Cryptosporidium spp causing persistent diarrhea. We conclude that stool microscopy should be routinely performed in children with persistent diarrhea since protozoal infections can be cured with effective treatment and control can be achieved by proper health education.

Induction of resistance to fluoroquinolones in clinical and environmental isolates of Pseudomonas aeruginosa.

An attempt to induce resistance to ciprofloxacin in vitro was made against clinical and environmental isolates of Pseudomonas aeruginosa. This in vitro manipulation of strains resulted in the increase of minimum inhibitory concentration from 0.4 microg/ml to 1 microg/ml of the original strains to 9.0 to 12.5 microg/ml indicating development of resistance to ciprofloxacin and a major decrease in the size of zone diameters of norfloxacin and ofloxacin indicating cross resistance to these agents. Results indicate the induced resistance to ciprofloxacin can promote development of cross resistance to other fluoroquinolones. This suggests that caution should be taken while using fluoroquinolones for the treatment of Pseudomonas aeruginosa infections.

Characterization of Candida species isolated from cases of lower respiratory tract infection.

OBJECTIVES: (1) To identify and characterize the Candida species isolates from lower respiratory tract infection. (2) to determine the rate of isolation of Candida species from sputum samples. METHODS: This study was carried out in the Department of Microbiology, Manipal Teaching Hospital, Pokhara, Nepal from June 2002 to January 2003. A total of 462 sputum samples were collected from patients suspected lower respiratory tract infection. The samples were processed as Gram staining to find out the suitability of the specimen, cultured on Sabouraud's Dextrose Agar (SDA) and also on blood agar and chocolate agar to identify the potential lower respiratory tract pathogens. For the identification of Candida, sputum samples were processed for Gram stain, culture, germ tube test, production of chlamydospore, sugar fermentation and assimilation test. For the identification of bacteria, Gram stain, culture, and biochemical tests were performed by standardized procedure. RESULT: Out of 462 samples, 246 (53.24%) samples grew potential pathogens of lower respiratory tract. Among them Haemophilus influenzae 61(24.79%) and Streptococcus pneumoniae 57 (23.17%) were the predominant bacterial pathogens. Candida species were isolated from 30 samples (12.2%). The majority of Candida species amongst the Candida isolates were Candida albicans 21(70%) followed by Candida tropicalis 4(13.33%). Candida krusei 3(10%), Candida parapsilosis 1(3.33%) and Candida stellatoidea 1(3.33%). The highest rate of isolation of Candida was between the age of 71 and 80. CONCLUSION: Candida isolation from sputum samples is important as found in the present study in which Candida species were the third most common pathogen isolated from patients with lower respiratory tract infection.

Isolation & antimicrobial susceptibility of Shigella from patients with acute gastroenteritis in Western Nepal.

BACKGROUND & OBJECTIVE: Shigellae play an important role as a causative organism of acute gastroenteritis, which is a global health problem with significant morbidity and mortality in especially in developing countries. This study was carried out to determine the isolation and pattern of antimicrobial resistance of Shigella in patients with acute gastroenteritis in western Nepal. METHODS: The study included all patients with acute gastroenteritis who visited a tertiary care hospital at Pokhara, Nepal during a 2-year period (2002-2004). The isolates was confirmed as Shigella by biochemical reaction and slide agglutination test using specific antisera. Antibiotic sensitivity test was determined by agar diffusion method and minimum inhibitory concentration (MIC) of the drugs was detected. RESULTS: Of the 770 stool samples, 83 (10.8%) yielded Shigella. Shigella flexneri caused 56 (67.4%) of the total cases of shigellosis followed by S. dysenteriae 12 (14.5%), S. sonnei 10 (12%) and S. boydii 5 (6%). Of the 83 isolates, 67 (80.7%) showed resistance to various drugs and 62 (74.7%) were resistant to two or more drugs. Resistance to cotrimoxazole was 80.7 per cent followed by tetracycline 74.7 per cent, ampicillin 53.0 per cent, nalidixic acid 31.3 per cent and ciprofloxacin 2.4 per cent. The MIC(50) and MIC(90) values of those drugs were also very high. All isolates were sensitive to cefotaxime and ceftriaxone. INTERPRETATION & CONCLUSION: The findings of our study suggested that Shigellae was an important etiological agent for acute gastroenteritis, with a high rate of drug resistance and requires constant monitoring in this region.

Effect of "HAART" on CD4+ T lymphocyte counts in HIV seropositive south-Indian individuals--a follow up study.

Because of the drastic cut down in the prices of antiretroviral drugs, the antiretroviral therapy has become more affordable in India. 16 HIV-1 infected individuals who were on HAART were followed up for 12 months. The CD4 + T Cell count estimation was done at mean intervals of 6 months and 12 months. Antiretroviral therapy showed good response in 14(87.5%) and deterioration in 2 (12.5%) cases.

Prevalence of Moraxella catarrhalis infections of the lower respiratory tract in elderly patients.

OBJECTIVES: To determine: *rate of isolation of Moraxella catarrhalis in elderly patients having lower respiratory tract infection *The antibiotic susceptibility pattern of Moraxella catarrhalis isolates. *The predisposing factors responsible for Moraxella catarrhalis infections of lower respiratory tract. MATERIAL AND METHOD: This is a prospective study carried out at Manipal Teaching Hospital, Pokhara during May 2002 to April 2003. A total of 716 sputum samples collected from patients with suspected lower respiratory tract infection were investigated. The samples were subjected to Gram stain, culture and sensitivity. Sputum samples were inoculated on blood and chocolate agar and incubated at 37 degrees C for 18 to 24 hours in candle jar containing 3-5% Co2. For the identification of bacterial isolates, the cultural and colonial characteristics were recorded and identified with the use of biochemical test. The susceptibility of bacterial isolates to antimicrobial agent was performed following Kirby-Bauer method. RESULT: Out of the 716 samples, 355 (49.58%) grew normal commensals of the upper respiratory tract. Respiratory pathogens were recovered from 361 (50.41%) samples. The most common respiratory pathogen was H. influenzae (26. 86%), followed by S. pneumoniae (21.16%). Moraxella catarrhalis accounted for 6.90%. Rate of isolation of Moraxella catarrhalis was higher in males than in females. Out of 25 isolates 16 were from males and 9 were from females. Frequency of isolation of Moraxella catarrhalis was more frequently seen in age group 61-70 years. It was most commonly recovered in winter. The most effective antibiotics were amoxicillin-clavulanate and ceftriaxone and least was ampicillin. CONCLUSION: Moraxella catarrhalis isolation from sputum especially in persons above 60 years of age and in the absence of other well established pathogens should not be disregarded as they can cause lower respiratory tract infection in these individuals.

Effect of trace elements on surface hydrophobicity and adherence of Escherichia coli to uroepithelial cells.

Trace elements have significant effect on the physiology of bacteria. Variation in the concentration of trace elements may affect the expression of virulence by microorganisms. The effect of trace elements on hydrophobicity and adherence of E.coli to uroepithelial cells was studied. Increasing concentrations of Ca2+, Mg2+, Fe3+ and Zn2+ significantly decreased the surface hydrophobicity. Toxic trace elements like Co2+, Cu2+, Mn2+ and Ni2+ did not alter surface hydrophobicity. With regards to adherence of E.coli to uroepithelial cells, only Mg2+ had significant effect. Toxic trace elements decreased the rate of cell adherence. The pathogenic strains of E.coli showed higher surface hydrophobicity and better cell adherence compared to the nonpathogenic strains. There was good correlation between surface hydrophobicity and cell adherence at higher concentrations (0.1 to 0.2mM) of Fe2+ and Zn2+. The results indicated that trace elements can significantly affect surface hydrophobicity and adherence of E.coli to uroepithelial cells. Such effect may have a significant impact on the initial stages of bacterial infection.

Spectrum of opportunistic infections in AIDS cases.

Human Immunodeficiency viruses are the initial causative agents in AIDS, but most of the morbidity and mortality in AIDS cases result from opportunistic infections, Identification of such pathogen is very important for clinicians and health planners to tackle the AIDS epidemic in more effective manner. The present study describes the clinical and laboratory profile of 100 AIDS causes who presented to a referral hospital. Oral candidiasis (59.00%) was found to be the most common opportunistic infection, followed by tuberculosis (56.00%), Cryptosporidium infection (47.00%) and Pneumocystis carinii (7.00%). Presence of oral candidiasis and weight loss is highly predictive of low DC4 count and can be considered as a marker of HIV disease progression. The patients coinfected with HIV and tuberculosis are also on rise. Recognition of dual infection and taking adequate steps to deal with this epidemic is needed. As Cryptosporidium infection was detected in large number, provision of safe drinking water and maintaining good hygiene is important for prevention. Early diagnosis of opportunistic infection and prompt treatment, delays the progression towards AIDS. 91.00% of patients were infected with HIV1 and 4.00% had HIV2 infection and 5.00% were dully infected. 87.00% of patients were males and 13.00% were belonging to 21-40 years of age. Majority of them were belonging to lower socioeconomic status and heterosexual route of transmission was the commonest mode of spread.

Bacteraemia in high-risk patients.

In this study, we noticed a high incidence of bacteraemia in high-risk patients especially due to nonfermenter gram negative bacilli (NFGNB) and coagulase negative staphylococci (CoNS). Bacteraemia caused by some rare bacteria such as Moraxella spp., Aeromonas spp., Flavobacterium meningosepticum was also noted during the study. Antibiotic resistance pattern showed that many isolates were Multi Drug Resistant (MDR). This can be attributed to nosocomial-infection, which may occur due to more and more invasive procedures for diagnosis and therapy during long stay of patients in the hospital. Also, the MDR strains and the wide spread oxacillin resistant CoNS (OR-CoNS) and slowly emerging vancomycin resistant CoNS (VR-CoNS) associated with nosocomial infections pose a great threat to the clinicians. We recommend the usage of commonly used antibiotics along with cephalosporins for the patients admitted to these high-risk units, before the antibiotic susceptibility test findings.

Evaluation of antibacterial activity of Mangifera indica on anaerobic dental microglora based on in vivo studies.

The present study was carried out to compare the subgingival plaque microflora in mango leaf users. Fifty subjects of both sexes, 25 of them used tooth brush and 25 used mango leaf as their home care hygiene device were included in the study. The microbiological evaluation for specific bacterial counts of Actinobacillus actinomycetemcomitans, Prevotella intermedia, Porphyromonas gingivalis, Fusobacterium nucleatum and Peptostreptococcus micros were carried out for all subject. Specific microbial evaluation revealed significant decrease in the proportion of P. intermedia and P. gingivalis in mango leaf users compared to tooth brush users. It shows that mangiferin possesses antibacterial activity in vivo against specific periodontal pathogens such as P. intermedia and P. gingivalis. Use of mango leaf in conjunction with a tooth brush will be a good home care device for maintenance of oral hygiene.

Rotavirus and enteric pathogens in infantile diarrhoea in Manipal, South India.

The etiology of Rotavirus in acute diarrhoeal illness in children 0-5 years of age, admitted to the pediatric wards of Kasturba Medical College Hospital, Manipal was studied over a period of 5 years. Rotavirus in the faeces detected by Latex agglutination test accounted for 19.56% of the diarrhoea with maximum incidence (65%) in the 7-12 months of age group. Bacterial aetiological agents continued to play a significant role (69.6%) in diarrhoeal diseases. Enteroaggregative E. coli was common in the age group between 25-36 months, Shigellosis in 37-60 months and Salmonella typhimurium enteritis in 7-12 months of age. The other pathogens isolated were vibrio cholerae (4.98%), species of aeromonas (15.92%), along with cryptosporidium (6.47%) and candida albicans (3.98%). In a control group consisting of 100 children without history of diarrhoea, 2 were positive for rotavirus, 3 for cryptosporidium and 12 for Escherichia coli.

Characterization, antibiotic susceptibility pattern and detection of beta-lactamases in Enterococci.

One hundred strains of Enterococci obtained from various clinical specimens over a period of six months were speciated of which 56 were E. faecalis and 44 were E. faecium. Antimicrobial susceptibility pattern showed 90% of them were resistant to penicillin and 20% of them were resistant to vancomycin. Comparative evaluation of Beta-lactamase production by iodometric method and cloverleaf method showed that the latter was cost effective and easy to perform for routine use.

Bacteriological spectrum of cholecystitis and its antibiogram.

Bile Cultures for aerobic and anaerobic bacteria were carried out on 125 samples from patients with chronic cholecystitis with cholelithiasis. Cultures grew 71(56.8%) aerobes and 17(13.6%) anaerobic microorganisms. Polymicrobial infection was seen in 7(16.2%) cases. E. coli (45.07%) and Klebsiella (25.35%) were predominant among the aerobes and Bacteroides fragilis (58.82%) was predominant among the anaerobes. Highest incidence of the disease was observed in the fourth decade of life and females predominated in this study.

Hepatic abscess caused by Salmonella typhi.

A 64 years diabetic man presented with recurrent episodes of fever and abdominal pain. Ultrasonography revealed the presence of an abscess in the right lobe of the liver and a distended gall bladder with multiple calculi. Salmonella typhi was grown from the liver aspirate. Cholelithiasis may act as a predisposing factor for hepatic abscess formation in Salmonella carriers.