Tulsi Das Chugh

HIV and Malnutrition: Effects on Immune System

HIV or human immunodeficiency virus infection has assumed worldwide proportions and importance in just a span of 25 years. Continuous research is being done in many parts of the world regarding its treatment and vaccine development, and a lot of money has flown into this. However, fully understanding the mechanisms of immune depletion has still not been possible. The focus has also been on improving the quality of life of people living with HIV/AIDS through education, counselling, and nutritional support. Malnutrition further reduces the capacity of the body to fight this infection by compromising various immune parameters. Knowledge of essential components of nutrition and incorporating them in the management goes a long way in improving quality of life and better survival in HIV-infected patients.

Blastomycosis in India: report of an imported case and current status

We report a case of disseminated blastomycosis in a female resident of Delhi, who acquired the infection during travel to the USA, which was successfully treated with oral itraconazole. In addition, we present a critical literature review, indicating that blastomycosis is endemic in India but its areas of endemicity, prevalence, and the natural habitat of the etiologic agent, remain undetermined. The diagnosis of blastomycosis was made by examination of Gomoris methenamine silver stained sections of tissue obtained from a biopsy of a subcutaneous, abdominal nodular. These studies revealed thick-walled, broad-based budding yeast cells compatible with Blastomyces dermatitidis, and consistent with the isolation of the fungus in cultures inoculated with posterior auricular lymph node aspirate. Microscopically, the isolate had thin, septate hyphae and characteristic spherical to pyriform, smooth-walled microconidia. Its identity was confirmed by conversion to its typical yeast form on pea seed agar at 37°C and by DNA sequencing of ITS and BAD 1 promoter regions.

Antimicrobial resistance among blood culture isolates of Salmonella enterica in New Delhi

INTRODUCTION Enteric fever is a global public health problem, especially in developing countries. Antimicrobial resistance is a major issue enteric fever management. This study examined current pattern of antimicrobial susceptibility among Salmonella enterica isolates from enteric fever cases at a tertiary care centre in New Delhi, India. METHODOLOGY Blood cultures from patients with enteric fever during January 2010- July 2012 were processed using the BACTEC automated system. Antimicrobial susceptibility was tested using Kirby Bauers disc diffusion method and/or Phoenix 100 automated system. RESULTS Of 344 isolates of Salmonella enterica, 266 (77.3%) were S. Typhi, 77 (22.4%) were S. Paratyphi A, and one (0.3%) was S. Paratyphi B. Resistance to nalidixic acid (NA(R)) (96.7%) was most common, followed by ciprofloxacin (37.9%), and azithromycin (7.3%). Multi-drug resistance was observed only in S. Typhi (3.4%). Among NA(R) strains, 61.8% were sensitive, 11.1% were moderately sensitive, and 23.9% were resistant to ciprofloxacin (0.8%, 57.4%, and 37.9% respectively according to revised CLSI breakpoint criteria for ciprofloxacin). Resistance to third-generation cephalosporin was found in seven (2%) strains of S. enterica. CONCLUSION Increasing rates of nalidixic acid, fluoroquinolone and azithromycin resistance among S. enterica, particularly in S. Paratyphi A strains, is of concern, as S. Paratyphi A infection is becoming increasingly common and is not prevented by current vaccinations. Our results favour use of cefexime or possibly chloramphenicol as first choice for uncomplicated enteric fever. MICs for third-generation cephalosporins and susceptibility pattern must be closely monitored in view of its emerging resistance among Salmonella enterica.

High prevalence of non-tuberculous mycobacterial disease among non-HIV infected individuals in a TB endemic country--experience from a tertiary center in Delhi, India.

Non-tuberculous mycobacteria (NTM) considered mostly as colonizers or ignored as environmental contaminants in the past, are now increasingly recognized as important pulmonary pathogens in both immunocompromised and immunocompetent population.1 Specific risk factors identified are HIV infection, cystic fibrosis, underlying chronic lung disease, previous tuberculosis (TB), and work in the mining industry.1 These are also reported to cause surgical-site infections, post-injection abscesses, osteomyelitis, catheter-related blood-stream infections, and central nervous system infections.2 Non-tuberculous mycobacteria rates of infection and disease has significantly increased in recent years and rates vary widely depending on population and geographic location.1 Most reports are from developed countries that have low rates of TB. However, in countries with high burden of TB, including India, NTM pulmonary disease often goes unrecognized and is misdiagnosed as pulmonary TB because clinical presentation of NTM and Mycobacterium tuberculosis (MTB) diseases are indistinguishable from each other. Prevalence of NTM is unknown in India as NTM disease is not a reportable condition and there is lack of awareness among clinicians coupled with lack of laboratory capacity to diagnose these infections.3 Among few reports available, NTM isolation rates are reported to range from 0.5 to 8.6% in India.4 A recent study from central India reported prevalence of NTM increased from 1.0% in 2005 to 3.5% in 2008 and 88.6% of the NTM isolated were clinically relevant.4 Identification of NTM is of clinical relevance as most of the NTM are notably resistant or only partially susceptible to the standard anti-tubercular drugs and the treatment strategies and the duration of these infections differ from MTB. We conducted retrospective review of isolation rates of Mycobacterium tuberculosis complex (MTC) and NTM, the species of NTM characterized and their clinical significance during January 2011–June 2012 at our tertiary care hospital (700 bedded) in Delhi, India. The study was approved by the ethical committee of our institute. A total of 436 clinical specimens were processed for mycobacteria culture, 237 from pulmonary (sputum, bronchoalveolar lavage, bronchial wash, and endotracheal aspirates) and 199 from extrapulmonary sites (urine, pus, peritoneal fluid, lymph node aspirate, synovial fluid, endometrial biopsy, CSF). Specimens were digested and decontaminated by the standard N-acetyl-l-cysteine–NaOH method and inoculated into BACTEC mycobacteria growth indicator tube (MGIT) 960 vials (BD Diagnostics, Sparks, MD, USA) and Lowenstein–Jensen (LJ) medium slants (Hi Media laboratories, Mumbai, India). Smear microscopic examination was performed using Zeihl Neelsen (ZN) and fluorochrome stains. All positive MGIT vials were subjected to identification of MTC, by p-nitrobenzoic acid (PNBA) assay on MGIT 960 as described elsewhere5 and SD TB MPT64 antigen rapid assay by immunochromatographic method (Standard Diagnostics, Seoul, South Korea). p-Nitrobenzoic acid resistant and/or MPB 64 antigen negative isolates (suspected to be NTM) were subjected to a multiplex PCR using primers for mycobacterium genus (targeting hsp65), MTC (targeting ESAT6), and Mycobacterium avium complex (targeting MAC) specific genes.3 Confirmed NTM isolates were further speciated by pigment production, growth on MacConkey agar, rate of growth, nitrate reduction test, tellurite reduction, urease production, tween-80 hydrolysis, arylsulfatase, heat-stable catalase, iron uptake, and tolerance to 5% NaCl.6 Drug-susceptibility testing was performed for MTC for PSIRE (pyrazinamide, streptomycin, isoniazid, rifampicin, and ethambutol) by BACTEC MGIT 960 (1% proportional method). Of 436 specimens, 109 (25.6%) were positive for acid-fast bacilli by smear microscopy (ZN and/or fluorescent) and 131 (30.7%) specimens were culture positive. Of 131 positive cultures, 118 (90.1%) isolates were identified as MTC (71.2% from pulmonary and 28.8% from extrapulmonary samples) and 13 (9.9%) isolates as NTM species. The NTM were isolated from pulmonary specimens in nine (69.2%) patients, and four (30.8%) were isolated from non-pulmonary specimens, one each from urine, ascitic fluid, bone, and blood specimens. The most common NTM species characterized was Mycobacterium kansasii (4) followed by Mycobacterium chelonae (3), Mycobacterium xenopi (2), Mycobacterium scrofulaceum (1), M. avium (1), Mycobacterium asiaticum (1), and Mycobacterium fortuitum (1). Clinical details and speciation of the NTMs isolated are shown in Table 1. Fluorescent staining was more sensitive as it detected 12 additional culture positive cases that were negative by ZN stain (of these, four were NTM). As NTM are ubiquitous in nature, NTM pulmonary infections consistent with the American thoracic society (ATS) and British thoracic society (BTS) guidelines (defined in Table 1) were considered clinically relevant.7,8 Of nine patients with pulmonary NTM isolated, seven (77.9%) had definite NTM disease and two (15.4%) had probable NTM disease; among four patients with extrapulmonary specimens, two (50%) had definite NTM disease, one (25%) had probable NTM disease, and one (25%) had possible disease or colonization (Table 1). Majority of patients were males (69.2%) and 46.1% (6/13) were older in age (≧60 years). The main underlying risk factors found to be associated with NTM infections were pre-existing pulmonary disease (54%), chronic obstructive pulmonary disease (COPD; 23.1%), past and/or present history of TB (30.8%, two pulmonary TB and one Pott’s spine cases were diagnosed by both smear for AFB and culture positivity for MTB and a case of osteomyelitis was smear positive for AFB), chronic smoking (15.4%), diabetes (23.1%), steroids (7.6%), and malignancy (7.6%). No predisposing condition was detected in three patients (23.1%). All 13 patients with NTM disease were HIV seronegative (ARCHITECT® HIV Ag/Ab Combo Assay, Abbott diagnostics). Table 1 Clinical and microbiological features of non-tuberculous mycobacteria (NTM) isolated Between PNBA and MPB64 antigen assay results, 100% concordance was observed. All mycobacteria grew both in MGIT and LJ medium; however mean isolation time was much shorter with MGIT than with LJ (11 vs 28 days). Furthermore, mean recovery time of MTC from pulmonary specimens was lesser than that of non-pulmonary specimens (10 vs 16 days) by MGIT culture. Among NTMs, slow-growing mycobacteria grew in mean time of 12.9 days. Rapidly growing mycobacteria (RGM) bloodstream infection due to M. chelonae in one of the patient could be detected by MGIT in 2.2 days. Of the MTC, 67% were sensitive to all tested drugs, 14.7% were multidrug-resistant (MDR), and 17.6% were mono-resistant. Treatment details of the patients were not retrieved. While clinical diagnosis of NTM pulmonary disease is challenging, reliance only on positive smear microscopy for the initiation of treatment for suspected TB in most TB endemic countries and not on Mycobacteria culture, species identification, and drug-resistance testing results, is unfortunate as acid-fast bacilli visualized in smears may not necessarily be MTB. Moreover, NTM co-infections with MTB disease are not infrequent, though rarely diagnosed.10 As NTM strains exhibits high drug-resistance to first-line anti-tubercular drugs, many of NTM infections would be considered TB treatment failures, and subsequently treated for multidrug-resistant TB (MDR-TB) disease. The same was highlighted in a recent report from China, where NTM accounted for 30% of suspected MDR-TB cases and 4% of retreatment TB cases.11 In another study from New Delhi, India, detected NTM were detected by multiplex PCR in 17.6% of the suspected MDR-pulmonary TB cases and in 12.4% of the suspected extrapulmonary TB cases.3 These findings highlight the necessity of laboratory speciation of mycobacteria and initiation of treatment for mycobacterial infections based on in vitro susceptibility testing. In the present study, 12 of the 13 NTM infections (92.3%) were provisionally diagnosed as pulmonary or extrapulmonary TB based on clinical presentation and smear microscopy findings. Of these, three patients (23.1%) having past history of TB were considered for retreatment (MDR-TB suspected) and one patient was found to be co-infected with MTB (pulmonary NTM and Pott’s spine). None of the patient in this series was HIV seropositive. In a recent 3 years study from India, 42% of AFB cultures were positive and approximately 2% of these were NTM. Pulmonary infections represented 81% of all NTM cases and the major predisposing condition was underlying lung disease (54%) including 40% patients with a past or present history of pulmonary TB while only 2% patients were known HIV-positive.12 High prevalence of NTM infections observed among non-HIV seropositive individuals in a TB endemic country in this report, underscores the need for increased awareness of these emerging human pathogens and importance of mycobacteria speciation to reduce morbidity and mortality resulting from these diseases. Use of liquid culture medium and molecular methods in clinical laboratories can significantly reduce turn-around time particularly for diagnosis of infections due to slow-growing NTM and MDR-TB. However, with improved facilities for recovery of NTMs that may result in increased frequency of isolation of these organisms, NTM disease requires clinical correlation and differentiation from colonization.

Rhodotorula fungemia: two cases and a brief review

Rhodotorula is emerging as an important cause of nosocomial and opportunistic infections. We present two cases of Rhodotorula mucilaginosa fungemia diagnosed over a period of 3 months at our hospital. The first case was of a pre-term neonate in the neonatal ICU who presented with respiratory failure and sepsis. The second involved an adult female who had been injured in a road traffic accident requiring an operation for a hematoma and was later shifted to the medical ICU. For a new hospital like ours, finding two cases of Rhodotorula fungemia within a span of 3 months prompted us to describe them in this report. These cases emphasize the emerging importance of Rhodotorula mucilaginosa as a pathogen and the importance of identification and MIC testing for all fungal isolates recovered from the blood stream.

Comparison of an Automated System with Conventional Identification and Antimicrobial Susceptibility Testing

The present study was designed to compare a fully automated identification/antibiotic susceptibility testing (AST) system BD Phoenix (BD) for its efficacy in rapid and accurate identification and AST with conventional manual methods and to determine if the errors reported in AST, such as the (very major errors) VME (false susceptibility), (major errors) ME (false resistance), and (minor errors) MiE (intermediate category interpretation) were within the range certified by FDA. Identification and antimicrobial susceptibility test results of eighty-five clinical isolates including both gram-positive and negative were compared on Phoenix considering the results obtained from conventional manual methods of identification and disc diffusion testing of antibiotics as standards for comparison. Phoenix performed favorably well. There was 100% concordance in identification for gram-negative isolates and 94.83% for gram-positive isolates. In seven cases, Phoenix proved better than conventional identification. For antibiotic results, categorical agreement was 98.02% for gram-positive and 95.7% for gram-negative isolates. VME was 0.33%, ME 0.66%, MiE 0.99% for gram-positive isolates and 1.23% VME, 1.23% ME, and 1.85% MiE for gram-negative isolates. Therefore, this automated system can be used as a tool to facilitate early identification and susceptibility pattern of aerobic bacteria in routine microbiology laboratories.

Nocardial Infections: An Under-Diagnosed Malady of Immunocompromised Hosts

Nocardial Infections: An Under-Diagnosed Malady of Immunocompromised Hostse Nocardia spp. is emerging as important cause of infections especially in the immunosuppressed patients. Infection is serious with high morbidity and mortality; treatment can be prolonged and difficult with marked tendency to recur. However, a high index of clinical suspicion is required for diagnosis. With growing population of the immunocompromised, it can be assumed that many of these infections go unreported and are largely under-diagnosed.

Microbiology-The Science behind Cure and Prevention

Microbiology is a science of ever-changing circumstances and evolutions. There is a constant race between the man and microbes and unflinchingly they try to outsmart each other. Updating our knowledge in all aspects of microbiology can bring out cure from the microbial pathogens and better, their prevention.