Shooting up: the interface of microbial infections and drug abuse.

Illicit drug control has been on the global agenda for more than a century. Infections have long been recognized as one of the most serious complications of drug abuse. Drug users are susceptible to pulmonary, endovascular, skin and soft tissue, bone and joint, and sexually transmitted infections caused by a wide range of bacterial, viral, fungal and protozoal pathogens. In addition, injection drug users are at increased risk for parenterally acquired infections such as human immunodeficiency virus, hepatitis B virus, hepatitis C virus, tetanus and malaria. Factors related to drug use, such as unsterile injection practices, contaminated drug paraphernalia and drug adulterants, increase the exposure to microbial pathogens. Illicit drugs also affect several components of the complex immune system and thus modulate host immunity. In addition, lifestyle practices such as multiple sexual partners, overcrowded housing arrangements and malnutrition serve as co-factors in increasing the risk of infection. In this review we present an overview of the unique aspects of microbial pathogenesis, immune modulation and common infections associated with drug use. We have restricted the definition of drug abuse to the use of illegal drugs (such as opiates, marijuana, cocaine, heroin and amphetamines), not including alcohol and nicotine.

Conventional and molecular characterization of coagulase-negative staphylococcus in hospital isolates.

BACKGROUND: During the last decade, coagulase-negative staphylococci (CoNS) have emerged as a major cause of nosocomial infections. They constitute a major component of the normal skin and mucosal microflora, and are particularly responsible for catheter- and medical device-related sepsis. They present unique problems in diagnosis and treatment of infections. PURPOSE: The present study has been designed to evaluate phenotypic and genotypic characteristics of CoNS among nosocomial isolates. SETTING AND DESIGN: This study was carried out in a tertiary care hospital. Data from 150 samples collected from 73 hospitalized patients and 15 healthy volunteers between October 2003 and May 2005 were analyzed. PATIENTS AND METHODS: A total of 100 CoNS strains responsible for sepsis or implant-associated infections and 50 saprophytic strains were studied. Invasive CoNS strains were selected on the basis of different colony morphologies, drug resistance patterns, and biofilm formation. The same criteria were used to select saprophytic isolates. Multiplex PCR was used to explore the ica, mecA, and atlE genes, which might contribute to the pathogenicity of CoNS and the formation of biofilms. RESULTS: Most of the invasive strains that formed the biofilm were resistant to multiple antibiotics, with more than 80% resistant to methicillin. ica and mecA genes were detected significantly in pathogenic strains (chi-square test, P<0.0001) whereas atlE was ubiquitously amplified in all the strains. All those strains which had ica and mecA genes were resistant to multiple antibiotics and were positive for biofilm formation. CONCLUSION: These genetic markers thus appear to discriminate between potential invasive virulent and saprophytic strains of CoNS.

Novel restriction enzyme SSiI for the detection of mutation in GyrA gene of Salmonella enterica serovar Typhi.

AIM: Enteric fever is an ongoing problem in the developing nations. Resistance and reduced susceptibility to ciprofloxacin narrows the therapeutic options in enteric fever. The present study was carried out with the objective of determining molecular basis of resistance to fluoroquinolone among the clinical isolates of Salmonella enterica serovar Typhi from different parts of India. MATERIALS AND METHODS: A total of 60 S.Typhi clinical isolates were subjected to antimicrobial susceptibility testing and determination of minimum inhibitory concentration (MIC) to ciprofloxacin and nalidixic acid. Polymerase chain reaction (PCR) for GyrA gene followed by restriction fragment length polymorphism (RFLP) with restriction enzyme (RE) SSiI was performed to detect mutation at position Ser83. Further confirmation of mutation was done by nucleotide sequencing of GyrA gene. RESULTS: Isolates showed 100% sensitivity to first-line drugs ampicillin, chloramphenicol, and cotrimoxazole. Twelve of the 60 isolates (18%) were susceptible to nalidixic acid (NASST) and the remaining 48 (82%) were resistant to nalidixic acid (NARST). Of these 48 NARST strains, 46 (97.5%) had reduced susceptibility to ciprofloxacin (MIC 0.25-1.0 microg/mL), whereas 2 strains (2.75%) were resistant to ciprofloxacin (MIC 4.0 microg/mL). In RFLP analysis, all the NASST strains showed 3 fragments, whereas all the NARST strains showed 2 fragments due to the loss of 1 restriction site as a result of mutation. All the NARST strains with reduced susceptibility to ciprofloxacin (n = 46) had a single mutation in gyrA gene (Ser 83-->Tyr or Ser 83-->Phe), whereas double mutations (Ser 83-->Phe and Asp 87-->Asn) were found in each of the 2 ciprofloxacin-resistant strains. None of the NASST strains (n = 12) revealed any mutation. CONCLUSION: Our study exemplifies the correlation between nalidixic acid screening test, MIC values, and the detection of mutation in GyrA gene by PCR-RFLP with a novel RE SSiI.This was further confirmed by nucleotide sequencing.

Investigational antiretroviral drugs.

HIV disease is a chronic infection that requires lifelong treatment with the aim of suppressing the circulating viral load in order to improve the host immune status. The development of safe and effective antiretroviral agents with unique resistance profiles or novel mechanisms of action are an important goal for the long-term management of HIV-infected patients. The antiretroviral drug classes include entry and fusion inhibitors, nucleoside reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors, integrase inhibitors, and protease inhibitors. Current antiretroviral therapeutic regimens are associated with the emergence of issues like HIV drug resistance, drug toxicities, associated poor patient adherence to therapy, co-existence of other opportunistic, and blood borne viral infections. Newer antiretroviral agents may provide some alternatives to modulate the therapy as per the requirements of the HIV infected patients.

Differentiation of wild-type varicella-zoster strains from India and the Oka vaccine strain using a VZV open reading frame - 62 based PCR-RFLP technique.

Since the introduction of varicella vaccination in India, surveillance of circulating VZV strains has gained significance. Differentiating wild-type VZV strains from the Oka vaccine strain can be achieved only by molecular genotyping methods. The development of PCR methods for VZV strain differentiation has been hampered by the fact that the VZV genome is highly conserved. We used VZV ORF 62 PCR-RFLP analysis to identify and differentiate wild-type VZV strains in India from the Oka vaccine strain. Digestion of VZV ORF 62 amplicons with SmaI, enabled accurate strain differentiation; the Oka strain was positive for three SmaI sites, compared to two SmaI sites in the wild-type VZV strains that we tested.

Differentiation of wild-type varicella-zoster strains from India and the Oka vaccine strain using a VZV open reading frame - 62 based PCR-RFLP technique

Since the introduction of varicella vaccination in India, surveillance of circulating VZV strains has gained significance. Differentiating wild-type VZV strains from the Oka vaccine strain can be achieved only by molecular genotyping methods. The development of PCR methods for VZV strain differentiation has been hampered by the fact that the VZV genome is highly conserved. We used VZV ORF 62 PCR-RFLP analysis to identify and differentiate wild-type VZV strains in India from the Oka vaccine strain. Digestion of VZV ORF 62 amplicons with SmaI, enabled accurate strain differentiation; the Oka strain was positive for three SmaI sites, compared to two SmaI sites in the wild-type VZV strains that we tested.

Profile of primary resistance in HIV-1-infected treatment-naive individuals from Western India.

The majority of the HIV drug resistance (HIVDR) testing studies have focused on subtype B virus. The predominance of subtype C in the Indian subcontinent along with greater access to antiretroviral therapy (ART) necessitates studies on HIVDR genotyping. We determined the prevalence of mutations associated with protease inhibitors (PI), nucleoside reverse transcriptase inhibitors (NRTI), and nonnucleoside reverse transcriptase inhibitors (NNRTI) from plasma of 40 antiretroviral drug-naive study participants in Indian HIV-1 pol gene sequences. Of these, 36 sequences belonged to subtype C, two to subtype A1, and two were subtype A1C recombinants. The heterosexual route was the most common route of transmission. Drug resistance-associated mutations were observed in 10% (4/40) of the study participants. The resistance mutation observed in the protease gene was V82A, whereas in the RT gene, M41L, D67N, M184V, and A98G were documented. This is the first study reporting major protease mutations by genotyping in ART-naive individuals from western India.

Molecular characterization of clinical varicella-zoster strains from India and differentiation from the oka vaccine strain.

With the introduction of varicella vaccination in India, surveillance of circulating varicella-zoster strains has gained significance. The aim of the present study was to achieve molecular characterization of circulating varicella-zoster virus (VZV) strains and differentiation from the Oka vaccine strain. In this study, the genotype of 100 clinical VZV strains was analyzed. Vesicle fluid was collected from patients with VZV infections (92 cases of varicella and 8 cases of herpes zoster). The PCR-RFLP analysis of two polymorphic loci--a PstI restriction site in ORF 38 and a BglI restriction site in ORF 54 was used to characterize and differentiate them from the vaccine strain. All the wild-type strains were positive for the PstI restriction site in ORF 38. This differentiated them from the Oka vaccine strain, which is PstI negative. The wild-type strains as well as the Oka vaccine strain were positive for the BglI restriction site in ORF 54. Thus, the genotype of all the VZV strains examined had the wild-type pattern represented as PstI(+) BglI(+). None of the strains had the PstI(-) BglI(+) genotype characteristic of the Oka strain or the PstI(+) BglI(-) wild-type pattern. To conclude, PstI and BglI serve as good reference markers in the genotyping of circulating varicella strains in India and serve to differentiate them from the vaccine strain as well as other wild-type strains.