Godfred A. Menezes

Antimicrobial resistance trends in blood culture positive Salmonella Typhi isolates from Pondicherry, India, 2005–2009

Typhoid fever is caused by Salmonella enterica serovar Typhi, a major public health concern in developing countries. Recently, there has been an upsurge in the occurrence of bacterial isolates that are resistant to ciprofloxacin, and the emergence of broad spectrum β-lactamases in typhoidal salmonellae constitutes a new challenge for the clinician. A total of 337 blood culture isolates of S. Typhi, isolated from Pondicherry, India, between January 2005 and December 2009, were investigated using phenotypic, molecular and serological methods. Of the 337 isolates, 74 (22%) were found to be multidrug resistant (MDR) and 264 (78%) nalidixic acid resistant (NAR). Isolates with reduced susceptibility to ciprofloxacin possessed single mutations in the gyrA gene. A high rate of resistance (8%) was found to ciprofloxacin. All isolates with a ciprofloxacin MIC ≥ 4 mg/L possessed both double mutations in the QRDR of the gyrA gene and a single mutation in the parC gene. Active efflux pump mechanisms were also found to be involved in ciprofloxacin resistance. Finally, a large number of PFGE patterns (non-clonal genotypes) were observed among the S. Typhi isolates. In conclusion, a high rate of ciprofloxacin resistance was observed in comparison to other endemic areas in blood culture isolates of S. Typhi from Pondicherry, India, with steadily increasing NAR but decreasing MDR isolations over the study period. This is most likely to be due to an increased use of ciprofloxacin as a first-line drug of choice over more traditional antimicrobial agents for the treatment of typhoid fever.

Antimicrobial resistance in typhoidal salmonellae

Infections with Salmonella are an important public health problem worldwide. On a global scale, it has been appraised that Salmonella is responsible for an estimated 3 billion human infections each year. The World Health Organization (WHO) has estimated that annually typhoid fever accounts for 21.7 million illnesses (217,000 deaths) and paratyphoid fever accounts for 5.4 million of these cases. Infants, children, and adolescents in south-central and South-eastern Asia experience the greatest burden of illness. In cases of enteric fever, including infections with S. Typhi and S. Paratyphi A and B, it is often necessary to commence treatment before the results of laboratory sensitivity tests are available. Hence, it is important to be aware of options and possible problems before beginning treatment. Ciprofloxacin has become the first-line drug of choice since the widespread emergence and spread of strains resistant to chloramphenicol, ampicillin, and trimethoprim. There is increase in the occurrence of strains resistant to ciprofloxacin. Reports of typhoidal salmonellae with increasing minimum inhibitory concentration (MIC) and resistance to newer quinolones raise the fear of potential treatment failures and necessitate the need for new, alternative antimicrobials. Extended-spectrum cephalosporins and azithromycin are the options available for the treatment of enteric fever. The emergence of broad spectrum β-lactamases in typhoidal salmonellae constitutes a new challenge. Already there are rare reports of azithromycin resistance in typhoidal salmonellae leading to treatment failure. This review is based on published research from our centre and literature from elsewhere in the world. This brief review tries to summarize the history and recent trends in antimicrobial resistance in typhoidal salmonellae.

EMERGENCE OF VANCOMYCIN INTERMEDIATE STAPHYLOCOCCUS SPECIES IN SOUTHERN INDIA

Since the emergence of meticillin-resistant Staphylococcus aureus (MRSA), vancomycin has been the only uniformly effective treatment for staphylococcal infections in India, teicoplanin and linezolid not being commonly used. The incidence of vancomycin-intermediate S. aureus (VISA) and vancomycin-resistant S. aureus (VRSA) has been increasing in various parts of the world. The first clinical isolate of VRSA was reported from the United States in 2002 (CDC, 2002). More recently, some workers have reported vancomycin-resistant staphylococcal strains from Brazil (Palazzo et al., 2005), Jordan (Bataineh, 2006) and India (Tiwari & Sen, 2006). Vancomycin intermediateresistant Staphylococcus haemolyticus has been reported previously (Schwalbe et al., 1987), and perhaps this is a critical antecedent of VISA. As documented reports of VISA/VRSA in India are very few (Assadullah et al., 2003), we decided to monitor the vancomycin susceptibility of clinical meticillin-resistant Staphylococcus spp. in the tertiary care teaching hospital, JIPMER.

Determination of Antimicrobial Resistance in Salmonella spp.

Infections with Salmonella are an important public health problem worldwide. Salmonella are one of the most common causes of food-borne illness in humans. There are many types of Salmonella but they can be divided into two broad categories: those that cause typhoid and those that do not. The typhoidal Salmonella (TS), such as S. enterica subsp. enterica serovars Typhi and S. Paratyphi only colonize humans and are usually acquired by the consumption of food or water contaminated with human fecal material. The much broader group of non-typhoidal Salmonella (NTS) usually results from improperly handled food that has been contaminated by animal or human fecal material. Antimicrobials are critical to the successful outcome of invasive Salmonella infections and enteric fever. Due to resistance to the older antimicrobials, ciprofloxacin [fluoroquinolone (FQ)] has become the first-line drug for treatment. Nevertheless, switch to FQ has led to a subsequent increase in the occurrence of salmonellae resistant to this antimicrobial agent. The exact mechanism of this FQ resistance is not fully understood. FQ resistance has driven the use of third-generation cephalosporins and azithromycin. However, there are sporadic worldwide reports of high level resistance to expanded-spectrum cephalosporins (such as ceftriaxone) in TS and in NTS it has been recognized since 1988 and are increasing in prevalence worldwide. Already there are rare reports of azithromycin resistance leading to treatment failure. Spread of such resistance would further greatly limit the available therapeutic options, and leave us with only the reserve antimicrobials such as carbapenem and tigecycline as possible treatment options. Here, we describe the methods involved in the genotypic characterization of antimicrobial resistance in clinical isolates of salmonellae.

Antimicrobial resistance trends in blood culture positive Salmonella Paratyphi A isolates from Pondicherry, India.

Enteric fever is a public health problem with the upsurge in the occurrence of Salmonella isolates that are resistant to ciprofloxacin. In this study, a total of 284 blood culture isolates of S. Paratyphi A were investigated. Of these isolates, 281 (98.9%) were nalidixic acid resistant. A high rate (6.3%) of high-level resistance (≥4 μg/mL) was found to ciprofloxacin. The isolates with ciprofloxacin minimum inhibitory concentrations (MICs) of ≥12 μg/mL had 4 mutations, 2 mutations within the quinolone resistance-determining region of gyrA and 2 mutations also in parC. According to the Clinical Laboratory Standards Institute 2012 MIC breakpoints, 75.0% of isolates were resistant to ciprofloxacin. Finally, 3 major pulsed-field gel electrophoresis patterns were observed among the S. Paratyphi A isolates. The spread of fluoroquinolone resistant S. Paratyphi A necessitates a change toward ′evidence-based′ treatment for enteric fever. The research provides a perspective on the increasing prevalence of antimicrobial resistant S. Paratyphi A isolates in this region of India.

Seroprevalence of syphilis in patients attending a tertiary care hospital in Southern India

ABSTRACT Objective To report our experience with two tests, anti-cardiolipin antibody test [venereal disease reasearch laboratory (VDRL) test] and specific treponemal test ( Treponema pallidum hemagglutination assay), used for screening antenatal, high risk cases and cases from sexually transmitted infection in a tertiary care hospital from January 2006 till December 2008. Methods A total of 14 639 samples received from various patient groups including antenatal cases, patients attending sexually transmitted disease (STD) clinic, blood donors and HIV positive patients were screened. Results Among the 14 639 samples collected, 103 were positive by VDRL test. Of these 89 cases were confirmed by quantitative VDRL test and Treponema pallidum hemagglutination assay. The cumulative seroprevalence over two years was found to be 0.61% in this study. The syphilis seroprevalence reduced from 0.88% in 2006 to 0.40% in 2008. Among the various sub-populations studied, patients attending the sexually transmitted infection clinic showed a seroprevalence of 2.62%. The seroprevalence decreased significantly from 4.00% in 2006 to 1.39% in 2008. Conclusions Our study showed a statistically significant declining rate of syphilis in STD clinics as well as the overall seroprevalence. These findings could be interpreted as indicators of improved programmes for prevention and management of STDs.