Rising trend of antimicrobial resistance among Neisseria gonorrhoeae isolates and the emergence of N. gonorrhoeae isolate with decreased susceptibility to ceftriaxone

CONTEXT

Gonorrhoea is one of the most common sexually transmitted infections (STI) in developing countries and is a global health problem.

AIMS

To analyze the trend of antimicrobial susceptibility of Neisseria gonorrhoeae isolates over the years, in a tertiary care hospital of North India.

SETTINGS AND DESIGN

The study population comprised males with urethritis and females with endocervicitis attending STI clinic of our hospital.

MATERIALS AND METHODS

In our STI laboratory, all gonococcal isolates are subjected to antimicrobial susceptibility testing by disc diffusion method as per CLSI guidelines. β-Lactamase production is determined by chromogenic cephalosporin test. Minimum Inhibitory Concentration (MIC) for ceftriaxone is determined by E-test.

STATISTICAL ANALYSIS USED

Data were expressed as percentages. The differences in percentages were tested for statistical significance by using χ2 test and P values were determined.

RESULTS

The percentage of penicillinase producing N. gonorrhoeae (PPNG) increased from 8% in 1995-96 to 20% in 2004-05 and 88% in 2011-2013. Quinolone-resistant N. gonorrhoeae (QRNG) showed a significant increase from 12% in 1995-96 to 98.3% in 2004-05, while 84% isolates were found to be QRNG by 2011-2013. In January 2013 we detected our first gonococcal isolate with decreased susceptibility to third-generation cephalosporins; Ceftriaxone, Cefixime and Cefpodoxime (MIC for ceftriaxone = 0.19 μg/ml).

CONCLUSIONS

The results of our study highlighted an alarming increase in the percentage of PPNG and QRNG strains over the years. Emergence of N. gonorrhoeae isolates with decreased susceptibility to third-generation cephalosporins is a cause of concern and thus emphasises the importance of antimicrobial susceptibility testing.

Asymptomatic reproductive tract infections/sexually transmitted infections among HIV positive women

This study aims to highlight the importance of screening all HIV positive women for various reproductive tract infections/sexually transmitted infections (RTIs/STIs) irrespective of symptoms and to determine its occurrence in asymptomatic HIV positive women. Relevant specimens were collected for diagnosis of various RTIs/STIs. STIs were diagnosed in nearly one-third of the HIV positive asymptomatic patients which is quite high. The national strategy for STIs/RTIs control misses out large number of asymptomatic RTIs/STIs in HIV positive women which is responsible for silently transmitting these infections in the community. So this strategy should be modified to include screening of all HIV positives women irrespective of symptoms of STIs/RTIs.

Assessment of trends of ofloxacin resistance in Mycobacterium tuberculosis

PURPOSE

Ofloxacin (OFX) is one of the potent fluoroquinolone (FQ) recommended to treat MDR-TB. Over a decade, the preexposure of this drug for the treatment of other bacterial infections has resulted in acquisition of FQ resistance among Mycobacterium tuberculosis strains. Considering this possibility, a study was undertaken in a tertiary care center in the capital city (India) to assess the drug resistance trends of OFX among susceptible and multidrug resistant (MDR) strains of M. tuberculosis.

MATERIALS AND METHODS

A total of 102 M. tuberculosis isolates (47 susceptible to first-line drugs and 55 MDR isolates) were screened for susceptibility testing of OFX with a critical concentration of 2 μg/ml by Lowenstein Jensen (LJ) proportion method.

RESULTS

The results showed 40 (85.1%) isolates among 47 susceptible isolates and 34 (61.8%) isolates among 55 MDR isolates, were found to be susceptible to OFX. Fisher's exact test showed significant P-value (0.0136) demonstrating 1.377 fold (95% confidence interval) increased risk to become resistant to OFX than susceptible isolates. These finding shows decreased OFX susceptibility is not only limited to MDR isolates but also increasingly seen in susceptible strains as a result of drug abuse.

CONCLUSIONS

Our finding were not alarming, but highlights the general risk of acquiring resistance to OFX, jeopardizing the potential for these drugs to be used as second-line anti-TB agents in the management of drug-resistant TB and creating incurable TB strains .

Evaluation of nucleic acid probe for rapid identification of Mycobacterium tuberculosis complex in extra-pulmonary culture isolates

Patients infected with Non-tuberculous mycobacteria (NTM) usually do not respond to conventional anti-tubercular treatment and are misdiagnosed as infection with multi-drug resistant strains of mycobacterium tuberculosis (M.tb) due to lack of correct species identification, particularly in the developing countries like India. One of the challenges faced by clinicians in the treatment of tuberculosis is the absence of an easy, reliable and rapid identification tool that can accurately differentiate disease caused by M.tb complex from NTM. Keeping this in consideration, the performance of species specific nucleic acid probe i.e. Accuprobe was assessed and compared with conventional niacin production, nitrate reductase assay techniques for identification of M.tb complex in 80 mycobacterial isolates obtained from different extra-pulmonary sites. Accuprobe identified 62 isolates (77.5%) as M. tuberculosis complex and remaining 18 isolates (22.5%) as NTM whereas 64 isolates (80%) were identified as M.tb and rest 16 (20%) were interpreted as NTM by conventional biochemical techniques. The overall agreement between both techniques was 96.9% The sensitivity, specificity, positive predictive value(PPV) and negative predictive value (NPV) shown by accuprobe were 96.9%, 100%, 96.9%, and 88.9% respectively. Thus, accuprobe has showed impressive sensitivity and specificity giving results in < 3 hrs from culture-positive isolates and have sure edge over conventional biochemical methods which are, nonetheless, labour intensive and cumbersome to perform thus delaying prompt mycobacterial identification.

The use of E-test for the drug susceptibility testing of Mycobacterium tuberculosis - a solution or an illusion?

AIM

To evaluate E-test as a tool for rapid determination of drug susceptibility against the conventional LJ method focusing on reliability, expense, ease of standardization and performance of the technique in low resource settings.

MATERIALS AND METHODS

A total of 74 clinical isolates (2004-2005) of Mycobacterium tuberculosis were tested using E-test for susceptibility to streptomycin (STM), isoniazid (INH), rifampicin (RIF) and ethambutol (EMB) by E-strip and LJ (LJPM) proportion methods.

RESULTS

The LJPM method, the gold standard, detected resistance against STM in 16.2%, INH in 40.5%, RIF in 18.9% and EMB in 27% cases. In comparison, the resistance values showed by E-test was 66.67% for STM, 57.14% for INH 71.43% for RIF and 80% for EMB. The susceptible correlation was 90.32% for STM, 73.91% for INH, 93.33% for RIF and 59.26% for EMB. E-test correctly identified only eight of the 12 (66.6%) MDR isolates and wrongly identified four isolates which were not MDR. The overall agreement between the two methods was only 48.6%. Resistant isolates showed false positive resistance observed while using E-strip towards all the drugs.

CONCLUSION

E-strips are not quite feasible as a replacement for LJ-proportion method on a large scale due to high risk of cross contamination, laboratory infection, expense associated with it and high false positive resistance observed to all first line drugs. However, the good correlation observed for RIF between the two methods indicates that E-test could contribute to the role in rapid screening of MDR TB isolates as rifampicin mutations are invariably observed in MDR TB isolates.

Concomitant TB and cryptococcosis in HIV-infected patients

Four cases of concomitant tuberculosis and cryptococcosis infection in HIV-positive patients are described. As the HIV pandemic progresses and the proportion of patients with end-stage disease increases, a high suspicion of incidence and unusual forms of infections must always be kept in mind.

A study on the perinatal transmission of the hepatitis B virus

The purpose of this study was to determine the age wise prevalence of Hepatitis B virus (HBV) in children under five years and to analyze the relative importance of horizontal or vertical transmission. This study included 400 children in the age group of less than five years attending the outpatient department of pediatrics with minor complaints. History of HBV immunization was taken as the exclusion criteria. All the samples were tested for Hepatitis B surface antigen (HBsAg) and anti HBs using commercial ELISA kits. Liver function tests were performed on all the HBsAg positive patients. Hepatits B nucleocapsid antigen (HBeAg) was detected in few HBsAg positive mothers. Overall HBsAg positivity in children below five years was 2.25%. There was no statistically significant difference in HBsAg positivity in the different age groups by chi square test. HBsAg positivity in mothers was 4.25%. However only in three cases the pair of mother and child were both positive for HBsAg. The mean anti HBs positivity in children was 23.75%. There was no statistically significant difference in the anti HBs positivity in different age groups of children. The observation that there is no statistically significant difference in the prevalence of HBV infection (HBsAg and HBs) amongst different age groups of children below five years signifies that a large proportion of HBV infection in children of this age is acquired via vertical transmission. It is also indicated that this mode of disease transmission is responsible for the majority of chronic carriers. Universal immunization of all infants is desirable to decrease the carrier pool and it is inferred from the present study that Hepatitis B immunization should begin at birth to have greater impact.

Whole blood samples as an alternative to serum for detection of immunity to measles virus by ELISA

The aim of this study was to evaluate enzyme linked immunosorbent assay (ELISA) as a testing strategy for detection of antibodies against measles virus from microquantities of blood soaked onto filter paper. We studied 165 healthy children in the age group of 1 to 2 years, attending the outpatient department of pediatrics. Two sets of samples were collected from each child. One by venipuncture and the other on Whatman filter paper-3 discs of 20 mm size by finger or heel prick so that each strip is completely soaked with blood on both sides. These were tested for measles virus antibodies by ELISA using Melotest measles IgG commercial ELISA kit manufactured by Melotec S. A. (Barcelona, Spain). The resulting sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the filter paper (FP) ELISA compared to serum ELISA was 100, 90, 97.8, and 100%, respectively. The correlation coefficient r = 0.93% (p < 0.001) and the agreement between the two techniques was 98% as calculated by the Kappa statistical method. The present study has found filter paper testing by ELISA to be a promising qualitative technique for detection of immunity against measles.

Comparison of two blood collection techniques for measles antibody detection in children

BACKGROUND & OBJECTIVES

Though several seroprevalence and seroconversion studies have been conducted for measles using the filter paper haemagglutination inhibition (FPHAI), very few studies have compared the conventional serum HAI with the FPHAI. The present study was aimed at the evaluation of whole blood samples on filter paper as an alternative to serum specimens for detection of antibodies to measles virus.

METHODS

Serum and whole blood samples soaked on filter paper were collected from 165 randomly selected healthy children in the age groups of 1-2 yr. HAI test was performed on both sets of samples and the results compared.

RESULTS

Ninety samples that gave a titre of 8 or more by serum HAI also had titres of > or = 8 by FPHAI showing 100 per cent agreement between the two assays. Seventeen samples that had a serum HAI titre of 2 and 4 were missed by FPHAI due to the starting dilution of 8 of the latter. However, FPHAI gave no false positive results compared with serum HAI.

INTERPRETATION & CONCLUSION

Collection of the FP samples by finger prick is more acceptable and requires less expertise than venepuncture. Thus, in spite of the small percentage of missed cases by the filter paper method, this technique of sampling was found to be a convenient and reliable alternative to venepuncture, for detection of measles virus antibody especially in large scale seroepidemiological studies.