Seema Irfan

Emergence of a new antibiotic resistance mechanism in India, Pakistan, and the UK: a molecular, biological, and epidemiological study.

Summary Background Gram-negative Enterobacteriaceae with resistance to carbapenem conferred by New Delhi metallo-β-lactamase 1 (NDM-1) are potentially a major global health problem. We investigated the prevalence of NDM-1, in multidrug-resistant Enterobacteriaceae in India, Pakistan, and the UK. Methods Enterobacteriaceae isolates were studied from two major centres in India—Chennai (south India), Haryana (north India)—and those referred to the UKs national reference laboratory. Antibiotic susceptibilities were assessed, and the presence of the carbapenem resistance gene blaNDM-1 was established by PCR. Isolates were typed by pulsed-field gel electrophoresis of XbaI-restricted genomic DNA. Plasmids were analysed by S1 nuclease digestion and PCR typing. Case data for UK patients were reviewed for evidence of travel and recent admission to hospitals in India or Pakistan. Findings We identified 44 isolates with NDM-1 in Chennai, 26 in Haryana, 37 in the UK, and 73 in other sites in India and Pakistan. NDM-1 was mostly found among Escherichia coli (36) and Klebsiella pneumoniae (111), which were highly resistant to all antibiotics except to tigecycline and colistin. K pneumoniae isolates from Haryana were clonal but NDM-1 producers from the UK and Chennai were clonally diverse. Most isolates carried the NDM-1 gene on plasmids: those from UK and Chennai were readily transferable whereas those from Haryana were not conjugative. Many of the UK NDM-1 positive patients had travelled to India or Pakistan within the past year, or had links with these countries. Interpretation The potential of NDM-1 to be a worldwide public health problem is great, and co-ordinated international surveillance is needed. Funding European Union, Wellcome Trust, and Wyeth.

Phylogenetic diversity of Escherichia coli strains producing NDM-type carbapenemases

BACKGROUND The global accumulation of Escherichia coli with CTX-M extended-spectrum β-lactamases partly reflects the dissemination of clonal lineages, notably ST131 and ST405. More recently, E. coli have emerged that produce NDM carbapenemase. We sought to determine the clonal diversity of E. coli with this enzyme from English hospitals, and to compare them with isolates from Pakistan and India. METHODS The 18 NDM-positive E. coli were from hospitals in England (n = 10), Pakistan (n = 7) and India (n = 1). Isolates were compared by phylogenetic grouping, multilocus sequence typing and PFGE of XbaI-digested DNA. Isolates were screened by PCR for acquired AmpC genes, bla(CTX-M), and the 16S rRNA methylase genes armA and rmtC. RESULTS Most of the isolates belonged to phylogenetic groups B1 (n = 9) or D (n = 7); two were group A and none was group B2. Nine isolates from England and Pakistan belonged to the B1 lineage ST101, with seven of these clustering at >77% similarity by PFGE. Other lineages included ST405 (n = 3, group D), ST648 (n = 3, group D), the ST23 complex (one each of ST90 and ST410, both group A) and ST156 (n = 1, group D). Sixteen of 18 isolates had a group 1 CTX-M gene, 13 had a CIT-type acquired AmpC, and 16 had either or both of armA and rmtC. CONCLUSIONS The E. coli isolates producing NDM-1 carbapenemase belonged to six sequence types and included diverse clonal lineages. Nevertheless, isolates of B1-ST101 accounted for half the collection, and included isolates from both England and Pakistan. None of the isolates belonged to ST131 or to phylogroup B2.

Emergence of Carbapenem resistant Gram negative and vancomycin resistant Gram positive organisms in bacteremic isolates of febrile neutropenic patients: a descriptive study.

AbstractBackgroundThis study was conducted to evaluate drug resistance amongst bacteremic isolates of febrile neutropenic patients with particular emphasis on emergence of carbapenem resistant Gram negative bacteria and vancomycin resistant Enterococcus species.MethodsA descriptive study was performed by reviewing the blood culture reports from febrile neutropenic patients during the two study periods i.e., 1999–00 and 2001–06. Blood cultures were performed using BACTEC 9240 automated system. Isolates were identified and antibiotic sensitivities were done using standard microbiological procedures.ResultsSeven twenty six febrile neutropenic patients were admitted during the study period. A total of 5840 blood cultures were received, off these 1048 (18%) were culture positive. Amongst these, 557 (53%) grew Gram positive bacteria, 442 (42%) grew Gram negative bacteria, 43 (4%) fungi and 6 (1%) anaerobes. Sixty (5.7%) out of 1048 positive blood cultures were polymicrobial. In the Gram negative bacteria, Enterobacteriaceae was the predominant group; E. coli was the most frequently isolated organism in both study periods. Amongst non- Enterobacteriaceae group, Pseudomonas aeruginosa was the commonest organism isolated during first study period followed by Acinetobacter spp. However, during the second period Acinetobacter species was the most frequent pathogen. Enterobacteriaceae group showed higher statistically significant resistance in the second study period against ceftriaxone, quinolone and piperacillin/tazobactam, whilst no resistance observed against imipenem/meropenem. The susceptibility pattern of Acinetobacter species shifted from sensitive to highly resistant one with significant p values against ceftriaxone, quinolone, piperacillin/tazobactam and imipenem/meropenem. Amongst Gram positive bacteria, MRSA isolation rate remained static, vancomycin resistant Enterococcus species emerged in second study period while no Staphylococcus species resistant to vancomycin was noted.ConclusionThis rising trend of highly resistant organisms stresses the increasing importance of continuous surveillance system and stewardship of antibiotics as strategies in the overall management of patients with febrile neutropenia.

Metallo-β-lactamase-producing clinical isolates of Acinetobacter species and Pseudomonas aeruginosa from intensive care unit patients of a tertiary care hospital

Prompt detection of metallo-beta-lactamase (MBL) producing isolates is necessary to prevent their dissemination. Frequency of MBLs producing strains among multidrug resistant (MDR) Acinetobacter species and Pseudomonas aeruginosa was evaluated in critical care patients using imipenem-EDTA disk method. One hundred MDR Acinetobacter spp. and 42 Pseudomonas aeruginosa were checked for MBL production, from January to June 2001. MBL was produced by 96.6 % of imipenem-resistant Acinetobacter isolates, whereas 100% imipenem-resistant Pseudomonas aeroginosa isolates were MBL producers. Carbapenem resistance in MDR Acinetobacter spp. and Pseudomonas aeruginosa isolates in this study was due to MBLs. This calls for strict infection control measures to prevent further dissemination.

Increase in isolation of extended spectrum beta lactamase producing multidrug resistant non typhoidal Salmonellae in Pakistan

BackgroundIncreasing resistance to quinolones and ceftriaxone in non typhoidal Salmonellae is a global concern. Resistance to quinolone and 3rd generation cephalosporin amongst non typhoidal Salmonellae (NTS) from Pakistan has been reported in this study.MethodsRetrospective analysis of laboratory data was conducted (1990-2006). NTS were isolated and identified from clinical samples using standard microbiological techniques. Antimicrobial susceptibility testing was performed by Kirby Bauer. Extended spectrum beta lactamase production (ESBL) was detected using combined disc method. Ciprofloxacin sensitivity was detected by nalidixic acid screening method. Minimum inhibitory concentration (MIC) of ciprofloxacin was determined by agar dilution method. Statistical analysis was performed using SPSS version 13.ResultsAnalysis of 1967 NTS isolates showed a significant increase in ciprofloxacin resistance from 23% in 2002 to 50.5% in 2006, with increased mean MIC values from 0.6 to 1.3 ug/mL. Ceftriaxone resistant NTS also increased and ESBL production was seen in 98.7% isolates. These isolates exhibited high resistance against amoxicillin clavulanic acid (57%), gentamicin (69%), amikacin (44%) and piperacillin tazobactam (30%). No resistance to carbapenem was seen. Ceftriaxone resistance was significantly higher in children <1 year, in invasive isolates and in Salmonella Typhimurium.ConclusionsIncrease in quinolone and ceftriaxone NTS is a serious threat to public health requiring continuous surveillance and use of appropriate screening tests for laboratory detection.

Increasing Trend of Resistance to Penicillin, Tetracycline, and Fluoroquinolone Resistance in Neisseria gonorrhoeae from Pakistan (1992–2009)

Emergence and spread of drug resistant Neisseria gonorrhoeae is global concern. We evaluated trends of antimicrobial resistance in Neisseria gonorrhoeae over years 1992–2009 in Pakistan. Resistance rates were compared between years (2007–2009) and (1992–2006). Antimicrobial susceptibility testing was performed and interpreted according to Clinical Laboratory Standards Institute (CLSI) criteria using the disk diffusion methodology against penicillin, ceftriaxone, tetracycline and ofloxacin. Additional antibiotics tested in 100 strains isolated during 2007–2009, included cefotaxime, cefoxitin, cefuroxime, cefipime, ceftazidime, ceftizoxime, cefixime, cefpodoxime, spectinomycin and azithromycin. Neisseria gonorrhoeae ATCC 49226 was used as control. Chi-square for trend analysis was conducted to assess resistance trend over the study period. During study period significant increase in combined resistance to penicillin, tetracycline and ofloxacin was observed (P value <0.01). Resistance rates during the two study period also increased significantly (P value <0.01). Ceftriaxone resistance was not observed. None of the isolates were found to be resistant or with intermediate sensitivity to additional antibiotics. Our findings suggest that penicillin, ciprofloxacin, tetracycline should not be used in the empirical treatment of gonorrhea in Pakistan. Ceftriaxone and cefixime should be the first line therapy; however periodic MICs should be determined to identify emergence of strains with reduced susceptibility.

Clinical Isolates of Salmonella enterica Serovar Agona Producing NDM-1 Metallo-β-Lactamase: First Report from Pakistan

ABSTRACT We report two cases of infantile diarrhea due to multidrug-resistant, NDM-1 metallo-β-lactamase-producing Salmonella enterica serovar Agona from Pakistan. This study alerts toward possible risk of NDM-1 transmission to enteric fever pathogens and encourages microbiologists to consider active screening of carbapenem resistance in nontyphoidal Salmonella isolates.

Use of "Parasep filter fecal concentrator tubes" for the detection of intestinal parasites in stool samples under routine conditions

Parasitic gastrointestinal infections are a major cause of morbidity and mortality in the developing world, with stool microscopy being the mainstay of diagnostic practice. Both direct microscopy and concentration techniques can be utilized; direct microscopy may be time consuming and tedious; however clinical laboratories in developing countries lack trained staff who can effectively use concentration methods. In our practice we used the Parasep O and P filter concentrator tubes (manufactured by DiaSys Ltd, Berkshire, England. Product Code 146000) along with direct microscopic techniques and found that Parasep filters enhanced the ability to detect intestinal parasites that would have been missed on routine microscopy. We found the Parasep filter concentration method to be easy, cost-effective and reliable for routine stool examinations.

Fluoroquinolone and macrolide co-resistance in clinical isolates of Campylobacter species: a 15-year study in Karachi, Pakistan

Fluoroquinolone and macrolide antibiotics are generally considered as first-line drugs for the treatment of severe campylobacteriosis. This study was conducted to analyse the trend of erythromycin and ofloxacin resistance among Campylobacter spp. isolated from stool specimens over a period of 15 years (1992-2007) at The Aga Khan University clinical laboratory in Karachi, Pakistan. A total of 83 396 stool specimens were processed, with a 14% isolation rate for enteric pathogens. The isolation rate of Campylobacter spp. was low during 1992-93 (6%-13%), peaked in 1996 (46%), then ranged from 20% to 40%. We report a rising trend in ofloxacin resistance, re-emergence of erythromycin resistance and indications of co-resistance to both drugs in clinical isolates of Campylobacter spp.

Isolation frequency and susceptibility pattern of non-O1 and non-O139 Vibrio cholerae in a tertiary health care laboratory, 1999-2012.

In the past decade the importance of non-O1 and non-O139 strains of Vibrio cholerae has been highlighted globally. This study aimed to evaluate the frequency and antimicrobial susceptibility profile of non-O1 and non-O139 V. cholerae in Pakistan. Data of stool specimens yielding growth of non-O1 and non-O139 V. cholerae isolated at a national referral laboratory from 1999 to 2012 were retrospectively analysed and evaluated for resistance to ampicillin, tetracycline, chloramphenicol, co-trimoxazole and ofloxacin. A total of 95 800 stool samples submitted over 1999-2012 yielded 3668 strains of V. cholerae, of which 6% were non-O1 and non-O139 V. cholerae. A high isolation rate was found in the summer season, with a peak in the year 2003. Antimicrobial susceptibility data revealed increasing resistance to co-trimoxazole and ampicillin, but strains remained highly susceptible to ofloxacin. Active surveillance of serotypes and antimicrobial susceptibility is essential to predict future epidemics and define measures to curtail the disease.