Prevalence of Metallo-β-lactamase Producing Non-fermentative Pseudomonas Species from Clinical Isolates in Dhaka, Bangladesh

Antimicrobial drug resistance, a global concern, has been increasing unpredictably in microorganism causing human infections specially among Gram negative non-fermenting Pseudomonas spp. Carbapenems, a beta lactam antibiotics, are the most potent and effective drug usually kept reserved for treating the multi-drug resistant Psedomonas spp and other infections caused by organisms producing Extended Spectrum Beta Lactamase (ESBL) and AmpC. Clinical utility of carbapenem will reduce when resistant bacteria evolve due to production of carbapenem hydrolyzing Metallo-β-lactamase (MBL) which confers high-level resistance to all beta-lactam antibiotics except aztreonam. The various reports on the prevalence of MBLs are available from many countries but few from Bangladesh. We investigated the prevalence of MBL production in these Pseudomonads obtained from clinical sources in an uraban setting in Dhaka, Bangladesh. A total of 29,136 specimens were processed for culture from January 2011 and December 2015 from non duplicated patients attending diagnostic unit of icddr,b from different settings of Bangladesh. The specimens included urine 14,323; blood 11,378; other body fluid 2,487; sputum 535 and tracheal aspirate 413. All specimens were processed for culture following standard bacteriological methods and the Pseudomonas spp were identified following defined standard biochemical procedures. Metallo-β-lactamase (MBL) was determined by EDTA disk synergy (EDS) test. Antimicrobial susceptibility test was performed by disk diffusion method and susceptibility pattern was interpreted and reported following Clinical Laboratory Standard Institute (CLSI) guideline. From 29,136 specimens a total of 2,340(8%) were isolated and identified as Pseudomonas spp. Of the identified Pseudomonas spp, 238(57.6%) were from tracheal aspirate, 216(40.4%) from sputum, 902(36.7%) from other body fluids, 463(4.1%) from blood and 521(3.6%) from urine samples. From 2,340 Pseudomonas spp, by selective sampling, imipenem-meropenem resistant and intermediate susceptible 100 strains were tested for MBL production and 92 were found positive. Tracheal aspirate showed 38%, other body fluids 30%, Urine 17%, sputum 4% and blood 3% MBL production respectively. Irrespective of the sources of specimens, Pseudomonas spp showed 71% resistance to cefixime, 70% to ceftriaxone, 64% to gentamicin, 56% to piperecillin+tazobactam, 50% to ciprofloxacin, 49% to amikacin, 46% to netilmicin, 45% to ceftazidime, 30% to meropenem, 26% to imipenem and 19% to polymyxin B. As multi-drug resistant Pseudomonas showed high level of (92%) MBL production, so MBL detection testing facility may be a useful battery to determine MDR producing Pseudomonas from clinical isolates.

Capsular genotype and lipooligosaccharide locus class distribution in Campylobacter jejuni from young children with diarrhea and asymptomatic carriers in Bangladesh

Campylobacter jejuni-related diarrheal diseases is one of the major health issues among young children (0-59 months old) in low-income countries. Monitoring of the capsular (capsule polysaccharide, CPS) types of virulent C. jejuni strains in regions where the disease is endemic is of great importance for the development of a customized capsule-based multivalent vaccine. Therefore, we aimed to determine the prevalence of CPS genotypes among C. jejuni strains isolated from young children with enteritis (n = 152) and asymptomatic carriers matched by age, sex, and residence defined as the control group (n = 215) in Bangladesh. CPS genotyping was performed using a newly established multiplex polymerase chain reaction (PCR) method and lipooligosaccharide (LOS) locus classes (A-E) were characterized using PCR as well. We identified 24 different CPS genotypes among the 367 isolates. Four prevalent capsular types, HS5/31 complex (n = 27, 18%), HS3 (n = 26, 17%), HS4A (n = 10, 7%), and HS8/17 (n = 10, 7%) covered almost 50% of the strains from enteritis patients and 43% of the isolates from controls. In combination, the CPS genotype and LOS class was not discriminative between cases and controls. Dominant capsular types previously identified in C. jejuni strains isolated from patients with Guillain-Barré syndrome in Bangladesh were rarely detected in strains isolated from the young children. A similar distribution was evident among enteritis- and control-related strains when comparison was done between CPS types and LOS classes. This is the first systematic study presenting the distribution of CPS genotypes of C. jejuni strains isolated in Bangladesh from children with diarrhea and controls, with capsular genotypes HS5/31 complex, HS3, HS4A, and HS8/17 being prevalent in both. In conclusion, systematic studies are required to develop a multivalent capsule-based vaccine for children in low-income countries.

In silico identification of epitopes from house cat and dog proteins as peptide immunotherapy candidates based on human leukocyte antigen binding affinity

The objective of this descriptive study was to determine Felis domesticus (cat) and Canis familiaris (dog) protein epitopes that bind strongly to selected HLA class II alleles to identify synthetic vaccine candidate epitopes and to identify individuals/populations who are likely to respond to vaccines. FASTA amino acid sequences of experimentally validated allergenic proteins of house cat and dog were identified using International Union of Immunological Societies (IUIS) allergen nomenclature database. NetMHCII 2.2 server was used to determine binding affinities in the form of 1-log 50 k and in nM with commonly found HLA II alleles. Screening of house cat and dog allergenic proteins identified 4 (with 2 isoforms for chain 1 and 3 isoforms for chain 2 for fel d 1) and 6 proteins, respectively. Number of strong binders from each protein against each HLA type was determined as potential candidate for allergen immunotherapy. HLA-DRB1*0101 bound maximum number of epitopes (207 and 275 from house cat and dog, respectively) while HLA-DRB1*0802 bound none. We conclude that HLA specific epitope prediction can help identify synthetic peptide vaccine candidates and predict response as well.

Sharps injuries among health care workers in Cairo University Hospitals

BACKGROUND

Health care workers (HCWs) are exposed to blood borne pathogens, through job-related risk factors like sharps injuries (SIs). Sharps injuries can be prevented by safer devices and through education and training of universal precautions and safe work practices.

OBJECTIVES

The present study aims to examine the current situation of infection control at Cairo University Hospitals in Egypt, through studying SIs among health care workers and evaluating the preventive measures.

SUBJECTS AND METHODS

The first part of this study was cross-sectional in design. A self-administered Arabic questionnaire was designed for this study based on EPINet (Exposure Prevention Information Network) Needle Stick and Sharps injuries reporting Sheet. The second part of the study was an interventional design to evaluate the effectiveness of preventive measures which were introduced since the beginning of 2011.

RESULTS

Forty percent of the participants (416/1036) reported at least one sharps injury in the preceding year (2010), of which more than 70% (293/416) experienced more than one injury. 88.9% (370/416, p < 0.001) of HCWs did not report their injury. Following intervention measures injury rates were significantly reduced from 36.9/100 person in 2010 in the intensive care units, to 12.4/100 person during 2011, (X2 = 21.419 and P value < 0.001).

CONCLUSION

There is a high occurrence of sharps injuries in Cairo University Hospitals. Implementation of safety devices and adequate training will lead to reduction of SIs among HCWs.

Potentiating toxicological interaction of single-walled carbon nanotubes with dissolved metals

The present study explored the ecotoxicology of single-walled carbon nanotubes (SWCNTs) and their likely interaction with dissolved metals, with a focus on the effect of in vivo exposure in marine mussels. Any nano-scale effects were negated by the tendency of uncoated SWCNTs to agglomerate in water, particularly with high ionic strength as is the case in estuarine and full-strength seawater. However, SWCNTs, in combination with natural organic matter, remained suspended in seawater for long enough to become available to filter-feeding mussels, leading to their concentration on and increased contact with gill epithelia during exposure. For the first time, the authors describe a potentiating toxicological effect, expressed as DNA strand breaks obtained using the comet assay, on divalent metals afforded by negatively charged SWCNT agglomerates in seawater at concentrations as low as 5 µg L⁻¹. This is supported by the observation that SWCNTs alone were only toxic at concentrations ≥100 µg L⁻¹ and that the SWCNT-induced DNA damage was correlated with oxidative stress only in the absence of metals. If these laboratory experiments are confirmed in the natural environment, the present results will have implications for the understanding of the role of carbon nanotubes in environmental metal dynamics, toxicology, and consequently, regulatory requirements.

Presence of enterotoxigenic Escherichia coli in biofilms formed in water containers in poor households coincides with epidemic seasons in Dhaka

AIMS

The objective of this study was to investigate if biofilms may be potential reservoirs for the waterborne pathogen enterotoxigenic Escherichia coli (ETEC) in household water in Dhaka, Bangladesh.

METHODS AND RESULTS

Biofilms formed on submerged glass slides. Mature biofilms were found significantly more often on glass slides collected in the monsoon period between the two annual ETEC peaks in Bangladesh, that is, between May and August than the rest of the year (P < 0.03). Sixty-four per cent (49/77) of all biofilms analysed by quantitative real-time PCR were positive for ETEC. Significantly more ETEC-PCR positive biofilms were found during the epidemic peaks and during flooding periods than the rest of the year (P < 0.008). Planktonic ETEC was present in the household water during all seasons, but there was no correlation between presence or numbers of ETEC in water and the epidemic peaks.

CONCLUSIONS

We conclude that ETEC is continuously present in water and biofilms in household water reservoirs in Dhaka, which has a high prevalence of ETEC diarrhoea. The frequency of biofilms with ETEC was significantly associated (P < 0.008) with seasonal epidemic peaks of ETEC diarrhoea.

SIGNIFICANCE AND IMPACT OF THE STUDY

We show for the first time that enterotoxigenic Escherichia coli (ETEC), the causative agent of acute watery diarrhoea and travellers' diarrhoea is present in biofilms in household water tanks in Dhaka, Bangladesh.

Inhibition of sphingosine kinase 1 enhances cytotoxicity, ceramide levels and ROS formation in liver cancer cells treated with selenite

High doses of selenite have been shown to induce cell death in acute myeloid leukemia and lung cancer cells. In this study, we combined selenite treatment with modulators of sphingolipid metabolism in the hepatocellular carcinoma cell line Huh7. Treatment with 20 μM of selenite reduced the viability of Huh7 cells by half and increased the levels of long chain C14-, C16-, C18- and C18:1- ceramides by two-fold. Inhibition of neutral sphingomyelinase with 3-O-methylsphingosine significantly reduced the cytotoxic effect of selenite. In line with this result, selenite caused a 2.5-fold increase in the activity of neutral sphingomyelinase. The sphingosine kinase 1 (SK1) inhibitor 2-(p-hydroxyanilino)-4-(p-chlorophenyl)thiazole (SK1-II) sensitized the cells to the cytotoxic effects of selenite. Preincubation with 10 μM of SK1-II prior to treatment with 10 μM of selenite caused induction of apoptosis and gave rise to a 2.5-fold increase in C14-, C16-, C18- and C18:1- ceramides. Instead, 50 μM of SK1-II combined with 10 μM of selenite caused accumulation of cells in G1/S phases, but less apoptosis and accumulation of ceramides. The formation of reactive oxygen species (ROS) after treatment with 10 μM of selenite was maximally enhanced by 1 μM of SK1-II. Moreover, combined treatment with SK1-II and 10 μM of selenite synergistically reduced the number of viable Huh7 cells, while the non-tumorigenic hepatocyte cell line MIHA remained unaffected by the same treatment. These results raise the possibility that a combination of selenite and SK1 inhibitors could be used to treat liver cancer cells, that are regarded as drug resistant, at doses that are non-toxic to normal liver cells.

Emergence of multidrug-resistant NDM-1-producing Gram-negative bacteria in Bangladesh

The main objective of this study was to investigate the prevalence of bla (NDM-1) in Gram-negative bacteria in Bangladesh. In October 2010 at the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) laboratories, 1,816 consecutive clinical samples were tested for imipenem-resistant Gram-negative organisms. Imipenem-resistant isolates were tested for the bla (NDM-1) gene. Among 403 isolates, 14 (3.5 %) were positive for bla (NDM-1), and the predominant species were Klebsiella pneumoniae, Acinetobacter baumannii, and Escherichia coli. All bla (NDM-1)-positive isolates were resistant to multiple antibiotics. Among β-lactamase genes, bla (CTX-M-1-group) was detected in ten isolates (eight bla (CTX-M-15)), bla (OXA-1-group) in six, bla (TEM) in nine, bla (SHV) in seven, and bla (VIM) and bla (CMY) in two isolates each. The 16S rRNA methylase gene, armA, was detected in five K. pneumoniae isolates and in one E. coli isolate. rmtB and rmtC were detected in a Citrobacter freundii and two K. pneumoniae isolates, respectively. qnr genes were detected in two K. pneumoniae isolates (one qnrB and one qnrS) and in an E. coli isolate (qnrA). Transferable plasmids (60-100 MDa) carrying bla (NDM-1) were detected in 7 of the 11 plasmid-containing isolates. Pulsed-field gel electrophoresis (PFGE) analysis grouped K. pneumoniae isolates into three clusters, while E. coli isolates differed significantly from each other. This study reports that approximately 3.5 % of Gram-negative clinical isolates in Bangladesh are NDM-1-producing.

Incidence and predictors of infection in patients undergoing primary isolated coronary artery bypass grafting: a report from a tertiary care hospital in a developing country

AIM

Infection following coronary artery bypass grafting (CABG) is a leading cause of morbidity, mortality, and increased length of hospital stay. Many studies have investigated the predictive value of known risk factors for infection in patients following CABG and conclusions have been variable and may reveal regional or institution-specific influence. The purpose of this prospective study was to determine the pre- and peri-operative risk factors for infection in patients undergoing coronary artery bypass surgery in a developing country.

METHODS

A prospective study was undertaken to collect data on 12 reported risk factors for all patients undergoing CABG during a five-year period at The Aga Khan University Hospital, Pakistan. The relationship of these risk factors to infection following CABG was evaluated.

RESULTS

Out of 767 consecutive patients admitted for CABG, a total of 73 (9.51%) developed 92 infections following surgery. Sternal Surgical Site Infection (SSI) developed in 30 patients (3.91%), of which 29 (96.7%) were superficial and 1 (3.33%) was deep. There were 37 leg wound infections at the site of conduit harvest, and 2 cases of infection at the intra-aortic balloon pump. There were 12 cases of sepsis and 11 urinary tract infections. There were 26 cases (35.6%) of leukocytosis and 17 patients (23.3%) showed elevated erythrocyte sedimentation rate (ESR). Staphylococcus aureus was the most frequently isolated pathogen (39.7%). Bacteremia data was not collected. Of the total cases of infection following CABG, 59 required prolonged hospitalization or readmission. Univariate analysis was performed using a p-value of <0.2 as the inclusion criteria for further analysis using logistic regression. Multivariate analysis with adjusted Relative Risk (RR) showed that diabetes (P=0.002, RR=2.3, 95% CI=1.4-4.0), obesity (P=0.036, RR=2.2, 95% CI=1.0-4.4), use of an intra-aortic balloon pump (P=0.001, RR=3.6, 95% CI=1.7-7.7), female gender (P=0.004, RR=2.5, 95% CI=0.2-0.8) and prolonged mechanical ventilation (P=<0.0001, RR=6.7, 95% CI=2.8-15.5) were independent predictors of infection in the study population.

CONCLUSION

This study suggests that diabetes, obesity, use of an intra-aortic balloon pump and female gender are independent predictors of infection in patients undergoing CABG. Early and strict diabetic control and pre-operative weight reduction may reduce the incidence of infection following CABG. Contamination of these patients may occur before, during and after the operation and efforts to curb such contamination must be intensive. Further prospective studies need to be undertaken to identify and establish these and other risk factors for infection in the region and elsewhere.