Molecular Characterization of Class A-ESBLs, Class B-MBLs, Class C-AmpC, and Class D-OXA Carbapenemases in MDR Acinetobacter baumannii Clinical Isolates in a Tertiary Care Hospital, West Bengal, India

Background Acinetobacter calcoaceticus baumannii (ACB) complex has become a major concern nowadays because of its increasing involvement in several severe infections associated with catheter-related bloodstream and urinary tract infections, ventilator-associated pneumonia, cerebrospinal shunt-related meningitis, and wound infections. Multiple drug-resistant (MDR) ACB cases have been described with an increasing trend where at least it is resistant to a minimum of three antimicrobial groups. The mortality rate associated with A. baumannii is significantly higher than all Acinetobacter spp. isolates with the most prevalence seen in India and Thailand. The rapid spread of high resistance to most potent antimicrobial drugs is due to its ability to incorporate resistance determinants despite multifactorial reasons such as alteration in permeability of cell membrane by either losing expression of outer membrane porins or excess production of efflux pumps. This study aims to characterize resistance determinants responsible for MDR at the genetic level and emphasizes the use of genotyping in routine diagnosis as genotype analysis is reliable and valid. Methodology A total of 289 ACB complex clinical isolates were included in this study. The study for species-level identification of A. baumannii was conducted at the Department of Microbiology, IQ City Medical College Hospital, Durgapur, West Bengal. In addition, the detection of encoded genes associated with class A-extended spectrum beta-lactamases (i.e., CTX-M, KPC, SHV, and TEM genes), class B-metallo-β-lactamases (i.e., IMP, NDM, and VIM genes), Class C-AmpC cephalosporinase, and classD-OXA carbapenemases (i.e., blaOXA-10/11, blaOXA-24, blaOXA-48, blaOXA-58, blaOXA-143, and blaOXA-235 was done using real-time polymerase chain reaction. Results All 289 non-repetitive ACB complex clinical isolates were confirmed as A. baumannii, of which 277 (96%) isolates were MDR. There were no findings of blaCTX-M, blaKPC, blaSHV, blaTEM, blaIMP, blaVIM, blaAmpC, blaOXA-10/11, blaOXA-24, blaOXA-48, blaOXA-58, blaOXA-143, and blaOXA-235 genes in our study. However, there were four (1.44%) positive findings of the blaNDM gene. All MDR isolates (n = 277) were positive for the blaOXA-51 gene. In addition, blaOXA-23 was positive in 269 (97.12%) isolates. Conclusions The oxacillinase production corresponding to blaOXA-23 and blaOXA-51 were the most prevalent antibiotic resistance determinants among MDR A. baumannii in our study. Four (1.44%) isolates had the multiple genes blaOXA-51, blaOXA-23, and blaNDM that shows the coexistence of diverse genetic elements involved in MDR A. baumannii, resulting in total resistance except for a few potent drugs such as colistin and tigecycline. Genotyping is helpful in determining the contribution of the isolates in understanding their association with encoded genes, which, in turn, helps in designing effective surveillance and control strategies in the management of such MDR isolates.

Application of water quality index for the assessment of suitability of natural sources of water for drinking in rural areas of east Sikkim, India

In Sikkim, especially in the rural areas where there is no supply of treated water for drinking and other domestic uses, natural surface water is the only source. The objective was to assess the water quality of natural sources of water in the rural areas of East Sikkim using a water quality index (WQI) for different seasons. A total of 225 samples, that is, 75 in winter, 75 in summer, and 75 in monsoon were collected from different sources for physicochemical analysis, and a WQI was calculated. The water quality values ranged 32.01-96.71. The results showed that most of the water samples were in poor condition (85.3%) and very few of them were in good condition (2.6%). The water quality of the natural sources indicated that the water is poor-quality and not totally safe for human consumption, and that it needs treatment before consumption.

Antibiotic susceptibility profile of bacteria isolated from natural sources of water from rural areas of East sikkim

Background:

Contamination of water, food, and environment with antibiotic-resistant bacteria poses a serious public health issue.

Objective:

The objective was to study the bacterial pollution of the natural sources of water in east Sikkim and to determine the antimicrobial profile of the bacterial isolates.

Materials and Methods:

A total of 225 samples, 75 each during winter, summer, and monsoon season were collected from the same source in every season for bacteriological analysis by membrane filtration method. Antibiotic susceptibility test was performed using standard disc diffusion method.

Results:

A total of 19 bacterial species of the genera Escherichia, Klebsiella, Proteus, Salmonella, Shigella, Enterobacter, Citrobacter, Morganella, Pseudomonas, Acinetobacter, Flavobacterium, and Serratia were isolated and their antimicrobial sensitivity tested. Generally, most bacterial isolates except Salmonella and Shigella species were found resistant to commonly used antibiotics such as ampicillin (57.5%), trimethoprim/sulfamethoxaole (39.1%), amoxicillin/clavulanic acid (37.4%), cefixime (34.5%), tetracycline (29.1%), ceftazidime (26.3%), ofloxacin (25.9%), amikacin (8.7%), and gentamicin (2.7%) but sensitive to imipenem and piperacillin/tazobactam.

Conclusion:

Natural sources of water in east Sikkim are grossly contaminated with bacteria including enteropathogens. The consumption of untreated water from these sources might pose health risk to consumers.

Bacteriological profile of septicemia and the risk factors in neonates and infants in sikkim

BACKGROUND

Bacterial infections remain an important cause of pediatric mortality and morbidity. It might be possible to reduce these factors by early diagnosis and proper management.

AIM

The aim of the study was to analyze the bacteriological profiles with their antibiogram, and to register the risk factors for septicemia in neonates and infants.

SETTING AND DESIGN

This observational cross-sectional study was conducted in a tertiary care teaching hospital at Gangtok, Sikkim, India, and included clinically suspected cases of septicemia in neonates and infants.

MATERIALS AND METHODS

Blood culture reports were studied in 363 cases of clinically suspected septicemia in neonates and infants, using the standard technique of Mackie and McCartney. The antibiotic sensitivity was performed by Kirby-Bauer's disc diffusion method. Risk factors for sepsis in the children were registered.

RESULTS

Blood culture was positive in 22% of cases. Gram-negative septicemia was encountered in 61% of the culture-positive cases. Pseudomonas and Enterobacter species were the predominant pathogens amongst gram-negative organisms. Most gram-negative organisms were sensitive to Amikacin, Ciprofloxacin, and Co-trimoxazole. The most common gram-positive organism isolated was Staphylococcus aureus (97%). More than 70% of Staphylococci isolated were resistant to Penicillin, but were sensitive to Clindamycin (70%) and Vancomycin (40%). The most important risk factors of septicemia in our study population were preterm birth (31%), followed by respiratory distress (5%) and low birth weight (4%).

CONCLUSION

As the cultures showed variable antibiogram with complicated patterns of resistance, culture and sensitivity test should be performed in all cases of septicemia.

Methicillin-resistant Staphylococcus aureus: prevalence and current susceptibility pattern in sikkim

Background:

Prevalence of methicillin-resistant Staphylococcus Aureus (MRSA) strains is reported to be increasing globally.

Objectives:

The study was conducted to find the magnitude and antibiotic susceptibility pattern of MRSA infection in a referral tertiary care teaching hospital of Sikkim, India.

Materials and Methods:

In this cross sectional study, 827 clinical specimens were collected from different departments of Central Referral Hospital. One hundred and ninety-six carrier screening nasal swabs were obtained from health care workers of the hospital. Subsequently, the antimicrobial susceptibility test was performed for the confirmed MRSA isolates as per Clinical and Laboratory Standards Institute (CLSI).

Results:

Methicillin resistance was seen in 152 isolates of S. aureus – 111 from clinical specimens and 41 from carrier screening samples. MRSA positivity among males was significantly higher than females. Extremely significant MRSA-positive cases were observed from ages less than 30 years, in-patient cases, particularly with a stay of more than 15 days and with a previous history of intake of broad spectrum antibiotics. Incidentally, there was no significant difference of MRSA positivity with a previous history of hospitalization. The extent of MRSA and drug resistance pattern was significantly different among various samples of S. aureus-positive isolates. The strains tested exhibited decreased susceptibility to vancomycin and imipenem. Most vulnerable of the carrier were the cleaners, that was a significant observation. Incidentally, there was no resistance in the carriers to both vancomycin and imipenem.

Conclusion:

MRSA is prevalent in our hospital and strains resistant to methicillin and vancomycin were quite high.

Extended Spectrum Beta-lactamase Detection in Gram-negative Bacilli of Nosocomial Origin

BACKGROUND

Resistance to third generation cephalosporins by acquisition and expression of extended spectrum beta lactamase (ESBL) enzymes among gram-negative bacilli is on a rise. The presence of ESBL producing organisms significantly affects the course and outcome of an infection and poses a challenge to infection management worldwide.

MATERIALS AND METHODS

In the period from June 2007 to 2008, we collected 1489 samples from patients suspected of nosocomial infection. The isolates were identified based on colony morphology and biochemical reaction. Gram negative bacilli resistant to third generation cephalosporins were tested for ESBL by double disc synergy test (DDST- a screening test)and then phenotypic confirmatory test. Antimicrobial susceptibility testing was done by modified Kirby Bauer disc diffusion method.

RESULTS

From the sample of 238 gram-negative bacilli, we isolated Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Citrobacter freundii, Proteus mirabilis, Morganella morganii and Enterobacter cloacae. Following both methods, 34% isolates were ESBL-positive. The ESBL producing isolates were significantly resistant (p < 0.01) to ampicillin, piperacillin, piperacillin/tazobactam, trimethoprim/sulfamethoxazole, tetracycline, ciprofloxacin and gentamicin as compared to non-ESBL producers. Multidrug resistance was significantly (p < 0.01) higher (69.14%) in ESBL positive isolates than non-ESBL isolates (21.66%).

CONCLUSION

High prevalence of ESBL in our hospital cannot be ignored. ESBL producers can be detected by DDST and phenotypic confirmatory test with equal efficacy. The sensitivity of screening test improved with the use of more than one antibiotic and addition of one or two antibiotics would not increase cost and labor. We recommend DDST using multiple antibiotics in all microbiology units as a routine screening test.

Solar disinfection improves drinking water quality to prevent diarrhea in under-five children in sikkim, India

BACKGROUND

Solar radiations improve the microbiological quality of water and offer a method for disinfection of drinking water that requires few resources and no expertise and may reduce the prevalence of diarrhea among under-five children.

AIMS AND OBJECTIVES

To find out the reduction in the prevalence of diarrhea in the under-five children after consumption of potable water treated with solar disinfection method.

MATERIALS AND METHODS

This was a population-based interventional prospective study in the urban slum area of Mazegoan, Jorethang, south Sikkim, during the period 1(st) May 2007 to 30(th) November 2007 on 136 children in the under-five age group in 102 households selected by random sampling. Main outcome measure was the assessment of the reduction of the prevalence of diarrhea among under-five children after consumption of potable water treated with solar disinfection method practiced by the caregivers in the intervention group keeping water in polyethylene terephthalate (PET) bottles as directed by the investigators. The data were collected by the interview method using a pre-tested questionnaire prepared on the basis of socio-demographics and prevalence of diarrhea. The data were subjected to percentages and chi-square tests, which were used to find the significance.

RESULTS

After four weeks of intervention among the study group, the diarrhea prevalence was 7.69% among solar disinfection (SODIS) users, while 31.82% prevalence was observed among non-users in that period; the reduction in prevalence of diarrhea was 75.83%. After eight weeks of intervention, the prevalence of diarrhea was 7.58% among SODIS users and 31.43% among non-users; the reduction in diarrhea was 75.88% in the study group. The findings were found to be statistically significant.

CONCLUSIONS

In our study, we observed that the prevalence of diarrhea decreased significantly after solar disinfection of water was practiced by the caregivers keeping potable water in PET bottles in the intervention group.