Incidence of carbapenem resistant nonfermenting gram negative bacilli from patients with respiratory infections in the intensive care units

Novel Antimicrobial Peptide SAAP Mutant as a Better Adjuvant to Sulbactam-Based Treatments Against Clinical Strains of XDR Acinetobacter baumannii

The production of extended spectrum β-lactamases (ESBLs) in extensively drug-resistant (XDR) strains of Acinetobacter baumannii has created havoc amongst clinicians making the treatment procedure challenging. Carbapenem-resistant strains have displayed total ineffectiveness towards newer combinations of β-lactam-β-lactamase inhibitors (βL-βLI) in tertiary healthcare settings. Therefore, the present study was aimed to design potential β-lactamase antimicrobial peptide (AMP) inhibitors against ESBLs produced by the strains. We have constructed an AMP mutant library with higher antimicrobial efficacy (range: ~ 15 to 27%) than their parent peptides. The mutants were thoroughly screened based on different physicochemical and immunogenic properties revealing three peptides, namely SAAP-148, HFIAP-1, myticalin-C6 and their mutants with safe pharmacokinetics profile. Molecular docking highlighted SAAP-148_M15 displaying maximum inhibitory potential with lowest binding energies against NDM1 (- 1148.7 kcal/mol), followed by OXA23 (- 1032.5 kcal/mol) and OXA58 (- 925.3 kcal/mol). The intermolecular interaction profiles displayed SAAP-148_M15 exhibiting hydrogen bonds and van der Waals hydrophobic interactions with the crucial residues of metallo β-lactamase [IPR001279] and penicillin-binding transpeptidase [IPR001460] domains. Coarse-grained clustering and molecular dynamics simulations (MDS) further validated the stable backbone profile and minimal residue-level fluctuations of the protein-peptide complex that were maintained throughout the simulation timeframe. The present study hypothesised that the combination of sulbactam (βL) with SAAP-148_M15 (βLI) holds immense potential in inhibiting the ESBLs alongside restoration of sulbactam activity. The current in silico findings upon further experimental validations can pave path towards designing of successful therapeutic strategy against XDR strains of A. baumannii.

Designing Anti-Microbial Peptides Against Major β-Lactamase Enzymes in Clinically Important Gram-Negative Bacterial Pathogens: An In-Silico Study

Anti-microbial resistance (AMR) creating healthcare concerns worldwide requires ardent exploration of therapeutic alternatives. Although anti-microbial peptides (AMP) are popular for broad-spectrum activity, recent evidence of increasing resistance to membrane-acting AMPs by ESKAPE pathogens has compelled us to design novel AMPs as therapeutic candidates. A library of 60 AMPs comprising natural AMPs and their mutants was constructed through in-silico methods. After physico-chemical property evaluations, each peptide in the library was subjected to flexible molecular docking against four major β-lactamases in Gram-negative ESKAPE pathogens. Among the potent AMP mutants, a Lactoferricin B-Mutant (M4) possessed uniformly high affinity with SHV1, OXA48, NDM1, and AmpC having energies -842.0Kcal/mol, -774.8Kcal/mol, -1103.3Kcal/mol, and -858.8Kcal/mol respectively. Coarse-grained clustering and flexibility analysis further accounted for the residue-level stable configurations of the protein-peptide complexes with high affinity. Highest affinity of Lactoferricin B_M4 was found with NDM1 due to H-bonds, salt-bridges, and hydrophobic interactions with the metallo-β-lactamase domain including crucial active-site residue Asp124. Molecular dynamics simulation further confirmed the stability of Lactoferricin B_M4-NDM1 complex having low residue-level root-mean square deviations (RMSD), atomic-level fluctuations, and radius of gyration (Rg). The study encourages experimental validations and similar methods to identify potential AMPs against drug-resistant pathogens.

Multidrug-resistant Acinetobacter septicemia in neonates: A study from a teaching hospital of Northern India

BACKGROUND:

Acinetobacter species are typical nosocomial pathogens causing infections and high mortality, almost exclusively in compromised hospitalized patients. Acinetobacter sp. are intrinsically less susceptible to antibiotics and have propensity to acquire resistance. Multidrug-resistant (MDR) Acinetobacter sp. blood infection in the neonatal intensive care unit patients create a great problem in hospital settings.

AIMS:

A prospective data analysis was performed over a one year period of all neonates admitted with sepsis who developed Acinetobacter infection and their antibiotic susceptibility pattern was carried out.

MATERIALS AND METHODS:

Blood samples of infected neonates were collected aseptically and cases of Acinetobacter septicemia were identified. Speciation of Acinetobacter species was done. Various risk factors were identified and their drug-sensitivity test was performed.

RESULTS:

The incidence of neonatal septicemia due to Acinetobacter species was 13.7% (49/357). Predominant species isolated was Acinetobacterbaumannii (98%). The major symptoms were lethargy and poor feeding. The major signs were tachypnea, intercostal retraction, and respiratory distress. The major fetal risk factors were low birth weight and prematurity. High degree of resistance was observed to the various antibiotics used. Majority of the isolates (95.9%) were MDR while 93.68% were resistant to carbapenems as well as extensively drug resistant. However, all the strains were sensitive to colistin.

CONCLUSION:

MDR Acinetobacter septicemia in neonatal patients is becoming alarmingly frequent and is associated with significant mortality and morbidity. Therefore, rational antibiotic use is mandatory along with an effective infection control policy in neonatal intensive care areas of each hospital to control Acinetobacter infection and improve outcome.

Evaluation of different phenotypic tests for detection of metallo-β-lactamases in imipenem-resistant Pseudomonas aeruginosa

PURPOSE

Pseudomonas aeruginosa causes a wide spectrum of infections including bacteremia, pneumonia, urinary tract infection, etc., Metallo-beta-lactamase (MBL) producing P. aeruginosa is an emerging threat and cause of concern as they have emerged as one of the most feared resistance mechanisms. This study was designed to know the prevalence of MBL production in P. aeruginosa and to evaluate the four phenotypic tests for detection of MBL production in imipenem-resistant clinical isolates of P. aeruginosa.

METHODS

Totally, 800 isolates of P. aeruginosa isolated from various clinical samples were evaluated for carbapenem resistance and MBL production. All imipenem-resistant strains were tested for carabapenemase production by modified Hodge test. Screening for MBL production was done by double-disc synergy test and combined disc test (CDT). Confirmation of MBL production was done by the E-test (Ab BioDisk, Solna, Sweden).

RESULTS

Out of the 800 isolates of P. aeruginosa, 250 isolates were found resistant to imipenem. Based on the results of E-test, 147 (18.37%) isolates of P. aeruginosa were positive for MBL production. The CDT has the highest sensitivity and specificity for the detection of MBL production as compared to other tests.

CONCLUSION

The results of this study are indicative that MBL production is an important mechanism of carbapenem resistance among P. aeruginosa. Use of simple screening test like CDT will be crucial step toward large-scale monitoring of these emerging resistant determinants. Phenotypic test for MBL production has to be standardized, and all the isolates should be routinely screened for MBL production.

In vitro effect of fosfomycin on multi-drug resistant gram-negative bacteria causing urinary tract infections

Background

Rising rates of resistance to antimicrobial drugs among Enterobacteriaceae limit the choice of therapeutic agents to treat urinary tract infections. In this context we assessed the in-vitro effect of fosfomycin against extended-spectrum beta-lactamases, AmpC beta-lactamases and carbapenemase-producing strains of Escherichia coli, Klebsiella pneumoniae, Enterobacter spp, and Pseudomonas aeruginosa isolated from the patients with urinary tract infection (UTI) and also studied the effect of fosfomycin on their biofilm formation.

Materials and methods

A total of 326 multidrug-resistant (MDR) isolates comprising of Escherichia coli, Klebsiella pneumoniae, Enterobacter spp, and Pseudomonas aeruginosa from the urine samples of the patients with a diagnosis of UTI were included in the study. MIC 50 and MIC 90 were detected by agar dilution method and the capacity to form biofilm in the presence of fosfomycin by these MDR isolates was assessed by the tissue culture plate method.

Results

The MIC50 for meropenem (0.5 µgm/mL) and nitrofurantoin (32 µgm/mL) was within the susceptible range only for E. coli. Fosfomycin was the only antibiotic that inhibited 100% E.coli, 70% Klebsiella spp, and 50% Pseudomonas spp and 40% Enterobacter spp which included the extended-spectrum beta-lactamases producers. It showed a similar effect on carbapenemase producers and AmpC producers. Fosfomycin disrupted biofilm in 67% (n=141) E.coli, 74% (n=50) Klebsiella spp, 88% (n=27) Pseudomonas spp and 36% (n=23) Enterobacter spp at 24 hrs of incubation with a concentration of 2 fold dilution lower than that of the MIC.

Conclusion

Fosfomycin showed a good inhibitory effect on the biofilms produced by the MDR organisms studied here.

Prevalence of Extended Spectrum Betalactamase (ESBL) and Metallobetalactamase (MBL) Producing Pseudomonas aeruginosa and Acinetobacter baumannii Isolated from Various Clinical Samples

This study was conducted with an objective to find the prevalence of extended spectrum betalactamase (ESBL) and metallobetalactamase (MBL) in P. aeruginosa and A. baumannii isolates obtained from various clinical samples. It was conducted in the Department of Microbiology, Adesh Institute of Medical Sciences and Research, Bathinda, over a period of two years from July 2014 to June 2016. Clinical specimens including urine, pus, blood, high vaginal swabs, respiratory samples, and various body fluids were processed and P. aeruginosa and A. baumannii isolates were identified by standard protocols. Antibiotic sensitivity testing for all isolates was done using Kirby-Bauer disc diffusion method. Disc potentiation test was performed to check ESBL and MBL production in these bacteria. Maximum ESBL positive isolates of P. aeruginosa were observed among pus samples and maximum MBL positive isolates were detected in tracheal aspirates. A. baumannii showed maximum positivity for ESBL and MBL production in endotracheal secretions. This study gives an alarming sign towards high prevalence of cephalosporin and carbapenem resistance due to production of extended spectrum betalactamases and metallobetalactamases, respectively. Early detection, stringent antibiotic policies, and compliance towards infection control practices are the best defenses against these organisms.

Coexistence of metallo-beta-lactamase-encoding genes in Pseudomonas aeruginosa

BACKGROUND & OBJECTIVES

The emergence and rapid spread of carbapenem resistance mediated by metallo-beta-lactamase (MBL) in Pseudomonas aeruginosa is of major concern due to limited therapeutic options. This study was aimed at detecting the presence of MBL and its association with integrons in imipenem-resistant P. aeruginosa isolates and to determine their genetic relatedness.

METHODS

A total of 213 P. aeruginosa isolates were collected from two tertiary care centres and tested against anti-pseudomonal antibiotics by antimicrobial susceptibility testing, followed by the detection of MBL production by combined disk method. Minimum inhibitory concentration (MIC) of meropenem was determined by E-test. Multiplex polymerase chain reaction (PCR) was performed for the detection of blaSPM, blaIMP, blaVIM, blaNDM, blaGIM and blaSIM. PCR was carried out to characterize the variable region of class 1 integron. Transcongujation assay was carried out for the confirmation of plasmid-mediated resistance. Enterobacterial repetitive intergenic consensus sequence (ERIC)-PCR was performed for determining the genetic relatedness among P. aeruginosa isolates.

RESULTS

Of the 213 P. aeruginosa isolates, 22 (10%) were found to be carbapenem resistant and these were from pus 18 (82%), urine 2 (9%), sputum 1 (5%) and tracheal wash 1 (5%). Among 22 isolates, 18 (81.8%) were found to be MBL producers by phenotypic method and MIC range of meropenem was 8 to >32 μg/ml. PCR amplification showed that 20 (91%) isolates carried any one of the MBL genes tested: blaVIM and blaNDM in seven (32%) and six (27%) isolates, respectively; blaVIM and blaNDMin three (14%); blaIMP and blaNDM in two (9%); blaVIM and blaIMP in one (5%) isolate. The blaVIM, blaIMP and blaNDM were found to co-exist in one isolate. None of the isolates were positive for blaSPM, blaSIM and blaGIM. All 22 isolates carried class I integron. Of the 20 MBL-positive isolates, transconjugants were obtained for 15 isolates. ERIC-PCR analysis showed all isolates to be clonally independent.

INTERPRETATION & CONCLUSIONS

Our results showed 10.3 per cent of carbapenem resistance among P. aeruginosa isolates, and the coexistence of MBL-encoding genes among P. aeruginosa mediated by class I integron.

Epidemiological study of prevalence, determinants, and outcomes of infections in medical ICU at a tertiary care hospital in India

OBJECTIVES

To determine the prevalence of infections, risk factors, and outcomes in a medical intensive care unit (ICU), we performed a hospital-based study.

MATERIALS AND METHODS

Consecutive patients were enrolled and details of risk factors and bacteriological data were obtained. Outcomes were death/transfer to palliative care or recovery. Statistical analyses were performed.

RESULTS

Four hundred and eighty-seven patients were admitted during the study period (age 55.6 ± 19 yr, men 68%). Diseases responsible were respiratory (37%), gastrointestinal/liver (22%), neurological (20%), renal (8%), and trauma (6%) related. Majority of admissions were direct (45%) or transfers from other hospitals (41%). Most important comorbidities were hypertension (41%), diabetes (31%), and chronic obstructive pulmonary disease (15%). Median APACHE-2 score was 13.0 (IQR 1-25). Antibiotics were administered in 98%. Bacteriological cultures were positive in 28% (n = 623). Respiratory infections were the most common (45.5%) followed by blood (23.3%) and urinary (16.1%). Gram-negative bacteria were common-Acinetobacter baumannii (20.9%), Klebsiella pneumoniae (19.7%), Escherichia coli (18.3%), and Pseudomonas aeruginosa (14.0%). There a high prevalence of resistance to common antibiotics. Patients with positive cultures were older, transferees (46 vs 37%, P = 0.07), with respiratory disease (48 vs. 33%, P = 0.003), with more than two comorbidities (33 vs 21%, P = 0.009), and higher APACHE-2 score (17.7 ± 8 vs. 13.3 ± 8, P = 0.07). Three hundred and fifty-two (72.3%) recovered, 68 (13.9%) died, and 67 (13.8%) were transferred to palliative care. Survival was associated with younger age, lower APACHE-2 score, negative cultures, and shorter duration in ICU (P < 0.05). Mortality was greater in patients with Acinetobacter (OR 2.36, 1.17-4.73), Klebsiella (OR 2.81, 1.33-5.92), Pseudomonas (OR 8.03, 2.83-22.76), or Enterobacter (OR 6.73, 1.29-35.12) infection.

CONCLUSIONS

There is high prevalence of infections in patients in a medical ICU in India. Gram-negative bacteria are the most prevalent and resistance to antibiotics is high. Risk factors are age, hospital transfers, APACHE-2 score, and multiple comorbidities.

Bacteria Etiological Agents Causing Lower Respiratory Tract Infections and Their Resistance Patterns

Background:

Lower respiratory tract infections (LTRIs) are among the most common infectious diseases with potential life-threatening complications.

Methods:

The study consisted of 426 patients with suspected LTRIs from mid and far western region of Nepal between September 2011 and July 2014. The specimens were collected and processed according to the standard microbiological methods at the Central Laboratory of Microbiology of Nepalgunj Medical College, Nepal.

Results:

Among the isolated Gram-positive organisms, Streptococcus pneumonia (n = 30, 51.7%) was the most predominant pathogen, followed by Staphylococcus aureus (n = 28, 48.3%). Among the isolated Gram-negative organisms, Pseudomonas aeruginosa (n = 71, 35.32%) was the most predominant pathogen, followed by Haemophilus influenzae (n = 68, 33.83%), Klebsiella pneumonia (n = 36, 17.19%), and Escherichia coli (n = 26, 12.94%). The pattern of resistance varied regarding the bacteria species, and there were multi-resistant isolates. Also, a significant difference (P < 0.05) was observed between males and females for each type of bacterial species. Among 259 isolates, 86 (33.20%) were from children aged 1-10 years, which were statistically significant (P < 0.05) compared to the other age groups.

Conclusions:

P. aeruginosa and H. influenzae (Gram-negative) and S. pnemoniae (Gram-positive) were the most common bacterial isolates recovered from LTRIs. Age group of 1-10 years old was at a higher risk. Many isolates showed appreciable levels of antibiotic resistance due to antibiotic abuse. There is a need to increase surveillance and develop better strategies to curb the increasing prevalence of LRTI in this region of Nepal.

Characterization by phenotypic and genotypic methods of metallo-β-lactamase-producing Pseudomonas aeruginosa isolated from patients with cystic fibrosis

Pseudomonas aeruginosa continues to be a predominant cause of infections with high intrinsic resistance to antibiotics, resulting in treatment failure. P. aeruginosa is the leading cause of respiratory infections among cystic fibrosis (CF) patients. Resistance to carbapenem antibiotics among P. aeruginosa has been reported. Thus, this study was undertaken to characterize the metallo-β-lactamase (MBL) production of P. aeruginosa by phenotypic and genotypic methods. A total of 572 sputum samples were collected from cystic fibrosis patients along with the patient demographic details in a questionnaire. In total, 217 P. aeruginosa isolates were collected and an antibiogram revealed that 159 (73.3%) and 141 (64.9%) of these colonies exhibited resistance to imipenem and meropenem, respectively. Ceftazidime and tobramycin resistance were both identified in 112 (51.6%) isolates, and resistance to piperacillin-tazobactam, gatifloxacin and netilmicin was detected in 96 (44.2%) respective samples. A total of 62 (28.6%) respective samples were resistant to cefoperazone, cefepime and ceftriaxone. The least antibiotic resistance was shown to amikacin and ceftizoxime with 51 (23.5%) and 32 (14.7%) respective colonies resistant to the antibiotics. The minimum inhibitory concentration (MIC) for imipenem revealed a reduction in the MIC values. MBL screening by the zone enhancement method using ceftazidime plus EDTA discs demonstrated that 63 (56.25%) of the colonies were positive for MBL. A total of 53 (84.1%) samples expressed blaVIM and 48 (76.1%) expressed blaIMP genes, as detected by duplex polymerase chain reaction. In conclusion, carbapenem resistance is of great clinical concern in cystic fibrosis patients with P. aeruginosa infection. Therefore, mandatory regular screening and monitoring the resistance in P. aeruginosa among CF patients is required.

Determination of MIC distribution of arbekacin, cefminox, fosfomycin, biapenem and other antibiotics against gram-negative clinical isolates in South India: a prospective study

OBJECTIVES

To determine the in vitro activity of antibiotics, including arbekacin, cefminox, fosfomycin and biapenem which are all still unavailable in India, against Gram-negative clinical isolates.

METHODS

We prospectively collected and tested all consecutive isolates of Escherichia coli, Klebsiella spp., Pseudomonas aeruginosa and Acinetobacter spp. from blood, urine and sputum samples between March and November 2012. The minimum inhibition concentration (MIC) of 16 antibiotics was determined by the broth micro-dilution method.

RESULTS

Overall 925 isolates were included; 211 E. coli, 207 Klebsiella spp., 153 P. aeruginosa, and 354 Acinetobacter spp. The MIC50 and MIC90 were high for cefminox, biapenem and arbekacin for all pathogens but interpretative criteria were not available. The MIC50 was categorized as susceptible for a couple of antibiotics, including piperacillin/tazobactam, carbapenems and amikacin, for E. coli, Klebsiella spp. and P. aeruginosa. However, for Acinetobacter spp., the MIC50 was categorized as susceptible only for colistin. On the other hand, fosfomycin was the only antibiotic that inhibited 90% of E. coli and Klebsiella spp. isolates, while 90% of P. aeruginosa isolates were inhibited only by colistin. Finally, 90% of Acinetobacter spp. isolates were not inhibited by any antibiotic tested.

CONCLUSION

Fosfomycin and colistin might be promising antibiotics for the treatment of infections due to E. coli or Klebsiella spp. and P. aeruginosa, respectively, in India; however, clinical trials should first corroborate the in vitro findings. The activity of tigecycline should be evaluated, as this is commonly used as last-resort option for the treatment of multidrug-resistant Acinetobacter infections.

Microbiological profile of lower respiratory tract infections in neurological intensive care unit of a tertiary care center from Central India

Background:

Lower respiratory tract infections (LRTI's) are the most frequent infections among patients in intensive care units. The consequences of increased drug resistance are far reaching since bacterial infection of the lower respiratory tract (LRT) is a major cause of death from infectious disease.

Objective:

The study was conducted with the aim of determining the bacterial etiology of LRTI in the neuro intensive care unit (NICU) as well as to update the clinicians with the various antimicrobial alternatives available in the treatment of LRTI.

Subjects and Methods:

The study was conducted for the period of 3 years from January 2010 to December 2012 in the Microbiology Department of a Teaching Tertiary Care Hospital. The LRT specimens from 230 patients admitted in a NICU during the study period were processed. Following culture, the isolated organisms were identified and antimicrobial sensitivity was performed by standard methods.

Results:

Out of the 230 LRT specimens evaluated, 198 (86.08%) were culture positive. A total of 254 pathogens were recovered with a predominance of Gram-negative isolates (n = 243; 96.05%) Pseudomonas aeruginosa was the most dominant pathogen followed by Klebsiella pneumoniae. Alarmingly high percentage of extended spectrum beta-lactamase and methicillin resistant Staphylococcus aureus isolates were detected. The resistance to cephalosporins, aminoglycosides and carbapenem were remarkable.

Conclusions:

Therefore, we can conclude that for effective management of LRTI's, an ultimate and detailed bacteriological diagnosis and susceptible testing is required to overcome global problem of antibiotic resistance.

Control of multidrug resistant bacteria in a tertiary care hospital in India

BACKGROUND

The objective of this study was to assess the impact of antimicrobial stewardship programs on the multidrug resistance patterns of bacterial isolates. The study comprised an initial retrospective analysis of multidrug resistance in bacterial isolates for one year (July 2007-June 2008) followed by prospective evaluation of the impact of Antimicrobial Stewardship programs on resistance for two years and nine months (July 2008-March 2011).

SETTING

A 300-bed tertiary care private hospital in Gurgaon, Haryana (India)

FINDINGS

METHODS

Study Design• July 2007 to June 2008: Resistance patterns of bacterial isolates were studied.• July 2008: Phase I intervention programme Implementation of an antibiotic policy in the hospital.• July 2008 to June 2010: Assessment of the impact of the Phase I intervention programme.• July 2010 to March 2011: Phase II intervention programme: Formation and effective functioning of the antimicrobial stewardship committee. Statistical correlation of the Defined daily dose (DDD) for prescribed drugs with the antimicrobial resistance of Gram negatives.

RESULTS

Phase I intervention programme (July 2008) resulted in a decrease of 4.47% in ESBLs (E.coli and Klebsiella) and a significant decrease of 40.8% in carbapenem-resistant Pseudomonas. Phase II intervention (July 2010) brought a significant reduction (24.7%) in carbapenem-resistant Pseudomonas. However, the resistance in the other Gram negatives (E.coli, Klebsiella, and Acinetobacter) rose and then stabilized. A positive correlation was observed in Pseudomonas and Acinetobacter with carbapenems and cefoperazone-sulbactam.Piperacillin-tazobactam showed a positive correlation with Acinetobacter only. E.coli and Klebsiella showed positive correlation with cefoparazone-sulbactam and piperacillin-tazobactam.

CONCLUSION

An antimicrobial stewardship programme with sustained and multifaceted efforts is essential to promote the judicious use of antibiotics.

Acinetobacter infections in a tertiary level intensive care unit in northern India: epidemiology, clinical profiles and outcomes

BACKGROUND

Nosocomial Acinetobacter infections are an increasing concern in intensive care units (ICU).

OBJECTIVES

To study the demographic and clinical characteristics and the outcomes of ICU patients with Acinetobacter infections.

METHODS

A retrospective, 1-year audit of all Acinetobacter infections diagnosed in ICU patients between January 1 and December 31, 2009.

RESULTS

Acinetobacter infection occurred in 94 patients (108 episodes). The most common site of infection was the respiratory tract (83 patients, 76.85%), with medical patients being more susceptible than surgical patients to Acinetobacter lung infections (P=0.04), particularly late-onset ventilator-associated pneumonia (VAP) (P=0.04). The majority (63.8%) of infections were acquired in the ICU, and patients with ICU acquired infections were intubated significantly longer than the other patients (P=0.02). Seventy percent of the infections were caused by multidrug-resistant (MDR) strains, and the overall crude mortality rate was over 70%. The most important factors affecting mortality were the duration of intubation (P=0.001) and the inappropriate use of antibiotics (P=0.021) after diagnosis of the infection.

CONCLUSIONS

Acinetobacter infections are highly prevalent in the ICU, with medical patients being more susceptible to lung infections, particularly late-onset VAP. The early and appropriate selection of antibiotics is the most important determinant of survival among these patients.

Multidrug resistant acinetobacter

Emergence and spread of Acinetobacter species, resistant to most of the available antimicrobial agents, is an area of great concern. It is now being frequently associated with healthcare associated infections. Literature was searched at PUBMED, Google Scholar, and Cochrane Library, using the terms ‘Acinetobacter Resistance, multidrug resistant (MDR), Antimicrobial Therapy, Outbreak, Colistin, Tigecycline, AmpC enzymes, and carbapenemases in various combinations. The terms such as MDR, Extensively Drug Resistant (XDR), and Pan Drug Resistant (PDR) have been used in published literature with varied definitions, leading to confusion in the correlation of data from various studies. In this review various mechanisms of resistance in the Acinetobacter species have been discussed. The review also probes upon the current therapeutic options, including combination therapies available to treat infections due to resistant Acinetobacter species in adults as well as children. There is an urgent need to enforce infection control measures and antimicrobial stewardship programs to prevent the further spread of these resistant Acinetobacter species and to delay the emergence of increased resistance in the bacteria.

Multi-drug resistant Acinetobacter ventilator-associated pneumonia

Background:

Ventilator-associated pneumonia (VAP) due to a multi-drug resistant (MDR) Acinetobacter is one of the most dreadful complications, which occurs in the critical care setting.

Aims and objectives:

To find out the incidence of Acinetobacter infection in VAP cases, to determine various risk factors responsible for acquisition of Acinetobacter infection and to determine the antimicrobial susceptibility pattern of Acinetobacter.

Materials and Methods:

A total of 60 endotracheal aspirate specimens from intubated patients diagnosed clinically and microscopically as VAP were studied bacteriologically. All clinical details and prior exposure to antibiotics were recorded.

Results:

An incidence of 11.6% of Acinetobacter VAP cases was recorded. Various underlying conditions like head injury, cerebral hemorrhage and chronic obstructive pulmonary disease (COPD) were found to be associated with Acinetobacter VAP. Acinetobacter strains exhibited MDR pattern.

Conclusion:

Strict infection control measures, judicious prescribing of antibiotics, antibiotic resistance surveillance programs and antibiotic cycling should be adopted to control infections due to these bacteria in patients admitted to intensive care units.

Metallo Beta lactamase producing pseudomonas aeruginosa and its association with diabetic foot

Pseudomonas aeruginosa strains that produce metallo beta lactamases (MBLs) are becoming increasingly prevalent in wound infections. The aim of the present study is to determine the clinical features, incidence, and to find out the antimicrobial susceptibility pattern of Pseudomonas aeruginosa in diabetic foot infections. Pus samples for bacterial culture were collected from 310 patients admitted with diabetic foot infections. Antimicrobial sensitivity testing was performed by the Kirby-Bauer disc diffusion method. Carbapenem resistance screening and confirmation of MBL was done by the modified imipenem-ethylenediaminetetraacetic acid (EDTA) double disc synergy test. A total of 54 Pseudomonas aeruginosa was isolated from 310 diabetic foot cases. Males were affected more than females with an M:F ratio of 1.6:1. Most patients belonged to the fifth decade of life with a mean age of 49 ± 16.8 years. All the patients were previously diagnosed with diabetes mellitus with duration of the disease at 16 ± 10.2 years and 63% were prescribed oral hypoglycaemic agents. Wound characteristics were classified according to Wagner's classification majority of Pseudomonas aeruginosa were isolated from Wagner's II and III grade wound. A number of 26 (89.7%) patients underwent debridement, while 9 (31%) patients underwent toe disarticulation, and 7 (24.1%) patients underwent below-the-knee (BKA) amputation. Antibiotic sensitivity testing revealed 20.3% of Pseudomonas aeruginosa were resistance to carbapenem and 81.8% of these were MBL mediated resistance. Infection with multi drug resistance organisms (MDROs) is common in diabetic foot ulcers and is associated with inadequate glycemic control and increased requirement for surgical treatment. There is a need for continuous surveillance of resistant bacteria to provide the basis for empirical therapy and reduce the risk of complications.

Prevalence of metallo-β-lactamase-producing Pseudomonas aeruginosa isolated from diabetic foot ulcer patients

Metallo-beta-lactamase (MBL)-producing Pseudomonas aeruginosa strains have been reported to be an important cause of nosocomial infections. There is not enough information from India regarding their prevalence in diabetic foot ulcer (DFU) patients. The present study was undertaken over a period of two year from December 2008 to March 2011 to study the incidence of MBL producing P. aeruginosa isolated from 162 DFU patients with various grades of ulcer (Texas classification). Forty isolates of P. aeruginosa were obtained from patients. These isolates were subjected to susceptibility testing to anti-pseudomonal drugs as per Clinical Laboratory and Standards Institute (CLSI) guidelines, and were further screened for the production of MBL by disc potentiation testing using ethylenediaminetetraacetic acid (EDTA)-impregnated imipenem and meropenem discs. Of the 40 isolates of P. aeruginosa, 22 (55%) isolates were found resistant to carbapenems (imipenem) and 18 (81.1%) were found to be MBL producers using imipenem+(EDTA) and 15(68.1%) by meropenem+EDTA. This rapid dissemination of MBL producers is worrisome and necessitates the implementation of not just surveillance studies but also proper and judicious selection of antibiotics, especially carbapenems.

Investigation of pulmonary infection pathogens in neurological intensive care unit

Purpose:

The purpose of this study is to investigate the distribution and antimicrobial susceptibility of pathogenic bacteria in inpatients with pulmonary infection in the neurological intensive care unit (NICU).

Methods:

A total of 947 sputum specimens of 428 inpatients from May 2007 to May 2008 in the NICU were enrolled in the study, and bacterial identification and antibiotic susceptibility tests were analyzed using a VITEK 2 system.

Results:

A total of 400 positive bacterial strains were separated from 947 sputum specimens, with Gram-negative bacteria accounting for 69.0% of the total strains collected. The most common strain of Gram-negative bacteria was Klebsiella pneumoniae (20.5%). Gram-positive bacteria accounted for 10.0% of the total strains, with the most common strain being Staphylococcus aureus (2.5%). Fungal species accounted for 21.0% of the total strains, and the most common strain collected was Candida albicans (12.25%). Imipenem was the most effective antibiotic against Gram-positive and Gram-negative bacteria. The drug resistance rate of Gram-positive bacteria to penicillin G was 100%, and the Gram-positive bacteria were 100% sensitive to teicoplanin, vancomycin, and linezolid.

Conclusions:

Gram-negative bacterial infections account for the majority of pulmonary infections in the NICU, with fungal infections being the second most common infection type observed. In addition, fungal infections seem to be related to mortality in the NICU.

Antibiotic sensitivity pattern of gram negative bacilli isolated from the lower respiratory tract of ventilated patients in the Intensive care unit

Background:

Lower respiratory tract infections (LRTIs) are the most frequent infections among patients in Intensive care units (ICUs).

Aims:

To know the bacterial profile and determine the antibiotic susceptibility pattern of the lower respiratory tract isolates from patients admitted to the ICU.

Settings and Design:

Tertiary care hospital, retrospective study.

Materials and Methods:

Transtracheal or bronchial aspirates from 207 patients admitted to the ICU were cultured, identified, and antibiotic sensitivity was performed by standard methods.

Statistical Analysis Used:

SPSS software was used for calculation of % R of 95% confidence interval (CI).

Results:

Of 207 specimens, 144 (69.5%) were culture positive and 63 (30.4%) showed no growth. From 144 culture positives, 161 isolates were recovered, of which 154 (95.6%) were Gram negative bacilli (GNB). In 17 (11.0%) patients, two isolates per specimen were recovered. The most common GNB in order of frequency were Pseudomonas aeruginosa (35%), Acinetobacter baumannii (23.6%), and Klebsiella pneumoniae (13.6%). A very high rate of resistance (80-100%) was observed among predominant GNB to ciprofloxacin, ceftazidime, co-trimoxazole, and amoxycillin/clavulanic acid combination. Least resistance was noted to meropenem and doxycycline.

Conclusion:

Nonfermenters are the most common etiological agents of LRTIs in ICU. There is an alarmingly high rate of resistance to cephalosporin and β-lactam-β-lactamase inhibitor group of drugs. Meropenem was found to be the most sensitive drug against all GNB. Acinetobacter and Klebsiella spp. showed good sensitivity to doxycycline.