Antimicrobial resistance in major pathogens of hospital-acquired pneumonia in Asian countries

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.

An overview of cilastatin + imipenem + relebactam as a therapeutic option for hospital-acquired and ventilator-associated bacterial pneumonia: evidence to date

Introduction: Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are prevalent nosocomial infections with a worrisomely increasing prevalence of multidrug-resistant causative organisms, including those with resistance to carbapenems. The addition of relebactam, a β-lactamase inhibitor, to imipenem treatment restores the antimicrobial activity against the most of multidrug-resistant Gram-negative bacteria, including some carrying β-lactamase enzyme-type carbapenemases.Areas covered: The aim of this article is to summarize the current evidence regarding imipenem/relebactam for the treatment of HAP/VAP. The authors discuss its chemistry, pharmacokinetics/pharmacodynamics, microbiology, tolerance and clinical efficacy. The results of clinical trials have demonstrated an efficacy of imipenem/relebactam similar to that of its comparator for the treatment of patients with HAP/VAP. Different studies have also shown its good safety profile, which is better than that of the combination of other β-lactams with other antibiotics.Expert opinion: This drug should be incorporated as a new therapeutic option for the treatment of patients with HAP/VAP, especially as an alternative treatment in patients with confirmed infections caused by multidrug-resistant Gram-negatives.

Multidrug-resistance in methicillin-resistant Staphylococcus aureus (MRSA) isolated from a subtropical river contaminated by nearby livestock industries

Methicillin-resistant Staphylococcus aureus (MRSA) is a major threat to public health that causes infections in hospitals, communities, and animal husbandry. Livestock-associated MRSA (LA-MRSA) is defined as MRSA possessing staphylococcal cassette chromosome mec (SCCmec) IV or V, both of which lacks the Panton-Valentine leukocidin (PVL) gene but has variable combinations of antimicrobial susceptibility. This study focused on Taiwan's subtropical river basin and the Puzih River, which converges from tributaries flowing through downtown and animal husbandry areas. MRSA was detected at a rate of 7.8% in the tributaries, which was higher than downstream (2.1%). The ratio of multidrug-resistant (MDR) MRSA (n = 30) to total MRSA isolates (n = 39) was 0.769, and most of the MDR MRSA isolates (66.7%, 20/30) exhibited resistance to chloramphenicol, ciprofloxacin, clindamycin, erythromycin, sulfamethoxazole-trimethoprim, and tetracycline. The number of MDR MRSA isolates in the tributaries was also higher than the downstream regions of the Puzih River. The majority of MRSA isolates (64.1%) observed in this study possessed SCCmec type IV without PVL, which is typical for LA-MRSA. Enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) typing aided the discrimination of resistance patterns among SCCmec types. This study highlights the threat to human health posed by the waterborne transmission of MDR LA-MRSA.

Antimicrobial resistance patterns and their encoding genes among clinical isolates of Acinetobacter baumannii in Ahvaz, Southwest Iran

Acinetobacter baumannii is one of the most important organisms in nosocomial infections. Antibiotic resistance in this bacterium causes many problems in treating patients. This study aimed to investigate antibiotic resistance patterns and resistance-related, genes in clinical isolates of Acinetobacter baumannii. This descriptive study was conducted on 124 isolates of Acinetobacter baumannii collected from clinical samples in two teaching hospitals in Ahvaz. The antibiotic resistance pattern was determined by disk diffusion. The presence of genes coding for antibiotic resistance was determined using the polymerase chain reaction method. Out of 124 isolates, the highest rate of resistance was observed for rifampin (96.8%). The resistance rate for imipenem, meropenem, colistin, and polymyxin-B were 78.2%, 73.4%, 0.8% and 0.8%, respectively. The distribution of qnrA, qnrB, qnrS, Tet A, TetB, and Sul1genes were 52.6%, 0%, 3.2%, 93.5% 69.2%, and 6.42%, respectively. High prevalence of tetA, tetB, and qnrA genes among Acinetobacter baumannii isolated strains in this study indicate the important role of these genes in multidrug resistance in this bacteria. • Acinetobacter baumannii is an important human pathogen that has attracted the attention of many researchers Antibiotic resistance in this bacterium causes many problems in treating patients. • The resistance rate for imipenem, meropenem, colistin, and polymyxin-B were 78.2%, 73.4%, 0.8% and 0.8%, respectively. The distribution of qnrA, qnrB, qnrS, Tet A, TetB, and Sul1genes were 52.6%, 0%, 3.2%, 93.5% 69.2%, and 6.42%, respectively.

Susceptibility of Klebsiella Pneumoniae Isolated from Pus Specimens of Post-Surgery Patients in Medan, Indonesia to Selected Antibiotics

AIM:

This study was to determine the sensitivity of Klebsiella pneumonia isolated from pus specimens of post-surgery patients in Medan, Indonesia to selected antibiotics.

METHODS:

Samples were collected at the Laboratory of Microbiology, Faculty of Medicine, Universitas Sumatera Utara, Medan, Indonesia. The isolated bacteria were identified by Gram’s stain, colony characteristics, and biochemical tests. Susceptibility of K. pneumoniae isolates were tested to selected antibiotics including amikacin, meropenem, levofloxacin, ciprofloxacin, co-trimoxazole, ceftazidime, cefoperazone, cefuroxime, cefepime, cefotaxime, tetracycline, chloramphenicol, amoxicillin and ampicillin with Kirby Bauer method by measuring the inhibitory zone.

RESULTS:

A total of 20 K. pneumoniae isolates were obtained in this study. The results showed that K. Pneumonia isolates exhibited good sensitivity to amikacin (100%) and meropenem (80%). Sensitivity of levofloxacin (60%), ceftazidime (55%), ciprofloxacin (55%), cefoperazone (50%), and co-trimoxazole (50%) were moderate for the bacterial isolates. K. Pneumoniae isolates indicated low sensitivity to cefuroxime (45%), chloramphenicol (35%), cefepime (30%), cefotaxime (30%), tetracycline (30%), amoxicillin (5%), and ampicillin (5%).

CONCLUSION:

This study concludes that K. pneumoniae isolates are most sensitive to amikacin and less sensitive to ampicillin and amoxicillin.

A Systematic Review and Meta-analysis of Ventilator-associated Pneumonia in Adults in Asia: An Analysis of National Income Level on Incidence and Etiology

Background

Ventilator-associated pneumonia (VAP) is the commonest hospital-acquired infection (HAI) in intensive care. In Asia, VAP is increasingly caused by resistant gram-negative organisms. Despite the global antimicrobial resistance crisis, the epidemiology of VAP is poorly documented in Asia.

Methods

We systematically reviewed literature published on Ovid Medline, Embase Classic, and Embase from 1 January 1990 to 17 August 2017 to estimate incidence, prevalence, and etiology of VAP. We performed a meta-analysis to give pooled rates and rates by country income level.

Results

Pooled incidence density of VAP was high in lower- and upper-middle-income countries and lower in high-income countries (18.5, 15.2, and 9.0 per 1000 ventilator-days, respectively). Acinetobacter baumannii (n = 3687 [26%]) and Pseudomonas aeruginosa (n = 3176 [22%]) were leading causes of VAP; Staphylococcus aureus caused 14% (n = 1999). Carbapenem resistance was common (57.1%).

Conclusions

VAP remains a common cause of HAI, especially in low- and middle-income countries, and antibiotic resistance is high.

Chemical pharmacotherapy for hospital-acquired pneumonia in the elderly

INTRODUCTION

Hospital-acquired pneumonia (HAP) is a potentially serious infection that primarily affects older patients. The number of patients affected by multidrug-resistant (MDR) bacteria is increasing, including infection from strains of Staphylococcus aureus, Enterobacteriaceae, and Pseudomonas aeruginosa.

AREAS COVERED

This article focuses specifically on HAP, excluding patients afflicted by ventilator-associated pneumonia (VAP). The pathogenesis and clinical features of HAP in the elderly are discussed as well as specific drug pharmacokinetic and pharmacodynamic considerations in elderly patients. The current recommended guidelines for the management of HAP are also discussed. Finally, the authors provide evidence on the empirical therapy used for the treatment of HAP and widely consider specific-pathogen treatment of HAP in elderly patients.

EXPERT OPINION

In patients not at risk of MDR organism infection, antibiotics including piperacillin-tazobactam, cefepime, carbapenems or fluorquinolones are recommended. However, the emergence of MDR organisms as causal agents of HAP makes it necessary to accurately assess risk factors to these pathogens and revise our knowledge on specific antimicrobial susceptibility patterns from each institution. The authors believe that broader-spectrum empiric antibiotic therapies that target P. aeruginosa and methicillin-resistant S. aureus are best recommended in elderly patients at risk of HAP infection by MDR strains.

Five-year Audit of Infectious Diseases at a Tertiary Care Hospital in Karachi, Pakistan

Purpose To estimate the burden of infectious diseases and the seasonality of mosquito-borne diseases seen at The Indus Hospital, Karachi (TIH). Methodology We performed a retrospective data analysis of all infectious diseases (ID) cases, retrieved from medical records over a five-year period starting from 1 January 2012 till 31 December 2016 at The Indus Hospital (TIH), which is a 150-bed, charity-based, tertiary-care health facility. The collected data has been categorized into three groups: (A) public health-related diseases, including community and environmental IDs, i.e., mosquito-borne diseases such as malaria and dengue, respiratory tract infections, diarrheal diseases, typhoid, and hepatitis; (B) systemic infection related IDs that target individual anatomical or physiological systems such as the respiratory tract, urinary tract, skin and soft tissue, and the cardiac system, and lastly, those IDs which are (C) programmatically managed at TIH, namely cases from the tuberculosis (TB), human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS), and malaria clinics, and the rabies prevention center. As the study is an audit, ethical approval was waived by the institutional review board (IRB). Result Overall data from 71,815 patients were assessed. In the public health group (A), the main bulk of diseases were due to malaria, tuberculosis, respiratory tract infections (upper and lower), and diarrheal diseases in both males and females in descending order; there was preponderance of malaria, respiratory tract infections, and diarrheal diseases in males, and of tuberculosis among females. Among the systemic diseases group (B), urinary tract infections (UTIs) had a disproportionately high incidence, followed by skin and soft tissue infections, while bone and joint infections and diabetic foot had equal incidence. In the programmatic group (C), the highest number of cases seen was dog bites followed by drug-sensitive TB. Overall, the six most common infections were malaria, cases of dog bites, tuberculosis, respiratory tract infections, diarrheal diseases, and hepatitis C. More women than men had TB; diarrheal disease and respiratory tract infections were more common in children. UTIs were the most common systemic infections among both men and women. Conclusion There is a great need to have an effective surveillance mechanism of preventable diseases at the national level. Our study highlights the diversity of cases that should direct medical curriculum development, post-graduate training, and health services improvement.

Endemic carbapenem-nonsusceptible Acinetobacter baumannii-calcoaceticus complex in intensive care units of the national referral hospital in Jakarta, Indonesia

Background

Carbapenem-nonsusceptible A. baumannii-calcoaceticus complex have emerged worldwide, but the epidemiology in Indonesian hospitals has not been studied.

Methods

A prospective observational study was performed on the intensive care units (ICUs) of the national referral hospital in Jakarta-Indonesia, in 2013 and 2014. All consecutive adult patients admitted and hospitalized for >48 h in ICUs were included. Basic and clinical data at admission were recorded. Carbapenem-nonsusceptible A. baumannii-calcoaceticus complex from clinical cultures and standardized screening were included. Environmental niches and healthcare workers (HCWs) were also screened. PCR was used to detect carbapenemase genes, and Raman spectroscopy as well as multilocus sequence typing (MLST) for typing.

Results

Of 412 included patients, 69 (16.7%) carried carbapenem-nonsusceptible A. baumannii-calcoaceticus complex on admission, and 89 (25.9%) became positive during ICU stay. The acquisition rate was 43 per 1000 patient-days at risk. Six isolates were cultured from environment and one from a HCW. Acquisition of carbapenem-nonsusceptible A. baumannii-calcoaceticus complex was associated with longer ICU stay (median interquartile range [IQR]: 11 days [5-18], adjusted hazard ratio [aHR]: 2.56 [99% confidence interval (CI):1.76-3.70]), but not with mortality (adjusted odds ratio: 1.59 [99%CI: 0.74-3.40] at the chosen level of significance). The bla_OXA-23-like gene was detected in 292/318 (91.8%) isolates, including isolates from the environment and HCW. Typing revealed five major clusters. Sequence types (ST)195, ST208, ST218, ST642 as well as new STs were found. The dominant clone consisted of isolates from patients and environment throughout the study period.

Conclusions

Carbapenem-nonsusceptible A. baumannii-calcoaceticus complex are endemic in this setting. Prevention requires source control and limiting transmission of strains.

Trial registration

The study was retrospectively registered at www.trialregister.nl (No:5541). Candidate number: 23,527, NTR number: NTR5541, Date registered NTR: 22nd December 2015.

Emerging trends of nosocomial pneumonia in intensive care unit of a tertiary care public teaching hospital in Western India

BACKGROUND

Nosocomial pneumonia poses great challenge to an intensivist. Detailed information about hospital-acquired pneumonia (HAP) and ventilator-acquired pneumonia (VAP) is crucial for prevention and optimal management, thus improving quality Intensive Care Unit (ICU) care. Hence, we aimed to study the current trend of nosocomial pneumonia in ICU.

MATERIALS AND METHODS

It was a prospective observational cohort study, conducted in the ICU of a tertiary care teaching public hospital over a period of 18 months. We studied clinical profile and outcome of 120 adult patients who developed VAP/HAP during the study period. We also analyzed the causative organisms, antibiotic sensitivity, and resistance pattern in these patients.

RESULTS

Out of 120 patients, 29 patients were HAP and 91 patients were VAP. Mortality was 60% (72), and development of VAP and requirement of mechanical ventilation showed significant association with mortality (P < 0.00001). Most common organism causing HAP was Staphylococcus aureus (43.4%) and VAP was Klebsiella pneumoniae (49%). Maximum antibiotic sensitivity was found to piperacillin + tazobactam (58.8%), followed by imipenem (49.5%) and meropenem (41.8%), whereas maximum antibiotic resistance was found to cefepime (95.1%), followed by ceftazidime and amoxicillin (91.2%).

CONCLUSION

Nosocomial pneumonia showed high incidence (17.44%) and mortality (60%). Common organisms identified were S. aureus and K. pneumoniae. Resistance was high for commonly used antibiotics and high antibiotic sensitivity for piperacillin + tazobactam and carbapenem. Contexte: La pneumonie nosocomiale pose un grand défi à un intensiviste. Des informations détaillées sur la pneumonie acquise dans les hôpitaux (HAP) et la pneumonie acquise par le ventilateur (VAP) sont essentielles pour la prévention et la gestion optimale, améliorant ainsi les soins de soins intensifs de qualité (UTI). Par conséquent, nous avons cherché à étudier la tendance actuelle de la pneumonie nosocomiale en UTI. Matériaux et méthodes: il s'agissait d'une étude de cohorte observationnelle prospective menée dans l'UCI d'un hôpital public d'enseignement tertiaire sur une période de 18 mois. Nous avons étudié le profil clinique et le résultat de 120 patients adultes qui ont développé le VAP / HAP pendant la période d'étude. Nous avons également analysé les organismes responsables, la sensibilité aux antibiotiques et le modèle de résistance chez ces patients. Résultats: Sur 120 patients, 29 patients étaient HAP et 91 patients étaient VAP. La mortalité était de 60% (72), et le développement du VAP et l'exigence de ventilation mécanique ont montré une association significative avec la mortalité (P < 0,00001). L'organisme le plus fréquent causant HAP était Staphylococcus aureus (43,4%) et VAP était Klebsiella pneumoniae (49%). Une sensibilité antibiotique maximale a été observée chez la pipéracilline + tazobactam (58,8%), suivie de l'imipénème (49,5%) et du méropénem (41,8%), alors que la résistance antibiotique maximale a été observée à cefépime (95,1%), suivie de ceftazidime et de l'amoxicilline (91,2%) .

CONCLUSION

la pneumonie nosocomiale a montré une incidence élevée (17,44%) et la mortalité (60%). Les organismes communs identifiés étaient S. aureus et K. pneumoniae. La résistance était élevée pour les antibiotiques couramment utilisés et une forte sensibilité aux antibiotiques pour la pipéracilline + le tazobactam et le carbapénème.

Antibacterial activity of amino- and amido- terminated poly (amidoamine)-G6 dendrimer on isolated bacteria from clinical specimens and standard strains

Background: Nanoscale poly (amidoamine) dendrimers have been investigated for their biological demands, but their antibacterial activity has not been widely discovered. Thus, the sixth generation of poly (amidoamine) dendrimer (PAMAM-G6) was synthesized and its antibacterial activities were evaluated on Gram-negative bacteria; P. aeruginosa, E. coli, A. baumannii, S. typhimurium, S. dysenteriae, K. pneumoniae, P. mirabilis, and Gram-positive bacteria, and S.aureus and B. subtilis, which were isolated from different clinical specimens and standard strains of these bacteria. Methods: In this study, 980 specimens including urine (47%), blood (27%), sputum (13%), wounds (8%), and burns (5%) were collected from clinical specimens of 16 hospitals and clinics in city of Sabzevar, Iran. Then, the target bacteria were isolated and identified using standard methods. Minimum inhibitory concentration and minimum bactericidal concentrations against Gram-positive and Gram-negative bacteria were determined according to guidelines described by clinical and laboratory standards institute (CLSI). Standard discs were prepared using 0.025, 0.25, 2.5, and 25 μg/mL concentrations of PAMAM-G6 on Mueller-Hinton agar plates to determinate the zone of inhibition. The cytotoxicity of PAMAM-G6 dendrimer was evaluated in HCT116 cells by MTT assay. Results: The most important isolated bacteria were E. coli (23.65%), S. aureus (24.7%), P. aeruginosa (10.49%), B. subtilis (7.7%), S. typhimurium (8.87%), A. baumannii (7.02%), K. pneumoniae (7.1%), P. mirabilis (6.46%), and S. dysenteriae (3.6%). Moreover, it was found that poly (amidoamine)-G6 exhibited more antibacterial efficacy on standard strains than isolated bacteria from clinical samples (p<0.05). The cytotoxicity of PAMAM-G6 to the cells showed that cytotoxicity depended on the concentration level and exposure time. Conclusion: The PAMAM-G6 dendrimer showed a positive impact on the removal of dominant bacterial isolated from clinical specimens and standard strains.

Emergence and Dissemination of ST131 Escherichia coli Isolates Among Patients with Hospital-Acquired Pneumonia in Asian Countries

We investigated the molecular epidemiology and microbiological characteristics of 51 Escherichia coli isolates causing hospital-acquired pneumonia (HAP) in eight Asian areas. Sequence type 131 (ST131) was the most prevalent among E. coli isolates causing HAP, especially in South Korea, Thailand, and the Philippines. The current study showed that CTX-M-15-producing E. coli ST131 has emerged in and disseminated among patients with HAP in Asia. Our data suggest that this pandemic clone poses an important public health threat even in nosocomial infections.

Investigational drugs in phase I and phase II clincial trials for the treatment of hospital-acquired pneumonia

INTRODUCTION

Hospital acquired pneumonia (HAP) is one of the main infections acquired by patients during a stay in hospital. The main issue when dealing with patients with HAP and ventilator associated pneumonia (VAP) is the increasing role of multi-drug resistant organisms (MDROs).

AREAS COVERED

In this review the authors summarize the actual situation of MDROs as a cause of HAP and VAP. They also review the current treatment options stated in the most important international guidelines. Finally, they focus on the investigational drugs that have reached the phase III stage of development and the novel compounds that are being studied in phase I and II clinical trials.

EXPERT OPINION

Thanks to their excellent activity against MDROs, drugs in development for the treatment of HAP and VAP can significantly improve the therapeutic options available. In selected patients, the possibility to administer directed therapy with monoclonal antibodies to specific pathogens is an exciting strategy in the fight against widespread resistance.

Clinical importance and epidemiology of quinolone resistance

The quinolone class of antimicrobial agents is one of most widely used classes of antimicrobial agents in outpatient and inpatient treatment. However, quinolone resistance in gram-positive and gram-negative bacteria has emerged and increased globally. This resistance limits the usefulness of quinolones in clinical practice. The review summarizes mechanisms of quinolone resistance and its epidemiology and implications in the most common clinical settings, urinary tract infections, respiratory tract infections, intraabdominal infections, skin and skin structure infections, and sexually transmitted diseases.

Emergence of carbapenem-resistant Acinetobacter baumannii as the major cause of ventilator-associated pneumonia in intensive care unit patients at an infectious disease hospital in southern Vietnam

Ventilator-associated pneumonia (VAP) is a serious healthcare-associated infection that affects up to 30 % of intubated and mechanically ventilated patients in intensive care units (ICUs) worldwide. The bacterial aetiology and corresponding antimicrobial susceptibility of VAP is highly variable, and can differ between countries, national provinces and even between different wards in the same hospital. We aimed to understand and document changes in the causative agents of VAP and their antimicrobial susceptibility profiles retrospectively over an 11 year period in a major infectious disease hospital in southern Vietnam. Our analysis outlined a significant shift from Pseudomonas aeruginosa to Acinetobacter spp. as the most prevalent bacteria isolated from quantitative tracheal aspirates in patients with VAP in this setting. Antimicrobial resistance was common across all bacterial species and we found a marked proportional annual increase in carbapenem-resistant Acinetobacter spp. over a 3 year period from 2008 (annual trend; odds ratio 1.656, P = 0.010). We further investigated the possible emergence of a carbapenem-resistant Acinetobacter baumannii clone by multiple-locus variable number tandem repeat analysis, finding a blaOXA-23-positive strain that was associated with an upsurge in the isolation of this pathogen. We additionally identified a single blaNDM-1-positive A. baumannii isolate. This work highlights the emergence of a carbapenem-resistant clone of A. baumannii and a worrying trend of antimicrobial resistance in the ICU of the Hospital for Tropical Diseases in Ho Chi Minh City, Vietnam.

Consensus statement on the management of methicillin-resistant Staphylococcus aureus nosocomial pneumonia in Asia

Nosocomial pneumonia (NP; encompassing hospital-acquired, health care-associated and ventilator-associated pneumonia) is one of the most common nosocomial infections and is associated with a mortality rate of 18.7%-40.8% in Asian countries. The burden of methicillin-resistant Staphylococcus aureus (MRSA) infections in Asia is high, and approximately 13% of NP cases in Asia are caused by this pathogen. Evidence regarding optimal management of MRSA NP continues to evolve and is complicated by the fact that a significant proportion of cases are likely to be caused by isolates with reduced susceptibility to the main therapeutic agent, vancomycin. The Asian Consensus Taskforce on MRSA Nosocomial Pneumonia has developed this statement to provide consensus points on diagnosis, antimicrobial treatment and prevention strategies for MRSA NP in the Asian context, based on our review of Asian data, previous international guidelines and recent scientific evidence.

Drug-resistant ventilator associated pneumonia in a tertiary care hospital in Saudi Arabia

BACKGROUND:

There is a wide geographic and temporal variability of bacterial resistance among microbial causes of ventilator-associated pneumonia (VAP). The contribution of multi-drug resistant (MDR) pathogens to the VAP etiology in Saudi Arabia was never studied. We sought to examine the extent of multiple-drug resistance among common microbial causes of VAP.

MATERIALS AND METHODS:

We conducted a retrospective susceptibility study in the adult intensive care unit (ICU) of King Abdulaziz Medical City, Riyadh, Saudi Arabia. Susceptibility results of isolates from patients diagnosed with VAP between October 2004 and June 2009 were examined. The US National Healthcare Safety Network definition of MDR was adopted.

RESULTS:

A total of 248 isolates including 9 different pathogens were included. Acinetobacter spp. was highly (60-89%) resistant to all tested antimicrobials, including carbapenems (three- and four-class MDR prevalence were 86% and 69%, respectively). Pseudomonas aeruginosa was moderately (13-31%) resistant to all tested antimicrobials, including antipseudomonal penicillins (three- and four-class MDR prevalence were 13% and 10%, respectively). With an exception of ampicillin (fully resistant), Klebsiella spp. had low (0-13%) resistance to other tested antimicrobials with no detected MDR. Staphylococcus aureus was fully susceptible to vancomycin with 42% resistance to oxacillin. There were significant increasing trends of MDR Acinetobacter spp. however not P. aeruginosa during the study. Resistant pathogens were associated with worse profile of ICU patients but not patients’ outcomes.

CONCLUSION:

Acinetobacter in the current study was an increasingly resistant VAP-associated pathogen more than seen in many parts of the world. The current finding may impact local choice of initial empiric antibiotics.

A PROspective study on the Usage patterns of Doripenem in the Asia-Pacific region (PROUD study)

Doripenem is approved in the Asia-Pacific (APAC) region for treating nosocomial pneumonia (NP) including ventilator-associated pneumonia (VAP), complicated intra-abdominal infections (cIAIs) and complicated urinary tract infections (cUTIs). Clinical usage of doripenem (500mg intravenously, infused over 1h or 4h every 8h for 5-14 days) in APAC was evaluated in a prospective, open-label, non-comparative, multicentre study of inpatients (≥18 years) with NP, VAP, cIAI or cUTI. A total of 216 [intention-to-treat (ITT)] patients received doripenem: 53 NP (24.5%); 77 VAP (35.6%); 67 cIAI (31.0%); and 19 cUTI (8.8%). Doripenem MIC90 values for Pseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli and Klebsiella pneumoniae were 32, 32, 0.094 and 0.64μg/mL, respectively. Doripenem was used most commonly as monotherapy (86.6%) and as second-line therapy (62.0%). The clinical cure rate in clinically evaluable patients was 86.7% at the end of therapy (EOT) and 87.1% at test of cure (TOC) (7-14 days after EOT). In the ITT population, overall clinical cure rates were 66.2% at EOT and 56.5% at TOC. The median duration of hospital stay, intensive care unit (ICU) stay and mechanical ventilation was 20, 12 and 10 days, respectively. Of 146 discharged patients, 7 were re-admitted within 28 days of EOT; 1 VAP patient was re-admitted to the ICU. The all-cause mortality rate was 22.7% (49/216). The most common treatment-related adverse events were diarrhoea (1.4%) and vomiting (1.4%). Doripenem is a viable option for treating APAC patients with NP, VAP, cIAI or cUTI. [ClinicalTrials.gov: NCT 00986102].

Ventilator associated pneumonia in a medical intensive care unit: Microbial aetiology, susceptibility patterns of isolated microorganisms and outcome

Background:

Ventilator-associated pneumonia (VAP) is a common complication of ventilatory support for patients with acute respiratory failure and is associated with increased morbidity and mortality.

Aim of the Study:

The present study was undertaken to do quantitative cultures of aerobic bacteria, perform the antibiotic susceptibility testing from the endotracheal aspirates and clinical outcome of the clinically suspected patients of VAP.

Methods:

A prospective study was performed over a period of one year in a tertiary care hospital, enrolling patients on mechanical ventilation (MV) for ≥48 hr. Endotracheal aspirates (ETA) were collected from patients with suspected VAP, and direct gram's stain criteria was used to accept the sample. Quantitative cultures of ETA were performed with the threshold for microbiological diagnosis of VAP was taken as ≥10⁵ colony forming units (cfu)/ml.

Results:

Out of 53 cases, 2 (3.77%) were polymicrobial. Multidrug resistant bacteria, mainly Acinetobacter baumannii 49.09% (27/55) and Pseudomonas aeruginosa 30.91% (17/55) were the most common pathogens isolated. Metallo-beta lactamases (MBLs) was produced by 47.06% (8/17) of Pseudomonas aeruginosa and 62.96% (17/27) of Acinetobacter baumannii.

Conclusion:

The bacteriological approach for the management of VAP helps the clinicians in choosing the appropriate antibiotics. This study showed that quantitative cultures of endotracheal aspirate at a cutoff point of 10⁵ cfu/ml is one of the alternative to bronchoscopy in the diagnosis of clinically suspected ventilator associated pneumonia.

Global fluoroquinolone resistance epidemiology and implictions for clinical use

This paper on the fluoroquinolone resistance epidemiology stratifies the data according to the different prescription patterns by either primary or tertiary caregivers and by indication. Global surveillance studies demonstrate that fluoroquinolone resistance rates increased in the past years in almost all bacterial species except S. pneumoniae and H. influenzae, causing community-acquired respiratory tract infections. However, 10 to 30% of these isolates harbored first-step mutations conferring low level fluoroquinolone resistance. Fluoroquinolone resistance increased in Enterobacteriaceae causing community acquired or healthcare associated urinary tract infections and intraabdominal infections, exceeding 50% in some parts of the world, particularly in Asia. One to two-thirds of Enterobacteriaceae producing extended spectrum β-lactamases were fluoroquinolone resistant too. Furthermore, fluoroquinolones select for methicillin resistance in Staphylococci. Neisseria gonorrhoeae acquired fluoroquinolone resistance rapidly; actual resistance rates are highly variable and can be as high as almost 100%, particularly in Asia, whereas resistance rates in Europe and North America range from <10% in rural areas to >30% in established sexual networks. In general, the continued increase in fluoroquinolone resistance affects patient management and necessitates changes in some guidelines, for example, treatment of urinary tract, intra-abdominal, skin and skin structure infections, and traveller's diarrhea, or even precludes the use in indications like sexually transmitted diseases and enteric fever.

Role of the small RNA RyhB in the Fur regulon in mediating the capsular polysaccharide biosynthesis and iron acquisition systems in Klebsiella pneumoniae

BACKGROUND

The capsular polysaccharide (CPS) and iron acquisition systems are important determinants of Klebsiella pneumoniae infections, and we have previously reported that the ferric uptake repressor (Fur) can play dual role in iron acquisition and CPS biosynthesis. In many bacteria, Fur negatively controls the transcription of the small non-coding RNA RyhB to modulate cellular functions and virulence. However, in K. pneumoniae, the role played by RyhB in the Fur regulon has not been characterised. This study investigated Fur regulation of ryhB transcription and the functional role of RyhB in K. pneumoniae.

RESULTS

Deletion of fur from K. pneumoniae increased the transcription of ryhB; the electric mobility shift assay and the Fur-titration assay revealed that Fur could bind to the promoter region of ryhB, suggesting that Fur directly represses ryhB transcription. Additionally, in a Δfur strain with elevated CPS production, deletion of ryhB obviously reduced CPS production. The following promoter-reporter assay and quantitative real-time PCR of cps genes verified that RyhB activated orf1 and orf16 transcription to elevate CPS production. However, deletion of ryhB did not affect the mRNA levels of rcsA, rmpA, or rmpA2. These results imply that Fur represses the transcription of ryhB to mediate the biosynthesis of CPS, which is independent of RcsA, RmpA, and RmpA2. In addition, the Δfur strain's high level of serum resistance was attenuated by the deletion of ryhB, indicating that RyhB plays a positive role in protecting the bacterium from serum killing. Finally, deletion of ryhB in Δfur reduced the expression of several genes corresponding to 3 iron acquisition systems in K. pneumoniae, and resulted in reduced siderophore production.

CONCLUSIONS

The regulation and functional role of RyhB in K. pneumoniae is characterized in this study. RyhB participates in Fur regulon to modulate the bacterial CPS biosynthesis and iron acquisition systems in K. pneumoniae.

Resistance surveillance studies: a multifaceted problem--the fluoroquinolone example

INTRODUCTION

This review summarizes data on the fluoroquinolone resistance epidemiology published in the previous 5 years.

MATERIALS AND METHODS

The data reviewed are stratified according to the different prescription patterns by either primary- or tertiary-care givers and by indication. Global surveillance studies demonstrate that fluoroquinolone- resistance rates increased in the past several years in almost all bacterial species except Staphylococcus pneumoniae and Haemophilus influenzae causing community-acquired respiratory tract infections (CARTIs), as well as Enterobacteriaceae causing community-acquired urinary tract infections. Geographically and quantitatively varying fluoroquinolone resistance rates were recorded among Gram-positive and Gram-negative pathogens causing healthcare-associated respiratory tract infections. One- to two-thirds of Enterobacteriaceae producing extended-spectrum β-lactamases (ESBLs) were fluoroquinolone resistant too, thus, limiting the fluoroquinolone use in the treatment of community- as well as healthcare-acquired urinary tract and intra-abdominal infections. The remaining ESBL-producing or plasmid-mediated quinolone resistance mechanisms harboring Enterobacteriaceae were low-level quinolone resistant. Furthermore, 10-30 % of H. influenzae and S. pneumoniae causing CARTIs harbored first-step quinolone resistance determining region (QRDR) mutations. These mutants pass susceptibility testing unnoticed and are primed to acquire high-level fluoroquinolone resistance rapidly, thus, putting the patient at risk. The continued increase in fluoroquinolone resistance affects patient management and necessitates changes in some current guidelines for the treatment of intra-abdominal infections or even precludes the use of fluoroquinolones in certain indications like gonorrhea and pelvic inflammatory diseases in those geographic areas in which fluoroquinolone resistance rates and/or ESBL production is high. Fluoroquinolone resistance has been selected among the commensal flora colonizing the gut, nose, oropharynx, and skin, so that horizontal gene transfer between the commensal flora and the offending pathogen as well as inter- and intraspecies recombinations contribute to the emergence and spread of fluoroquinolone resistance among pathogenic streptococci. Although interspecies recombinations are not yet the major cause for the emergence of fluoroquinolone resistance, its existence indicates that a large reservoir of fluoroquinolone resistance exists. Thus, a scenario resembling that of a worldwide spread of β-lactam resistance in pneumococci is conceivable. However, many resistance surveillance studies suffer from inaccuracies like the sampling of a selected patient population, restricted geographical sampling, and undefined requirements of the user, so that the results are biased. The number of national centers is most often limited with one to two participating laboratories, so that such studies are point prevalence but not surveillance studies. Selected samples are analyzed predominantly as either hospitalized patients or patients at risk or those in whom therapy failed are sampled; however, fluoroquinolones are most frequently prescribed by the general practitioner. Selected sampling results in a significant over-estimation of fluoroquinolone resistance in outpatients. Furthermore, the requirements of the users are often not met; the prescribing physician, the microbiologist, the infection control specialist, public health and regulatory authorities, and the pharmaceutical industry have diverse interests, which, however, are not addressed by different designs of a surveillance study. Tools should be developed to provide customer-specific datasets.

CONCLUSION

Consequently, most surveillance studies suffer from well recognized but uncorrected biases or inaccuracies. Nevertheless, they provide important information that allows the identification of trends in pathogen incidence and antimicrobial resistance.

Ventilator-associated pneumonia in intensive care units in Hubei Province, China: a multicentre prospective cohort survey

A multicentre prospective cohort study was performed in 17 intensive care units (ICUs) in tertiary care hospitals in Hubei Province, China. Ventilator-associated pneumonia (VAP) was defined according to modified criteria from the published literature. Among 4155 ventilated patients, the crude incidence and incidence rate of VAP were 20.9% and 28.9 cases per 1000 ventilator-days. Multivariate analysis using logistic regression revealed risk factors including male sex [risk ratio (RR): 1.5; P<0.001], coma (RR: 2.1; P<0.001), chronic obstructive pulmonary disease (RR: 1.4; P<0.001), infections at other sites (RR: 1.6; P=0.001), serious disease predating the onset of VAP (RR: 1.6; P<0.001) and interventions including antacid treatment (RR: 1.4; P<0.001), antimicrobial treatment (RR: 5.1; P<0.001), bronchoscopy (RR: 1.5; P=0.041) and tracheostomy (RR: 1.4; P=0.014). The most frequently isolated causative pathogens were Pseudomonas aeruginosa and Acinetobacter baumannii. Of all Staphylococcus aureus isolates, 45.7% were meticillin resistant. Rates, risk factors and causal pathogens of VAP in ICUs in Hubei differ from those reported from developed countries. These data show the need for more effective infection control interventions in Hubei, China.

Lipocalin 2 is protective against E. coli pneumonia

Background

Lipocalin 2 is a bacteriostatic protein that binds the siderophore enterobactin, an iron-chelating molecule produced by Escherichia coli (E. coli) that is required for bacterial growth. Infection of the lungs by E. coli is rare despite a frequent exposure to this commensal bacterium. Lipocalin 2 is an effector molecule of the innate immune system and could therefore play a role in hindering growth of E. coli in the lungs.

Methods

Lipocalin 2 knock-out and wild type mice were infected with two strains of E. coli. The lungs were removed 48 hours post-infection and examined for lipocalin 2 and MMP9 (a myeloid marker protein) by immunohistochemical staining and western blotting. Bacterial numbers were assessed in the lungs of the mice at 2 and 5 days after infection and mortality of the mice was monitored over a five-day period. The effect of administering ferrichrome (an iron source that cannot be bound by lipocalin 2) along with E.coli was also examined.

Results

Intratracheal installation of E. coli in mice resulted in strong induction of lipocalin 2 expression in bronchial epithelium and alveolar type II pneumocytes. Migration of myeloid cells to the site of infection also contributed to an increased lipocalin 2 level in the lungs. Significant higher bacterial numbers were observed in the lungs of lipocalin 2 knock-out mice on days 2 and 5 after infection with E. coli (p < 0.05). In addition, a higher number of E. coli was found in the spleen of surviving lipocalin 2 knock-out mice on day 5 post-infection than in the corresponding wild-type mice (p < 0.05). The protective effect against E. coli infection in wild type mice could be counteracted by the siderophore ferrichrome, indicating that the protective effect of lipocalin 2 depends on its ability to sequester iron.

Conclusions

Lipocalin 2 is important for protection of airways against infection by E. coli.

Antimicrobial activity of Ankaferd Blood Stopper® against nosocomial bacterial pathogens

The aim of this study is to investigate the in vitro antimicrobial activity of Ankaferd Blood Stopper® against methicillin-resistant Staphylococcus aureus (MRSA), Enterococcus species, Escherichia coli, Pseudomonas species, Acinetobacter species and Klebsiella species of nosocomial origin. Ankaferd inhibited growth in 72.4% to 100% of the bacteria tested, depending on the type of the isolate. As a result, it can be stated that Ankaferd inhibits the in vitro growth of nosocomial bacteria. This is a novel, important finding since severe hospital infections coexist with many hemostatic disorders, and the use of Ankaferd may increase hemostatic potential in such clinical conditions.