Antibiotic resistance among nosocomial isolates in a Croatian intensive care unit--results of a twelve-year focal surveillance of nosocomial infections

Growing emergence of drug-resistant Pseudomonas aeruginosa and attenuation of its virulence using quorum sensing inhibitors: A critical review

A perilous increase in the number of bacterial infections has led to developing throngs of antibiotics for increasing the quality and expectancy of life. Pseudomonas aeruginosa is becoming resistant to all known conventional antimicrobial agents thereby posing a deadly threat to the human population. Nowadays, targeting virulence traits of infectious agents is an alternative approach to antimicrobials that is gaining much popularity to fight antimicrobial resistance. Quorum sensing (QS) involves interspecies communication via a chemical signaling pathway. Under this mechanism, cells work in a concerted manner, communicate with each other with the help of signaling molecules called auto-inducers (AI). The virulence of these strains is driven by genes, whose expression is regulated by AI, which in turn acts as transcriptional activators. Moreover, the problem of antibiotic-resistance in case of infections caused by P. aeruginosa becomes more alarming among immune-compromised patients, where the infectious agents easily take over the cellular machinery of the host while hidden in the QS mediated biofilms. Inhibition of the QS circuit of P. aeruginosa by targeting various signaling pathways such as LasR, RhlR, Pqs, and QScR transcriptional proteins will help in blocking downstream signal transducers which could result in reducing the bacterial virulence. The anti-virulence agent does not pose an immediate selective pressure on growing bacterium and thus reduces the pathogenicity without harming the target species. Here, we review exclusively, the growing emergence of multi-drug resistant (MDR) P. aeruginosa and the critical literature survey of QS inhibitors with their potential application of blocking P. aeruginosa infections.

Antimicrobial resistance patterns of Pseudomonas aeruginosa in tertiary care hospitals of Makkah and Jeddah

BACKGROUND

The clinical significance of Pseudomonas aeruginosa has greatly increased due to its ability to rapidly develop resistance to major groups of antibiotics.

OBJECTIVES

Our objective was to determine the pattern of antimicrobial resistance of P aeruginosa.

DESIGN

Prospective, descriptive study.

SETTING

Four tertiary care hospitals in Makkah and Jeddah.

METHODS

Clinical isolates of P aeruginosa were processed following standard microbiological procedures. A Microscan Walk Away system was used for the identification and antibiotic susceptibility of P aeruginosa isolates.

MAIN OUTCOME MEASURES

Percentage of resistance of P aeruginosa to antibiotics.

RESULTS

The overall drug resistance among 121 strains of P aeruginosa was low to moderate to commonly used anti-pseudomonal drugs (4.9% to 30.6%). Significantly less resistance was exhibited by piperacillin tazobactam (4.9%; P < .05) and meropenem showed significantly high resistance (30.6%; P < .05) as compared to other antibiotics, followed by ticarcillin (22.3%) and imipenem (19%), irrespective of the site of infection. The antibiotics with < 10% resistance were cefepime (8.3%), amikacin (7.4%) and piperacillin-tazobactam, which showed lowest resistance (4.9%). Although, data varied between hospitals, meropenem and ticarcillin had the highest drug resistance in all hospitals. Multidrug resistance was 10.7%.

CONCLUSION

Low-to-moderate rates of drug resistance among P aeruginosa isolates were observed. Meropenem resistance was high irrespective of the site of infection. This pattern of resistance indicates probable overuse of broad-spectrum antibiotics like carbapenems. Overuse needs to be addressed by each institution, and consideration given to regulating use of broad-spectrum antibiotics.

LIMITATIONS

Results cannot be generalized as the study did not include all tertiary hospitals in these cities.

Multidrug-resistant hospital-associated infections in a pediatric intensive care unit: a cross-sectional survey in a Thai university hospital

OBJECTIVE

To determine the incidence and associated factors of multidrug-resistant hospital-associated infections (MDR-HAI) in a pediatric intensive care unit (PICU) of a university hospital in Thailand.

METHOD

A prospective study was performed in the PICU of King Chulalongkorn Memorial Hospital during the period May-December 2005. Children aged < or = 15 years who developed a PICU-related HAI were studied.

RESULTS

Forty-four patients (median age 6 months; male:female = 1.4:1) developed 58 episodes of PICU-related HAI. The HAI rate was 28.3 per 1000 patient-days. Thirty episodes (52%) were MDR-HAI. The following were found more frequently in MDR-HAI when compared to non-MDR-HAI: Acinetobacter baumannii (50% vs. 23%, p = 0.04), female sex (60% vs. 29%, p = 0.02), admission to the PICU with a medical condition (90% vs. 64%, p = 0.03), PICU stay longer than 7 days prior to the development of HAI (67% vs. 36%, p = 0.03), and previous use of broad-spectrum antibiotics (83% vs. 43%, p = 0.002). Independent risk factors for MDR-HAI included female sex (OR = 5.5, p = 0.03) and previous use of a broad-spectrum antibiotic (OR = 9.7, p = 0.01).

CONCLUSION

The incidence of MDR-HAI was high in the PICU. Female sex and previous use of a broad-spectrum antibiotic were independent risk factors for MDR-HAI.

Impact of aminoglycoside cycling in six tertiary intensive care units: prospective longitudinal interventional study

AIM

To determine the effect of aminoglycoside cycling in six tertiary intensive care units (ICU) on the rates of sepsis, aminoglycoside resistance patterns, antibiotic consumption, and costs.

METHODS

This was a prospective longitudinal interventional study that measured the effect of change from first-line gentamicin usage (February 2002-February 2003) to amikacin usage (February 2003-February 2004) on the aminoglycoside resistance patterns, number of patients with gram-negative bacteremia, consumption of antibiotics, and the cost of antimicrobial drugs in 6 tertiary care ICUs in Zagreb, Croatia.

RESULTS

The change from first-line gentamicin to amikacin usage led to a decrease in the overall gentamicin resistance of gram-negative bacteria (GNB) from 42% to 26% (P<0.001; z-test of proportions) and netilmicin resistance from 33% to 20% (P<0.001), but amikacin resistance did not change significantly (P=0.462), except for Acinetobacter baumanni (P=0.014). Sepsis rate in ICUs was reduced from 3.6% to 2.2% (P<0.001; chi(2) test), with a decline in the number of nosocomial bloodstream infections from 55/100 patient-days to 26/100 patient-days (P=0.001, chi(2) test). Furthermore, amikacin use led to a 16% decrease in the overall antibiotic consumption and 0.1 euro/patient/d cost reduction.

CONCLUSION

Exclusive use of amikacin significantly reduced the resistance of GNB isolates to gentamicin and netilmicin, the number of GNB nosocomial bacteremias, and the cost of total antibiotic usage in ICUs.

Acinetobacter infections: a growing threat for critically ill patients

There has been increasing concern regarding the rise of Acinetobacter infections in critically ill patients. We extracted information regarding the relative frequency of Acinetobacter pneumonia and bacteraemia in intensive-care-unit (ICU) patients and the antimicrobial resistance of Acinetobacter isolates from studies identified in electronic databases. Acinetobacter infections most frequently involve the respiratory tract of intubated patients and Acinetobacter pneumonia has been more common in critically ill patients in Asian (range 4-44%) and European (0-35%) hospitals than in United States hospitals (6-11%). There is also a gradient in Europe regarding the proportion of ICU-acquired pneumonias caused by Acinetobacter with low numbers in Scandinavia, and gradually rising in Central and Southern Europe. A higher proportion of Acinetobacter isolates were resistant to aminoglycosides and piperacillin/tazobactam in Asian and European countries than in the United States. The data suggest that Acinetobacter infections are a growing threat affecting a considerable proportion of critically ill patients, especially in Asia and Europe.

Occurrence and antimicrobial resistance pattern of inpatient and outpatient isolates of Pseudomonas aeruginosa in a Saudi Arabian hospital: 1998–2003

OBJECTIVES

The objective of this study was to describe the pattern and trends of antibiotic resistance of Pseudomonas aeruginosa over a six-year period in a Saudi Arabian hospital.

METHODS

This was a retrospective study of the antibiotic resistance of outpatient and inpatient isolates of P. aeruginosa. Only one isolate per patient per year was included in the study.

RESULTS

During the study period a total of 2679 isolates of P. aeruginosa were available for analysis. Outpatient isolates constituted 48% of the total number, and of these 23.4% were obtained from wound cultures. For the inpatient isolates, 33.6% and 30% were obtained from the respiratory tract and wounds, respectively. There was no significant increase in the resistance rates of outpatient isolates to the tested antibiotics over time. On the other hand, inpatient isolates showed a statistically significant increase in resistance rates to piperacillin, ceftazidime, imipenem, and ciprofloxacin (p<0.001). Over the study period, the resistance rates of outpatient and inpatient isolates to piperacillin, ceftazidime, imipenem, and ciprofloxacin were 4.6% and 11.5%, 2.4% and 10%, 2.6% and 5.8%, and 3% and 6%, respectively. Gentamicin demonstrated the highest resistance among all tested aminoglycosides for outpatient isolates (6%) and inpatient isolates (6.7%). Resistance to more than two classes of antibiotics was present in 1-2% of inpatient isolates and in 0% of outpatient isolates.

CONCLUSION

Antibiotic resistance continues to be a problem especially in inpatient isolates and is likely to be related to increased antibiotic use. Thus, continued monitoring of antibiotic resistance is of great importance to ensure the proper use of antibiotics and to detect any increasing trends in resistance.