Heteroresistance: a concern of increasing clinical significance?

Recent studies have focused on issues related to heteroresistance, including its definition, methods of detection and frequency. Most such studies have reported data concerning infections caused by Staphylococcus aureus, but the clinical significance of heteroresistance is unclear. Six studies have described infections caused by S. aureus strains that were heteroresistant to vancomycin, with two suggesting an association between the emergence of heteroresistance and treatment failure or mortality, and four suggesting no such association. Further studies are required to evaluate the clinical implications of heteroresistance in an era in which rates of antimicrobial resistance are increasing alarmingly worldwide.

Meta-analysis: randomized controlled trials of clindamycin/aminoglycoside vs. beta-lactam monotherapy for the treatment of intra-abdominal infections

AIM

To compare the effectiveness and safety of clindamycin/aminoglycoside with broad-spectrum beta-lactam monotherapy in patients with intra-abdominal infections by performing a meta-analysis of randomized controlled trials (RCTs).

METHODS

The relevant 28 RCTS were retrieved from PubMed searches and reviewed by two reviewers independently.

RESULTS

beta-lactam monotherapy was more effective regarding cure of the infection than clindamycin/aminoglycoside (3177 clinically evaluable patients, fixed effects model, OR = 0.67, 95% CI: 0.55-0.81). The same result was found in several subset analyses. There was no difference in all-cause mortality and attributable-to-infection mortality [2382 intention-to-treat (ITT) patients, fixed effects model, OR = 1.25, 95% CI: 0.74-2.11 and 1976 ITT patients, OR = 1.19, 95% CI: 0.59-2.41, respectively]. There was no difference regarding overall adverse events and ototoxicity (1460 ITT patients, OR = 1.05, 95% CI: 0.80-1.37, and 1404 ITT patients, OR = 3.22, 95% CI: 0.72-14.45, respectively). However, treatment with clindamycin/aminoglycoside was more likely to be associated with nephrotoxicity compared to beta-lactam (3065 ITT patients, OR = 3.7, 95% CI: 2.09-6.57). Clindamycin/aminoglycoside was less likely to be associated with antibiotic-associated diarrhoea compared to beta-lactam (3050 ITT patients, OR = 0.68, 95% CI: 0.46-1.00).

CONCLUSION

The results of our meta-analysis suggest that beta-lactams are more effective in the treatment of intra-abdominal infections compared with clindamycin/aminoglycoside.

Effect of meteorological variables on the incidence of lower urinary tract infections

Several types of infections involving the respiratory tract have a seasonal variation. We further examined whether lower urinary tract infections (UTIs) are associated with meteorological parameters. We retrospectively evaluated the correlation of the weekly percentage of house call visits for lower UTIs (relatively to all house call visits, excluding those for respiratory tract infections), performed by "SOS Doctors" specialized physicians in Attica, Greece (1/11/2000-18/1/2005), with the average weekly temperature and humidity, recorded at the same area, 3 days earlier. Three thousand two hundred and twenty-one visits for lower UTIs were recorded in patients of 62.9 +/- 21.0 years of age. House call visits for lower UTIs, as defined above, correlated with the average weekly temperature (Spearman's rho+0.468) and humidity (Spearman's rho -0.394); similarly, if respiratory tract infections were not excluded from the calculations (Spearman's rho +0.491 and -0.406, respectively); or if a 2-day lag between measurements was used (Spearman's rho +0.468 and -0.386, respectively). All the above findings were significant (p<0.001). In conclusion, in a population that consisted mainly of patients of advanced age, higher temperature and decreased humidity are associated with an increase in house call visits for lower UTIs. The awareness of this association may facilitate preventive public health strategies. [corrected]

Meta-analysis: ertapenem for complicated intra-abdominal infections

BACKGROUND

Ertapenem is a new member of the carbapenem class of antibiotics, with a favourable pharmacokinetic profile, but a narrower spectrum of antimicrobial activity, compared with older representatives of this class.

AIM

To evaluate the effectiveness and safety of ertapenem for treatment of complicated intra-abdominal infections.

METHODS

We performed a meta-analysis of randomized-controlled trials identified in PubMed, Cochrane and Scopus that compared ertapenem with other antimicrobial regimens, in patients of all ages, with complicated intra-abdominal infections. The primary outcomes evaluated were clinical success (cure or improvement) in the modified intention-to-treat population and clinical adverse events.

RESULTS

Six randomized-controlled trials involving patients with complicated intra-abdominal infections, mainly of mild-to-moderate severity (three with a double-blind design; one performed in children) that compared ertapenem treatment (once daily) against piperacillin/tazobactam, ceftriaxone plus metronidazole and ticarcillin/clavulanic acid (in three, two and one randomized-controlled trials respectively) were included. No difference was found between adult patients with complicated intra-abdominal infections treated with ertapenem vs. comparators, regarding clinical success (five randomized-controlled trials, 2002 patients, fixed-effect model, odds ratio: 1.11, 95% confidence interval (CI): 0.89-1.39); clinical adverse events (four randomized-controlled trials, 1530 patients, fixed-effect model, OR: 0.86, 95% CI: 0.61-1.20); microbiological success; mortality and withdrawals because of adverse events. Ertapenem was associated with more laboratory adverse events (four randomized-controlled trials, 1530 patients, fixed-effect model, OR: 1.73, 95% CI: 1.14-2.61), but none was reported as serious.

CONCLUSION

This meta-analysis provides additional evidence that ertapenem can be used as effectively and safely, as other recommended antimicrobial regimens, for the treatment of complicated intra-abdominal infections, particularly of mild-to-moderate severity.

Adjunctive dexamethasone therapy for bacterial meningitis in adults: a meta-analysis of randomized controlled trials

The objective of this review was to study the effectiveness of dexamethasone for the treatment of adult patients with bacterial meningitis. Data was extracted from randomized controlled trials (RCTs) comparing dexamethasone with placebo or no treatment and pooled using meta-analysis techniques. Treatment with dexamethasone was associated with a non-significant lower mortality than placebo or no treatment [odds ratio (OR) = 0.68, 95% confidence interval (CI) 0.45-1.04]. If a RCT conducted in Malawi was excluded from the analysis, dexamethasone was associated with lower mortality than placebo or no treatment (OR = 0.58, 95% CI 0.40-0.83). Dexamethasone was associated with lower mortality in patients with definite meningitis (OR = 0.55, 95% CI 0.31-0.96), short duration of symptoms (OR = 0.61, 95% CI 0.38-1.00), Streptococcus pneumoniae meningitis (OR = 0.26, 95% CI 0.08-0.78), patients in countries with high (OR = 0.45, 95% CI 0.23-0.87) and medium Human Development Index (OR = 0.65, 95% CI 0.42-1.00). No benefit was seen in patients with longer duration of symptoms (OR = 0.80, 95% CI 0.47-1.36) or no antibiotic use (OR = 0.68, 95% CI 0.36-1.28). Dexamethasone was associated with fewer episodes of hearing impairment in high quality RCTs (OR = 0.64, 95% CI 0.43-0.94). The currently available evidence suggests that dexamethasone should be administered to all adult patients with bacterial meningitis. Large studies are needed to clarify the role of the duration of symptoms, disease severity, and antibiotic administration before the initiation of treatment with dexamethasone on modifying the outcomes.

Trimethoprim-sulfamethoxazole for methicillin-resistant Staphylococcus aureus: a forgotten alternative?

Methicillin-resistant Staphylococcus aureus (MRSA) is a growing infectious concern, mainly in the context of its rapid adaptation to novel antibiotic options for its treatment and the growing morbidity, mortality, and healthcare costs associated with its emergence. the authors sought to investigate whether an older antibiotic, such as trimethoprim-sulfamethoxazole (SXT), may have a role in treating MRSA-related infections, according to the available literature on the subject. The authors reviewed literature data on: resistance of MRSA to SXT worldwide in recent years, efficacy of SXT for MRSA decolonization or prophylaxis from MRSA infections, and clinical therapeutic efficacy of SXT in treating mild or severe community-acquired or hospital-acquired MRSA infections. Resistance varies worldwide, in general being low in the industrialized world and higher in developing countries. SXT is one of the numerous understudied options for MRSA decolonization and is growingly recognized as potentially effective in preventing MRSA infections in certain settings. Limited data on its therapeutic efficacy are encouraging, at least for mild, community-acquired infections. SXT may represent a cost-effective alternative weapon against MRSA. Its utility against this increasingly threatening pathogen need clarification through further clinical trials.

Elderly versus nonelderly patients with invasive aspergillosis in the ICU: a comparison and risk factor analysis for mortality from the AspICU cohort

Data regarding the epidemiology and diagnosis of invasive aspergillosis in the critically ill population are limited, with data regarding elderly patients (≥75 years old) even scarcer. We aimed to further compare the epidemiology, characteristics and outcome of elderly versus nonelderly critically ill patients with invasive aspergillosis (IA) Prospective, international, multicenter observational study (AspICU) including adult intensive care unit (ICU) patients, with a culture and/or direct examination and/or histopathological sample positive for Aspergillus spp. at any site. We compared clinical characteristics and outcome of IA in ICU patients using two different diagnostic algorithms. Elderly and nonelderly ICU patients with IA differed in a number of characteristics, including comorbidities, clinical features of the disease, mycology testing, and radiological findings. No difference regarding mortality was found. According to the clinical algorithm, elderly patients were more likely to be diagnosed with putative IA. Elderly patients had less diagnostic radiological findings and when these findings were present they were detected late in the disease course. The comparison between elderly survivors and nonsurvivors demonstrated differences in clinical characteristics of the disease, affected sites and supportive therapy needed. All patients who were diagnosed with proven IA died. Increased vigilance combined with active search for mycological laboratory evidence and radiological confirmation are necessary for the timely diagnosis of IA in the elderly patient subset. Although elderly state per se is not a particular risk factor for mortality, a high SOFA score and the decision not to administer antifungal therapy may have an impact on survival of elderly patients.

Systematic review: fluoroquinolones for the treatment of intra-abdominal surgical infections

BACKGROUND

Intra-abdominal infections result in substantial morbidity and mortality. Fluoroquinolones are among the various regimens that are used for the treatment of these infections.

AIM

To evaluate the available data from laboratory and clinical studies regarding the use of fluoroquinolones for the treatment of patients with intra-abdominal infections.

METHODS

We searched for relevant laboratory and clinical studies in the PubMed and the Cochrane Library databases.

RESULTS

Good pharmacokinetic and pharmacodynamic properties of fluoroquinolones in inflamed abdominal tissue are reported in several laboratory studies. In six prospective non-randomized clinical studies of patients with intra-abdominal infections, the clinical success achieved with the use of fluoroquinolones ranged from 77% to 94%. In 10 randomized-controlled trials fluoroquinolone-based regimens were compared with other commonly used (mainly beta-lactam-based) regimens. Clinical success, bacterial eradication, withdrawal because of toxicity and mortality were similar between the compared treatment arms except from two randomized-controlled trials, in which clinical success was statistically higher in the fluoroquinolone treatment arm.

CONCLUSIONS

Fluoroquinolones seem to be an effective and relatively safe option for the treatment of patients with intra-abdominal infections.

Bloodstream infections in ICU with increased resistance: epidemiology and outcomes

BACKGROUND

Aim of this study was to evaluate the epidemiology and outcomes of hospital-acquired bloodstream infections (HA-BSI) in Greek intensive care units (ICU).

METHODS

Secondary analysis of data from 29 ICU collected during the EUROBACT study, a large prospective, observational, multination survey of HA-BSI. First episodes of HA-BSI acquired in the ICU or within 48 hours prior to admission were recorded.

RESULTS

Gram-negative bacteria predominated namely Acinetobacter sp, Klebsiella sp, Pseudomonas sp (73.3% of monomicrobial infections) followed by Gram-positive cocci (18.3%); fungi (7.6%) and anaerobes (0.8%). Overall 73.3% of isolates were multidrug resistant (MDR), 47.1% extensively resistant (XDR) and 1.2% pan-drug resistant (PDR). Carbapenems were the most frequent empirically prescribed antibiotics, while colistin was the most frequently adequate; for both, calculated mean total daily doses were suboptimal. Overall 28-day all-cause mortality was 33.3%. In the multivariate analysis, factors adversely affecting outcome were higher SOFA score at HA-BSI onset (OR 1.19; 95% CI 1.08-1.31, P=0.0006), need for renal supportive therapy (OR 2.75; 95% CI 1.35-5.59, P=0.0053), and for vasopressors/inotropes (OR 2.68; CI 1.18-6.12, P=0.02); adequate empirical treatment had a protective effect (OR 0.48; CI 0.24-0.95, P=0.03).

CONCLUSION

TIMELY administration of adequately dosed treatment regimens and early ICU admission of critically ill patients could help in improving outcomes.

Rituximab in critically ill patients

Rituximab is a monoclonal chimeric antibody used in the treatment of CD20-positive B-cell malignancies and rheumatoid arthritis. However, it is used in several other off-label indications including acute graft-versus-host disease. We sought to critically examine the role of rituximab in the treatment of acute graft versus host disease (aGVHD) in critically ill patients and the potential associations with infectious complications in transplant recipients.

Comparison of community-acquired pneumonia due to methicillin-resistant and methicillin-susceptible Staphylococcus aureus producing the Panton-Valentine leukocidin

OBJECTIVE

To investigate the clinical features and prognosis of patients with methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) community-acquired pneumonia (CAP) producing the Panton-Valentine leukocidin (PVL).

METHODS

PubMed and Scopus were searched. Inclusion was stratified according to S. aureus susceptibility and clinical, microbiological and outcome data of patients with S. aureus CAP; both primary and secondary cases of CAP (hematogenous spread from other sites of infection) were included.

RESULTS

We identified 71 articles reporting data on patients with MRSA (n = 76) and MSSA (n = 31) PVL-positive CAP. There were no differences in demographics and history among patients with MRSA and MSSA CAP. Features associated with MRSA CAP were gastrointestinal tract symptoms (P = 0.016) and unilobar infiltrates (P = 0.043). Features associated with MSSA CAP were airway hemorrhage (P = 0.01), multilobar infiltrates (P = 0.043) and acute respiratory distress syndrome (ARDS, P = 0.023). Although MSSA patients were more likely to receive initial appropriate antimicrobial therapy (P < 0.001), there was no difference in mortality between the two groups (P = 0.919). Univariate analysis showed that influenza-like symptoms (P < 0.001), multi-organ failure (P < 0.001), admission to the intensive care unit (P < 0.001), mechanical ventilation (P < 0.001), leucopenia (P < 0.001), shock (P = 0.001), development of complications (P = 0.003), vein thrombosis (P < 0.001), disseminated intravascular coagulation (P = 0.03), acidosis (P = 0.012), rash (P = 0.024), ARDS (P = 0.021), necrotizing pneumonia (P = 0.026), and use of macrolides after culture results (P = 0.011) were factors associated with death.

CONCLUSIONS

Patients with MRSA PVL-positive CAP did not have higher rates of mortality than patients with MSSA PVL-positive CAP.