Synergistic effect of non-steroidal anti-inflammatory drugs (NSAIDs) on antibacterial activity of cefuroxime and chloramphenicol against methicillin-resistant Staphylococcus aureus

OBJECTIVES

Currently, only a few antibiotics are available to treat methicillin-resistant Staphylococcus aureus (MRSA). One alternative approach includes adjuvants to antibiotic therapy. Non-steroidal anti-inflammatory drugs (NSAIDs) are non-antibiotic drugs reported to exhibit antibacterial activity. The objective of this study was to investigate the interaction between NSAIDs with selected antibiotics (cefuroxime and chloramphenicol) against strains of S. aureus.

METHODS

The antibacterial activity of four NSAIDs (aspirin, ibuprofen, diclofenac and mefenamic acid) were tested against ten pathogenic bacterial strains using the microdilution broth method. The interaction between NSAIDs and antibiotics (cefuroxime/chloramphenicol) was estimated by calculating the fractional inhibitory concentration (FICI) of the combination.

RESULTS

Aspirin, ibuprofen and diclofenac exhibited antibacterial activity against the selected pathogenic bacteria. The interaction between ibuprofen/aspirin with cefuroxime was demonstrated to be synergistic against methicillin-sensitive S. aureus (MSSA) and the MRSA reference strain, whereas for MRSA clinical strains additive effects were observed for both NSAIDs and cefuroxime combinations. The combination of chloramphenicol with ibuprofen/aspirin was synergistic against all of the tested MRSA strains and displayed an additive effect against MSSA. A 4-8192-fold reduction in the cefuroxime minimum inhibitory concentration (MIC) and a 4-64-fold reduction of the chloramphenicol MIC were documented.

CONCLUSIONS

Overall, the NSAIDs ibuprofen and aspirin showed antibacterial activity against strains of S. aureus. Although individually less potent than common antibiotics, these NSAIDs are synergistic in action with cefuroxime and chloramphenicol and could potentially be used as adjuvants in combating multidrug-resistant MRSA.

Comparison of outcome and clinical characteristics of bacteremia caused by methicillin-resistant, penicillin-resistant and penicillin-susceptible Staphylococcus aureus strains

BACKGROUND

The aim of this study was to assess the association of methicillin resistance and penicillinase production with clinical characteristics and outcome of Staphylococcus aureus bacteremia.

METHODS

For 126 patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia, 378 age- and gender-matched controls with methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia were selected. Of controls, 126 had bacteremia caused by penicillin-susceptible strains (PSSA) and 252 by penicillinase-producing strains (PRSA). Underlying diseases, clinical course and mortality were retrospectively assessed.

RESULTS

Patients with MRSA bacteremia were more often smokers than patients with MSSA bacteremia (OR 2.34, 95% CI 1.27-4.32). MRSA bacteremia was more often healthcare-associated (OR 4.23, 95% CI 2.47-7.24), associated with central venous catheters (OR 2.09, 95% CI 1.27-3.47), glucocorticoid therapy (OR 1.82, 95% CI 1.12-2.93) and prior surgery (OR 2.32, 95% CI 1.43-3.76). Patients with MRSA bacteremia received appropriate empiric antibiotic (31%) less often than controls (98%). Mortality within 28 days was higher in MRSA bacteremia (26.8%) than in MSSA bacteremia (15.5%) (OR 2.00, 95% CI 1.20-3.34), PRSA bacteremia (17.0%) (OR 1.79 95% CI 1.04-3.09) or PSSA bacteremia (12.5%) (OR 2.56 95% CI 1.27-5.15). The difference remained after adjusting for underlying diseases and foci. There was no significant difference in clinical course between PRSA and PSSA bacteremias.

CONCLUSIONS

MRSA bacteremia was associated with poorer outcome than either PRSA or PSSA bacteremia. We corroborated several risk factors found in previous studies.

Combined interventions are effective in MRSA control

BACKGROUND

A large healthcare-associated epidemic mainly caused by one methicillin-resistant Staphylococcus aureus (MRSA) strain broke out in Pirkanmaa County, Finland, in 2001. This study describes the impact of infection control and screening practices on the epidemic.

METHODS

The number of hospital-acquired (HA)-MRSA findings obtained from clinical and screening samples during the epidemic was calculated. Strains were typed by pulsed-field electrophoresis (PFGE) or spa typing. Strain type distribution was studied in relation to sample type, year of the epidemic and site of transmission. Several infection control interventions were launched stepwise and screening protocols were expanded.

RESULTS

A total of 4118 cases were identified during 2001-2014, of which 3527 were classified as HA. One strain (spa t067) dominated in the epidemic. HA-MRSA cases decreased constantly from the year 2011. The number of new HA-MRSA cases was 57% less in the year 2014 (n = 171) as compared with the year 2011 (n = 399). The proportion of the epidemic strain declined significantly over the years. Screening samples comprised 71% (2439/3527) and clinical samples 29% (1034/3527) of HA-MRSA findings. The number of HA-MRSA cases found from clinical samples started to decrease when screening was expanded. An increase in hand-rub consumption was associated with a decrease in transmissions in Tampere University Hospital (TAUH).

CONCLUSION

Implementation of universal screening together with several other interventions is effective in containing an MRSA epidemic. The proportion of other than Pirkanmaa epidemic (PE)-MRSA strain findings increased throughout the period, indicating the changing epidemiology of MRSA.

Nosocomial bloodstream infections in a Finnish tertiary care hospital: a retrospective cohort study of 2175 episodes during the years 1999-2001 and 2005-2010

BACKGROUND

Nosocomial infections are major causes of morbidity in hospitalized patients.

METHODS

Retrospective laboratory-based surveillance during 1999-2001 and 2005-2010 identified 2175 cases of nosocomial bloodstream infections (BSIs) in Tampere University Hospital (TAUH), Finland.

RESULTS

Analysis revealed that 57% of BSIs were caused by a gram-positive organism, 27% by a gram-negative organism, 5% by a fungal organism, and 11% were polymicrobial. The most common cause of nosocomial BSI was coagulase-negative staphylococci (23%). Candida species caused 5% of the infections. The 7-day and 30-day case fatalities were 8% (161/2158) and 15% (313/2175), respectively, and were highest in BSIs caused by Candida albicans (22% and 44%) and Pseudomonas aeruginosa (17% and 25%). The median age of patients was 54 years in 1999-2001, 57 years in 2005-2007, and 60 years in 2008-2010 (p < 0.001). The median time from hospital admission to the onset of BSI was 11 days (quartiles 5-18 days). This period was shortest for Streptococcus agalactiae BSI and longest for Candida non-albicans fungemia (1 vs 19 days). The case fatality rate in nosocomial BSI decreased during the years studied: 7-day and 30-day case fatalities were 9% and 16% during 1999-2001, 8.5% and 16% during 2005-2007, and 5% and 12% during 2008-2010, respectively (p < 0.003 and p = 0.022, respectively).

CONCLUSIONS

Gram-positive infections predominate in nosocomial BSIs. The median age of patients with nosocomial BSI has risen during the study years. The case fatality associated with nosocomial BSI has decreased.