Staphylococcus aureus bacteremia: A continuing challenge

How to cite this article:
Singla N, Bansal N, Chander J. Staphylococcus aureus bacteremia: A continuing challenge. Ann Trop Med Public Health 2011;4:51-2


How to cite this URL:
Singla N, Bansal N, Chander J. Staphylococcus aureus bacteremia: A continuing challenge. Ann Trop Med Public Health [serial online] 2011 [cited 2020 Aug 14];4:51-2. Available from:


Over the past decade, incidence of Staphylococcus aureus bacteremia (SAB) has increased substantially with a reported rate of 26%, 21.6%, and 19.5% in North America, Latin America, and Europe, respectively. [1] Concurrently, treatment of SAB is becoming more difficult because of the increasing prevalence of multidrug resistant strains especially methicillin-resistant S. aureus (MRSA) highlighting the critical need for a consistent approach to their diagnosis and management. SAB also places a substantial cost and resource burden on health care systems due to the various life-threatening complications like infective endocarditis and metastatic infections. [2] Approximately one-third of patients with S. aureus blood stream infections (BSI) develop local complications or distant septic metastases involving bones and joints (especially when prosthetic materials are present), the epidural space, intervertebral discs and both native as well as prosthetic cardiac valves. In addition, patients can develop visceral abscesses in the spleen and kidneys with a 12-weeks mortality rate as high as 22%. [3] Fowler et al. identified 4 risk factors for complicated S. aureus BSIs, namely, presence of persistent bacteremia (positive blood culture results after 72−96 h of appropriate treatment), community acquisition, the presence of skin lesions suggestive of distant metastases and persistent fever. [3] A delay in the administration of appropriate treatment leads to an increase in the risk of complications and higher mortality. Therefore, persistent bacteremia should alert the clinician for prompt investigation and treatment.

S. aureus was found to be the most common cause of early-onset bacteremia in a study involving 6697 patients with BSIs who were identified in 59 US hospitals during 2002−2003. [2] Similarly, SAB, 18.43% (108/586) was found to be the most common cause of Gram-positive bacteremia and second most common cause of bacteremia (after Acinetobacter spp 25.76%) at our teaching and tertiary care medical institute during the time period July 2009−December 2009. Out of these, 62.4% were isolated from males and 42.1% were from pediatric age group. MRSA constituted 77.1% of total bloodstream S. aureus isolates from ICU patients, 44.8% of inpatients, and 38.9% of outpatients. Other studies have also reported similar rates of MRSA with 49.1% isolated from inpatients and 41.4% from outpatients. [4] In Europe, rates of methicillin resistance vary from 25% to 50% in most of the countries namely Spain, Portugal, United Kingdom, France, Italy, Greece, and Turkey. [5]

The primary sources of infection in the hospitals are the colonized patients and hospital staff. The anterior nares are the main reservoir in humans with approximately 1.5%−3.0% likely to be persistently colonized with MRSA. The adult population at the highest risk of invasive S. aureus infection includes patients who are on renal replacement therapy, with HIV infection, solid organ transplant recipients, intravenous drug abusers, patients with a high alcohol intake, patients with intravenous catheters and with heart disease, cancer, diabetes mellitus, or stroke. [6]

Strains of S. aureus have developed resistance to number of antibiotics including penicillins, cephalosporins, methicillin, vancomycin, and linezolid. In our study, the resistance percentages of MRSA and methicillin sensitive  S.aureus (MSSA) isolates to various antibiotics namely penicillin, amoxycillin, cefadroxil, cotrimoxazole, gentamicin, netilmicin, ciprofloxacin, erythromycin, clindamycin, and amikacin were 100%, 100%, 100%, 33.3%, 45.5%, 36.6%, 57.9%, 43.8%, 28.5%, 40.6%, and 79.5%, 20.7%, 12.7%, 15.2%, 5.8%, 2.6%, 21.6%, 13.7%, 7%, 1.6%, respectively. However, all the S. aureus strains were found to be sensitive to vancomycin and linezolid. Numerous guidelines for the prevention and management of SAB exist but these are not uniform in their recommendations. The empirical therapy is of critical importance as delay in use of antibiotic treatment, even by only 45 h, has been shown to increase the risk of infection-related mortality and the duration of hospitalization. [2] Vancomycin no doubt is currently the recommended treatment especially for MRSA BSI but the rate of treatment failure remains high. Vancomycin is less effective than b-lactams against MSSA infection and there is evidence of a vancomycin MIC creep for both MSSA and MRSA. [6],[7] The changing epidemiology of S. aureus bacteremia and its inherent virulent nature demands rigorous management of both suspected and confirmed cases of SAB to prevent further complications.



1. Biedenbach DJ, Moet GJ, Jones RN. Occurrence and antimicrobial resistance pattern comparisons among bloodstream infection isolates from the SENTRY Antimicrobial Surveillance Program (1997-2002). Diagn Microbiol Infect Dis 2004;50:59-69.
2. Shorr AF, Tabak YP, Killian AD, Gupta V, Liu LZ, Kollef MH. Healthcare-associated bloodstream infection: A distinct entity? Insights from a large US database. Crit Care Med 2006;34:2588-95.
3. Fowler VG Jr, Olsen MK, Corey GR, Woods CW, Cabell CH, Reller LB, et al. Clinical identifiers of complicated Staphylococcus aureus bacteremia. Arch Intern Med 2003;163:2066-72.
4. Styers D, Sheehan DJ, Hogan P, Sahm DF. Laboratory-based surveillance of current antimicrobial resistance patterns and trends among Staphylococcus aureus: 2005 status in the United States. Ann Clin Microbiol Antimicrob 2006;5:2.
5. EARSS management team. European Antimicrobial Resistance Surveillance System Annual Report 2006. Bilthoven, The Netherlands: National Institute for Public Health and the Environment, 2007.
6. Cervera C, Almela M, Martinez-Martinez JA, Moreno A, Miro JM. Risk factors and management of gram-positive bacteremia. Int J Antimicrob Agents 2009;34S:S26-30.
7. Kim SH, Kim KH, Kim HB. Outcome of vancomycin treatment in patients with methicillin-susceptible Staphylococcus aureus bacteremia. Antimicrob Agents Chemother 2008;52:192-7.

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1755-6783.8053

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