Amoxiclav 500

This observation highlights the importance of knowing the final susceptibility data prior to consolidating to monotherapy with an oral agent, and that macrolides may have beneficial anti-inflammatory effects, though further research is needed. Although the evidence for treating bacteremic pneumococcal pneumonia using a highly active and absorbable oral agent is fairly robust, S.

pneumoniae BSI secondary to other sites of infection sites is less well studied and may require a more conservative approach.

Gram-Positive Cocci, ? -hemolytic Streptococcus species. ?-Hemolytic Streptococci include groups A to H, of which groups A (S. agalactiae) are the most commonly implicated in BSIs. 36 Group A Streptococcus (GAS) is classically associated with streptococcal pharyngitis and Group B Streptococcus (GBS) is associated with postpartum endometritis and neonatal meningitis, though both are virulent organisms with a potential to cause invasive infection throughout the body and in all age-groups. Up to 14% of GAS and 41% GBS BSIs have no clear source; 37,38 given these are skin pathogens, such scenarios likely represent invasion via microabrasion.

As ?-hemolytic streptococcal BSI is often observed in the context of necrotizing skin and soft tissue infections, surgical source control is particularly important. 39 GAS remains exquisitely susceptible to penicillin, and intravenous penicillin remains the mainstay for invasive disease; GBS has higher penicillin resistance rates than GAS.

40 Clindamycin should be added when

there

42 Thus, oral penicillin V and/or clindamycin is a potentially risky strategy, with no clinical trials supporting this approach; however, they may be reasonable options in selected patients with source control and stable hemodynamics.

Amoxicillin has high bioavailability (85%) and may be effective; however, there is lack of supporting data. Highly bioavailable agents such as levofloxacin and linezolid have GAS and GBS activity 43 and might be expected to produce satisfactory outcomes.

Because no clinical trials have compared these agents with intravenous therapy for BSI, caution is advised. Although bacteriostatic against Staphylococcus, linezolid is bactericidal against Streptococcus.

44 Fluoroquinolone resistance amongst ?-hemolytic Streptococcus is rare (approximately 0.5%) but does occur.

aureus (including methicillin susceptible and resistant strains: MSSA and MRSA, respectively) and coagulase-negative species, which include organisms such as S.

aureus is the most common cause of BSI mortality in the United States, 1 with mortality rates estimated at 20%–40% per episode.

46 Infectious disease consultation has been associated with decreased mortality and is recommended. 47 The guidelines of the Infectious Diseases Society of America for the treatment of MRSA recommend the use of parenteral agents for BSI. 48 It is important to consider if a patient with S. Although trimethoprim-sulfamethoxazole (TMP-SMX) has favorable pharmacokinetics and case series of using it successfully for BSI exist, 49 TMP-SMX showed inferior outcomes in a randomized trial comparing oral TMP-SMX with intravenous vancomycin in a series of 101 S.

aureus BSI are limited, and IDSA guidelines advise against their use in this setting because they are predominantly bacteriostatic. 48 Linezolid has favorable pharmacokinetics, with approximately 100% bioavailability, and S. 52 Several randomized trials have compared oral linezolid with intravenous vancomycin for S.

aureus infection (of whom 18% had BSI) to linezolid versus vancomycin and observed similar clinical cure rates. 53 A pooled analysis showed oral linezolid was noninferior to vancomycin specifically for S.

54 However, long-term use is often limited by hematologic toxicity, peripheral or optic neuropathy (which can be permanent), and induced serotonin syndrome.

Additionally, linezolid is bacteriostatic, not bactericidal against S.

aureus BSI would not be recommended; however, it may be used as a second-line treatment option in selected cases.

Tedizolid has similar pharmacokinetics and spectrum of activity with fewer side effects; however, clinical data on its use for S. 55 Fluoroquinolones such as levofloxacin and the newer agent delafloxacin have activity against S.

aureus, including MRSA, but on-treatment emergence of fluoroquinolone resistance is a concern, and data on delafloxacin for BSI are lacking. 56,57 Older literature suggested the combination of ciprofloxacin and rifampin was effective against right-sided S. aureus endocarditis, 58 and other oral fluoroquinolone-rifamycin combinations have also been found to be effective 59 However, this approach is currently not a standard therapy, nor is it widely used.

aureus BSI should be made in conjunction with an infectious diseases specialist; 14 days is currently regarded as a minimum.

Published data regarding oral treatment of coagulase-negative Staphylococcus (CoNS) BSI are limited. Most CoNS bacteremia and up to 80% Staphylococcus epidermidis bacteremia represent blood culture contamination, though true infection from CoNS is not uncommon, particularly in patients with indwelling catheters.

60 An exception is the CoNS species Staphylococcus lugdunensis, which is more virulent, and bacteremia with this organism usually warrants antibiotics.

Oral antimicrobial therapy is currently not a standard treatment practice for CoNS BSI that is felt to represent true infection; however, linezolid has been successfully used in case series. aureus, infective endocarditis must be ruled out when treating enterococcus BSI; a scoring system has been proposed to assist in deciding if such patients require echocardiography.

62 Intravenous ampicillin is a preferred, highly effective agent for enterococci treatment when the organism is susceptible.

44 However, oral ampicillin has poor bioavailability (50%), and data for its use in BSI are lacking. For susceptible strains, amoxicillin has comparable efficacy for enterococci and enhanced bioavailability (85%); high dose oral amoxicillin could be considered, but there is minimal clinical trial data to support this approach.

Fluoroquinolones exhibit only modest activity against enterococci and would be an inferior choice for BSI. 63 Although often sensitive to oral tetracyclines, data on their use in enterococcal BSI are insufficient. Nitrofurantoin can be used for susceptible enterococcal urinary tract infection; however, it does not achieve high blood concentrations and should not be used for BSI.

There is significant data comparing oral linezolid with intravenous daptomycin for vancomycin-resistant enterococci (VRE) BSI.

In a systematic buy amoxicillin 500mg without prescription review including 10 trials using 30-day all-cause mortality as the primary outcome, patients treated with daptomycin demonstrated higher odds of death (OR 1.61, 95% CI 1.08–2.40) compared with those treated with linezolid.

64 However, more recent data suggested that higher daptomycin doses than those used in these earlier trials resulted in improved VRE BSI outcomes.

65 A subsequent study reported that

VRE

Evidence Regarding Anaerobic Bacterial Blood Stream Infection. Anaerobic bacteria include Bacteroides, Prevotella, Porphyromonas, Fusobacterium, Peptostreptococcus, Veillonella, and Clostridium. Anaerobes account for approximately 4% of bacterial BSIs, and are often seen in the context of polymicrobial infection.

67 Given that anaerobes are difficult to recover, and that antimicrobial resistance testing is more labor intensive, antibiotic therapy choices are often made empirically. 67 Unfortunately, antibiotic resistance amongst anaerobes is increasing.

68 However, metronidazole remains highly active against a majority of anaerobes, with only a handful of treatment failures reported, 69 and has a highly favorable pharmacokinetic profile for oral treatment. Oral metronidazole remains an effective choice for many anaerobic BSIs.

Considering the polymicrobial nature of many anaerobic infections, source control is important, and concomitant GNR infection must be ruled out before using metronidazole monotherapy. Clindamycin has significant anaerobic activity, but Bacteroides resistance has increased significantly in recent years, as high as 26%-44%. 70 Amoxicillin-clavulanate has good anaerobic coverage, but bioavailability of clavulanate is limited (50%),

making

Although BSIs are traditionally treated with intravenous antimicrobials, many BSIs can be safely and effectively cured using oral antibiotics. When appropriately selected, oral antibiotics offer lower costs, fewer side effects, promote antimicrobial stewardship, and are easier for patients.

Ultimately, the decision to use oral versus intravenous antibiotics must consider the characteristics of the pathogen, patient, and drug.

None of the authors report any conflicts of interest.

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