From the Guidelines

Nitrofurantoin is the best antibiotic for a 70-year-old female with hemorrhagic cystitis and no significant medical history.

Efficacy: Nitrofurantoin has been shown to be effective in treating uncomplicated cystitis, with a cure rate comparable to other recommended antibiotics 1.
Resistance: Nitrofurantoin has a low resistance rate among E. coli strains, making it a good choice for empirical treatment 1.
Safety: Nitrofurantoin is generally well-tolerated and has a low risk of adverse effects, making it a good choice for older adults 1.
Guideline Recommendations: The American College of Physicians and the Infectious Diseases Society of America recommend nitrofurantoin as a first-line treatment for uncomplicated cystitis in women 1.

Local Resistance Rates: It is essential to consider local resistance rates when choosing an antibiotic, as resistance patterns can vary by region 1.
Patient Factors: Patient factors, such as allergy history and tolerance, should also be considered when choosing an antibiotic 1.

From the Research

The treatment of hemorrhagic cystitis typically involves a stepwise approach, with options ranging from conservative management to surgical interventions 2.
Conservative management may include establishing bladder drainage, manual clot evacuation, and continuous bladder irrigation through a large-bore urethral catheter 2.
Intravesical options for treating hemorrhagic cystitis include alum, aminocaproic acid, prostaglandins, silver nitrate, and formalin, with formalin typically reserved as a last-line treatment due to its caustic effects on the bladder mucosa 2.

For the treatment of acute uncomplicated cystitis, a single oral dose of fosfomycin trometamol is often recommended as the antibiotic of choice, with alternative options including certain fluoroquinolones or co-trimoxazole 3.
Nitrofurans and fosfomycin trometamol are recommended as first-line therapy antibiotics for the treatment of cystitis, due to their low resistance rates among uropathogens such as Escherichia coli 4.
The choice of antibiotic should consider the level of resistance of uropathogens, as well as the ecological safety of the antimicrobial therapy to minimize the risk of selecting multi-drug resistant strains of microorganisms 4.

The patient's age and lack of significant medical history should be taken into account when selecting an antibiotic, with consideration given to potential side effects and interactions with other medications.
However, there is no specific evidence to recommend a particular antibiotic for a 70-year-old female patient with hemorrhagic cystitis, and treatment should be individualized based on the patient's unique needs and circumstances 5, 2, 3, 6, 4.