Trick of the Trade: IV ceftriaxone for gonorrhea

How many times have you given your patient IM ceftriaxone for that presumed gonococcal infection? … still counting? Many of us learned (or at least thought we learned) that ceftriaxone has to be administered IM to get the ‘depot’ effect.

Myth Busted

There doesn’t appear to be a true depot effect. IV and IM ceftriaxone have very similar pharmacokinetic profiles. Let me prove it to you, straight from the FDA-approved ceftriaxone package insert.

Table 1: Average plasma concentration (mcg/mL) as measured over time after 500 mg of ceftriaxone administration

Ceftriaxone route	0.5 hr	1 hr	2 hr	4 hr	6 hr	8 hr	12 hr	16 hr	24 hr
IV	82	59	48	37	29	23	15	10	5
IM	22	33	38	35	30	26	16	unknown	5

Table 2: Average urine concentration (mcg/mL) as measured over time after 500 mg of ceftriaxone administration

Ceftriaxone route	0-2 hrs	2-4 hrs	4-8 hrs	8-12 hrs	12-24 hrs	24-48 hrs
IV	526	366	142	87	70	15
IM	115	425	308	127	96	28

The plasma concentrations are almost identical after IM and IV administration through 24 hours (Table 1).
Even the urinary concentrations are similar up to 24-48 hours after a dose (Table 2).
The volume of distribution is the same for both parenteral routes, too. This means that its penetration into the “affected area” is similar.
According to a 2012 CDC Report the minimum inhibitory concentration (MIC) for N. gonorrhoeae strains to ceftriaxone is 0.125 mcg/mL. IV therapy provides concentrations above this resistance cutoff well after 24-48 hours, similar to IM therapy.

Trick of the Trade

If the patient already has an IV line, we can give IV ceftriaxone for gonorrhea instead of IM.

In fact, the Japanese Society for Sexually Transmitted Diseases has recommended monotherapy with a single IV dose of 1 g ceftriaxone since 2008. (Aoki 2021)

While most of the time patients with STD (or STI, if you prefer) complaints don’t have an IV line established, occasionally they do. My hospital stocks 1 gm and 2 gm premixed IV bags of ceftriaxone, so we could potentially just give 1 gm IV in these rare cases to ensure adequate levels (even 500 mg might be just fine).

Of course, the other way to avoid the painful injection is to mix the ceftriaxone with lidocaine… or avoid contracting gonorrhea altogether.

Disclaimer

This post is intended for educational purposes to explore the kinetic data for IM and IV therapy. The CDC guidelines should be followed for treatment of STDs.

References

Product Information: ROCEPHIN(R) IV, IM injection, ceftriaxone sodium IV, IM injection. Genentech USA, Inc. (per Manufacturer), South San Francisco, CA, 2010.
Workowski KA, Berman S; Centers for Disease Control and Prevention (CDC). Sexually transmitted diseases treatment guidelines, 2010. MMWR Recomm Rep 2010;59(RR-12):1-110. [PMID: 21160459]. Free MMWR PDF download.

Original: October 9, 2012; Last Updated: December 24, 2021

By Bryan D. Hayes, PharmD, DABAT, FAACT, FASHP|2022-02-03T10:29:27-08:00Oct 9, 2012|Infectious Disease, Tox & Medications, Tricks of the Trade|

Paucis Verbis: Does this adult patient need blood cultures?

Do you order blood cultures for all your ED patients with a fever? Obviously no. What’s your decision making process on ordering this test? There are really no findings or tests with high specificity (rules-IN bacteremia), except interestingly “shaking chills”. Notice almost all the criteria listed below approach a likelihood ratio (LR) of 1.0. Two prediction rules do exist, however, to help you virtually rule-OUT bacteremia:

SIRS
Shapiro prediction rule

The list of LRs also will be helpful to show learners in the ED that an isolated serum WBC number is useless risk-stratifier.

Patient Case

A 55 y/o man with a PMH of hypertension presents with a community-acquired pneumonia on CXR, no fevers, no chills, no vomiting.

Temperature 37.8 C, BP 160/90, HR 100, RR 16, Sat 100% RA
Serum WBC 20K (no bands)
Platelets 300K
Creatinine 1.1 mg/dL

What is the patient’s pre-test and post-test probability for having bacteremia? Use these helpful stats from the Rational Clinical Examination series from JAMA.

PV Card: Blood Cultures for Suspected Bacteremia

Adapted from [1]
Go to ALiEM (PV) Cards for more resources.

Answer to patient case

Start with 7% pretest probability for bacteremia with a community acquired pneumonia.
Using the clinical prediction rules, the WBC 20K and HR 100 bpm are criteria for SIRS but do not fulfill the Shapiro prediction criteria. LR = 1.8 * 0.08 = 0.144. Post-test probability for bacteremia = 0.06%.
If the patient had instead a normal HR of 80 bpm, both the SIRS and Shapiro criteria would have been negative. LR = 0.09 * 0.08 = 0.0072. Post-test probability for bacteremia = << 0.1%.

This discussion doesn’t address WHETHER we should get blood cultures despite a risk for bacteremia in the setting of uncomplicated pneumonia receiving IV antibiotics or pyelonephritis with a pending urine culture.

References

Coburn B, Morris A, Tomlinson G, Detsky A. Does this adult patient with suspected bacteremia require blood cultures? JAMA. 2012;308(5):502-511. [PubMed]
Shapiro N, Wolfe R, Wright S, Moore R, Bates D. Who needs a blood culture? A prospectively derived and validated prediction rule. J Emerg Med. 2008;35(3):255-264. [PubMed]

By Michelle Lin, MD|2021-10-10T08:43:50-07:00Aug 17, 2012|ALiEM Cards, Infectious Disease|

Paucis Verbis: Influenza – To treat or not to treat?

Influenza season typically peaks in the United States during the Jan-Feb months and can start as early as October. You can read about the 2011-12 seasonal flu data on the CDC website.

Should you give a patient with influenza an antiviral agent or just provide supportive therapy?

This Paucis Verbis card summaries the CDC’s Advisory Committee on Immunization Practices (ACIP) recommendations for this upcoming 2011-12 flu season. I also let patients with uncomplicated influenza who are going to be managed as outpatients know that a 5-day course of osteltamivir or zanamivir will cost them about $50-80. Often that sways them towards declining a prescription and “toughing out” an extra day of the flu.

PV Card: Influenza

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Adapted from [1]
Go to ALiEM (PV) Cards for more resources.

Reference

Centers for. Infectious disease. Antiviral agents for the treatment and chemoprophylaxis of influenza. Ann Emerg Med. 2011;58(3):299-303; discussion 303-4. [PubMed]

By Michelle Lin, MD|2021-10-12T15:44:24-07:00Oct 28, 2011|ALiEM Cards, Infectious Disease|

Paucis Verbis: Neutropenic fever in cancer patients

A 65 y/o man with a history of prostate cancer presents to your ED from home appearing fairly well and a mild cough for 3 days. His vital signs are:

Temperature 39 C
BP 160/80
HR 60
RR 14
Oxygen saturation 99% on room air

His absolute neutrophil count (ANC) comes back at 300 cells/mm3. His chest xray shows a right middle lobe pneumonia and a central line catheter tip ending in the SVC.

Is this patient “high” or “low” risk per the Multinational Association for Supportive Care in Cancer (MASCC)?
Does this person require inpatient admission?
What antibiotics would you start on this patient?

Answers

The patient’s MASCC score is 5 (mild symptoms) + 5 (no hypotension) + 4 (no COPD) + 4 (solid tumor) + 3 (no dehydration) + 3 (outpatient) = 24 = LOW RISK
NOTE: “Burden of febrile neutropenia” is a subjective scoring of the patient’s symptoms
The patient is, however, ultimately HIGH RISK clinically because of the finding of pneumonia on CXR. Admit.
Abx = Cefipime + Vancomycin

FYI: Vancomycin is not always indicated in cancer patients with a neutropenic fever.

PV Card: Neutropenic Fever in Cancer Patients (IDSA 2010)

Thanks to Alissa and Hemal for suggesting the topic!

Reference

Freifeld A, Bow E, Sepkowitz K, et al. Clinical practice guideline for the use of antimicrobial agents in neutropenic patients with cancer: 2010 update by the infectious diseases society of america. Clin Infect Dis. 2011;52(4):e56-93. [PubMed]

By Michelle Lin, MD|2021-10-12T15:54:10-07:00Oct 7, 2011|ALiEM Cards, Heme-Oncology, Infectious Disease|

Trick of the Trade: Needlestick hotline 888-448-4911

You are a fourth-year medical student and super-excited to be doing your first supervised central line procedure on an actual patient. You have done so many central lines on mannequins and simulations. You feel ready. In your excitement, however, you stick yourself with the 22 gauge finder needle after you successfully get a flash-back of the patient’s venous blood.

After handing off the procedure to your senior resident, you go into a mild panic. Your patient is a known HIV patient with an unknown CD4 count and viral load. After taking off your gloves and washing your hands, you report this to the attending.

Should you start post-exposure prophylaxis medications for HIV? You remember that if post-exposure HIV medications are recommended, you should start it immediately and definitely within 2 hours of exposure.

It’s difficult to concentrate when faced with so many questions whirling in your mind.

(more…)

By Michelle Lin, MD|2019-01-28T22:38:19-08:00Sep 27, 2011|Infectious Disease, Tricks of the Trade|

Paucis Verbis: Does this DM leg ulcer have osteomyelitis?

We sometimes see diabetic patients in the ED for a worsening foot ulcer. Sometimes it’s the chief complaint. Other times, however, you just notice it on physical exam. So, be sure you examine the feet of your diabetic patients. Occasionally, you’ll be surprised by what you find.

Several questions come up with diabetic foot ulcers:

Is it a true diabetic foot ulcer, or is it an arterial or venous insufficiency ulcer?
Is there underlying osteomyelitis?
How can I best diagnostically work this foot ulcer up for osteomyelitis?
What is the Wagner grade of this ulcer? (I think it’d be Grade 2.)

Thanks to JAMA‘s Clinical Rational Examination series, there is a systematic review of diabetic leg ulcers and osteomyelitis. Here are the highlights:

PV Card: Diabetic Leg Ulcer and Osteomyelitis

Below is the Fagan nomogram to help you plot out your post-test probability based on your likelihood ratios. The example given is if your pretest probability is 25% and your LR is 10. Your post-test probability would be 80%.

Reference

Butalia S. Does This Patient With Diabetes Have Osteomyelitis of the Lower Extremity? JAMA. 2008;299(7):806. doi: 10.1001/jama.299.7.806

By Michelle Lin, MD|2021-10-12T15:56:51-07:00Sep 23, 2011|ALiEM Cards, Infectious Disease, Orthopedic|

Paucis Verbis: Spinal epidural abscess

One of the most challenging diagnoses to make is that of a spinal epidural abscess (SEA), especially if you work in an Emergency Department which cares for many IV drug users and HIV patients. There’s never before been a published diagnostic guideline or algorithm which helps you with risk-stratification.

In the Journal of Neurosurgical Spine, a diagnostic guideline was prospectively evaluated on a small population (n=31) as compared to historical controls (n=55). They found that an ESR test had a sensitivity of 100% if a patient had at least 1 risk factor for SEA. A CRP test was much less helpful.

Not a practical algorithm

Unfortunately, they didn’t study the utilization rate of the MRI scanner with this guideline. Are they getting better results (fewer diagnostic delays and fewer cases of patients later in their clinical course) because they are just MRI-scanning more people? Almost everyone in my ED with back pain would fall into the Urgent/Emergent MRI box… I’m not a fan of this algorithm.

Regardless, this algorithm may help you in shaping your diagnostic decision and medical decision making documentation.

PV Card: Spinal Epidural Abscess

Reference

Davis D, Salazar A, Chan T, Vilke G. Prospective evaluation of a clinical decision guideline to diagnose spinal epidural abscess in patients who present to the emergency department with spine pain. J Neurosurg Spine. 2011;14(6):765-770. [PubMed]

By Michelle Lin, MD|2021-10-12T16:17:13-07:00Aug 5, 2011|ALiEM Cards, Infectious Disease, Neurology|

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