An audit of first generation cephalosporin usage

journal of Hospital hfection (I 999) 4 I : 229-232

An audit of first generation cephalosporin usage N. Shetty*,

R. I. Shulmant

and G. M. Scott*

*Departments of Clinical Microbiology and -/-Pharmacy, University College London Hospitals, London WC I E 6Dk3

Summary:

Cefadroxil is a semi-synthetic first generation oral cephalosporin with advantages of almost 100% excretion in the urine within six hours and low cost. It was freely available in the formulary and we undertook an audit of its usage, the indications cited, underlying clinical conditions and relevant microbiology in 106 cases. Following the audit, cefadroxil was restricted, available only on the advice of a microbiologist. Subsequently, another survey was carried out to document the reasons for requesting cefadroxil by clinical staff and the alternatives suggested in each case. The first survey revealed that in 91% cases, cefadroxil had been used inappropriately. The second suggested that the reasons for requesting it were based upon misunderstanding by clinicians as to its value. The only useful indication identified was the treatment of susceptible bacteruria in pregnancy. A suitable oral alternative could be identified for all other cases where an antibiotic was indicated. We believe that first generation cephalosporins such as cefadroxil have little role in hospital practice and should therefore be restricted. Keywords:

Cefadroxil,

first generation cephalosporins;

Introduction Cefadroxil is a semi-synthetic cephalosporin suitable for oral administration. The antibacterial spectrum has been studied extensively and has been shown to have a lower degree of activity against most species as compared with other cephalosporins of the same class.’ Even though it is relatively resistant to staphylococcal p lactamases, its activity against staphylococci is unpredictable and it has no activity against methicillin-resistant strains. It is active against susceptible streptococci causing upper respiratory tract infections but has no useful activity against

Received 17 June 23 September 1998

1998;

revised

0 195-670 I /99/030229 + 04 $12.0010

manuscript

accepted

inappropriate

antibiotic

usage; audit antibiotic

use.

Haemophilus or CoryneNeisseria, bacterium species. It may be effective against a range of enterobacteria causing urinary tract infections including some ampicillin-resistant Eschevichia coli, though it is degraded by many enterobacterial p-lactamases.’ Gram-negative orthe hospital encountered in ganisms environment such as Citrobactev, Enterobacter, indole-positive Proteus and Serratia species are all resistant to cefadroxil. In addition, it is only slowly bactericidal against susceptible Gramnegative bacilli.* Among the organisms causing anaerobic infections, many gut-associated anaerobes are resistant to cefadroxil.* Almost 100% dose can be recovered from the urine within the first 6 hours,

0 1999 The Hospital Infection Society

N. Shetty

230

Table I

et al.

A review of relevant microbiology from the deportments using cefadroxil. Microbiology

N

Department

cefadroxil

of positive cultures (S)

cefadroxil

(no. of isolates)

Negative cultures

Cultures

(R) or inappropriate

Urology

22

E. coli (3)

Pseudomonas spp. including F! aeruginosa (4) E. foecalis (I)

I3

I

Orthopaedics Obstetrics

24 I2

0 0

5. aureus (2)

I8 IO

4 0

UTI in pregnancy Chest medicine

IO IO

E. coli (3) M. cotarrhalis

4 9

2 0

5 I

I I

4

5

Gynaecology Ear, Nose and Throat Plastic/General surgery

Dental prophylaxis S, susceptible;

7 2 I3

(1) 0 0

0

S. aureus (I) Group B streptococcus (I) E. faecalis (I) 0 Group

not done

B streptococcus (I)

P aeruginosa (I) Ent. agglomerans (I) Bacteroides spp. (I) S. aureus (I)

6

R, resistant;

N = number

of cefadroxil

prescriptions.

producing very high urinary concentrations of up to 1 gram or more per litre.3 It has been used in pregnancy without any apparent evidence of has been implicated fetal damage.4y5 Cefadroxil in Clostridium difficile colitis and in the emergence of serious infections with enterococci.6’7 Despite its limited applicability, cefadroxil and other similar first generation cephalosporins are popular in general and hospital practice. To assess the usage of cefadroxil in a hospital setting, we conducted a survey of 106 cases where it had been prescribed, with particular interest in the departments involved and the indications for its use. The study was undertaken with the wider view of curtailing inappropriate cephalosporin use in the hospital, in an attempt to control associated hospital infections such as C. difJiciZe toxin-associated diarrhoea.

Methods The cefadroxil audit was conducted jointly by the departments of microbiology and pharmacy over a period of six months. Patients who had

cefadroxil prescribed were documented and followed up with particular reference to the nature of their underlying illness. Other data included antibiotic usage for treatment or prophylaxis, the nature of preceding or concurrent therapy, indications for use and relevant positive microbiological results.

Restriction

of cefadroxil

and re-audit

Following analysis of the initial survey, it was decided to restrict use of cefadroxil to the treatment of urinary tract infections in pregnancy. The results of the audit were presented to the hospital’s Use of Medicines Committee. A bulletin summarizing the results was distributed to all medical staff describing the new restriction. Cefadroxil was then removed from ward stocks. All other requests for cephadroxil would have to be approved by a microbiologist. Any such request was documented, a record of the advice given by the microbiologist was maintained and a re-audit conducted. In addition, the pharmacy computer was used to identify cefadroxil usage

Cefadroxil

audit in a teaching hospital

before and after the restriction was imposed.

231

on prescribing

Table II

Re-audit of cefodroxil requests.

Cefadroxil requests: clinical reasons

Number (N=21)

Results The 106 cases to whom cefadroxil was prescribed came from eight different departments (Table I). The indications for prescriptions were as follows: (a) Continuation of intravenous cefuroxime perioperative prophylaxis using an oral agent, without signs of post-operative infection, was documented in 27% cases. (b) Cefadroxil was prescribed for the treatment of suspected post-operative wound infections and pyrexia in 26% patients, in whom there was no microbiological evidence of post-operative infection. (c) Cefadroxil was prescribed for use on discharge from hospital, after surgery or after successful treatment of urinary tract and chest infections, and for patients with a variety of obstetric (other than urinary infections in pregnancy) and gynaecological problems where continuation of antibiotic therapy was not considered justified (30%). (d) Cefadroxil was used for urinary tract infection (UTI) in pregnancy in 9% and for dental prophylaxis in 6% cases. Microbiological findings from patients for whom cefadroxil was prescribed are also given in Table 1. Among the inappropriate organisms treated with cefadroxil there were two strains of Entevococcus spp., five P. aeruginosa/Pseudomonas spp. and another with a predominant growth of Bacteroides spp. Group B streptococci were either part of normal flora (gynaecology) or inappropriately treated with cefadroxil (obstetrics). Treatment of S. aweus and M. catarvhalis infections with cefadroxil was considered inappropriate as more effective drugs are available to treat these infections.

Alternatives prescribed on recommendation microbiologists

of

Post surgical wound inflammation Head injury Pelvic inflammatory disease, prostatitis/ urethritis

4

IV to oral switch after cefuroximel ceftazidime IV cefuroxime given as surgical prophylaxis Allergic to penicillin, respiratory tract infection IV to oral switch in severe UTI

8

wound swab and empirical flucloxacillin No therapy Refer to relevant department for investigation and treatment, cefadroxil inappropriate No therapy

2

No therapy

I

Macrolide

2

Trimethoprim

I 3

gives the reasons for thinking the antibiotic also documents the renecessary and commendations from the microbiology department. An antibiotic was not indicated in 14 out of 21 requests, three cases of pelvic inflammatory disease needed further investigation and for the remainder, a more appropriate alternative was prescribed. The average usage of cefadroxil in the hospital before the audit was 2750 capsules per month. Following restriction, the average use dropped dramatically to 262 capsules per month. Assuming that the average dose presecribed was 500 mg 12 hourly for 5 days, this usage represents a change of 275 patients to 26 patients per month on cefadroxil. The audit process resulted in 249 patients per month, on average, receiving more appropriate treatment.

Discussion Re-audit after restriction ofcefadroxil There were 21 requests for the use of cefadroxil in the two weeks immediately after the restriction notice was issued (Table II). Analysis of these

It is evident that cefadroxil was used inappropriately in the majority of cases. Continuation of prophylactic antibiotics beyond the day of surgery is contrary to the recognized

N. Shetty et al.

232

principles of antibiotic prophylaxis.8 In cases where post-operative infections are suspected, appropriate therapy depends on the clinical circumstances and microbiological evidence of infection. In addition, many of these infections are caused by hospital acquired organisms and would be unlikely to respond to cefadroxil. Furthermore, cefadroxil is not the drug of choice for obstetric and gynecological problems where cover for streptococci, chlamydiae and anaerobic micro-organisms is required. Prolonged antibiotic therapy, reflected in the common practice of prescribing drugs on discharge from hospital, is usually unnecessary.’ Cefadroxil is not the drug of choice for dental prophylaxis, where anaerobic and microaerophilic mouth flora need to be covered; clindamycin or coamoxiclav are more appropriate. Cefadroxil is allowable with caution in pregnancy and may be appropriate to treat UTIs in pregnancy provided the isolate is susceptible. The results indicate that clinicians often authorize a switch from intravenous cephalosporins to oral alternatives. It was evident from the microbiology results of a wide variety of specimens, that more suitable and cost-effective oral alternatives such as flucloxacillin, amoxycillin and trimethoprim are available to treat wound, chest and urinary tract infections respectively. Gram-negative bacteria in sites other than urine will not respond to cefadroxil; the enterococci are resistant, whilst Moraxella and Neisseria species are only moderately susceptible to cefadroxil. The process described in this paper illustrates how practice at a large teaching hospital can be changed by a multi-disciplinary collaborative audit approach. As a result of this audit we have now successfully disseminated educational material as regards the limited usefulness of cefadroxil and curtailed the inappropriate prescription of oral cephalosporins.

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