Hypoprothrombinemia During Cefmetazole Treatment: A Case Report

Abstract

BACKGROUND Cefmetazole (CMZ), containing an N-methyl-tetrazole-thiol (NMTT) side chain, is a therapeutic option for diverticulitis in Japan. Cephems containing an NMTT, a methyl-thiadiazol, and a thiadiazolethiol side chain are known to induce coagulation disorders. CASE REPORT A 76-year-old woman developed hypoprothrombinemia after receiving oral levofloxacin (LVFX) 250 mg q24h for 2 days followed by intravenous CMZ 2 g q8h for sigmoid diverticulitis. On day 5 of CMZ administration (after 12 doses in total), black stool was observed. On the following day (after 14 doses), prothrombin time (PT) prolongation was noted; PT and international normalized ratio (INR) were 37.1 s and 2.47, respectively. We diagnosed the patient with hypoprothrombinemia because of vitamin K deficiency caused by markedly elevated protein levels induced by vitamin K absence or antagonist-II on day 6 of CMZ administration. Intravenous vitamin K administration and CMZ cessation rapidly restored PT and led to the disappearance of black stool. CONCLUSIONS The causes of vitamin K deficiency were considered to be an impaired vitamin K cycle due to CMZ and decreased vitamin K intake because of malnutrition. These findings are consistent with CMZ's reported adverse effects. Decreased vitamin K production due to alterations in the gut bacterial flora by LVFX and CMZ was also postulated as a cause. If a bleeding tendency is noted during diverticulitis treatment with NMTT-containing cephems, switching to intravenous quinolones or carbapenems is recommended. It remains unclear how this reaction can be avoided; however, prudent monitoring of bleeding signs and PT-INR is recommended.

Figure 1.

Plain computed tomography findings on the first visit. The scan shows inflammation around diverticula in the sigmoid colon. The diverticula are circled and its inflammation is indicated with arrows.

Figure 2.

Clinical course and coagulation tests. APTT – activated partial thromboplastin time; PT-INR – prothrombin time-international normalized ratio; LVFX – levofloxacin; CMZ – cefmetazole; Vit K – vitamin K; PIVKA-II – protein induced by vitamin K absence or antagonist-II; BW – body weight.