Red discoloration of urine caused by Serratia rubidae: A rare case
A 40-year-old female patient presented with fever, urgency, frequency, and burning micturition since 6 days. The patient also gave a history of passage of pale reddish urine since the last 2 days. She was a known type 2 Diabetes mellitus patient, on oral hypoglycemic drugs for the last 10 years. The blood investigations were as follows: Fasting blood glucose-330 mg/dl, urea 24 mg/dl, creatinine-0.98 mg/dl. The patient did not give any history suggestive of previous episodes of UTI.\nThe mid-stream urine sample collected aseptically was cloudy, with a reddish tinge. The urine routine microscopy interestingly showed 5-7 pus cells/high power field and bacilli but no red blood cells. The dipstick test performed for detecting microscopic hematuria was also negative. The gram stain showed pus cells and gram-negative cocco-bacilli. Urine sample was inoculated onto blood agar and MacConkey agar, incubated overnight at 37°C aerobically. Semi-quantitative technique was followed for colony count. After overnight incubation, pure growth of red pigmented colonies with a significant colony count of >105 CFU/ml was observed. Red pigment was also produced on Nutrient agar. On further testing, it was found to be a motile gram negative cocco-bacillus. Biochemical reactions showed catalase-positive, oxidase-negative, showed K/A (alkaline slant/acid butt) with gas production on triple sugar iron agar, ortho-Nitrophenyl-β-galactoside (ONPG)-positive fermented acid with adonitol, arabinose, lactose, raffinose, sucrose, and xylose. It did not ferment sorbitol and rhamnose. Indole was not produced but utilized citrate. It was confirmed as Serratia rubidae by standard biochemical techniques.[] Strain was found to be susceptible to ciprofloxacin, piperacillin, cotrimoxazole ceftazidime, amikacin, meropenem and was resistant to nitrofurantoin and polymixin B by the Kirby–Bauer disc diffusion technique as per Clinical Laboratory Standards Institute (CLSI) guidelines []. The minimum inhibitory concentration of ciprofloxacin was 0.02 μg/ml. The patient was treated with ciprofloxacin to which the patient responded well with the relief of the symptoms. Repeat mid-stream urine sample after 3 weeks did not yield any growth on the culture medium and the urine microscopy was normal.