Indian Journal of Pathology and Microbiology

: 2018  |  Volume : 61  |  Issue : 4  |  Page : 628--629

Abnormal morphological appearance of Klebsiella pneumoniae in blood culture: A microscopic observation

Kumar Saurabh, Vijaya Lakshmi Nag, Anuradha Sharma, Anand Kumar Maurya, Vivek Hada 
 Department of Microbiology, All India Institute of Medical Sciences, Jodhpur, Rajasthan, India

Correspondence Address:
Vijaya Lakshmi Nag
Department of Microbiology, All India Institute of Medical Sciences, Jodhpur, Rajasthan

How to cite this article:
Saurabh K, Nag VL, Sharma A, Maurya AK, Hada V. Abnormal morphological appearance of Klebsiella pneumoniae in blood culture: A microscopic observation.Indian J Pathol Microbiol 2018;61:628-629

How to cite this URL:
Saurabh K, Nag VL, Sharma A, Maurya AK, Hada V. Abnormal morphological appearance of Klebsiella pneumoniae in blood culture: A microscopic observation. Indian J Pathol Microbiol [serial online] 2018 [cited 2023 Feb 1 ];61:628-629
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A 59-year-old female came to the medicine outpatient department with complaints of right flank pain, intermittent fever associated with chills and rigor, bilateral pedal edema without any urinary complains, decreased appetite and episodes of vomiting after intake of food since 5 days. On general examination, icterus was present, and the vitals were stable. On systemic examination, there were no significant findings. A provisional diagnosis of acute febrile illness was made, and the patient was admitted to medicine ward, and cefixime (200 mg BD) was started. She was afebrile during admission; hence, blood was not sent for culture and sensitivity. Her other laboratory results were as follows: total leukocyte count (17,000/cmm), neutrophils (88%), total bilirubin (4.7 mg/dL), direct bilirubin (1.18 mg/dL), indirect bilirubin (3.52 mg/dL), serum glutamic pyruvic transaminase (26 U/L), serum glutamic-oxaloacetic transaminase (31 U/L), alkaline phosphatase (120 U/L), total protein (6.66 g/dL), albumin (3.40 g/dL), globulin (3.26 g/dL), and serum creatinine (1.67 mg/dL). She was not having HIV, Hepatitis B virus, or Hepatitis C virus infection. Urine culture showed insignificant growth. Ultrasonography of abdomen revealed cholelithiasis along with right-sided mild hydroureteronephrosis (HUN) and pyelonephritis. Further, contrast-enhanced computed tomography - kidney, ureter, and bladder also revealed an approximately 9 mm × 7 mm calculus in the right lower ureter with moderate HUN. After about 2 days of admission, the patient developed fever, which was continuous in nature along with further increase in total leukocyte count (22,700/cmm) and neutrophil count (92.4%). A set of blood sample was sent for culture and sensitivity. One of the cultures (a) was positive at 2 days 19 h and another one (b) was positive at 3 days 5 h by automated culture system. Direct Gram stain from one of the culture bottles (a) showed plenty of Gram-negative bacilli with a central bulge while Gram stain from other bottle (b) showed multiple long filamentous Gram-negative bacilli with large central bulge, few even resembling fungal hyphae [Figure 1]. Identification and sensitivity of the isolate were performed both by conventional laboratory methods (biochemical reactions and Kirby-Bauer method) and by automated Microscan walkaway-96 plus system (minimum inhibitory concentration values are taken into account). Isolate from both the bottles was identified as Klebsiella pneumoniae, which was sensitive to antibiotics such as cefepime, ceftriaxone, ceftazidime, piperacillin-tazobactam, ciprofloxacin, meropenem, imipenem, ertapenem, amoxiclav, gentamicin, tobramycin, aztreonam, amikacin, tigecycline, polymyxin-B, and cotrimoxazole. Meanwhile, right-sided Double J-stenting was done, and the patient was prescribed meropenem, 1 g i. v QID and levofloxacin. She gradually became afebrile and improved clinically. Repeat blood culture sent after 5 days of antibiotic treatment, turned out to be negative. She was discharged with advice to follow-up for removal of DJ stent and furthermore for review of ureteric stone and cholelithiasis in the concerned departments.{Figure 1}

K. pneumoniae is a most frequent pathogen causing pulmonary and extrapulmonary infections, including classical pneumonia, enteritis, meningitis, urinary tract infections, and septicemia. K. pneumoniae classically appears as Gram-negative rods with its short and stout appearance. Beta-lactam antibiotics inhibiting the cell wall synthesis are known to produce morphological changes in Gram-negative organisms and minimal inhibitory concentration (MIC) testing can be done to confirm such changes.[1] Their effect on Escherichia coli cells has been shown to proceed through four stages: elongation, bulge formation, bulge stagnation, and lysis.[2] Samples collected from patients already on antibiotics may show the presence of abnormally appearing bacteria. Such abnormal forms have been reported in the past from samples such as sputum, CSF, and blood from patients who were on prior antibiotic.[3],[4],[5] Morphological change in K. pneumoniae has been reported previously in response to cefotaxime which appears to be an adaptive response of the bacteria to the antibiotic stress, leading further to drug resistance.[6] In the present case, the patient was receiving cefixime from 2 days before collection of blood sample for blood culture. A small amount of this antibiotic might have been carried over with the blood into the blood culture media causing these aberrant forms. Antimicrobial sensitivity for cefixime by either Kirby-Bauer method or MIC testing could not be done in this case, but rising cefixime resistance has already been demonstrated in different clinical isolates of E. coli.[7] The presence of such abnormal forms may also indicate a sublethal antibiotic concentration at the infection site, which can result from a low dose or intermittent antibiotic therapy.[4]

Prior knowledge of such aberrant morphological appearances helps to avert any misdiagnosis or confusions. At this point of time, it must be stressed that we should strictly adhere to the practice of collecting culture samples before starting any antibiotic therapy.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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