Impact of prior antibiotic use in culture-negative endocarditis: review of 86 cases from southern Pakistan.
BACKGROUND
A large number of patients treated at our hospital for endocarditis have negative cultures. Taking into consideration the fact that many of these patients receive antibiotics prior to referral, we decided to study culture-negative endocarditis in Pakistan.


METHODS
The medical records of all patients admitted to the Aga Khan University Hospital, Pakistan, for the period from 1988 to 2001, with an underlying diagnosis of infective endocarditis (IE) and negative cultures, were reviewed.


RESULTS
Of the 159 patients diagnosed with IE by revised Duke criteria, 86 (54.1%) had persistent negative cultures. More than half of these patients (52%) had received antibiotics before being referred to our center. Patients with culture-negative endocarditis were less likely to be classified as definite endocarditis by revised Duke criteria (p<0.001, 95% CI 0.07-0.3) or to have large vegetations (p=0.021, 95% CI 0.05-0.5), and more likely to have a mitral valve prolapse (p=0.003, 95% CI 1.6-2.3). Definite endocarditis (p=0.042, 95% CI 1.02-7.4), heart failure (p=0.008, 95% CI 1.4-12.7), renal failure (p=0.017, 95% CI 1.16-40.7), embolism (p=0.019, 95% CI 1.2-38.8), and neurological complications (p=0.02, 95% CI 1.16-9.2) were associated with an increased mortality.


CONCLUSIONS
Culture-negative endocarditis is very common among patients with IE in Pakistan. The presentation, laboratory findings, and complications are similar to those for culture-positive endocarditis. It is postulated that previous antibiotic treatment is the most common cause of culture-negative endocarditis in our hospital.
Siddiqui
Bilal Karim
BK
Department of Medicine, Aga Khan University Medical College, PO Box 3500, Stadium Road, Karachi 74800, Pakistan.
Tariq
Muhammad
M
Jadoon
Atif
A
Alam
Mahboob
M
Murtaza
Ghulam
G
Abid
Bilal
B
Sethi
Muhammad Jawad
MJ
Atiq
Mehnaz
M
Abrar
Sohail
S
Smego
Raymond A
RA
D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001419:Bacteria / Q000302:isolation & purification; D001424:Bacterial Infections / Q000175:diagnosis* / Q000188:drug therapy* / Q000382:microbiology / Q000401:mortality; D003470:Culture Media; D003937:Diagnosis, Differential; D004452:Echocardiography; D004697:Endocarditis, Bacterial / Q000175:diagnosis* / Q000188:drug therapy* / Q000382:microbiology / Q000401:mortality; D005260:Female; D006785:Hospitals, University; D006801:Humans; D008297:Male; D008875:Middle Aged; D010154:Pakistan / Q000453:epidemiology; D011237:Predictive Value of Tests; D012307:Risk Factors; D013997:Time Factors; D055815:Young Adult
D000900:Anti-Bacterial Agents; D003470:Culture Media