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Background and Objectives: Salmonella typhi, Mycobacterium tuberculosis, and Burkholderia pseudomallei are among the most important monocyte-tropic bacterial agents causing pyrexia of unknown origin (PUO), with a significant number of endemic infections in both South and Southeast Asian regions. These infections pose a major risk to travelers to these regions as well., Methods: We developed and evaluated a multiplex nested polymerase chain reaction (PCR) for the simultaneous detection of the three pathogens in 305 patients' buffy coat samples., Results: The assay for S. typhi and B. pseudomallei was able to detect down to 1 colony forming unit/5 μL PCR input and M. tuberculosis was detected down to 20 genome copies/5 μL PCR input. S. typhi was detected in 10 (3.3 %) individuals, B. pseudomallei in 10 individuals (3.3 %), and M. tuberculosis in 18 individuals (5.9 %). Co-infections of M. tuberculosis and B. pseudomallei were detected in three individuals and S. typhi and B. pseudomallei in two individuals., Conclusion: This protocol is efficient for PUO diagnosis especially in Asian countries.

Background & Objectives: Apoptosis causes a decline in the counts of uninfected bystander CD4+ T cells in HIV infection. The rate of disease progression of HIV infection is considered to be faster in the developing countries. The present study was carried out to investigate certain markers for apoptosis in immunopathogensis of disease in HIV infected south Indian population., Methods: Soluble Fas (sFas) antigen and Fas ligand levels in plasma samples from 39 antiretroviral treatment naïve patients was estimated and compared with T cell subsets and HIV-1 viral load., Results: The mean sFas antigen levels among controls and the CDC A, B and C clinical stages were 2.77, 3.08, 3.26 and 3.28 ng /ml respectively, higher though not significantly among HIV-1 infected individuals compared to controls. The mean sFas ligand levels in CDC A, B and C stages were 0.138, 0.125 and 0.117 ng/ml respectively were higher (P<0.001) than controls (0.073 ng/ml) and positively correlated with total lymphocyte % (r=0.43, P =0.007). sFas antigen levels were negatively correlated with total WBC count (r=-0.34, P=0.04), CD4% (r=-0.4, P=0.01) and CD4:CD8 ratio (r=-0.37, P=0.02). There was an increase in plasma levels of sFas antigen and Fas ligand over time in asymptomatics., Interpretation & Conclusion: The high levels of sFas antigen and Fas ligand seen in HIV infected individuals suggest increased activation and apoptosis of T cells, due to constant stimulation of the immune system by inter-current infections of HIV infected individuals in south India.

Background & Objective: Individuals infected with HIV-1 have higher levels of chemokine producing cells compared to uninfected individuals. It is important to know the changes in chemokine levels associated with rate of progression of disease. There is a paucity of information on the plasma chemokines in HIV-1 infected individuals from India. We therefore carried out this study to estimate the levels of three chemokines namely macrophage inflammatory protein alpha (MIP1alpha), MIP1beta and RANTES, in relation to disease status in HIV-1 infected individuals and compared with uninfected individuals., Methods: RANTES and MIP1alpha were estimated using ELISA in 114 HIV-1 infected and 30 controls, whereas MIP1beta was estimated in 101 HIV infected individuals only and 30 controls. The values were compared to the T cell subsets, HIV-1 viral loads and plasma cytokines (interferon gamma and interleukin-10)., Results: Compared to controls the mean MIP1alpha and RANTES level among the HIV-1 infected individuals was higher while MIP1beta level was lower in HIV infected individuals except CDC C groups. There was a significant positive correlation for MIP1á with HIV-1 viral load and IFNgamma, for MIP1alpha with viral load and IL10. There was a significant negative correlation between MIP1alpha with CD4 count and CD4: CD8 ratio and MIP1beta with CD4 count and CD8 count. There was a negativecorrelation between RANTES values and CD8 per cent., Interpretation & Conclusion: In conclusion, our study showed a significantly higher level of beta chemokines in south Indian HIV-1 infected individuals compared to controls. These beta chemokines may have the inhibitory effect on HIV-1 only during the initial period and with the progression of disease this inhibitory effect wanes as shown by the positive correlation of beta chemokines with HIV-1 viral load.

The non-typhoidal salmonellae (NTS) are recognized agents of gastroenteritis worldwide. Some of the NTS do not produces cytotoxic changes in tissue culture and not much is known about the endotoxicity of the clinical isolates of NTS (mostly Salmonella enterica serotype Typhimurium and Salmonella enterica serotype Enteritidis). We examined the exotoxic (cytotoxin) and endotoxic activity of clinical isolates of NTS in two assay models namely Vero cell culture and the nematode, Caenorhabditis elegans. Bacteria-free culture supernatants of 40 isolates NTS were tested in 96 well microtitre plate containing confluent monolayers of Vero cells. For the effects on C. elegans, the worms were exposed to bacteria free culture supernatants in 24 well microtitre plate for 24 h and then transferred to OP50 Escherichia coli lawn culture. The endotoxic activity of the live bacterium was studied by feeding the worms in the lawn culture of NTS separately. No cytopathic effect was observed with NTS tested in Vero cell culture assay. Likewise, the worms exposed to the bacteria-free culture supernatants were found active up to 7 days. In the co-culture killing assay, worms were found dead with characteristic stiff and straight appearance by 16(th) day. The worms were alive up to 21 days in OP50 E. coli. Bacteria-free culture supernatants did not have any deleterious effect on worms or in Vero cell culture, suggesting that there is no soluble toxic factor (diffusible toxin) in the culture supernatants. However, live NTS were found to be lethal to the worms; indicating that direct interaction between viable NTS and C. elegans is necessary for killing.

Background & Objective: Typhoid fever still continues to be a major public health problem around the world. A simple, reliable and affordable rapid diagnostic test has been a long felt need of the clinicians. We therefore prospectively evaluated the sensitivity and specificity of Typhidot test., Methods: The study was carried out between January 2002 and December 2003, on a total of 563 samples from patients clinically suspected to have typhoid fever; blood culture as well as serum for Typhidot test were received., Results: Of the 563 samples, Typhidot test and blood culture were positive in 36 patients, both the tests were negative for 503 patients. Typhidot test was positive for 9 patients with S. Paratyphi A infection. The sensitivity and specificity of the test using blood culture as gold standard were 92.3 and 98.8 per cent respectively for the typhoid fever., Interpretation & Conclusion: Typhidot test is rapid, easy to perform and reliable test for diagnosing typhoid fever, useful for small less equipped laboratories as well as for those with better facilities.

Oral lesions of tuberculosis though uncommon, are seen in both the primary and secondary stages of the disease. In secondary tuberculosis, the oral manifestations may be accompanied by lesions in the lungs, lymph nodes, or in any other part of the body and can be detected by a systemic examination. Primary oral tuberculosis may present as a diagnostic challenge for the clinician. Here we report two patients with primary tuberculosis in the oral cavity who presented to the dental department, were diagnosed and referred for medical management.

In total, 309 blood culture supernatants were tested for the presence of Burkholderia pseudomallei antigen using an in-house coagglutination test prepared by sensitising Cowan I staphylococcal cells with B. pseudomallei polyclonal antiserum. The coagglutination test gave a sensitivity, specificity, positive predictive value and negative predictive value of 100% in comparison with blood culture. A subset of 102 supernatants was also tested for B. pseudomallei antigen using a monoclonal antibody-based latex agglutination test. The sensitivity, specificity, positive predictive value and negative predictive values of this test were 100%, 90%, 75% and 100%, respectively.

Background and Objectives: Hantaviruses are rodent-borne viruses of the family Bunyaviridae that have been identified as aetiological agents of two human diseases, haemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). There are no reports of hantavirus infections in humans from India, hence this pilot study was undertaken to provide the serological evidence of hantavirus infections in humans in south India., Methods: Serum samples were obtained from individuals with acute febrile illness and from voluntary blood donors, majority of whom were from south India. Serum samples were tested for anti-hantavirus IgM using a commercial enzyme immunoassay (EIA). Samples found positive by the EIA were tested by an indirect immunofluorescence assay (IFA) using slides coated with Seoul virus (SEOV) infected cells as substrate., Results: Of the 152 serum samples from individuals with pyrexic illness, 23 (14.7%) were positive for anti-hantavirus IgM by EIA. In contrast, only 5.7 per cent of healthy blood donors were positive by this assay. Eighteen of the 22 (82%) EIA-positive samples from patients were positive by the IFA assay. In contrast, only 2 of the 5 (40%) blood donor EIA positive samples were positive in the IFA assay., Interpretation and Conclusion: The finding of this study indicated the possible presence of hantavirus infections in the human population of India presenting both as asymptomatic and symptomatic infections. Further studies need to be done to confirm the findings on a larger sample using molecular techniques.

Background & Objective: Bacterial resistance has greatly hampered effective treatment of patients in clinical settings. Non-fermenting Gram-negative bacilli (NFGNB) are common nosocomial pathogens. In this study we attempted to develop a convenient test for early detection of carbapenemase and metallo-beta-lactamase (MbetaL) production in NFGNB. Lack of sufficient reports from India in this area indicated the need for this study., Methods: A total of 50 imipenem resistant NFGNB were speciated, and their resistance reconfirmed by disk diffusion and minimum inhibitory concentration (MIC) determination by agar dilution. Two different methods namely modified Hodge and EDTA disk synergy tests were evaluated for carbapenemase and metallo-beta-lactamase (MbetaL) production., Results: Of the 50 imipenem resistant NFGNB, 48 and two respectively fell in the resistant and intermediate range in MIC using agar dilution. Majority of these were Pseudomonas aeruginosa (n=28), followed by Burkholderia cepacia (n=9). The modified Hodge test could detect 28 strains as carbapenemase and MbetaL producers, while the EDTA disk synergy test was able to detect an additional 8 strains producing MbetaL and carbapenemase., Interpretation & Conclusion: Pseudomonas aeruginosa was found to be the predominant NFGNB in our hospital setting and EDTA disk synergy could detect more carbapenemase and metallo-beta- lactamase producers compared to modified Hodge test.

A case of Mycobacterium fortuitum bacteraemia in an immunocompromised patient confirmed by four positive serial blood cultures is reported here. The patient was a known case of acute lymphoblastic leukemia (ALL) on intensive chemotherapy. The source of bacteraemia was most probably a peripherally inserted vascular catheter. After initiation, of treatment with amikacin to which the strain was sensitive and clarithromycin and removal of the central line the patient's fever defervesced and repeat blood cultures were negative. This is the first time we have encountered an immunocompromised patient with M. fortuitum septicaemia in our hospital. The possibility of an infection with rapidly growing mycobacteria is important to consider when conventional organisms are not isolated in culture especially in the context of patients with malignancy.

Background & Objective: The global surveillance of human immunodeficiency virus (HIV) subtypes (clades) helps understand the global distribution and incidence of different HIV subtypes. As knowledge about subtypes circulating in an area is needed for developing a candidate vaccine, prevalence of the subtypes HIV-1 and HIV-2 were studied in south India. The profile of cytokines interleukin 10 (IL10) and interferon gamma (IFNgamma) in both types of infection were also analysed as these are considered indicators of disease progression., Methods: Patients who belonged to the 4 south Indian States i.e. Tamil Nadu, Kerala, Karnataka and Andhra Pradesh were included. HIV-1 subtyping was carried out by the heteroduplex mobility analysis (HMA) while that of HIV-2 was done by direct sequencing. The quantitation of IFNgamma and IL-10 was carried out using commercial ELISA kits., Results: Among the 82 HIV-1 infected individuals subtyped, 78 (95.1%) were subtype C while all 12 HIV-2 strains were subtype A. IL-10 concentration was significantly higher among HIV infected individuals compared to normal healthy controls. IFNgamma was significantly higher among symptomatic and AIDS groups compared to asymptomatic HIV-1 infected individuals., Interpretation & Conclusion: HIV-1 subtype C and the HIV-2 subtype A are the major subtypes circulating in south India. The study showed a trend towards a shifting of the cytokine profile from Th1 to Th2/Th0 in HIV-1, HIV-2 infections, and HIV-1 and HIV-2 dual infected individuals as the disease progresses. This trend observed is not unlike that reported from the West, despite the difference in subtype profile.

Background & Objectives: Aeromonas spp. are known to cause a variety of infections in humans and this organism has been isolated from a variety of sources including environmental sources. The pathogenicity of the environmental isolates in and around Vellore has not been studied. This study was conducted to determine the cytotoxicity of the Aeromonas spp. isolated from water bodies, soil sediments, plankton and sewers in and around Vellore., Methods: Aeromonas spp. isolated from environmental sources were identified by standard procedures. Representative isolates of Aeromonas spp. were tested for cell free cytotoxic factor in tissue culture system. Undiluted and diluted cell free filtrates of isolates and known toxigenic and non-toxigenic bacteria were added to Vero cell monolayer in microtitre plates. After appropriate incubation in 5 per cent CO2 atmosphere, the microtitre plate was examined for cytopathic effect. Cell detachment and shrinkage of Vero cells were recorded as toxic changes., Results: All 36 environmental isolates demonstrated cytopathic effect of which 41.7, 50 and 8.3 per cent belonged to A. hydrophila, A. veronii biotype sobria and A. caviae respectively., Interpretation & Conclusion: The results demonstrated the presence of potentially pathogenic environmental aeromonads in and around Vellore and they produced cytotoxin.

Fluoroquinolones are considered the most effective drugs for the treatment of typhoid fever and hence are widely used in the empiric treatment of acute undifferentiated febrile illnesses in India. Recent reports of Salmonella enterica serotype Typhi (S. Typhi) strains with increasing minimum inhibitory concentration (MIC) of ciprofloxacin have raised the fear of potential treatment failures. In this case series of 109 consecutive patients hospitalized with typhoid fever (S. Typhi grown from blood), we documented clinical failure (fever persisting >6 days) in 25 of 46 (54.3%) adults who could be evaluated. Among these, eight (17.4%) had microbiological failure (S. Typhi recovered from blood after 6 days of ciprofloxacin therapy) despite adequate serum ciprofloxacin levels, and all required alternative drugs for treatment. These 8 S. Typhi strains, although susceptible to ciprofloxacin (MIC < 1 microg/mL) (NCCLS 2000), had MICs (median MIC 0.5 microg/mL) that were increased 15-fold compared to S. Typhi strains from patients with typhoid fever seen at our center in 1995 (median MIC 0.032 microg/mL), and were nalidixic acid resistant S. Typhi (NARST) (MIC > or =32 microg/mL). The poor treatment outcomes with ciprofloxacin therapy in patients infected with NARST strains that exhibit an increased ciprofloxacin MIC call for a need to revise the ciprofloxacin breakpoints for S. Typhi.

Background & Objectives: Melioidosis caused by Burkholderia pseudomallei is an emerging disease in India. This study examined the toxin activity of bacteria-free culture filtrate in three different cell lines (cytotoxic assay) and its effect on Caenorhabditis elegans (nematode toxicity assay). Endotoxic activity of the viable bacteria was also studied in C. elegans (co-culture killing assay)., Methods: For toxin studies, serial doubling dilutions of unheated, heated crude and ultra filtrate of bacteria-free culture supernatants of B. pseudomallei were tested in 96-well microtitre plate containing confluent mono layers of McCoy, Hep-2 and HeLa cell lines. For the effects on C. elegans, the worms were exposed to heated and unheated bacteria-free culture supernatants in 24-well microtitre plate for 24h and then transferred to OP50 Escherichia coli lawn culture. The endotoxic activity of the live bacterium was studied by feeding the worms in the lawn culture of B. pseudomallei., Results: All the clinical isolates (n=38) produced cytotoxic changes in all the cell lines. No difference was observed in the cytotoxicity of unheated, heated and ultra-filtered culture supernatant. The septicaemic isolates were observed to produce cytotoxic changes in high dilutions (1:160) of culture filtrate. None of the unheated and heated crude filtrate had deleterious effect on C. elegans, while all the live bacteria were found to be lethal to the nematode., Interpretation & Conclusion: The culture supernatants, though produced cytopathic effect in various tissue cultures, failed to have any deleterious effect on the worms. However, live bacteria were lethal to the worms B. pseudomallei. Use of C. elegans model to detect virulence attributes of B. pseudomallei is recommended as an alternative to tissue culture methods as this can be carried out in laboratories where a tissue culture set up is not available.

The objective of this study was to consider the invasive properties of Streptococcus pyogenes in human pharyngeal epithelial cells, and to correlate these with their clinical significance. Clinical isolates of S. pyogenes obtained from blood cultures over a period of 10 years, and throat and skin isolates from a community-based study, were used in this investigation. The S. pyogenes isolates were inoculated in HEp-2 cells and subsequently treated with antibiotics to kill the extracellular bacteria. The cells were then lyzed, and a colony count was carried out to check for invasion. The throat and skin isolates had 45.7%, 25.7% and 28.5% of low, intermediate and high invasion efficiencies, respectively, while 80%, 8.6% and 11.4% of the blood isolates had low, intermediate and high invasion efficiencies. We concluded that the throat and the skin isolates from superficial infections were more invasive than the blood isolates, which is an interesting and paradoxical feature.

Culture is the only reliable method available at present for the diagnosis of melioidosis. Though serological tests have been described, their value in routine diagnosis is controversial. All indirect immunofluorescent assay (IFA) was therefore evaluated to determine its use in the diagnosis of melioidosis. Whole cell antigen prepared from a laboratory isolate of Burkholderia pseudomallei was used to assay IgG and IgM antibodies. Fourteen of the 22 (63.6%) culture proven cases had IgM antibodies while only 10 (45.5%) had IgG antibodies. Negative predictive value of IgM assay was 92 per cent. Positive predictive value was 100 per cent if both IgM and IgG were considered together. The present study done on a limited number of samples suggests that IFA may be useful in routine diagnosis of melioidosis.

The genetic types and subtypes of HIV vary from region to region. This study looked at the relative prevalence of HIV-2 subtypes in south India. Nucleotide sequencing of the HIV-2 envelope V3 region of strains from 11 individuals infected with HIV-2 and one individual who had dual infection with HIV-1 and HIV-2 was performed. Phylogenetic analysis showed that all individuals were infected with HIV-2 subtype A. These strains were from individuals who live in different regions of south India. In all, up to present, 17 strains inclusive of the authors' 12 have been sequenced, and subtype A of HIV-2 is seen in both monoinfections and dual infections with HIV-1 in India.

Background: This retrospective study was conducted to evaluate the characteristics and therapeutic response among patients with multidrug-resistant tuberculosis (MDR TB)., Methods: One hundred subjects with isolates resistant to isoniazid and rifampicin were included over a three-year period (1997-1999). There were 82% males with a mean age of 36 years, mean duration of symptoms of 29 months, and a previous history of tuberculosis in 85% (pulmonary 96% and extrapulmonary 4%)., Results: HIV ELISA test was positive in two out of 28 (7%) patients while diabetes was diagnosed in 16 percent. Mean time to diagnose MDR TB was 5.5 months. Subjects had received a mean of 3.2 anti-TB drugs before the diagnosis of MDR TB was made. Forty-five patients were lost to follow-up. The rest had a median follow-up of 13.5 months (range 1-37 months). Follow-up AFB smear and culture results were available in 49 out of 55 and 26 out of 55 patients, respectively. Sputum smear became negative for AFB in 26 out of 49 (53%) and culture converison occurred in 16 out of 26 (61.5%) patients. Clinical and radiological response was noted in 31 (56%) and 13 (32.5%) out of 40 patients respectively. A mean of 5.5 drugs was used in those who achieved sputum conversion. Combination therapy containing ofloxacin in the regimen was noted to have a favourable response., Conclusion: Only a limited number of patients with MDR tuberculosis have a favourable response.

Background & Objectives: Melioidosis and the causative organism Burkholderia pseudomallei are being recognized gradually in various centres in India. In the septicaemic form, melioidosis is a serious and life threatening condition which requires early detection and specific treatment to avoid case fatality. A review of patients with septicaemic melioidosis at a tertiary care hospital in south India was carried out with a view to define the clinical features, predisposing conditions, if any, and the outcome., Methods: A total of 28 patients with culture proven septicaemic melioidosis during December 1993 to December 2002 were included. Information on clinical details and outcome was obtained and antibiotic susceptibility of the isolates studied., Results: Of the 28 patients of blood culture proven septicaemic melioidosis, the organism was also isolated from pus in two patients. The presenting clinical features were varied, most presenting as pyrexia of unknown origin or visceral abscesses, or septic arthiritis. Associated/predisposing conditions were present in 50 per cent of the patients, and diabetes mellitus was the commonest one. mortality was 58 per cent in our series., Interpretation & Conclusion: Melioidosis is an emerging infection in India. The magnitude of the problem can only be assessed by increasing awareness, both of its existence in the clinical setting and its identification in the laboratory.

Non-O1 Vibrio cholerae is known to cause diarrhoea as well as extra-intestinal infections in adults and children. However meningitis in children is a rare occurrence. We report a neonate who developed septicemia and meningitis due to Non-O1 Vibrio cholerae.

Background & Objectives: Vellore is an endemic area for cholera. The relative prevalence of clinical cases of Vibrio cholerae O1 and O139 has been fluctuating. Few studies have examined the susceptibility of local isolates to quinolones. The objective of the present study was to look at quinolone susceptibility and determine MIC of ciprofloxacin to representative clinical isolates of V. cholerae O1 and O139 in Vellore, obtained between 1997 and 1999., Methods: Antimicrobial susceptibility testing of V. cholerae strains was performed by disc diffusion technique and MIC determination by E test., Results: Five of 30 O1 and all the O139 serogroup isolates were susceptible to nalidixic acid. All isolates of both serogroups were sensitive to norfloxacin. All isolates of both serogroups gave MIC results in the susceptible range to ciprofloxacin; the MICs being lower for V. cholerae O139 (MIC50 = 0.004 microgram/ml and MIC90 = 0.047 microgram/ml) than for O1 serogroup (MIC50 = 0.38 microgram/ml and MIC90 = 0.5 microgram/ml)., Interpretation & Conclusion: V. cholerae O1 and O139 show differences in quinolone susceptibility, the reason for this is not clear. This could be because of longer exposure of the O1 serogroup to quinolone antimicrobials as compared to the O139 serogroup.

Background & Objective: The shift of the human immunodeficiency virus (HIV) from nonsyncytium inducing strains (NSI/R5) to syncytium inducing strains (SI/X4) seen in subtype B infections during progression to acquired immunodeficiency syndrome (AIDS) is less frequently reported in subtype C. NSI and SI strains differ in the co-receptor they utilize to infect a T-cell. We postulated that a larger pool of CD4 T cells expressing CCR5 would be present among individuals in the Indian population. To validate this hypothesis, we estimated the percentage of CD4 cells expressing CCR5 or CXCR4 molecules among healthy south Indian adults and HIV infected individuals., Methods: HIV-1 infected and uninfected adult volunteers, belonging to the four southern states of India with Tamil/Malayalam/Kannada or Telugu as their spoken language were prospectively recruited. A two colour flowcytometry examination of the blood sample was done using the following monoclonals; anti-CD45 (FITC)/CD14 (PE), anti IgG1 (FITC)/IgG2a (PE), anti-CD3 (FITC)/CD4 (PE), anti-CD3 (FITC)/CD8 (PE), anti-CD4 (FITC) and anti CCR5 (PE) or anti CXCR4 (PE)., Results: In the healthy population (n = 30) studied, 24.6 per cent of CD4 T cells expressed CCR5 and the percentage of CD4 T cells expressing CXCR4 was 80.4. Among the HIV infected individuals (n = 51) the percentage of CD4 T cells expressing CCR5 and CXCR4 was 26.8 and 78.7 per cent respectively., Interpretation & Conclusion: The percentage of CD4 cells expressing CCR5 and CXCR4 in both the HIV uninfected and infected adults was significantly higher in the south Indian population than in the West. The larger pool of CCR5 positive CD4 cells probably allows for the R5 HIV strain to have a replication advantage over X4 HIV strains. This may explain the lack of shift in the viral phenotype during disease progression and also the perceived rapid progression of the disease in India compared to the West.

The performance of a rapid particle agglutination test for human immunodeficiency virus (HIV) (Capillus HIV type 1 [HIV-1]/HIV-2) on hospital samples is compared with enzyme-linked immunosorbent assays. The test had a sensitivity and specificity of 99 and 98.9%, respectively. In addition, the test was reactive on plasma samples from all individuals infected with HIV-1 subtype C. This test can safely be used for voluntary counseling and testing in India.

Shigellosis has been a major cause of dysentery for many years at Vellore, south India. In the last two years the number of Shigella being isolated from samples of faeces from patients with diarrhoea has decreased (5% isolation rate in 1997 to 3.9% in 2001), although the microbiological methods and media used have not changed. Also, the nalidixic acid (NA) resistance has increased for S. sonnei (now 94%). This is noteworthy, since NA has been recommended for the empirical treatment of patients suspected to have shigellosis and this concept needs to be reconsidered based on available data.